Learn how to use the WISHA Lifting Calculator to evaluate manual material handling tasks.
Introduction to the WISHA Lifting Calculator
The WISHA Lifting Calculator is a great ergonomic evaluation tool for manual material handling tasks.
Developed by the Washington State Department of Labor and Industries, this lifting calculator is very simple in design and application.
This ergonomic assessment tool is an adaptation of the NIOSH Lifting Equation (1,2), which is based on scientific research on the primary causes of work-related back injuries. This calculator can be used to perform simple ergonomic risk assessments on a wide variety of manual lifting and lowering tasks, and can be also used as a screening tool to identify lifting tasks which should be analyzed further using the more comprehensive NIOSH Lifting Equation.
Data Collection
To use the WISHA Lifting Calculator, you will first need to collect the data needed to perform the evaluation. This information can be obtained by observing the job being performed, interviewing workers, and reviewing productivity and other work records.
You will need the following information for each lifting or lowering task evaluated:
Weight of objects the employee lifts.
Location or posture when employee performs lift.
Frequency of lifting – number of times employee performs lift.
Duration of lifting – number of hours per day spent lifting.
This information will then be entered into the WISHA Lifting Calculator to determine the Weight Limit and Lifting Index for the lift.
Jobs that require a wide variety of lifting and lowering tasks are a little harder to evaluate. If you are evaluating a multi-task job, I would suggest that you keep it simple by analyzing lifting requirements in two or three ways.
For example:
Analyze the worst case data by using the heaviest objects lifted from the most awkward positions. Use the frequency for these lifts only, not the total number of lifts. It’s not accurate to use the heaviest weight lifted with the frequency for all lifting, if there is a wide variety of lifting required.
Analyze the most commonly performed lifts.
Perform the analysis by using the average weight and position, using the frequency and duration for all of the lifting done in a typical workday.
Example: Using the WISHA Lifting Calculator
Step 1: Find the actual weight of objects the employee lifts. For multi-task jobs with a variety of lifting and lowering, you can use the heaviest object lifted and/or an average weight. In this example, the average weight lifted is 32 lbs.
Step 2: Determine the Unadjusted Weight Limit. Where are the employee’s hands when they begin to lift or lower the object? Note that spot on the calculator diagram. The number in that box is the Unadjusted Weight Limit in pounds. To determine the horizontal reach, measure the midpoint between the hands from the midpoint between the ankles.
Unadjusted Weight Limit = 35 lbs.
Step 3: Find the Limit Reduction Modifier.
Find out how many times the employee lifts per minute and the total number of hours per day spent lifting. Enter this information into the calculator and the Limit Reduction Modifier will be calculated for you.
In this example, the employee lifts once per minute for two hours or more.
Step 4: Twisting Adjustment
Select the twisting adjustment from the dropdown menu. If the employee is required by the job to twist more than 45 degrees while lifting, the Unadjusted Weight Limit is reduced by multiplying by 0.85.
Step 5: Calculate and Review Results
After entering the information in the calculator input boxes, the Weight Limit and Lifting Index will be calculated for you.
Compare the Weight Limit (26.25 lbs.) with the Actual Weight lifted (32 lbs.) from Step 1. If the Actual Weight lifted is greater than the Weight Limit calculated, then the lifting is a WMSD hazard and must be reduced below the hazard level or to the degree technologically and economically feasible.
In this example, the actual Weight of 32 lbs. is greater than the Weight Limit of 26.25 lbs. Therefore, this lifting task is considered a hazard and control measures should be implemented if possible.
Lifting Index
The Lifting Index (LI) provides a relative estimate of the level of physical demands and stress associated with a particular manual lifting or lowering task. The estimate of the level of physical stress is defined by the relationship or ratio of the weight of the Actual Weight and the Weight Limit. The Lifting Index is defined by the following equation:
Actual Weight ÷ Weight Limit = Lifting Index
In our example lifting task above, we can calculate the Lifting Index as follows:
32 lbs. ÷ 26.25 lbs. = 1.22 Lifting Index = 1.22
The higher the Lifting Index, the smaller the percentage of workers capable of safely performing the lifting and lowering job demands over time and the greater the injury risk. The ergonomic goal should be to design all lifting jobs to achieve a Lifting Index of 1.0 or less.
The Lifting Index great tool to compare the relative risk of multiple job tasks and prioritize ergonomic improvement efforts. For example, several high risk jobs could be ranked in order according to the Lifting Index and a control strategy could be developed according to the rank ordering.
People who work outdoors – on construction sites, doing avalanche surveys, or work on loading docks – face additional risk of injury aggravated by cold. Cold temperatures produce a reduction in the hands ability to feel (tissue sensitivity), function (dexterity) and grip strength. It also makes muscles and joints stiffer, and increases reaction time. As a consequence, workers must use greater force to grip and hold hand tools, which increases the risk of an MSI.
The effects of cold temperatures can be made worse by:
Not dressing appropriately for the environment and activity e.g. for physically active work, wear layers of clothing that can be removed as the worker warms up. For less active work, more layers may be needed.
Not keeping the head covered to retain body heat and not keeping the feet warm and dry.
Lifting or forceful exertion when chilled; stiff joints and muscles increase the risk of injury.
Vibration
Vibration affects tendons, muscles, joints and nerves. Vibration to a specific body part can decrease sensitivity and result in unnecessary increases in muscle contraction, which may lead to injury or fatigue of that part. Localized vibration from machines and hand tools can damage the nerves and blood vessels of the hands and arms. Whole-body vibration, experienced by people who operate heavy equipment such as truck and bus drivers, increases the risk of lower back pain and damage to the spinal discs. The body’s response depends on the duration, frequency and extent of the vibration.
The effects of vibration can be made worse by:
Machines and power tools that are not maintained. Well-maintained equipment minimizes vibration.
Not limiting exposure to vibration by failing to implement work practices and administrative controls such as task rotation and rest breaks.
Not wearing appropriate personal protection equipment where required e.g. vibration dampening gloves.
Simultaneous exposure to cold temperatures.
Illumination
Appropriate lighting and elimination of glare in the work area allows for adequate depth perception and contrast by the worker(s) when handling material such as when lifting and carrying objects. Improper lighting can be a contributing factor to a musculoskeletal injury. For example, poor lighting could cause the worker to misjudge weight and object shape resulting in inappropriate or poor lifting techniques.
The effects of illumination can be made worse by:
Lighting is not maintained e.g. replacing burned out bulbs.
Lighting in the work area was not designed for the type of work tasks being performed.
Characteristics of the organization of work
Work recovery cycles and task variability:
The objective of planned work recovery cycles and task variability is to avoid the onset of fatigue of specifi c muscles or body parts, which can put workers at an increased risk of injury.
Work recovery cycles and task variably can include rotating jobs, performing tasks with different physical or mental demands, or a rest break. The need for recovery cycles and task
variability depends on:
the nature of the task,
worker characteristics, and
environmental conditions.
Fatigue increases the risk of injury. Risk of injury depends largely on the ratio of work period to work recovery cycles/task variably, that is, the recovery time compared to exertion. Risk control for work
recovery cycles and task variably:
The demands of physical handling should be well below the normal exhaustion level for the worker. When developing work recovery cycles and task variability for a specifi ed task consider work rate, load weights and whether tasks involve vigorous or minor exertions.
To vary physical demands, consider alternating physical task with non-physical tasks, or long cycle tasks with shorter ones, or to a task where the demands on specifi c muscle and body parts are sufficiently different. Ideally,workers should be given the flexibly to vary type of tasks they perform.
Review the adequacy of work recovery cycles and task variability whenever there are changes in any
of these factors:
The requirements of a task
Environmental conditions
The work process
Physical capacity of workers
Work rate:
Individual workers vary in the rates at which they perform the same task. Some individuals need longer periods to recover from physical work to prevent injury.
The more critical or physically demanding the task, the more desirable it is to let the worker set the pace, where possible. Just as important, where possible, is to avoid sudden increase in workload.
Planning the work rate will also involve consideration of work recovery cycles/task variability and staffing schedules.
Other Considerations
Risk Factors can overlap:
More than one risk factor can be present in a task. The more risk factors in the task, the greater the
risk of injury. For example:
A worker bends forward from the waist to lift a box from the floor. The bending is an awkward posture (work posture) linked to the location of the box (out of proper lifting/bending* range?) on the floor (layout of the workplace). The box is wrapped with twine, which the worker grabs to lift the box (contact stress). If the worker repeatedly lifts boxes from the floor (repetition), or does similar lifting tasks all day (long duration, organization of work tasks), the risk of MSI is further increased.
Eliminating or Minimizing Risk Factors:
After identifying and assessing risk factors, the next step is to determine which control measures
should be implemented, and which ones eliminate or minimize the risk of MSI. Ask the following questions when considering control measures:
Can exposure to the risk factor be eliminated?
How can the intensity/magnitude of the job duty be reduced?
Can frequency of the job function be reduced?
Can duration be reduced?
Control measures for eliminating or minimizing risk factors:
Engineering Controls
Administrative Controls
Personal Protective Equipment (PPE) Controls
Engineering controls
The purpose of engineering controls is to design (or change by redesign) physical aspects of the workplace or tools to reduce or eliminate employee exposure to ergonomic risk factors. Engineering controls are preferred over other control methods. They are relatively permanent and benefit anyone performing the job – not just the individual who experienced an MSI.
Some examples are: adjusting work heights, minimizing reach distances, changing the layout of workstations, using adjustable or angled tools or equipment and the use of carts and other conveyors.
Administrative Controls
Administrative control functions include determining appropriate policy, procedures, education and training activities that affect the individual worker and the work environment. These actions are intended to reduce the workers’ exposure to MSI risks. This can be accomplished by reducing the duration of exposure and/or slowing the onset of fatigue and discomfort. For example, by ensuring that repetitive or demanding tasks incorporate opportunities for rest or recovery breaks (e.g. allow brief pauses to relax muscles; change work tasks; change postures or techniques).
To be effective, administration controls require:
support by management,
education and training,
employee awareness of risk factors, and
monitoring to ensure effectiveness of program and compliance of WCB requirements.
Personal Protective Equipment
Personal protective equipment may only be used as a substitute for reducing MSI risk factors where
engineering and administrative controls are not practicable. For example, workers may wear vibration-dampening gloves while using a chain saw or wear knee pads while working on their knees to install flooring.
MANUAL MATERIAL HANDLING:
Manual handling (i.e. lifting, carrying, pushing and pulling) of heavy, bulky, and/or irregularly shaped objects during work tasks) can lead to possible musculoskeletal injures. Under these circumstances a worker is more susceptible to injury as these type of tasks often require using awkward body postures, which can place considerable physical demands on the body, especially the back. The following information lists potential causes of MSI where such tasks are performed, as well as, examples of ways to prevent injuries (control measures) while performing these tasks.
Manual material handling examples:
manually loading and unloading material from vehicles, boxes or pallets
manually moving materials in warehouses, offices or outdoor work locations
stocking shelves, etc.
This section on material handling is divided into the following categories:
Lifting
Carrying
Extended reaching
Working heights
Pushing/pulling
Lifting
Lifting of heavy, bulky, and/or irregularly shaped items can increase the risk of MSI’s. Lifting too
heavy a load puts unnecessary strain on the body, particularly the back.Proper lifting techniques play an important role in ensuring no injuries occur while performing these tasks (e.g. hold object close to the body and lift with the legs not the back). It is important that lifting be performed between the shoulder and knuckles height.
Knuckle height is when the arms are straight down in front of the worker, the height above the floor where the knuckles of the hands are located is the lowest height a worker should be lifting from or bending down to. Lifting and handling materials above shoulder level or below knuckle level (particularly while bending or twisting) adds unnecessary stress to the spine and back muscles.
In some cases lifting may have to be performed from the floor level. Where a mechanical lift is
unavailable and the material does not allow for the proper use of body mechanics, workers must be trained in proper lifting procedures (e.g. seek assistance from a co-worker).
Control Measures:
Restrict lifting to between knuckle and shoulder height.
Minimize frequency of lift.
Where possible separate the material into more manageable loads.
Don’t put a load(s) on the fl oor if it needs to be manually lifted again later.
When moving an item, test its weight before lifting.
Don’t overestimate your ability to handle heavy items.
Get as close as possible to loads and get a firm grip before lifting.
Position yourself so that you are facing your load.
Avoid reaching, twisting and bending.
Be sure of your footing before performing the lift.
Where feasible, provide lifting aids (lift tables, mechanical or powered assists, hoists, etc.) to move heavy or bulky loads.
Ask for assistance if in doubt.
Establish safe lifting work procedures and ensure workers are trained in them.
Carrying
Depending on the distance an object is carried,it’s weight and size, there may be unnecessary strain placed on the body for long duration’s, which can attribute to an increase of MSI. It is important to be aware that the weight that can be safely carried by hand is less than the amount that can be safely lifted. This is due to the fact that carrying involves holding the object for a longer period in combination of having to physically move it. The longer the holding time (i.e.distance of travel while carrying object) the less weight that can be carried; the limiting factor is fatigue of the grip and shoulder muscles.
The grade of the floor is also a factor – carrying uphill or downhill increases the strain on the body, especially on stairways.
Control Measures:
Eliminate the need to carry by:
Using a cart, dolly, or pallet jack.
Using a conveyor.
Rearranging the work place.
Providing slides or tables between workstations.
If elimination of carrying is not feasible:
Reduce the weight by:
Reducing the size of the object.
Using lighter material for the object.
Reducing the capacity of the container.
Reducing the weight of the container itself.
If unable to reduce the weight, ask for assistance to move the object.
Reduce the distance material is carried by:
Moving the operation closer to the previous or following operation.
Using conveyors or rollers.
Changing the layout of the workplace.
Note: If carrying can not be eliminated, provide proper handles on object to ensure a good grip and proper positioning of object when carried by worker(s).
Extended Reaching
Extended reaching occurs when workers are required to reach to heights or distances outside of the range from knuckle to shoulder height, and more than about 18 inches from the front of the body. This can require bending, twisting, stretching, and holding the arms up high or other awkward postures. In such postures, the weight of objects (and even of the body itself) creates greater stress on muscles and tissues due to the “lever effect”. Extended reaching can cause musculoskeletal injuries to the neck and shoulders.
Control Measures:
Adjust work stations, fi xtures, parts, tools, etc. to put the most-used items within easy reach.
Keep workplaces clear of obstructions which increase reaching.
Use platforms, step stools or other such aids to reach locations above shoulder height.
Support or counter balance tools that are used above chest level.
Limit or avoid reaching to full arms length for or with loads, or exerting force with the arm extended.
Provide turntables, to allow easy access from all side.
Working Heights
Poor working heights in combination with any of the following can increase the risk of MSI:
duration of work,
repetition,
high forces,
weight,
static loading, and
cold.
If the work area is raised too high,the shoulders and arms must frequently be lifted upto compensate, which may lead to cramping and fatigue in the neck and shoulders.
If work heights are too low, the back and neck must be bent forward which can lead to neck and back pain or discomfort.
Ideally the height of work surfaces or the height of the worker’s position should be adjustable to
allow the employee to work from an appropriate neutral position at all times.
Control Measures:
Work at an appropriate height by using:
False bottom bins and lift tables to change the product height and reduce the need to bend or stoop.
Adjustable working platforms, stools, and ladders to allow for neutral positions of the limbs, neck and torso.
Tilt tables (e.g. drafting tables) to bring work closer.
Extended handles on tools.
Reduce the demand on the body by:
Limiting the period of time required to perform an operation that is overhead, to the side, or down low. This can be accomplished by changing tasks frequently (e.g. paper work that may be normally completed at the end of the shift could be done in intervals through out the day to allow the body to recover).
The right work angle keeps the shoulder in a more comfortable position.
Pushing/Pulling
The greater the force required to push or pull an object, the greater the risk of developing an MSI.
In general, pushing a load is preferable to pulling a load. While pulling a load, arm and shoulder extension and abduction (working behind the mid-line of the body) and twisting may create an MSI risk factor.
Posture is a key factor in limiting how much force can be exerted in pushing and pulling. With extended reaches, or other awkward postures, less force can be exerted. On the other hand, by leaning into a push or away from a pull, the operator can apply more force. For example, pushing a heavy hand truck down a long corridor is usually possible because the large muscles of the legs and trunk can be used. Moving the same hand truck in a tight space where upright posture must be maintained is more difficult because the smaller arm muscles must be used to maneuver it.
Push or pull force is affected by:
Body weight.
Height of the work (height of handles).
Distance of force application from body, or amount of trunk flexion/extension.
The amount of friction between the worker’s shoes and the floor.
How long the force must be applied.
The distance the object must be moved.
The availability of a brace or structure for the worker to push against.
The texture of the floor surface e.g. carpet, smooth, slippery.
Debris on surface areas.
Control Measures:
Eliminate the need to push or pull by using:
Conveyor system.
Fork lift.
Slide, chute, etc.
Powered carts instead of hand carts.
Reduce the force by:
Reducing the weight or size of the load.
Using wheels and casters.
Improving the size, composition, tread,maintenance and swivel properties of wheels on carts.
Using ramps.
Regular maintenance of equipment and floor surfaces e.g. lubrication of equipment; keep floor surfaces clean and clear of debris.
Redesigning the work area to minimize how far items need to be moved.
Installing automatic doors.
Making friction work for the worker– minimize the friction on the object (i.e. don’t push on carpets) and maximize traction for the worker by wearing appropriate shoes.
Providing well-designed handles in appropriate locations.
Ergonomics is the science of fitting jobs to people.Ergonomics encompasses the body of knowledge about physical abilities and limitations as well as other human characteristics that are relevant to job design. Ergonomics design is the application of this body of knowledge to the design of tools, jobs and the workplace for safe and efficient use by workers. Good ergonomics design makes the most efficient use of worker capabilities while ensuring that job demands do not exceed those capabilities.
Ergonomics Muscular-Skeletal Disorders
Muscular-Skeletal Disorders from improper ergonomics are any injury or illness of soft tissues of the upper extremity (fingers through upper arm), shoulders and neck, low back, and lower extremity (hips through toes) that is primarily caused or exacerbated by workplace ergonomics risk factors, such as sustained and repeated exertions or awkward postures and manipulations. Included are disorders of the muscles, nerves, tendons, ligaments, joints, cartilage and spinal disks. Medical conditions that generally develop gradually over a period of time & do not typically result from a single instantaneous event. MSDs do not include injuries caused by slip, trips, falls, or other similar accidents. They can differ in severity from mild periodic symptoms to severe chronic and debilitating conditions.
Examples of MSDs from improper ergonomics include:
Carpal tunnel syndrome
Epicondylitis
Synovitis
Muscle strains
Raynaud’s phenomenon
Sciatica
Tendonitis
Rotator cuff tendonitis
De Quervains’ disease
Carpet layers knee
Trigger finger
Low back pain
Signs of Muscular-Skeletal Disorders are objective physical findings.
Examples of signs of MSDs from improper ergonomics include:
Decreased range of motion
Decreased grip strength
Loss of function
Deformity
Swelling
Cramping
Redness/loss of color
Symptoms of MSDs are physical indications that MSDs are developing. Symptoms can vary in their severity depending on the amount of exposure the employee has had. Often symptoms appear gradually as muscle fatigue or pain at work that disappears during rest. Usually symptoms become more severe as exposure continues (e.g., tingling continues when your employee is at rest, numbness or pain makes it difficult to perform the job, and finally pain is so severe that the employee is unable to perform physical work activities). Examples of symptoms MSDS from improper ergonomics include:
Numbness
Burning
Pain
Tingling
Aching
Stiffness
Stages of Musculoskeletal Injuries
Musculoskeletal injury may progress in stages: early, intermediate and late.
Early Stage: The body aches and feels tired at work but symptoms disappear during time away from work. Early warning signs, for example sore shoulders and neck pain, often occur after the work activity stops (e.g. when driving home after a day of work). The effects may also be noticed the next morning such as aches and stiffness in the limbs or hands.The injury does not interfere with the ability to work and should heal completely if appropriate precautions are taken.At this stage there are often no visible signs of a problem.
Intermediate Stage: The injured area aches and feels weak near the start of work and continues
until well after work has ended. Work becomes more diffi cult to do. However, the injury will still heal completely if dealt with properly. Visible signs may be present.
Late Stage: The injured area aches and feels weak, even at rest. Sleep disturbance is a common
complaint.Even non-demanding tasks are very difficult.The injury may not heal completely but
effects can be eased if dealt with properly. Visible signs may be present.
Not everyone goes through these stages in the same way. It may be diffi cult to say exactly when one stage ends and the next begins. The fi rst sign of pain is a signal the muscles and tendons should
rest and recover and that medical attention may be required. If there is no recovery an injury can become longstanding and sometimes irreversible.The earlier workers recognize signs & symptoms, the quicker the employer will be able to respond.
Risk hazards consist of numerous ergonomics elements such as conditions of a job process, work station, or work method. Not all the below listed risk factors will be present in every MSD-producing task, nor is the existence of one of these factors necessarily sufficient to cause a MSD from improper ergonomics.
Repetitive and /or prolonged activities
Forceful exertions
Prolonged static postures
Exposure to heat or cold
Illumination
Vibration
Awkward postures, including reaching above the shoulders or behind the back.
Twisting the wrists and other joints.
Excessive vibration from power tools
Inappropriate or inadequate hand tools.
Continued bending at the waist.
Continued lifting from below knuckles or above shoulders.
Twisting at the waist, especially while lifting.
Lifting or moving heavy objects.
Lifting or moving asymmetric sized objects.
Prolonged sitting, especially with poor posture.
Lack of adjustable chairs, footrests, body supports, and work surfaces.
Poor grips on handles.
Slippery footing
MSD Hazard Control Methods
Ergonomics Engineering Controls, where feasible, are the preferred method for controlling MSD hazards. Engineering controls are the physical changes to jobs that control exposure to MSD hazards. Engineering controls act on the source of the hazard and control employee exposure to the hazard without relying on the employee to take self-protective action or intervention. Examples of ergonomics engineering controls for MSD hazards include changing, modifying or redesigning the following:
Workstations
Tools
Facilities
Equipment
Materials
Processes
Ergonomics Work Practice Controls are controls that reduce the likelihood of exposure to MSD hazards through alteration of the manner in which a job or physical work activities are performed. Work practice controls also act on the source of the hazard. However, instead of physical changes to the workstation or equipment, the protection work practice controls provide is based upon the behavior of managers, supervisors and employees to follow proper work methods. Work practice controls include procedures for safe and proper work that are understood and followed by managers, supervisors and employees. Examples of work practice controls for improper ergonomics MSD hazards include:
Safe and proper work techniques and procedures that are understood and followed by managers, supervisors and employees.
Conditioning period for new or reassigned employees.
Training in the recognition of MSS hazards and work techniques that can reduce exposure or ease task demands and burdens.
Administrative Controls are procedures and methods, typically instituted by the employer, that significantly reduce daily exposure to MSD hazards by altering the way in which work is performed. Examples of administrative controls for MSD hazards from improper ergonomics include:
Employee rotation
Job task enlargement
Adjustment of work pace (e.g., slower pace)
Redesign of work methods
Alternative tasks
Rest breaks
Environmental Ergonomics Factors:
Heat/Cold: Excessive heat and humidity effects the body’s blood circulation and causes cramps, burns/rashes and general discomfort. Cold exposures also effects the body’s blood circulation and causes hypothermia, loss of flexibility, distraction and poor dexterity. A generally comfortable temperature range is 68 to 74 degrees Fahrenheit – +/-10 degrees depending on the physical work load – with humidity between 20 to 60 percent.
Noise Level/Peaks: Excessive noise levels above 90 decibels (dBA) and noise peaks above 100 decibels (dBA) cause headaches and increases blood pressure, muscle tension and fatigue. High exposure over a long period of time causes deafness and other audiological disorders. Short term exposure causes irritability and distraction.
Illumination: Under-and over-lighted areas causes headaches, muscle strains, fatigue and eye injury. It effects the body by reduced visual acuity, distractions, and glare interference. Poorly lighted areas also provides an atmosphere for trip/fall hazards and poor coordination. Illumination is measured with a light meter, similar to that used by a photographer. Recommended illumination (measured in foot-candles) by job type:
Job Foot-candles
◦ General assembly 55 to 150
◦ Inspections 100 to 150
◦ Warehouse 50 to 100
◦ Storage 10 to 50
◦ Offices 100 to 200
Ergonomics Vibration: Excessive vibration causes pain to muscles, joints and internal organs; causes nausea and trauma to the hands, arms, feet and legs. Vibration is measured by its direction, acceleration and frequency on the body.
Ergonomics Environment: Otherwise known as work stress, included in this category are salary administration, job positions, rest breaks, Employee attitude, and boredom. Keeping the Employment Environment up-beat is difficult; however, light colored, well lighted, un-crowded and clean areas provide a positive environment. Employees should rest often depending on their work activity and temperature. Keeping the job moving and variation in activity reduces boredom.
Ergonomics Work Station Design
Using an old rule-of-thumb, if we try to design something that everyone can use, no one will be able to use it. The same principal holds true with ergonomic work station design. The idea of ergonomic work station design is to make it fit the user. It will have to be adjustable for many body heights, sizes, weights and reaches whether sitting or standing.
One of the first principals in Work Station Design is to consider the tallest Employee and the Employee with the shortest reach. The reason being is that we can not shorten an Employee’s height or lengthen an Employee’s reach. Platforms can be used to raise shorter Employees to the proper work height. Either sitting or standing, the Employee should be comfortable at his work station. The arms should rest at the Employees sides and the Employees back/neck should be kept straight; therefore, the work level must be waist-high.
Standing in one place for prolonged periods may lead to a host of injuries. Sit/stand work stations should be considered. If an Employee has to stand, providing something to lean on so the Employee will have the opportunity to rest. Also, providing a heavy rubber pad to stand on will help relieve neck, shoulder, back, and leg stress. Some common injury prone positions with the body effect are as follows:
Work Position Body Effect
Standing in one place Varicose veins, back stress pooling of blood in legs
Sitting without back support Low back stress
Chair too high Decreased circulation, (legs dangling over end) bruises
Shoulders rounded Upper/lower back stress, respiratory distress.
Leaning forward Lower back stress
Arms extended/over-reaching Stress to arm muscles, upper back stress
Elbows “winged” Joint stress at shoulder, poor use of bicep muscles
Stepping backwards Loss of balance, displaced gravity, muscle stress
Locking knees Stress to back of knee, poor blood circulation
With casual observation of work stations, each of these injury prone positions can be eliminated. Almost anytime an Employee has to raise a foot off of the floor to reach a moving or stationary object, they are hyper-extending and are in an injury prone position.
Ergonomics Tool Design
The last area of work station design is tool design. Many manufacturers are marketing tools that are “ergonomically designed”. However, just because a tool is ergonomically designed, it may do more harm than good. In many cases, just changing the way a toll is used may be and effective ergonomics solution.
Tools should be designed, modified or used in a manner which allows the hand to rest in a near neutral position. In some cases, heavy tools will need to be suspended from above, so the bulk of the weight is not supported by the Employee’s hands/arm. The handles of the tool should extend the full length of the palm, be soft/shock-resistant and large enough to be easily gripped. Trigger activated tools should be modified to allow multi finger operation which prevents the full required activation force from being applied by only one finger.
Ergonomics – Pro-Active Job Design
General Workstation Design Principles
1. Make the workstation adjustable, enabling both large and small persons to fit comfortably and reach materials easily.
2. Locate all materials and tools in front of the worker to reduce twisting motions. Provide sufficient work space for the whole body to turn.
3. Avoid static loads, fixed work postures, and job requirements in which operators must frequently or for long periods
— lean to the front or the side,
— hold a limb in a bent or extended position,
— tilt the head forward more than 15 degrees, or
— support the body’s weight with one leg.
4. Set the work surface above elbow height for tasks involving fine visual details and below elbow height for tasks requiring downward forces and heavy physical effort.
5. Provide adjustable, properly designed chairs with the following features
— adjustable seat height,
— adjustable up and down back rest, including a lumbar (lower-back) support,
— padding that will not compress more than an inch under the weight of a seated individual, and a
— chair that is stable to floor at all times (5-leg base).
6. Allow the workers, at their discretion, to alternate between sitting and standing. Provide floor mats or padded surfaces for prolonged standing.
7. Support the limbs: provide elbow, wrist, arm, foot, and back rests as needed and feasible.
8. Use gravity to move materials.
9. Design the workstation so that arm movements are continuous and curved. Avoid straight-line, jerking arm motions.
10. Design so arm movements pivot about the elbow rather than around the shoulder to avoid stress on shoulder, neck, and upper back.
11. Design the primary work area so that arm movements or extensions of more than 15 in. are minimized.
12. Provide dials and displays that are simple, logical, and easy to read, reach, and operate.
13. Eliminate or minimize the effects of undesirable environmental conditions such as excessive noise, heat, humidity, cold, and poor illumination.
Design Principles for Lifting and Lowering Tasks
1. Optimize material flow through the workplace by
reducing manual lifting of materials to a minimum,
establishing adequate receiving, storage, and shipping facilities, and
maintaining adequate clearances in aisle and access areas.
2. Eliminate the need to lift or lower manually by
increasing the weight to a point where it must be mechanically handled,
palletizing handling of raw materials and products, and
using unit load concept (bulk handling in large bins or containers).
3. Reduce the weight of the object by
reducing the weight and capacity of the container,
reducing the load in the container, and
limiting the quantity per container to suppliers.
4. Reduce the hand distance from the body by
changing the shape of the object or container so that it can be held closer to the body, and
providing grips or handles for enabling the load to be held closer to the body.
5. Convert load lifting, carrying, and lowering movements to a push or pull by providing
conveyors,
ball caster tables,
hand trucks, and
four-wheel carts.
PRIMARY RISK FACTORS
Force
The force that a worker exerts on an object is aprimary risk factor. Muscles and tendons can be
overloaded when a strong (high) force is appliedagainst the object (load). A risk can also occur when a weaker (low) force is applied repeatedly (repetition) or continuously over a long period of time (duration). Exerting high or low muscle force can interfere with circulation, lead to muscle fatigue and tissue damage.
These conditions can result from:
Gripping, pinching, holding
Lifting, lowering
Pushing, pulling, carrying
Stopping a moving object or resisting the kickback from tools
Factors that affect the amount of force applied include:
Size of the load
Weight of the load
Position of the load
How often the load is handled
How long of time the load is handled
Factors affecting grip force include:
Grip Type – a pinch grip requires 5x the force of a power grip
Wrist Posture – grip force decreases dramatically in flexion
Grip Size – handle size will infl uence grip force
Cold – results in increased force application
Gloves – improperly fi tted gloves hinder the ability to have or maintain a good grip
Vibration – vibrating tools cause an increase in the gripping force used to hold them
The effects of these forces can be made worse by:
Slippery or odd shaped objects that are difficult to hold.
Lack of handles or unsuitable handles on tools, or objects that are too small or too large.
Awkward body positions, such as bending down or reaching forward or overhead.
Vibrating tools or equipment.
Poorly fi tted or inappropriate gloves.
Pinch grip Power grip
Repetition
Repetition is the rate of recurrence with which a task or set of motions is performed. Using the same body part repeatedly to perform a task puts a worker at increased risk of MSI, as it does not allow for the rest or recovery of the affected muscles.
The effects of repetition can be made worse by:
The task or motion is repeated at a high rate over long durations.
There is not enough of a rest period to allow the stressed muscle or body part torecover.
Repetition is combined with other risk factors such as high forces and/or awkward posture.
When muscles and/or the body part is unaccustomed to task.
Contact Stress:
Contact stress occurs when a hard or sharp object comes in contact with a small area of the body.The tissues and nerves beneath the skin can be injured from the pressure. Local contact stress can
result from:
Ridges on tool handles digging into fingers.
Edges or work surfaces digging into forearms or wrists.
Striking objects with the hand, foot, or knee.
The effects of local contact stress can be made worse if:
The hard object contacts an area with minimal protective tissue,such as the wrist,palm,or fingers
Pressure is applied repeatedly or held for a long time.
Examples of local contact stress. Local contact stress occurs when hard or sharp edges of tools or objects dig into the skin.
What is confined space? Any enclosure having a limited means of entry & exit and it is not designed for continuous occupancy.
There will be a presence of any hazardous substances such as flammable and toxic gases, oxygen deficiency, hot or humid atmosphere or any combination of it.
Examples: Process vessels, Tanks, Bins, Stacks, Large pipe, Duct, Pits & Trench etc. Any excavation with depth more than 1.2 meter.
What are the Confined Space Hazards? A confined space may have one or combination of the following hazards: Oxygen deficiency
Presence of flammable, combustible or pyrophoric materials (HC, Sludge etc.)
Presence of toxic gases, corrosive or hazardous materials (H2S, Co, NH3 etc.)
Poor illumination, Ventilation & Communication.
High temperature and humidity.
Limited entry & exit / Restricted access.
Restricted movement inside.
Falling / Tripping hazards
Presence of reactive or self-igniting material.
Hazard due to electricity or moving machinery.
Hazard due to pressurized fluid.
Hazard due to nature of work carried out inside confined space.
What is the procedure for entering a confined space hazards? OR What are the important PRECAUTIONS for confined space? Procedure for entering confined space:
1. Permit must be procured form operations, making sure of the following.
a. Complete isolation of the space to be entered.
b. Draining, depressurization and purging or cleaning should be performed.
c. Gas test should be conducted to ensure no hazardous atmosphere is present.
d. Space ventilation.
2. A Pre task meeting must be conducted with all authorized entrants prior to entering confined space.
3. The attendant (Stand by man) shall be assigned at the entrance to maintain communication with employees working inside to ensure their safety. A log book shall be maintained at the entrance to keep track of the people inside the space.
4. Safety attendant must be trained and authorized to use gas testing equipment.
5. Entrants must wear body harness, and if necessary a life line be attached to the harness to avoid entry-rescue.
6. Lighting should be provided, if necessary a maximum of 24 volts, lighting should be used attached a GFCI.
7. Only intrinsically safe or explosion-proof equipment shall be used inside.
8. Depending on the situation, emergency rescue team may be put on standby.
9. If an emergency occurs within the confined space, the standby person must not enter it until rescue team arrived.
10. Barricade the area with warning sign board.
What you know about working in a confined space entry? OR Explain about confined space entry?
Any enclosure having a limited means of entry & exit and it is not designed for continuous employee occupancy.
Before entering in the confined space, must need to obtained a confined space entry work permit, make sure that all required isolation being done.
Frequently gas test is to be carried out to confirm that area is free of toxic gas or flammable atmosphere.
If the area is contaminated or it has oxygen deficiency the provided BA sets or air line respiratory system.
Conduct pre-task meeting for the employees who will be entering inside the confined area and get there signature to conform that they are aware of the hazards and safety measures.
The attendant (Stand by man) to assigned at the entrance. A log book shall be maintained at the entrance to keep track of the people inside the space. The attendant shall not be assigned to other duties. If an emergency occurs within the confined space, the standby person must not enter it until rescue team arrived.
The entering people should use body harness with lifeline for the emergency rescue purpose.
Any required electrical lighting or tools should not exceed more than 24 volts and attached with GFCI / ELCB. It should be intrinsically safe or explosive proof.
Barricade the area with warning sign board.
www.hseintegro.com
Confined Space video Link: https://www.youtube.com/watch?v=rbfWE7D9RZk
What is an accident and why should it be investigated?
The term “accident” can be defined as an unplanned event that interrupts the completion of an activity, and that may (or may not) include injury or property damage.
An incident usually refers to an unexpected event that did not cause injury or damage this time but
had the potential. “Near miss” or “dangerous occurrence” are also terms for an event that could have
caused harm but did not.
Please note: The term incident is used in some situations and jurisdictions to cover both an “accident”
and “incident”. It is argued that the word “accident” implies that the event was related to fate or
chance. When the root cause is determined, it is usually found that many events were predictable and
could have been prevented if the right actions were taken — making the event not one of fate or
chance (thus, the word incident is used). For simplicity, we will use the term accident to mean all of
the above events.
The information that follows is intended to be a general guide for supervisors or joint occupational
health and safety committee members. When accidents are investigated, the emphasis should be
concentrated on finding the root cause of the accident rather than the investigation procedure itself so
you can prevent it from happening again. The purpose is to find facts that can lead to actions, not to
find fault. Always look for deeper causes. Do not simply record the steps of the event.
Reasons to investigate a workplace accident include:
most importantly, to find out the cause of accidents and to prevent similar accidents in the future
to fulfill any legal requirements
to determine the cost of an accident
to determine compliance with applicable safety regulations
to process workers’ compensation claims
Incidents that involve no injury or property damage should still be investigated to determine the
hazards that should be corrected. The same principles apply to a quick inquiry of a minor incident and to the more formal investigation of a serious event.
Who should do the accident investigating?
Ideally, an investigation would be conducted by someone experienced in accident causation,
experienced in investigative techniques, fully knowledgeable of the work processes, procedures,
persons, and industrial relations environment of a particular situation.
Some jurisdictions provide guidance such as requiring that it must be conducted jointly, with both
management and labour represented, or that the investigators must be knowledgeable about the work
processes involved.
In most cases, the supervisor should help investigate the event. Other members of the team can
include:
employees with knowledge of the work
safety officer
health and safety committee
union representative, if applicable
employees with experience in investigations
“outside” expert
representative from local government
Should the immediate supervisor be on the team?
The advantage is that this person is likely to know most about the work and persons involved and the
current conditions. Furthermore, the supervisor can usually take immediate remedial action. The
counter argument is that there may be an attempt to gloss over the supervisors shortcomings in the
accident. This situation should not arise if the accident is investigated by a team of people, and if the
worker representative(s) and the members review all accident investigation reports thoroughly.
Why look for the root cause?
An investigator who believes that accidents are caused by unsafe conditions will likely try to uncover
conditions as causes. On the other hand, one who believes they are caused by unsafe acts will attempt
to find the human errors that are causes. Therefore, it is necessary to examine some underlying
factors in a chain of events that ends in an accident.
The important point is that even in the most seemingly straightforward accidents,seldom, if ever, is
there only a single cause. For example, an “investigation” which concludes that an accident was due
to worker carelessness, and goes no further, fails to seek answers to several important questions such
as:
Was the worker distracted? If yes, why was the worker distracted?
Was a safe work procedure being followed? If not, why not?
Were safety devices in order? If not, why not?
Was the worker trained? If not, why not?
An inquiry that answers these and related questions will probably reveal conditions that are more open
to correction than attempts to prevent “carelessness”.
What are the steps involved in investigating an accident?
The accident investigation process involves the following steps:
Report the accident occurrence to a designated person within the organization
Provide first aid and medical care to injured person(s) and prevent further injuries or damage
Investigate the accident
Identify the causes
Report the findings
Develop a plan for corrective action
Implement the plan
Evaluate the effectiveness of the corrective action
Make changes for continuous improvement
As little time as possible should be lost between the moment of an accident or near miss and the
beginning of the investigation. In this way, one is most likely to be able to observe the conditions as
they were at the time, prevent disturbance of evidence, and identify witnesses. The tools that
members of the investigating team may need (pencil, paper, camera, film, camera flash, tape
measure, etc.) should be immediately available so that no time is wasted.
What should be looked at as the cause of an accident?
Accident Causation Models
Many models of accident causation have been proposed, ranging from Heinrich’s domino theory to the sophisticated Management Oversight and Risk Tree (MORT).
The simple model shown in Figure 1 attempts to illustrate that the causes of any accident can be
grouped into five categories – task, material, environment, personnel, and management. When this
model is used, possible causes in each category should be investigated. Each category is examined
more closely below. Remember that these are sample questions only: no attempt has been made to
develop a comprehensive checklist.
Task
Here the actual work procedure being used at the time of the accident is explored. Members of the
accident investigation team will look for answers to questions such as:
Was a safe work procedure used?
Had conditions changed to make the normal procedure unsafe?
Were the appropriate tools and materials available?
Were they used?
Were safety devices working properly?
Was lockout used when necessary?
For most of these questions, an important follow-up
question is “If not, why not?”
Material
To seek out possible causes resulting from the
equipment and materials used, investigators might ask:
Was there an equipment failure?
What caused it to fail?
Was the machinery poorly designed?
Were hazardous substances involved?
Were they clearly identified?
Was a less hazardous alternative substance possible
and available?
Was the raw material substandard in some way?
Should personal protective equipment (PPE) have been used? Accident Causation
Was the PPE used?
Were users of PPE properly trained?
Again, each time the answer reveals an unsafe condition, the investigator must ask why this situation
was allowed to exist.
Environment
The physical environment, and especially sudden changes to that environment, are factors that need to
be identified. The situation at the time of the accident is what is important, not what the “usual”
conditions were. For example, accident investigators may want to know:
What were the weather conditions?
Was poor housekeeping a problem?
Was it too hot or too cold?
Was noise a problem?
Was there adequate light?
Were toxic or hazardous gases, dusts, or fumes present?
Personnel
The physical and mental condition of those individuals directly involved in the event must be explored.
The purpose for investigating the accident is not to establish blame against someone but the inquiry
will not be complete unless personal characteristics are considered. Some factors will remain
essentially constant while others may vary from day to day:
Were workers experienced in the work being done?
Had they been adequately trained?
Can they physically do the work?
What was the status of their health?
Were they tired?
Were they under stress (work or personal)?
Management
Management holds the legal responsibility for the safety of the workplace and therefore the role of
supervisors and higher management and the role or presence of management systems must always be
considered in an accident investigation. Failures of management systems are often found to be direct
or indirect factors in accidents. Ask questions such as:
Were safety rules communicated to and understood by all employees?
Were written procedures and orientation available?
Were they being enforced?
Was there adequate supervision?
Were workers trained to do the work?
Had hazards been previously identified?
Had procedures been developed to overcome them?
Were unsafe conditions corrected?
Was regular maintenance of equipment carried out?
Were regular safety inspections carried out?
This model of accident investigations provides a guide for uncovering all possible causes and reduces
the likelihood of looking at facts in isolation. Some investigators may prefer to place some of the
sample questions in different categories; however, the categories are not important, as long as each
pertinent question is asked. Obviously there is considerable overlap between categories; this reflects
the situation in real life. Again it should be emphasized that the above sample questions do not make
up a complete checklist, but are examples only.
How are the facts collected?
The steps in accident investigation are simple: the accident investigators gather information, analyze
it, draw conclusions, and make recommendations. Although the procedures are straightforward, each
step can have its pitfalls. As mentioned above, an open mind is necessary in accident investigation:
preconceived notions may result in some wrong paths being followed while leaving some significant
facts uncovered. All possible causes should be considered. Making notes of ideas as they occur is a
good practice but conclusions should not be drawn until all the information is gathered.
Injured workers(s)
The most important immediate tasks–rescue operations, medical treatment of the injured, and
prevention of further injuries–have priority and others must not interfere with these activities. When
these matters are under control, the investigators can start their work.
Physical Evidence
Before attempting to gather information, examine the site for a quick overview, take steps to preserve
evidence, and identify all witnesses. In some jurisdictions, an accident site must not be disturbed
without prior approval from appropriate government officials such as the coroner, inspector, or police.
Physical evidence is probably the most non-controversial information available. It is also subject to
rapid change or obliteration; therefore, it should be the first to be recorded. Based on your knowledge
of the work process, you may want to check items such as:
positions of injured workers
equipment being used
materials or chemicals being used
safety devices in use
position of appropriate guards
position of controls of machinery
damage to equipment
housekeeping of area
weather conditions
lighting levels
noise levels
time of day
You may want to take photographs before anything is moved, both of the general area and specific
items. Later careful study of these may reveal conditions or observations missed previously. Sketches
of the accident scene based on measurements taken may also help in subsequent analysis and will
clarify any written reports. Broken equipment, debris, and samples of materials involved may be
removed for further analysis by appropriate experts. Even if photographs are taken, written notes
about the location of these items at the accident scene should be prepared.
Eyewitness Accounts
Although there may be occasions when you are unable to do so, every effort should be made to
interview witnesses. In some situations witnesses may be your primary source of information because
you may be called upon to investigate an accident without being able to examine the scene
immediately after the event. Because witnesses may be under severe emotional stress or afraid to be
completely open for fear of recrimination, interviewing witnesses is probably the hardest task facing an investigator.
Witnesses should be kept apart and interviewed as soon as possible after the accident. If witnesses
have an opportunity to discuss the event among themselves, individual perceptions may be lost in the
normal process of accepting a consensus view where doubt exists about the facts.
Witnesses should be interviewed alone, rather than in a group. You may decide to interview a witness
at the scene of the accident where it is easier to establish the positions of each person involved and to
obtain a description of the events. On the other hand, it may be preferable to carry out interviews in a
quiet office where there will be fewer distractions. The decision may depend in part on the nature of
the accident and the mental state of the witnesses.
Interviewing
Interviewing is an art that cannot be given justice in a brief document such as this, but a few do’s and
don’ts can be mentioned. The purpose of the interview is to establish an understanding with the
witness and to obtain his or her own words describing the event:
DO…
put the witness, who is probably upset, at ease
emphasize the real reason for the investigation, to determine what happened and why
let the witness talk, listen
confirm that you have the statement correct
try to sense any underlying feelings of the witness
make short notes or ask someone else on the team to take them during the interview
ask if it is okay to record the interview, if you are doing so
close on a positive note
DO NOT…
intimidate the witness
interrupt
prompt
ask leading questions
show your own emotions
jump to conclusions
Ask open-ended questions that cannot be answered by simply “yes” or “no”. The actual questions you
ask the witness will naturally vary with each accident, but there are some general questions that
should be asked each time:
Where were you at the time of the accident?
What were you doing at the time?
What did you see, hear?
What were the environmental conditions (weather, light, noise, etc.) at the time?
What was (were) the injured worker(s) doing at the time?
In your opinion, what caused the accident?
How might similar accidents be prevented in the future?
If you were not at the scene at the time, asking questions is a straightforward approach to establishing
what happened. Obviously, care must be taken to assess the credibility of any statements made in the
interviews. Answers to a first few questions will generally show how well the witness could actually
observe what happened.
Another technique sometimes used to determine the sequence of events is to re-enact or replay them
as they happened. Obviously, great care must be taken so that further injury or damage does not
occur. A witness (usually the injured worker) is asked to reenact in slow motion the actions that
preceded the accident.
Background Information
A third, and often an overlooked source of information, can be found in documents such as technical
data sheets, health and safety committee minutes, inspection reports, company policies, maintenance
reports, past accident reports, formalized safe-work procedures, and training reports. Any pertinent
information should be studied to see what might have happened, and what changes might be
recommended to prevent recurrence of similar accidents.
What should I know when making the analysis and
conclusions?
At this stage of the investigation most of the facts about what happened and how it happened should
be known. This has taken considerable effort to accomplish but it represents only the first half of the
objective. Now comes the key question–why did it happen? To prevent recurrences of similar
accidents, the investigators must find all possible answers to this question.
You have kept an open mind to all possibilities and looked for all pertinent facts. There may still be
gaps in your understanding of the sequence of events that resulted in the accident. You may need to
reinterview some witnesses to fill these gaps in your knowledge.
When your analysis is complete, write down a step-by-step account of what happened (your
conclusions) working back from the moment of the accident, listing all possible causes at each step.
This is not extra work: it is a draft for part of the final report. Each conclusion should be checked to
see if:
it is supported by evidence
the evidence is direct (physical or documentary) or based on eyewitness accounts, or
the evidence is based on assumption.
This list serves as a final check on discrepancies that should be explained or eliminated.
Why should recommendations be made?
The most important final step is to come up with a set of well-considered recommendations designed
to prevent recurrences of similar accidents. Once you are knowledgeable about the work processes
involved and the overall situation in your organization, it should not be too difficult to come up with
realistic recommendations. Recommendations should:
be specific
be constructive
get at root causes
identify contributing factors
Resist the temptation to make only general recommendations to save time and effort.
For example, you have determined that a blind corner contributed to an accident. Rather than just
recommending “eliminate blind corners” it would be better to suggest:
install mirrors at the northwest corner of building X (specific to this accident)
install mirrors at blind corners where required throughout the worksite (general)
Never make recommendations about disciplining a person or persons who may have been at fault.
This would not only be counter to the real purpose of the investigation, but it would jeopardize the
chances for a free flow of information in future accident investigations.
In the unlikely event that you have not been able to determine the causes of an accident with any
certainty, you probably still have uncovered safety weaknesses in the operation. It is appropriate that
recommendations be made to correct these deficiencies.
The Written Report
If your organization has a standard form that must be used, you will have little choice in the form that
your written report is to be presented. Nevertheless, you should be aware of, and try to overcome,
shortcomings such as:
If a limited space is provided for an answer, the tendency will be to answer in that space despite
recommendations to “use back of form if necessary.”
If a checklist of causes is included, possible causes not listed may be overlooked.
Headings such as “unsafe condition” will usually elicit a single response even when more than one
unsafe condition exists.
Differentiating between “primary cause” and “contributing factors” can be misleading. All accident
causes are important and warrant consideration for possible corrective action.
Your previously prepared draft of the sequence of events can now be used to describe what happened.
Remember that readers of your report do not have the intimate knowledge of the accident that you
have so include all pertinent detail. Photographs and diagrams may save many words of description.
Identify clearly where evidence is based on certain facts, eyewitness accounts, or your assumptions.
If doubt exists about any particular part, say so. The reasons for your conclusions should be stated and followed by your recommendations. Weed out extra material that is not required for a full
understanding of the accident and its causes such as photographs that are not relevant and parts of
the investigation that led you nowhere. The measure of a good accident report is quality, not quantity.
Always communicate your findings with workers, supervisors and management. Present your
information ‘in context’ so everyone understands how the accident occurred and the actions in place to prevent it from happening again.
What should be done if the investigation reveals human error?
A difficulty that has bothered many investigators is the idea that one does not want to lay blame.
However, when a thorough worksite accident investigation reveals that some person or persons among management, supervisor, and the workers were apparently at fault, then this fact should be pointed out. The intention here is to remedy the situation, not to discipline an individual.
Failing to point out human failings that contributed to an accident will not only downgrade the quality of the investigation. Furthermore, it will also allow future accidents to happen from similar causes because they have not been addressed.
However never make recommendations about disciplining anyone who may be at fault. Any disciplinary steps should be done within the normal personnel procedures.
How should follow-up be handled?
Management is responsible for acting on the recommendations in the accident investigation report. The health and safety committee, if you have one, can monitor the progress of these actions.
Follow-up actions include:
Respond to the recommendations in the report by explaining what can and cannot be done (and why or why not).
Develop a timetable for corrective actions.
Monitor that the scheduled actions have been completed.
Check the condition of injured worker(s).
Inform and train other workers at risk.
Re-orient worker(s) on their return to work.
This brief guide describes what you, as an employer, need to do to protect your employees from falls from height. It will also be useful to employees and their representatives.
Following this guidance is normally enough to comply with the Work at Height Regulations 2005 (WAHR). You are free to take other action, except where the guidance says you must do something specific.
Falls from height are one of the biggest causes of workplace fatalities and major injuries. Common causes are falls from ladders and through fragile roofs. The purpose of WAHR is to prevent death and injury from a fall from height.
Work at height means work in any place where, if there were no precautions in place, a person could fall a distance liable to cause personal injury. For example you are working at height if you:
are working on a ladder or a flat roof;
could fall through a fragile surface;
could fall into an opening in a floor or a hole in the ground.
Take a sensible approach when considering precautions for work at height. There may be some low-risk situations where common sense tells you no particular precautions are necessary and the law recognises this.
There is a common misconception that ladders and stepladders are banned, but this is not the case. There are many situations where a ladder is the most suitable equipment for working at height.
Before working at height you must work through these simple steps:
avoid work at height where it is reasonably practicable to do so;
where work at height cannot be avoided, prevent falls using either an existing place of work that is already safe or the right type of equipment;
minimise the distance and consequences of a fall, by using the right type of equipment where the risk cannot be eliminated.
You should:
do as much work as possible from the ground;
ensure workers can get safely to and from where they work at height;
ensure equipment is suitable, stable and strong enough for the job, maintained and checked regularly;
make sure you don’t overload or overreach when working at height;
take precautions when working on or near fragile surfaces;
provide protection from falling objects;
consider your emergency evacuation and rescue procedures.
Who do the Regulations apply to?
If you are an employer or you control work at height (for example if you are a contractor or a factory owner), the Regulations apply to you.
How do you comply with these Regulations?
Employers and those in control of any work at height activity must make sure work is properly planned, supervised and carried out by competent people. This includes using the right type of equipment for working at height.
Low-risk, relatively straightforward tasks will require less effort when it comes to planning. Employers and those in control must first assess the risks. See the risk assessment website for more advice at www.hse.gov.uk/risk/risk-assessment.htm.
Take a sensible, pragmatic approach when considering precautions for work at height. Factors to weigh up include the height of the task; the duration and frequency; and the condition of the surface being worked on. There will also be certain low-risk situations where common sense tells you no particular precautions are necessary.
How do you decide if someone is ‘competent’ to work at height?
You should make sure that people with sufficient skills, knowledge and experience are employed to perform the task, or, if they are being trained, that they work under the supervision of somebody competent to do it.
In the case of low-risk, short duration tasks (short duration means tasks that take less than 30 minutes) involving ladders, competence requirements may be no more than making sure employees receive instruction on how to use the equipment safely (eg how to tie a ladder properly) and appropriate training. Training often takes place on the job, it does not always take place in a classroom.
When a more technical level of competence is required, for example drawing up a plan for assembling a complex scaffold, existing training and certification schemes drawn up by trade associations and industry is one way to help demonstrate competence.
What measures should you take to help protect people?
Always consider measures that protect everyone who is at risk (collective protection) before measures that protect only the individual (personal protection).
Collective protection is equipment that does not require the person working at height to act to be effective, for example a permanent or temporary guard rail.
Personal protection is equipment that requires the individual to act to be effective. An example is putting on a safety harness correctly and connecting it, via an energy-absorbing lanyard, to a suitable anchor point.
The step-by-step diagram in Figure 1 should be used alongside all other advice in this leaflet. You do not always need to implement every measure in Figure 1. For example when working on a fully boarded and guarded scaffold that is already up, not being altered or taken down, workers would not need to wear personal fall- arrest equipment as well.
What are the most common causes of accidents when working at height?
Roof work is high risk and falls from roofs, through fragile roofs and fragile roof lights are one of the most common causes of workplace death and serious injury. As well as in construction, these accidents can also occur on roofs of factories, warehouses and farm buildings when roof repair work or cleaning is being carried out.
The following are likely to be fragile:
roof lights;
liner panels on built-up sheeted roofs;
non-reinforced fibre cement sheets;
corroded metal sheets;
glass (including wired glass);
rotted chipboard;
slates and tiles.
Fragile roof accidents are preventable and information on safe working practices can be found in the HSE information sheet Fragile roofs: Safe working practices (see ‘Further reading’).
What do you need to consider when planning work at height?
The following are all requirements in law that you need to consider when planning and undertaking work at height. You must:
take account of weather conditions that could compromise worker safety;
check that the place (eg a roof) where work at height is to be undertaken is safe. Each place where people will work at height needs to be checked every time, before use;
stop materials or objects from falling or, if it is not reasonably practicable to prevent objects falling, take suitable and sufficient measures to make sure no one can be injured, eg use exclusion zones to keep people away or mesh on scaffold to stop materials such as bricks falling off;
store materials and objects safely so they won’t cause injury if they are disturbed or collapse;
plan for emergencies and rescue, eg agree a set procedure for evacuation. Think about foreseeable situations and make sure employees know the emergency procedures. Don’t just rely entirely on the emergency services for rescue in your plan.
How do you select the right equipment to use for a job?
When selecting equipment for work at height, employers must:
provide the most suitable equipment appropriate for the work (use Figure 1 to help you decide);
take account of factors such as:
the working conditions (eg weather);
the nature, frequency and duration of the work;
the risks to the safety of everyone where the work equipment will be used.
If you are still unsure which type of equipment to use, once you have considered the risks, the Work at height Access equipment Information Toolkit (or WAIT) is a free online resource that offers possible solutions. It provides details of common types of equipment used for work at height. HSE has also produced a guide on the safe use of ladders and stepladders (see ‘Further reading’).
How do you make sure the equipment itself is in good condition?
Work equipment, for example scaffolding, needs to be assembled or installed according to the manufacturer’s instructions and in keeping with industry guidelines.
Where the safety of the work equipment depends on how it has been installed or assembled, an employer should ensure it is not used until it has been inspected in that position by a competent person.
A competent person is someone who has the necessary skills, experience and knowledge to manage health and safety. Guidance on appointing a competent person can be found at www.hse.gov.uk/competence.
Any equipment exposed to conditions that may cause it to deteriorate, and result in a dangerous situation, should be inspected at suitable intervals appropriate to the environment and use. Do an inspection every time something happens that may affect the safety or stability of the equipment, eg adverse weather, accidental damage.
You are required to keep a record of any inspection for types of work equipment including: guard rails, toe-boards, barriers or similar collective means of protection; working platforms (any platform used as a place of work or as a means of getting to and from work, eg a gangway) that are fixed (eg a scaffold around a building) or mobile (eg a mobile elevated working platform (MEWP) or scaffold tower); or a ladder.
Any working platform used for construction work and from which a person could fall more than 2 metres must be inspected:
after assembly in any position;
after any event liable to have affected its stability;
at intervals not exceeding seven days.
Where it is a mobile platform, a new inspection and report is not required every time it is moved to a new location on the same site.
You must also ensure that before you use any equipment, such as a MEWP, which has come from another business or rental company, it is accompanied by an indication (clear to everyone involved) when the last thorough examination has been carried out.
What must employees do?
Employees have general legal duties to take reasonable care of themselves and others who may be affected by their actions, and to co-operate with their employer to enable their health and safety duties and requirements to be complied with.
For an employee, or those working under someone else’s control, the law says they must:
report any safety hazard they identify to their employer;
use the equipment and safety devices supplied or given to them properly, in
accordance with any training and instructions (unless they think that would be unsafe, in which case they should seek further instructions before continuing).
You must consult your employees (either directly or via safety representatives), in good time, on health and safety matters. Issues you must consult employees on include:
risks arising from their work;
proposals to manage and/or control these risks;
the best ways of providing information and training.
Employers can ask employees and their representatives what they think the hazards are, as they may notice things that are not obvious and may have some good, practical ideas on how to control the risks.
What must architects and building designers do?
When planning new-build or refurbishment projects, architects and designers have duties under The Construction (Design and Management) Regulations, to consider the need for work to be carried out at height over the lifespan of a building, eg to clean, maintain and repair it. They should design out the need to work at height if possible.
In mulling over the subject of safety, as I am prone to do, two questions keep popping up: Just what is safety? And, can you define safety in just a word or two?
During my presentations, I ask attendees to offer their definitions of safety. There are many responses and every one is different, which indicates to me that it might not be possible to arrive at a universally accepted definition of safety, though I’ll offer mine later.
I ask myself whether safety can be summed up in just one word, or maybe just two or three. Maybe not, as a large number of words come quickly to mind, all of which, in my mind, could certainly be construed to be critical components of safety.
How many of the following, if incorporated into safety programs, do you feel would enhance their effectiveness?
All of us
Considerate
Knowing
Risk
Alertness
Core value
Learning
Seeing
Attentive
Culture
Listening
Sharing
Awareness
Effective
Mentoring
State of Mind
Careful
Fixing
Minimizing mistakes
Thinking
Caring
Focus
Monitoring
Thoughtful
Caution
Following the rules
Nurturing
Training
Checklists
Going home
Observant
Up to Me
Comfort level
Guiding
Protecting
Understanding
Common sense
Hazards
Reporting
Warning
Concerned
Instinct
Responding
Well-being
Confidence
Investigating
Responsible
Working together
From the length of this list, it would appear that safety must be considered to be made up of a large number of elements. With so many possible elements that one might consider integral to safety, is it any wonder that safety programs may be less than they can be?
The list above is probably not complete, but incorporating as many of these elements as possible might go a long way toward an improved safety record.
The list of things that Safety is is a lot shorter. Here are few. How many more can you name?
Absence of accidents/injuries
Absence of risk
Absence of hazards
Excuses
Just a management responsibility
Complacent
No matter how hazard-free the workplace, there will still be near misses, accidents, and injuries. Why? Because people (both management and workforce):
Are human
Make mistakes
Put production ahead of safety
Take short cuts
Can be distracted
Fail to report unsafe conditions, unsafe behaviors, and near misses
Can make wrong choices or errors in judgment
Don’t always pay attention
Lose focus
Rush
Don’t always observe signs and/or rules
Often don’t “see” what is right in front of them
May choose not to work safely
May not provide guidance, oversight, and mentoring
May fail to wear PPE
Don’t watch out for each other
Don’t provide training, PPE, properly guarded machinery
Don’t identify and fix problems
Do something in a way that is not comfortable or safe, just to get it done
No safety program is perfect. Programs evolve based on what is learned from day-to-day experiences. Success depends on management and the workforce working together to both create as hazard-free a work environment as possible and to identify and abate risks, the potential for harm that hazards, unsafe conditions, and unsafe acts create.
Here’s where I offer my best definition of safety. Safety is a combination of safe working condition and safe behaviors.
Why do people take risks that are not inherent in their jobs? Let’s recognize that there are two types of risk – necessary and unnecessary.
There are occupations that involve inherent risk. If you Google “Most Dangerous Jobs,” you will find a few “Top 10” lists published by various sources. They don’t agree on a single Top 10 list, but there is a short list of perhaps 20 jobs that are cited, based upon various statistical risk categories, most prominently, work-related fatalities. The Bureau of Labor Statistics, in an article entitled “Dangerous Jobs: Compensation and Working Conditions, Summer — 1997” included an “Index of Relative Risk for Fatal Occupational Injuries, 1995,” which graphically showed that the most dangerous job, commercial fisherman, had a relative risk of 21.3 vs. a relative risk of 1 for All Occupations, based on per capita fatality rates.
Unnecessary risks are taken for reasons that, though the end results are expected to be good, the goal may not be reached before an accident or injury happens. These include, but are not limited to:
Simply don’t know the hazards (poor HazCom training)
Rushing to meet production goals or supervisor pressure
We don’t believe that we’re going to be hurt
We’ve done it before without injury
We think that we can get away with it (risky behavior)
Peer pressure
Company culture does not support safety
It’s the path of least resistance
The safe way may take time and extra effort
Shortcuts
Pleasing the supervisor
Distractions/lack of focus
Overcoming risk-taking requires an ongoing effort on the part of management, supervision and the workforce. It comes down to implementing an approach to safety that works for the organization. It starts with management, who must set the tone by:
Taking an active role in establishing safety as a core value, not just a priority
Providing meaningful training that is taken to heart and retained in practice
Establishing work rules that place safety on a par with production
Opting for engineering and administrative controls wherever possible
Ensuring that machinery has all of the required safety features
Providing adequate PPE and training in proper use, storage, maintenance, and disposal
Posting sufficient signage to provide constant reminders
Investigating all near misses, incidents, and accidents and following up with corrective action
Hiring practices that recruit people who are identified as safety conscious
Prevention through design
Supervisors need to:
Accept safety as a partner to production
Be role models by following all safety rules
Ensure that safety rules are disseminated, understood, and followed
Mentor employees, applauding safe actions and correcting unsafe actions in a non-confrontational manner
Welcome safety suggestions and observations
Discipline only as a last resort when all else fails to produce safe work
Employees need to:
Follow established work procedures and safety rules
Actively participate in and embrace safety training
Look out for each other
Report all accidents, incidents, and near misses
Report hazards and point out areas where safety can be strengthened
Maintain constant awareness of their surroundings
It takes constant effort on the part of each tier of an organization’s structure to create and maintain a safe working environment. The more elements that are implemented, the better the safety program will be.
For Safety Trainings, Audits, HAZOP, QRA,Safety Animated Video & Safety Services visit: www.hseintegro.com
Systematic technique to IDENTIFY potential HAZard and OPerating problems.2
A formal systematic rigorous examination to the process and engineering facets of a production facility.
A qualitative technique based on“guide–words”to help provoke thoughts about the way deviations from the intended operating conditions can lead to hazardous situations or operability problems
HAZOP is basically for safety
-Hazards are the main concern
-Operability problems degrade plant performance(product quality, production rate,profit)
Considerable engineering insight is required-engineers working independently could develop different result.
ORIGIN OF HAZOP
Initially prepared by Dr HGLawley ICI at Wilton in and associates of 1960’s.
Subsequently CJBullock and AJD Jenning from ChE Dept.Teeside Poly technical under super vision of T.A.Kletz applied the method at higher institution(post-graduate level).
In1977,Chemical Industries Association published the edited version.
Later Development-HAZOP:
ICI expanded the procedure called HAZARD STUDY steps1 to 6.
The ICI six steps:
Project exploration/preliminary project assessment to identify inherent hazards of process chemicals,site suitability and probable environmental impact.
Project definition–to identify and reduce significant hazards associated with items and areas,check conformity with relevant standards and codes of practices.
Design and procurement–to examine the PID in detail for identification of deviations from design intent capable of causing operability problems or hazards.
During final stages of construction–to check that all recommended and accepted actionsrecorded in steps i,ii and iii implemented.
During plant commissioning–to check that all relevant statutory requirements have been acknowledges and all installed safety systems are reliably operable.
During normal operation, sometime after start up especially if any modification been made.Tocheck if changes in operation has not invalidated the HAZOP report of step iii by introducingnew hazards.
This procedures are adopted fully or partly by many companies around the world.
Objective of HAZOP:
For identifying cause and the consequences of perceived mal operations of equipment and associated operator interfaces in the context of the complete system.
It accommodates the status of recognized design standards and codes of practice but rightly questions the relevance of these in specific circumstances where hazards may remain undetected.
How and Why HAZOP is Used:
HAZOP identifies potential hazards,failures and operability problems.
Its use is recommended as a principal method by professional institutions and legislators on the basis of proven capabilities for over 40 years.
It is most effective as a team effort consists of plant and designers,operating personnel,control and instrumentation engineer etc.
It encourages creativity in design concept evaluation.
Its use results in fewer commissioning and operational problems and better informed personnel,thus confirming overall cost effectiveness improvement.
Necessary changes to a system for eliminating or reducing the probability of operating deviations are suggested by the analytical procedure.
HAZOP provides a necessary management tool and bonus in so far that it demonstrates to insurers and inspect or evidence of comprehensive thoroughness.
HAZOP reports are an integral part of plant and safety records and are also applicable to design changes and plant modifications, there by containing accountability for equipment and its associated human interface throughout the operating life time.
HAZOP technique is now used by most major companies handling and processing hazardous material,especially those where engineering practice involves elevated operating parameters:
– oil and gas production– flammable and toxicchemicals– pharmaceuticals etc.,
Progressive legislation in encouraging smaller and specialty manufacturing sites to adopt the method also as standard practice
Purpose of HAZOP:
It emphasizes upon the operating integrity of a system,there by leading methodically to most potential and detectable deviations which could conceivably arise in the course of normal operating routine.
– including”start-up”and”shut-down”procedures
– as well as steady-state operations.
It is important to remember at all times that HAZOP is an identifying technique and not intended as a means of solving problems nor is the method intended to be used solely as an undisciplined means of searching for hazardous scenarios.
Documents Needed for HAZOP Study:
For Preliminary HAZOP
Process Flow Sheet(PFS or PFD)
Description of the Process
For Detailed HAZOP
Piping and Instrumentation Diagram(P&ID )
Process Calculations
Process Data Sheets
Instrument Data Sheets
Interlock Schedules
Layout Requirements
Hazardous Area Classification
Description of the Process
HAZOP Study Procedure:
Procedure in HAZOP study consist of examining the process and instrumentation(P&I) line diagram, process line by process line.
A list of guide words is used to generate deviations from normal operation corresponding to all conceivable possibilities.
Guide words covering every parameter relevant to the system under review:i.e. flow rate and quality, pressure, temperature, viscosity,components etc.Flow chart for application of HAZOP is shown in figure.
HAZOP Study :
Normal operation.
Foreseeable changes in operation,e.g.upgrading, reduced output, plant start-up and shut-down.
Suitability of plant materials, equipment and instrumentation.
Provision for failure of plant services,e.g.steam, electricity, cooling water.
Provision for maintenance.
Strength of HAZOP :
HAZOP is a systematic ,reasonably comprehensive and flexible.
It is suitable mainly for team use where by it is possible to incorporate the general experience available.
It gives good identification of cause and excellent identification of critical deviations.
The use of keywords is effective and the whole group is able to participate.
HAZOP is an excellent well-proven method for studying large plant in a specific manner.
HA ZOP identifies virtually all significant deviations on the plant, all major accidents should be identified but not necessarily their causes.
HAZOP Effectiveness:
The effectiveness of a HAZOP will depend on:2
a) the accuracy ofinformation (including P&IDs) available to the team — information should be complete and up-to-date
b) the skills and insights of the team members
c) how well the team is ableto use the systematic method as an aid to identifying deviations
d) the maintainingof a sense of proportion in assessing the seriousness of ahazard and the expenditure of resources in reducingits likelihood
e) the competence of the chairperson in ensuring the study team rigorously follows sound procedures.
Key elements of a HAZOP are:
HAZOP team
full description of process
relevant guidewords
conditions conducive to brain storming
recording of meeting
followup plan.
Preliminary HAZOP Example :Refer to reactor system shown.
The reaction is exothermic. A cooling system is provided to remove the excess energy of reaction. In the event of cooling function is lost, the temperature of reactor would increase.This would lead to an increase in reaction rate leading to additional energy release.
The result could be a runaway reaction with pressures exceeding the bursting pressure of the reactor.The temperature within the reactor is measured and is used to control the cooling water flow rate by a valve.
PerformHAZOPStudy
Preliminary HAZOP on Reactor-Example:
Preliminary HAZOP on Reactor – Answer:
Case Study– Shell &Tube Heat Exchanger :
Using relevant guide words, perform HAZOP study on shell & tube heatexchanger.
Refer to reactor system shown.
