Accident Investigation & Techniques

INTRODUCTION:

                                

                                Essentials of a successful Safety program include elimination of Physical Hazards, elimination of unsafe work practices, training to minimize the human factors that cause accidents, and through Accidents Investigation.

         Accidents Investigation may be defined as an analysis evaluation and report of an Accident based on Information gathered by an Investigation.

             Accidents Investigation should include inquiry into not only injury Accident, but non-injury Accidents and “Near-Misses”- those incidents such as a broken Crane Hook or Tank explosion that have a high potential for causing serious injury, Any epidemic of minor injuries should also receive careful attention to determine the under laying causes.

         

Accidents Investigation is Important. It is the basis for a large portion of accident prevention work, and it can mean the Success or Failure of a Safety Program.

PURPOSE OF THE ACCIDENT INVESTIGATION:

        The primary purpose of Accidents Investigation is to pinpoint causes so that similar Occurrences can be prevented, usually through one or more of the following measures:

1>. Mechanical Improvements.

2>. Improvements of Supervision and

3>. Employee Training.

  

Other purpose for Investigating Accidents are to:

1>. Create a record for future reference;

2>. Provide Information for Dissemination to other units;

3>. Direct attention to Safety in General;

4>. Satisfy local, State and federal Agencies; and spot areas where preventive maintenance might be needed.

           5>.Stimulate submission of suggestions for improvements.

PRINCIPLES OF ACCIDENTS INVESTIGATION:

          There are two cardinal principles of Accidents Investigation. These are given below –

         

The first is that 95 percent of Accidents involve both unsafe acts and Unsafe Conditions. The Investigator must look for all causes, both hazardous conditions and Human failures, but in every case he or she should investigate the conditions in which it is fairly obvious that on unsafe Acts caused the Accident.

          The second is that the Investigation must believe and must convince the workers that the purpose of Accidents Investigation is Fact-Finding, not Fault-Finding. This is the Accidents Investigator’s most difficult and most crucial job.

          Others causes are involve an Accidents–

Accidents may be caused by defective equipment, unsafe physical environment, untrained personnel, employee attitude, Employee morale and inadequate supervisory practices.

  

Accident Investigators must deal with many types of personalities under strained conditions. The occasion of an accident is a trying time for all concerned, and workers react to the pressure of the situation in various ways.

           

          Some become shy, nervous, apprehensive, and hesitate to talk for fear of self-incrimination. Others become hostile and resentful of what they feel is snooping. Still others, no matter how apparent their negligence, will insist that someone else or the equipment was to blame.

          It’s up to the Investigator to dissolve these barriers by using empathy. Empathy is the ability to put oneself in another’s position, to react to an experience as another reacts. By empathizing with the workers he interviews – by figuratively placing himself in the other guy’s shoes – the interviewer can better understand what the worker tells him.

          The worker, in turn, will be more convinced of the Investigator’s objective intention – to gather information and uncover the facts, not to fix blame. On the whole, workers are cooperative and understanding when they are convinced that they may be helpful in preventing someone else from experiencing a similar mishap.

          A good general pattern for the Accident Investigator to follow is:

1. Investigate all injury-producing accidents as soon after their occurrence as circumstances permit. Many companies require Investigation within 24 Hours.

2. Delay an interview with the injured man until he has received initial medical treatment, No matter how minor the injury. The Investigator should always be more concerned with the employee’s welfare than with fact-finding.

                                    

Even if the employee is willing to talk, insist that he receive medical attention first. If after treatment he is in pain or upset, postpone questioning until he is clam. The injured worker is usually the main source of information about the accident, and the accuracy and completeness of the information obtain from him depends to a great extent upon how the interview is conducted.

          3. Never use sarcasm, appear aggressive, or blame anyone. This only makes the worker withdraw or become belligerent. Some workers immediately sense and admit responsibility and become self-condemnatory. They know they’re wrong and don’t want or need to be reminded of it. Nothing can be gained with criticism or ridicule.

          On the other hand, the Investigator should empathize with the worker, show concern for him, be friendly, hear him out, and get his suggestions. And the Investigator should share his ideas with the worker.

  

WHO SHOULD INVESTIGATE ACCIDENTS?

Ø The primary investigation is essentially the function of the front line Supervisors. Accidents Investigation is considered a routine part of supervisor job responsibility, and safety personnel function as staff

Ø In the more serous cases, a Safety Engineer or Officers should verify the findings of the Supervisor and investigate every Important Accident.

Ø The statutory Investigation is done by the Factory Inspector.

Fatalities involve the highest level of Investigation, Frequently a plant committee and corporate group, Insurance carriers and Governmental bodies may also conduct Accident Investigations.

ACCIDENT SITE:

          The first concern of an accident scene, regardless of its. Seriousness is the care of the injured and protection of people and property. Thereafter, Investigation should commence without delay. The less the interviewing time, the more accurate would be the information that can be obtained. Facts would be more accurate because witness would not have had time to be biased by the opinions of the others and further they would be able to recollect events and details more accurately.

INTERVIEW OF WITNESSES:

If the injured man can not be interviewed the investigator should talk with witnesses. At all cost, avoid making them feel that they are informers. Re-emphasize to them the purpose of the investigation – to gather the facts to prevent recurrence of the accident.

A witness is any person or worker who can contribute information on an accident. It is describable to have the initial interview of witness carried out at the accident site. This would help both the investigator and the witness to more accurately relate the circumstances and details involves.

THE INVESTIGATION REPORT:

The general pre-printed accident investigation report form are used by industrial units. This could be a sample page form or form using several pages specimen report forms are given in Annexure.

Such forms contains the following information:

1>  Identifying information and related details.

2>  Description of the accident.

3>  Discussion.

4>  Case analysis.

5>  An action plane with recommendations.

 IDENTIFYING INFORMATION:

     These are facts surrounding the accidents.

a)     Time injury – Hour of the accident, Day, Time, Month, and Year.

b)    Location – The Plant / Department / Place of work.

c)     Person Injured – Name, Age, Sex, Wage, and Occupation.

d)    Injury Type – Part of body injured or Nature of injury.

e)     Agency of Accident.

f)      Hazardous Conditions.

g)     Unsafe Acts, Unsafe Condition.

h)    Witnesses.

i)       Find out what particular job and what purpose of the job the person works doing at the time of accident.

SUMMARY:

The main points to remember when Investigating Accidents are:

Ø Get to the scene promptly.

Ø Be sure the injured are treated first.

Ø Apply empathy in interviews with witnesses and the injured.

Ø Encourage suggestions.

Ø Be objective – seek the facts.

Ø Publicize the facts so that all may benefit & Follow up.

                      

Tips to Handle Food Safely

Medically known as food-borne illness or food-borne disease.

It occurs when eat or drink something contaminated with any number of disease-causing bacteria, viruses, or parasites. And it can result in diarrhea, vomiting, and fever, which can be serious if prolonged, and can lead to dehydration.

Most people rarely get sick from contaminated foods because their immune systems are strong enough to protect them. But when harmful bacteria multiply beyond safe limits due to unsafe food handling or lack of refrigeration, that's when food-poisoning strikes. When the immune system is impaired by sickness, age, or other factors, food poisoning is also more likely.

Raw foods from animals, such as eggs, meat and poultry, shellfish, and unpasteurized milk, are the foods most likely to be contaminated. Raw fruits and vegetables are of particular concern because washing decreases but does not eliminate contamination.

But food poisoning usually can be prevented by handling food safely. The four simple steps for safely preparing food at home:

1. Clean and wash hands, countertops, and other surfaces often. Bacteria can spread throughout the kitchen and get onto cutting boards, utensils, sponges, and countertops.

·         Wash your hands with hot soapy water before handling food and after using the bathroom, changing diapers, and touching pets. Avoid preparing foods if you have diarrhea.

·         Wash your cutting boards, dishes, utensils, and countertops with hot soapy water after preparing each food item and before you go on to the next food.

·         Use plastic or other nonporous cutting boards. These boards should be run through the dishwasher -- or washed in hot soapy water -- after each use.

·         Consider using paper towels to clean up kitchen surfaces. If you use cloth towels, wash them often in the hot cycle of your washing machine.

2. Separate and don't cross-contaminate. This is especially true when handling raw meat, poultry, and seafood, so keep these foods and their juices away from ready-to-eat foods.

·         Separate raw meat, poultry, and seafood from other foods in your grocery shopping cart and in your refrigerator.

·         If possible, use a different cutting board for raw meat products.

·         Always wash hands, cutting boards, dishes, and utensils with hot soapy water after they come in contact with raw meat, poultry, or seafood.

·         Never place cooked food on a plate that previously held raw meat, poultry, or seafood.

3. Cook food to proper temperatures to kill the harmful bacteria.

·         Use a clean thermometer that measures the internal temperature of cooked foods to make sure meat, poultry, casseroles, and other foods are cooked all the way through.

·         Cook roasts and steaks to at least 145 degrees Fahrenheit. Whole poultry should be cooked to 180 degrees Fahrenheit for doneness. Because bacteria can spread throughout ground beef (hamburger) during processing, always cook it to at least 160 degrees Fahrenheit.

·         Cook eggs until the yolk and white are firm. Don't use recipes in which eggs remain raw or only partially cooked.

·         Fish should be opaque and flake easily with a fork.

·         When cooking in a microwave oven, make sure there are no cold spots in food where bacteria can survive. For best results, cover food, stir, and rotate for even cooking. If there is no turntable, rotate the dish by hand once or twice during cooking.

·         Bring sauces, soups, and gravy to a rolling boil when reheating. Heat other leftovers thoroughly to 165 degrees Fahrenheit.

4. Refrigerate food promptly. Refrigerate foods quickly because cold temperatures keep harmful bacteria from growing and multiplying. Set your refrigerator no warmer than 40 degrees Fahrenheit and the freezer no warmer than 0 degrees Fahrenheit. Check these temperatures occasionally with an appliance thermometer.

·         Refrigerate or freeze perishables, prepared food, and leftovers within two hours.

·         Never defrost food at room temperature. Thaw food in the refrigerator, under cold running water, or in the microwave. Marinate foods in the refrigerator.

Divide large amounts of leftovers into small, shallow containers for quick cooling in the refrigerator. Don't pack the refrigerator full. Cool air must circulate to keep food safe

Useful information regarding comfortable seating arrangement at workplace.

Fundamentals of seating

The advantages of a sedentary posture at work are:

• Taking the weight off the legs.
• Possibility of avoiding unnatural postures.
• Reduced energy expenditure.
• Lower demands on blood circulation.

These advantages must be set against certain drawbacks:

Prolonged sitting leads to a slackening of the abdominal muscles (‘sedentary tummy’), and to a curvature of the spine which, in turn, is unfavorable for the organs of digestion and breathing.

But the most serious problem involves the spine and the muscles of the back, which in many sitting positions are not only not relaxed but positively stressed in various ways.

  

The purpose of a seat is to provide stable bodily support in a posture that is: 

(i) Comfortable over a period of time;

(ii) Physiologically satisfactory;

(iii) Appropriate to the task or activity in question.

All seats are uncomfortable in the long run, but some seats become uncomfortable more rapidly than others, and in any particular seat, some people will be more uncomfortable than others. 

Comfort may also be influenced by the task or activity that the user is engaged in at the time. 

In other words, comfort (or more strictly the rate of onset of discomfort) will depend upon the interaction of seat characteristics, user characteristics, and task characteristics. 

In designing a seat therefore, the objective is to support the lumbar spine in its neutral position without the need for muscular effort, thus allowing the user to adopt a position that is both physiologically satisfactory and comfortably relaxed. In general this will be achieved by: 

• A semi-reclined sitting position (to the extent that this is permitted by the demands of the working task);
• A seat that is neither lower nor deeper than necessary;
• A backrest that makes an obtuse angle to the seat surface (thus minimizing the need for hip flexion) and is contoured to the form of the user’s lumbar spine.

General experience as well as a number of studies have yielded the following ‘golden rules’ for office chairs:

1. Office chairs must be adapted to both traditional office work and the modern equipment of information technology, especially to jobs at VDT workstations.

2. Office chairs must be conceived for a forward and reclined sitting posture.

3. The backrest should have an adjustable inclination, and it should be possible to lock the backrest at any desired inclination.

4. A backrest height of 48–52 cm vertically above the seat surface is an ergonomic necessity today. The upper part of the backrest should be slightly concave. A width of 32–36 cm for the backrest is advisable. It may alternatively be concave in all horizontal planes with a radius of 40–50 cm.

5. The backrest must have a well formed lumbar pad, which should offer good support to the lumbar spine between the third vertebra and the sacrum, e.g., at a height of 10–20 cm above the lowest point of the seat surface.

6. The seat should measure 40–45 cm across and 38–42 cm from back to front. A slight hollow in the seat, with the front edge turned upwards about 4–6 ° will prevent the buttocks from sliding forward. A light padding of foam rubber-2cm thick, covered with non-slip, permeable material is a great aid to comfort.

7.  Foot rests are important, so that small people can avoid sitting with hanging feet.

8.  An office chair must fulfil all requirements of a modern seat adjustable height (38–54 cm), swivel, rounded front edge of the seat surface, castors or glides, 5-arm base and user-friendly controls. The most important dimensions for a seat and working desk are shown in Figure 75.

Key features of chair design:

1. Seats should swivel and have heights adjustable between 38 and 54cm. Footrests should be provided for short users.

2. Free space for the legs must be provided both underneath the seat to allow the user to

flex the knees by 90 degrees or more and underneath the work surface to allow knee extension when reclining.

3. A 5-point base is recommended for stability if the chair has castors.

4. The function of the backrest is to stabilize the trunk. A backrest height of approximately 50cm above the seat is required to provide both lumbar and partial thoracic support.

5. If the backrest reclines, it should do so independently of the seat to provide trunk–thigh angle variation and consequent variation in the distribution of forces acting on the lumbar–pelvic region.

6. Lumbar support can be achieved either by using extra cushioning to form a lumbar pad, or by contouring the backrest. In either case, there must be open space between the lumbar support and the seat pan vertically below it to allow for posterior protrusion of the buttocks.

7. The seat pan must have a slight hollow in the buttock area to prevent the user’s pelvisfrom sliding forwards. This keeps the lower back in contact with the backrest when reclining.

The leading edge of the seat should curl downwards to reduce under thigh pressure.

8. Arm rests should be high enough to support the forearms when the user is sitting erect.

They should also end well short of the leading edge of the seat so as not to contact the front edge of the desk. If the armrests support the weight of the arms, less load is placed on the lumbar spine.

9. Modern chairs tend to have a thin layer of high-density padding. Layers of thick foam tend to destabilize the sitter. The foam can collapse after constant use.

10. Cloth upholstery provides friction to enhance the stability of the sitter.

PREVENTION AND CONTROL OF NOISE HAZARDS

The source, transmission path and the receiver constitute the chain of sound transmission. Hence for any noise control strategy, the following three form the fundamental element;

Reduction of Noise at Source;

Reduction of noise by change in path; and

      Reduction of Noise at Receiver`s end.        

  

Reduction of Noise at Source: There are at least three areas in which control of noise generated by a source may be initiated. They are proper design, proper equipment operation (by changing method of operation) and equipment maintenance. The change in design shall be aimed at;

• Decreasing energy for driving vibrating system;
• Changing coupling between this energy and acoustic radiating system;
• Changing structure so that less sound is radiated.

Reduction of Noise by change in Path: In addition to source control, it is possible to obtain significant noise reduction at the receiver by controlling the noise along the path of transmission. This can be achieved by;

• Increasing the distance between source and receiver.
• Acoustic treatment of ceiling, walls, floor to absorb sound and reverberation.

Reduction of Noise at Receiver: There is little opportunity for noise control at the receiver. Normally, the permissible noise levels are set for the receiver, and engineering techniques must be used on the source and or path in order to limit the exposure of the receiver. Some techniques that can be adopted are as follows;

• Enclosing/isolating the workers;
• Rotational of Personnel to reduce exposure time;
• Changing job schedule of the affected employee.

  

ENGINEERING CONTROL MEASURES: The following are the examples of applying engineering principles to reduce noise level;

      1. Maintenance:

• Replacement or adjustment or worn and loose or unbalanced parts of machine.
• Lubrication of machine parts and or used of cutting oil;
• Properly shaped and sharpened cutting tools. 

      2. Substitution of Machines:

•  Larger, slower machines for smaller and faster ones.
•  Step dies for single operation dies;
• Rotating shears for square shears;
• Hydraulic for mechanical process;
• Belt drivers for gears.

3.     Substitution of Process:

• Compression for impact riveting;
• Welding for riveting;
• Processing for rolling and forging.

4.     Driving force of vibrating surfaces may be reduced by;

• Reducing the force;
• Minimizing rotation speed;
• Isolating.

5.     The response of vibrating surface may be reduced by;

• Damping;
• Additional supports;
• Increasing the stiffness of the material;
• Increasing mass of vibrating members.

6.     The sound radiation from vibrating surface can be reduced by;

• Reducing the radiating area;
• Reducing overall size;
• Perforating surfaces.

7.     Reduce sound transmission through solids by using;

• Flexible mountings; flexible sections in pipe runs;
• Flexible shaft coupling;
• Fabric sections in ducts;
• Resilient flooring.

8.     Reducing sound produced by gas flow;

• Intake and exhaust mufflers;
• Fan blades designed to reduce turbulence;
• Large low speed fan for smaller high speed fans;
• Reduced velocity of fluid flow;
• Increased cross-sections of streams;
• Reduced pressure and turbulence.

9.     Reducing noise by reducing its transmission through air;

• Use of sound absorbing materials on walls and ceilings in work-area.
•  Use of sound absorption material along the transmission path; complete enclosure of individual machine.
• Use of baffles;
• Confining high noise machine to insulated room.

      10.  Isolating operator by proving a relative sound proof both for the operator or attendant.

MEDICAL CONTROL MEASURES:

Industrial Audiometry:  In an Industrial audiometry, the testing of workers’ hearing acuity, may well identify hearing disabilities. Hearing is regularly tested, preferably from the time the worker joins the workplace, to observe if there is any discernible deterioration in hearing above that which is expected from loss due to ageing (Presbycusis).

A health practitioner trained in conducting hearing test, will test the worker`s baseline auditory threshold for both ears. The frequencies used for both reference and monitoring audiometry are 500 Hz, 1000 Hz, 1500 Hz, 2000 Hz, 3000 Hz, 4000 Hz, 6000 Hz and 8000 Hz.

Reference audiometry must be conducted as soon as possible after commence of employment, but should ideally be conducted before exposure to a noisy workplace occurs.

Monitoring audiometry should be performed within 3 months and then 12 months of the initial work exposure for comparison with the results of the reference audiometry.

If there is no significant change in the threshold shift or in the work situation, it may then be sufficient to retest at yearly intervals or as prescribed by OHS legislations. For workers exposed to high exposure levels, >100dB (A), more frequent audiometric testing may be required.

• Where significant hearing impairment is detected at the initial hearing audiometric test, the person should undergo a medical examination if a repeat test conducted on another day, confirms the original findings.
• Audiometric testing can be of benefit to both employers and workers in excessively noisy industries (foundries, canneries, metal industries, air transportation), but only if it is an integral part of a rigorous hearing conservation program.
• Audiometric testing in isolation from other elements of a hearing conservation program only serves to record the deterioration in hearing.
• In combination with other elements it can detect the early onset of NIHL and enable counter measures to be put in place.

 Hearing Conservation Program

Hearing conservation programs are designed to prevent long-term hearing impairment, principally by maintaining noise exposure within the limits required by the legislation.

Any of the technical control processes (Engineering Control Measures) discussed above might be used in such program. Certainly, the best are noise reduction program.

However, if noise sources cannot be quieted sufficiently, the workers must be provided with hearing protective devices.

Management`s commitment to training and proper education of the workforce in the purpose, use and benefits of protective devices must be matched by the rigid enforcement of such program.

The hearing conservation program aims;

• To prevent Noise Induced Hearing Loss (NIHL)
• To reduce cost of claims for workmen compensation.

A well-organized successful hearing conservation program shall have coordination and integration of the following three phases;

• Physical evaluation the noise exposure.
• Medical evaluation of the hearing of personnel exposed to noise; and
• Control of the noise exposure.

Team approach for Hearing Conservation Program

Function	Members involved
Identification of noise source	Industrial hygienist, supervisors, workers.
Reduction of noise exposure	Design/Plant Engineer, Industrial hygienist, supervisor, workers, audiologist.
The hearing measurement	Audiologist, ontologies, workers

           Note:  

       1. The medical personnel shall be the team leader.

       2. Equipment requirement includes audiometer / Evoke system; Noise level meter / sound level meter; Noise dosimeter.

STUDY OF SOME NOISE CONTROL MEASURES

Acoustic Enclosures for Diesel Generator: Lot of engineering techniques has been developed to bring down the noise level of the diesel generator set. One of such is the “Acoustic Enclosure” for the set. In some models, the sets are completed enclosed in an acoustic enclosure (Shown in figure). Whereas in other case, the walls and floors of the DG room are lined with noise absorbing materials, thereby bringing down the noise level.

Personal Protective Equipment:

Where it has been confirmed that the workplace noise levels are in excess of any regulatory noise limit and other noise reduction programs such as those above cannot be fully implemented, personal protective equipment must be used until such time that the noise exposure has been reduced to below the regulatory limits. Hence, PPE are considered as a last line of defense as it cannot eliminate the hazard but can only limit the effects of hazards.

Hearing protection should be used compulsorily if the noise or sound level at workplace exceeds 85 decibels (A)though the allowable limit is 90 dB(A).

Various PPE are available with varying degree of Noise Reduction Rating (NRR).

[NRR is a standard measure of sound blocking capabilities of any hearing protective device.]

There are basically four types of hearing protectors available,

• Acoustic Helmet;
• Ear Canal Caps;
• Ear Plugs; and
• Ear Muffs.

Of the above four, only two (ear plugs and ear muffs) are in widespread use.

Ear Plugs: Ear plugs are inserted to block the ear canal. They may be performed or moldable (foam ear plugs). Ear plugs are available both as disposable products or reusable plugs.

Ear plugs are soft, comfortable and provide un-obstructive hearing protection. They are recommended for high noise situations (up to 100 dBA TWA). They are most suited when exposed to continuous exposure. Other advantages of ear plugs are:

• Can be combined with ear muffs for additional protection.
• Can be used with other Personal Protective Equipment.
• Comfortable for a wide range of ear sizes.

Ear Muffs: Ear muffs consist of sound-attenuating material and soft ear cushions that fit around the ear and hard outer cups. They are held together by a head band.  Ear muffs are ideal for user who needs intermittent hearing protection against noise. Ear muffs are recommended for situations where people move in and out of noise often during the work day.

Combined usage: The combined usage of ear plugs with ear muffs is recommended for sound level more than 105 dBA. The dual protection however only adds 5 dB to the noise reduction provided by the more protective device of the two.

INDUSTRIAL NOISE REDUCTION PLAN- RECOMMENDATIONS

The industrial noise can be controlled at three different levels i.e. at source, along the transmitting path or at the receiver`s end, as discussed earlier. Here are the recommendations in a logical series of actions, which if followed, should lead to effective noise control.

1. Identify the noise problem areas in the plant. This can be done by conducting health surveys to measure the sound level at different areas of plant.
2. Establish the noise exposure of the employees in the potential problem areas as identified above. This can be measure by timing the exposure at each noise level for the employee.
3. Get to know the problem. Analyze the data and information collected above and identify the major noise frequencies. This in turn will help to identify the source or sources generating the major portions of the noise.
4. Use proper operations and maintenance to decrease noise generation. This can be done by applying the engineering control measures at source.
5. Adopt control measures to reduce the noise in the transmission path. Provide barriers, enclosures, or other absorption media in the transmission path to effectively control the noise.
6. Use administrative measures like change in the work assignment for the affected employees to effectively limit his or her noise exposure.
7. Provide Personal Protective Equipment to limit the noise exposure to the individual.