Methods to Lower Workplace PELs | Air Contaminants

According to OSHA policy, engineering controls and work practices are preferred over personal protective equipment to control employee exposures to airborne contaminants.

Engineering controls involve the use of a local exhaust ventilation, general ventilation, isolation of the worker and enclosure of the source of emissions, process modifications, equipment modifications, and substitution of nonhazardous or less hazardous chemicals. These methods may be used alone or in combination, depending upon the industrial processes involved. These controls are widely used and will effectively control exposures either by themselves, or coupled with changes in work practices.


Perhaps the most widely used technique for controlling chemical exposure is the use of ventilation. General ventilation uses the movement of air within the general work space to displace or dilute the contaminant with fresh outside air. General ventilation may not be the preferred control method, however, due to the large volumes of air movement required. Local exhaust ventilation uses a much smaller volume of air and controls emissions at the point or source from which contaminants are generated.


Isolation involves placing a physical barrier between the hazardous operation and the worker. Many modern, automated manufacturing processes are now fully enclosed in ventilated cabinets. The effectiveness of such a control technique depends on the frequency with which the workers have to enter the enclosure during normal operations.

In other situations, the worker, rather than the process or machine, can be placed in an enclosure having a controlled atmosphere. Many processes which involve potential chemical exposures are operated remotely by operators from air conditioned booths isolated from the hazardous materials.


Substitution refers to the replacement of a toxic chemical in a particular process or work area with another, less toxic or non-toxic product. Properly applied, substitution can be a very effective control technique.

However, care must be taken to ensure that the proposed substitute performs in a similar manner to the product being replaced. In addition, it is essential that the substitute be carefully evaluated to ensure that in controlling one hazard, another different hazard is not inadvertently introduced. The substitute must also be compatible with existing manufacturing equipment and processes.

The success of these engineering control techniques will depend on the physical properties of the chemicals and emissions encountered (boiling point, vapor pressure, etc.) and the process operating conditions. In some cases, particularly with cleaning solvents, substitution may provide the quickest and most effective means of reducing exposure. In other situations, a major effort may be required to alter processes or install or expand local or general dilution ventilation.

OSHA has found that engineering controls and improved work practices are available to reduce exposure levels to the new levels in almost all circumstances. However, in some circumstances, respiratory protection may be necessary to complement engineering controls. Respiratory protection may be necessary to achieve compliance in some specific operations in some industries.

Engineering controls vs. protective equipment

So in other words, the most desirable way to deal with an air contaminant is to alter the process so that the contaminant is no longer produced. If the process cannot be changed or materials substituted, a well designed ventilation system may be the best solution to the problem. If ventilation would require too large a volume of air to reduce the concentration of the contaminant, then respiratory protection may be a necessary short-term solution.

Court Decision Affecting PELs | Air Contaminants

Since the 1970s, much new information has become available which indicates that, in most cases, these early limits are outdated and insufficiently protective of worker health. To correct this situation, OSHA published a proposal in 1988 updating the air contaminant limits in general industry. When that proposal became a final rule in 1989, it lowered the existing PELs for 212 toxic air contaminants and established PELs for 164 previously unregulated air contaminants.

In July 1992, the Eleventh Circuit Court of Appeals vacated the 1989 final rule on the grounds that OSHA:
  • Failed to establish that existing exposure limits in the workplace presented significant risk of material health impairment or that new standards eliminated or substantially lessened the risk; and

  • Did not meet its burden of establishing that its new permissible exposure limits (PELs) were either economically or technologically feasible.
The Court’s decision to vacate the rule forced OSHA to revert back to the original protective limits. The Court granted several successive stays following the July 1992 decision, allowing the Agency time to consider further legal steps. A decision was made on March 1993 not to appeal to the Supreme Court, and the Eleventh Circuit Court’s decision stands today.

Should you comply with the 1989 PELs, even though they are no longer legally required? OSHA believes the 1989 PELs are more protective, and encourages employers to continue compliance efforts to meet these levels, particularly where engineering and work practice controls have already been implemented. OSHA always encourages employers to go beyond the minimum protections afforded by the standards.

PELs and TLVs | Air Contaminants

OSHA enforces hundreds of permissible exposure limits (PELs) for toxic air contaminants found in U.S. workplaces. These PELs set enforceable limits on the magnitude and duration of employee exposure to each contaminant. The amount of exposure permitted by a given PEL depends on the toxicity and other characteristics of the particular substance. Two different types of measurement are used for PEL determination. The concentration of gases and liquids in the air is measured in parts per million (ppm). Solids and liquids in the form of mists, dusts, or fumes, are measured in milligrams per cubic meter (mg/m3).

Exposure limits called Threshold Limit Values (TLVs) were developed by the American Conference of Governmental Industral Hygienists (ACGIH). TLVs represent the level of chemicals in the ambient air that most workers can be exposed to on a daily basis without harmful effects.

The air contaminant limits were adopted by OSHA in 1971 from existing national consensus standards issued by the American Conference of Governmental Industrial Hygienists and the American National Standards Institute (ANSI). Consequently, these PELs, which have not been updated since 1971, reflect the results of research conducted in the 1950s and 1960s.

Air Contaminants

What are Air Contaminants?

An air contaminant is any substance which is accidentally or unwillingly introduced into the air, having the effect of rendering the air toxic or harmful to some degree. The greatest concern when dealing with hazardous materials is air contamination.

Through inhalation, airborne particles of dust, fumes, vapors, mists, and gases may be taken into the body. These particles can irritate the skin, eyes, nose, throat, and lungs. They may be absorbed into the bloodstream and transported to affect additional organs.

Airborne contaminants present a significant threat to worker health and safety. Thus, identification and quantification of these contaminants through air monitoring is an essential component of every company’s health and safety program. Reliable measurements of airborne contaminants are useful for:
  • Selecting personal protective equipment;

  • Delineating areas where protection is needed;

  • Assessing the potential health effects of exposure; and

  • Determining the need for specific medical monitoring.

Protecting Workers in Cold Environments

When the weather becomes “frightful” during winter months, workers who have to brave the outdoor conditions face the occupational hazard of exposure to the cold. Prolonged exposure to freezing temperatures can result in health problems as serious as trench foot, frostbite, and hypothermia. Workers in such industries as construction, utilities, commercial fishing, and agriculture need to be especially mindful of the weather, its effects on the body, proper prevention techniques, and how to treat cold-related disorders.

The cold environment

An individual gains body heat from food and muscular activity and loses it through convection, conduction, radiation, and sweating to maintain a constant body temperature. When body temperature drops even a few degrees below its normal temperature of 98.6°F(37°C), the blood vessels constrict. Constricted vessels decrease peripheral blood flow to the skin surface, thus reducing heat loss. Shivering generates heat by increasing the body’s metabolic rate.

The four environmental conditions that cause cold-related stress are:
  1. Low temperatures,
  2. High/cool winds,
  3. Dampness, and
  4. Cold water.
Wind chill, a combination of temperature and velocity, is a crucial factor to evaluate when working outside. For example, when the actual air temperature of the wind is 40°F(4°C) and its velocity is 35 mph, the exposed skin receives conditions equivalent to the still-air temperature being 11°F (-11°C). A dangerous situation of rapid heat loss may arise for any individual exposed to high winds and cold temperatures.

Major risk factors for increasing cold-related stresses

  • Wearing inadequate or wet clothing increases the effects of cold on the body.

  • Taking certain drugs or medications such as alcohol, nicotine, caffeine, and medication that inhibits the body’s response to the cold or impairs judgment.

  • Having a cold or certain diseases, such as diabetes, heart, vascular, and thyroid problems, may make a person more susceptible to the winter elements.

  • Being a male increases a person’s risk to cold-related stresses. Men experience far greater death rates due to cold exposure than women, perhaps due to inherent risk-taking activities, body-fat composition, or other physiological differences.

  • Becoming exhausted or immobilized, especially due to injury or entrapment, may speed up the effects of cold weather.

  • Aging — the elderly are more vulnerable to the effects of harsh winter weather.

Effects of cold on the body

Trench foot is caused by long, continuous exposure to a wet, cold environment or actual immersion in water. Workers, such as commercial fisherman who experience these types of cold, wet environments daily, need to be especially cautious. Symptoms include:
  • Tingling and/or itching sensation,
  • Burning, pain, and
  • Swelling, sometimes forming blisters in more extreme cases.
Treatment includes moving individuals with trench foot to a warm, dry area where the affected tissue can be treated. Carefully wash and dry the area, rewarm, and slightly elevate. Seek medical assistance as soon as possible.

Frostbite occurs when the skin tissue actually freezes, causing ice crystals to form between cells and draw water from them. This leads to cellular dehydration. Although frostbite typically occurs at temperatures below 30°F (1°C), wind chill effects can cause frostbite at above-freezing temperatures. Ears, fingers, toes, cheeks, and noses are primarily affected. Symptoms of the exposed area include:
  • Uncomfortable sensations of coldness;
  • Tingling, stinging, or aching feeling followed by numbness; and
  • Skin appears white and cold to the touch (varies depending on whether rewarming has occurred).
Deeper frostbite involves freezing of deeper tissues, such as muscles and tendons, causing exposed areas to become numb, painless, hard to the touch.

To treat frostbitten parts, cover with dry, sterile gauze or soft, clean cloth bandages. Do not massage frost-bitten tissue because this sometimes causes greater injury. Severe cases may require hospitalization and even amputation of affected tissue. Take measures to prevent further cold injury.

If you suspect frostbite, seek medical assistance immediately. However, if hypothermia exists, it should be treated first.

General hypothermia occurs when body temperature falls to a level where normal muscular and cerebral functions are impaired. While hypothermia is generally associated with freezing temperatures, it may occur in any climate where a person’s body temperature falls below normal. Symptoms include:
  • Shivering,
  • Inability to do complex motor functions,
  • Lethargy, and
  • Mild confusion.
These initial symptoms occur as the core body temperature decreases to around 95°F (35°C). As body temperature continue to fall, hypothermia becomes more severe. The individual:
  • Falls into a state of dazed consciousness;
  • Fails to complete even simple motor functions;
  • Speech becomes slurred; and
  • Behavior may become irrational.
The most severe state of hypothermia occurs when body temperature falls below 90°F (32°C). At this point, the body moves into a state of hibernation, slowing the heart rate, blood flow, and breathing. Unconsciousness and full heart failure can occur in the severely hypothermic state.

Treatment of hypothermia involves conserving the victim’s remaining body heat and providing additional heat sources. Specific measures will vary depending upon the severity and setting (field or hospital). Handle hypothermic people very carefully because of the increased irritability of the cold heart. Seek medical assistance for persons suspected of being moderately or severely hypothermic.

Assume that a person is suffering from severe hypothermia when he is unresponsive and not shivering. Stop heat loss by:
  • Finding shelter,
  • Removing wet clothing,
  • Adding layers of dry clothing or blankets, or
  • Using a pre-warmed sleeping bag.
For mildly hypothermic cases or those more severe cases where medical treatment will be significantly delayed, apply external rewarming techniques. These include:
  • Body-to-body contact (e.g., placing the person in a prewarmed sleeping bag with a person of normal body temperature);
  • Chemical heat packs; or
  • Insulated hot water bottles.
Good areas to place these packs are the armpits, neck, chest, and groin. It is best to have the person lying down when applying external rewarming. You also may give mildly hypothermic people warm fluids orally, but avoid beverages containing alcohol or caffeine.

Preventing cold-related disorders

Personal protective clothing — perhaps the most important step in fighting the elements. Provide adequate layers of insulation, usually at least three layers of clothing:
  • An outer layer to break the wind and allow some ventilation (like Gore-Tex® or nylon).
  • A middle layer of wool or synthetic fabric (Qualofil® or Pile) to absorb sweat and retain insulation in a damp environment. Down is a useful lightweight insulator; however, it is ineffective once it becomes wet.
  • An inner layer of cotton or synthetic weave to allow ventilation.
Pay special attention to protecting feet, hands, face and head. Up to 40 percent of body heat can be lost when the head is exposed. Footgear should be insulated to protect against cold and dampness. Keep a change of clothing available in case work garments become wet.

Engineering controls in the workplace through a variety of practices help reduce the risk of cold-related injuries. Consider using an onsite source of heat, such as air jets, radiant heaters, or contact warm plates or shielding work areas from drafty or windy conditions.

Provide a heated shelter for employees who experience prolonged exposure to equivalent wind-chill temperatures of 20°F (6°C) or less and use thermal insulating material on equipment handles when temperatures drop below 30°F (1°C).

Safe work practices are necessary to combat the effects of exceedingly cold weather. Implement changes in work schedules and practices that:
  • Allow a period of adjustment to the cold before embarking on a full work schedule.
  • Permit employees to set their own pace and take extra “warm-up” work breaks when needed.
  • Reduce, as much as possible, the number of activities performed outdoors. When employees have to brave the cold, select the warmest hours of the day and minimize activities that reduce circulation.
  • Ensure that employees remain hydrated.
  • Establish a buddy system for working outdoors.
  • Provide training on the symptoms of cold-related stresses — heavy shivering, uncomfortable coldness, severe fatigue, drowsiness, or euphoria.
The quiet symptoms of potentially deadly cold-related ailments often go undetected until the victim’s health is endangered. Knowing the facts on cold exposure and following a few simple guidelines can ensure that outdoor workers stay safe and healthy.

Frost bite and hypothermia

When your body is unable to warm itself, serious cold-related illnesses and injuries can occur and permanent tissue damage and death may result. Hypothermia occurs when land temperatures are above freezing or water temperatures are below 98.6°F. Cold-related illnesses slowly overcome a person who has been chilled by low temperatures, brisk winds, or wet clothing. The most common cold related illnesses are frostbite, and hypothermia.

Frost bite

What happens to the body?
  • Freezing in deep layers of skin and tissue.
  • Pale, waxy-white skin color.
  • Skin becomes hard and numb.
  • Usually affects the fingers, hands, toes, feet, ears, and nose.
What should be done?
  • Move the victim to a warm dry area. Do not leave the individual alone.
  • Remove wet or tight clothes that may cut off blood flow to the affected area.
  • DO NOT rub the affected area. Rubbing causes damage to the skin and tissue.
  • Gently place the affected area in a warm (105°F) water bath and monitor the temperature to slowly warm the tissue. Don’t pour warm water directly on the affected area because it will warm the tissue too fast causing tissue damage. Warming takes about 25–40 minutes.
  • After the affected area has been warmed, it may become puffy and blister. The area may have a burning feeling or numbness. When normal feeling, movement, and skin color have returned, dry and wrap the affected area to keep it warm.
    Note:If there is a chance the affected area may get cold again, do not warm the skin. If the skin is warmed and then becomes cold again, it will cause severe tissue damage
  • Seek medical attention as soon as possible.

Hypothermia — A medical emergency

What happens to the body?
  • Normal body temperature (98.6°F) drops to or below 95°F.
  • Fatigue or drowsiness occurs.
  • Uncontrolled shivering.
  • Cool bluish skin.
  • Slurred speech.
  • Clumsy movements.
  • Irritable, irrational, or confused behavior.
What should be done?
  • Call for emergency medical help.
  • Move the victim to a warm, dry area. Don’t leave the individual alone.
  • Remove any wet clothing and replace with warm, dry clothing or wrap the victim in blankets.
  • Provide warm, sweet drinks (sugar water or sports-type drinks) if the victim is alert. Avoid drinks with caffeine (coffee, tea, or hot chocolate) or alcohol.
  • Have the victim move his/her arms and legs to create muscle heat. If unable to do this, place warm bottles or hot packs in the arm pits, groin, neck, and head areas. DO NOT rub the victim’s body or place the individual in a warm water bath. This may cause cardiac arrest.

How to protect your employees

Do not allow employees who have predisposing health conditions such as cardiovascular disease, diabetes, and hypertension to work long hours outdoors in winter weather. Also, remember that individuals who are in poor physical condition, have a poor diet, or are older are more susceptible to extreme temperatures. To ensure that employees are protected from the cold elements, provide instructions to:
  • Recognize the environmental and worksite conditions that lead to potential cold-induced illnesses and injuries.

  • Recognize the signs and symptoms of cold-induced illnesses/injuries and what to do to help a fellow employee.

  • Select proper clothing for cold, wet, and windy conditions.

  • Layer clothing to adjust to changing environmental temperatures. Wear a hat and gloves, in addition to underwear that will keep water away from the skin (polypropylene).

  • Avoid exhaustion or fatigue. Energy is needed to keep muscles warm.

  • Use the buddy system (work in pairs).

  • Drink warm, sweet beverages (sugar water, sports-type drinks). Avoid drinks with caffeine (coffee, tea, or hot chocolate) or alcohol.

  • Eat warm, high-calorie foods like hot pasta dishes.
Allow your employees to:
  • Take frequent short breaks in warm dry shelters to allow the body to warm up.

  • Work during the warmest part of the day.
Keeping one step ahead of the weather pays off for employee safety and health.

Protecting Workers in Hot Environments

Many workers spend some part of their working day in a hot environment. Workers in foundries, laundries, construction projects, and bakeries — to name a few industries — often face hot conditions which pose special hazards to safety and health. Heat stress results from a combination of internal (body) heat production from doing work and external heat exposure from the environment. Both aspects need to be controlled to reduce heat stress.

Environmental factors

Four environmental factors affect the amount of stress a worker faces in a hot work area:
  • High temperatures (90°F or above can cause heat stress);
  • High humidity (sweat doesn’t evaporate rapidly);
  • Intense radiant heat (such as from the sun or a furnace); and
  • Low air velocity (lowers the rate at which sweat evaporates).

Physical factors

Perhaps most important to the level of stress an individual faces are personal characteristics such as age, weight, fitness, medical conditions, and acclimatization to the heat.

The body reacts to high external temperature by circulating blood to the skin which increases skin temperature and allows the body to give off its excess heat through the skin. However, if the muscles are being used for physical labor, less blood is available to flow to the skin and release the heat.

Sweating is another means the body uses to maintain a stable internal body temperature in the face of heat. Sweating is effective only if the humidity level is low enough to permit evaporation and if the fluids and salts lost are adequately replaced.

Of course there are many steps a person might choose to take to reduce the risk of heat stress, such as moving to a cooler place, reducing the work pace or load, or removing or loosening some clothing. But, if the body cannot dispose of excess heat, it will store it. When this happens, the body’s core temperature rises and the heart rate increases. As the body continues to store heat, the individual begins to lose concentration and has difficulty focusing on a task, may become irritable or sick and often loses the desire to drink. The next stage is most often fainting and death is possible if the heat stress is not relieved.

Heat disorders

Heat stroke, the most serious health problem for workers in hot environments, is caused by the failure of the body’s internal mechanism to regulate its core temperature. Sweating stops and the body can no longer rid itself of excess heat. Signs include:
  • Mental confusion, delirium, loss of consciousness, convulsions or coma;
  • Rapid pulse;
  • Body temperature of 106°F or higher; and
  • Hot dry skin which may be red, mottled, or bluish.
Shock may result and victims of heat stroke will die unless treated promptly. While awaiting medical help, move the person to a cool area and soak his or her clothing with cool water. Fan vigorously to increase cooling. Prompt first aid can prevent permanent injury to the brain and other vital organs.

Heat exhaustion results from loss of fluid through sweating when a person fails to drink enough fluids or take in enough salt or both. The worker with heat exhaustion still sweats but experiences extreme weakness or fatigue, giddiness, nausea, or headache. The skin is clammy and moist, the complexion pale or flushed, and the body temperature normal or slightly higher.

Treatment is usually simple: the victim should rest in a cool place and drink an electrolyte solution (a beverage that quickly restores potassium, calcium, and magnesium salts). Severe cases may involve vomiting or loss of consciousness and require longer treatment under medical supervision.

Heat cramps are painful muscle spasms that are caused when workers drink large quantities of water but fail to replace their bodies’ salt loss. Tired muscles — those used for performing the work such as the arms and legs — are usually the ones most susceptible to cramps.

Cramps may occur during or after working hours and can be relieved by drinking adequate amounts of liquids and salt at meals. Salt tablets are not recommended. If quick relief is necessary, a saline solution will be given intravenously.

Fainting (heat syncope) can be a problem for the worker unacclimatized to a hot environment who simply stands still in the heat. Dehydration causes blood volume to decrease. The blood pools in dilated blood vessels of the skin on the lower body, making less blood available to the brain.

Victims usually recover quickly after a brief period of lying down. Moving around, rather than standing still, will usually reduce the possibility of fainting.

Heat rash, also known as prickly heat, occurs in hot and humid environments where sweat is not easily removed from the surface of the skin by evaporation. When extensive or complicated by infection, heat rash can be so uncomfortable that it inhibits sleep and impedes a worker’s performance or even results in temporary total disability. It can be prevented by keeping the skin clean and dry. Showering after working in a hot environment is helpful to prevent heat rash.

Preventing heat disorders

Most heat-related health problems can be prevented or the risk of developing them reduced. The two most important methods of preventing heat disorders are hydration and acclimatization because the increase the ability of the body to tolerate heat stress. Engineering and administrative controls are also important to reduce exposures. Use the following suggestions to lessen the risk of heat stress.
  1. A variety of engineering controls including general ventilation and spot cooling by local exhaust ventilation at points of high heat production can lower heat levels. Shielding provides a source of protection from radiant heat sources. Evaporative cooling and mechanical refrigeration will reduce heat. Additionally:
    • Eliminate steam leaks;
    • Use cooling fans;
    • Modify equipment;
    • Use power tools to reduce manual labor; and
    • Provide personal cooling devices or protective clothing to reduce the hazards of heat exposure.
  1. Work practices such as providing plenty of drinking water — as much as a quart per worker per hour — at the workplace can help reduce the risk of heat disorders. Train first aid workers to recognize and treat heat stress disorders. Provide the names of trained staff to all workers.

    Consider an individual worker’s physical condition when determining his or her fitness for working in hot environments. Older workers, obese workers, and those on some types of medication are at greater risk.

  2. Alternating work and rest periods with longer rest periods in a cool area can help workers avoid heat stress. If possible, schedule heavy work during the cooler parts of the day and provide protective clothing. Train supervisors to detect early signs of heat stress. Allow stressed workers to interrupt their work if they are extremely uncomfortable.

  3. Acclimatization to the heat through short exposures followed by longer periods of work in the hot environment can reduce heat stress. A physiological adaptation occurs with repeated exposure to hot environments:
    • Heart rate will decrease,
    • Sweating will increase,
    • Sweat will become more dilute, and
    • Body temperature will be lower.
    The ability to acclimatize varies among workers. Generally, individuals in good physical condition acclimatize more rapidly than those in poor condition.

    Approximately one week of gradually increasing the workload and time spent in the hot environment will usually lead to full acclimatization. On the first day the individual performs 50 percent of the normal workload and spends 50 percent of the time in the hot environment. Each day an additional 10 percent of the normal workload and time is added, so that by day six, the worker is performing the full workload for an entire day. The exposure time should be at least two hours per day for acclimatization to occur.

    Acclimatization is lost when exposure to hot environments does not occur for several days. After a one week absence, a worker needs to reacclimatize by following a schedule similar to that for initial acclimatization. The acclimatization will occur more rapidly, so increases in workload and time can increase by approximately 20 percent each day after the first day, reaching normal work conditions by day four.

    New employees and workers returning from an absence of two weeks or more should have five-day period of acclimatization. This period should begin with 50 percent of the normal workload and time exposure the first day and gradually building up to 100 percent on the fifth day.
  1. Employee education is vital so that workers are aware of the need to replace fluids and salt lost through sweat and can recognize dehydration, exhaustion, fainting, heat cramps, salt deficiency, heat exhaustion, and heat stroke as heat disorders. They need to know they should be drinking at least five to seven ounces of cool water every 15-20 minutes and to avoid taking salt tablets. Salt tablets irritate the stomach and can lead to vomiting, which can result in further dehydration.

Heat-related emergencies

When the body is unable to cool itself through sweating, serious heat illnesses may occur. The most severe heat-induced illnesses are heat exhaustion and heat stroke. If actions are not taken to treat heat exhaustion, the illness could progress to heat stroke and possible death.

Heat exhaustion

What happens to the body?
  • Headache and nausea.
  • Dizziness and fainting or passing out.
  • Fatigue and weakness.
  • Moist, clammy skin — pale or flushed.
  • Decreased and dark colored urine.
  • Rapid pulse.
  • Normal or slightly elevated temperature.
What should be done?
  • Move victim to a cool shaded area to rest. Don’t leave individual alone.
  • If the victim appears dizzy or light headed, have the individual lie on his/her back and raise the legs about 6-8 inches.
  • If nauseated, have the victim lie on his/her side.
  • Loosen and remove any heavy clothing.
  • Provide a small cup of cool water every 15 minutes (if the victim is not nauseated).
  • Cool by fanning, misting the skin with cool water, or applying a wet cloth.
  • If the victim does not feel better in a few minutes, call for emergency help.
NOTE: If heat exhaustion is not treated, the illness may advance to heat stroke.

Heat stroke — A medical emergency

What happens to the body?
  • Hot, dry skin ( usually no sweating).
  • Skin red, mottled, or bluish.
  • Rapid pulse.
  • Confused, loss of consciousness, convulsions.
What should be done?
  • Call for emergency help and start cooling the victim immediately.
  • Move the victim to a cool shaded area.
  • Lay the victim on his/her back. If the individual is having convulsions, remove any objects close by to prevent striking against them.
  • If nauseated, have the victim lie on his/her side.
  • Remove any heavy and outer clothing.
  • Provide a small cup of cool water every 15 minutes (if the victim is alert and not nauseated).
  • Cool by fanning, misting the skin with cool water, or applying a wet cloth or sheet.
  • If ice is available, place ice packs under the victim’s arm pits and groin area.

How to protect your employees

Provide employees with information regarding heat-induced illnesses. Train them to recognize the signs and symptoms of these illnesses; possible adverse health effects of exposure to heat; appropriated medical treatments to help themselves and fellow employees; and who to contact if a heat-related emergency occurs.
Other safety tips include drinking plenty of cool water (one small cup every 15-20 minutes); wearing light, loose-fitting, breathable (like cotton) clothing; and avoiding eating large meals before working in hot environments. They should avoid caffeine and alcoholic beverages because these beverages make the body lose water and increase the risk for heat illnesses.

Allow employees to:
  • Slowly build up tolerance to the heat and the work activity (usually takes about two weeks).
  • Perform the heaviest work in the coolest part of the day.
  • Take frequent short breaks in cool shaded areas. This allows their body’s to cool down.
  • Drink plenty of cool fluids.
Risks for heat-induced illnesses increase when:
  • Taking certain medications. Have employees check with their doctor, nurse, or pharmacy to find out if any medicines they are taking are affected by hot environments.
  • Individuals have had a heat-induced illness in the past.
  • Wearing personal protective equipment (like respirators or protective suits).

OSHA and hot environments

Although federal OSHA does not have a specific regulation covering heat stress hazards, the General Duty Clause of the Occupational Safety and Health Act of 1970 requires employers to furnish a place of employment that is free from recognized hazards that are causing or are likely to cause death or serious physical harm. OSHA has used the General Duty Clause to cite employers that have allowed employees to be exposed to potential serious physical harm from excessively hot work environments.

Temperature Extremes

A comfortable work environment is the result of a balance between temperature, humidity, and air distribution. The ambient environment is important because it influences the rate at which a person’s body heat is exchanged with the environment and consequently, the ease with which the body maintains a normal temperature. Ideally, everyone should have a comfortable working environment; however, there are some jobs that require people to work in extremely cold or hot temperatures. If you have employees who are exposed to extreme temperature conditions, you need to ensure that they are adequately protected.

Hot environments

Many people spend at least part of their working day in a hot environment. Hot workplace conditions can lead to harmful heat stress. Heat stress may result in several illnesses as well as decreased productivity and increased likelihood of injuries. In foundries, steel mills, bakeries, smelters, and glass factories, extremely hot or molten material is the main source of heat. Outdoor occupations such as construction, road repair, logging, telecommunications, electric power utilities, and agriculture expose workers to summer sunshine and heat. In laundries, restaurant kitchens, and canneries, high humidity adds to the heat burden. All these situations have the potential to create a work environment which can overcome the body’s ability to deal with heat.

Cold environments

People who work in freezer plants, meat-packing houses, cold storage facilities, lumbering, telecommunications, and electric utilities are often exposed to cold environments. The frequency of worker accidents is higher in cold environments because nerve impulses are inhibited and hands can stiffen and become clumsy. Temperature-related safety problems include ice, snow blindness, reflections from snow, and burns from skin contact with cold, metal surfaces.

The main factors contributing to cold injury are exposure to humidity and high winds, contact with wetness or metal, inadequate clothing, age, and general health. Contributing physical conditions include allergies, vascular disease, excessive smoking and drinking, sedative drugs, and some medicines. Cold disorders are classified as generalized as in hypothermia or localized such as frostbite.

The following information provides guidance to help make your workers’ job conditions as comfortable as possible without compromising their safety and health.

Revision 12/06 Electric Power, Generation, Transmission, and Distribution

In January of 1994, OSHA issued a new standard, 1910.269, to protect the safety and health of workers who operate and maintain electric power generation, transmission and distribution installations. It also revised the electrical protective equipment requirements for general industry with performance-oriented rules and issued standards for the safe use and care of electrical protective equipment. Compliance with OSHA’s rule and related revisions is expected to prevent about 60 worker deaths and more than 1,600 serious injuries annually which are caused by inadequate electrical protective equipment and training.


Existing electrical regulations contained in Subpart S of the General Industry Standards (29 CFR Part 1910) address electric utilization systems. Subpart S protects most employees from the hazards associated with such electric utilization equipment as lighting fixtures, appliances and portable electric tools and with the premises wiring that supplies this equipment.

However, Subpart S does not contain requirements protecting employees from the hazards arising out of the operation and maintenance of electric power generation, transmission or distribution installations. Employees performing work on or nearby these installations face far greater electrical hazards than those faced by other workers performing work on or nearby electric utilization systems covered by Subpart S. The voltages involved are much higher, and a large part of their work involves potential exposure to energized parts of the power system.
Employees engaged in the construction of electric power transmission or distribution systems are protected by the provisions of Subpart V of the Construction Standards (29 CFR Part 1926).

Management and labor representatives from the electric utility industry requested OSHA to adopt a set of rules on the operation and maintenance of power generation, transmission and distribution installations. Toward this end, these representatives of management and labor developed a draft standard and submitted it to OSHA. The agency used their draft, along with relevant national consensus standards, as a basis for a rule.

The final rules add a section addressing electric power generation, transmission and distribution to Subpart R of the General Industry Standards (29 CFR Part 1910) and revise the electrical protective equipment section.

Elements of the rule

Provisions of the rule protect workers engaged in the operation and maintenance of electric power generation, transmission and installations including those doing the high-voltage and high-power testing associated with such systems.

29 CFR 1910.269 covers the following types of work operations:
  • training
  • enclosed spaces
  • hazardous energy control
  • working on or near energized parts
  • deenergizing lines and equipment
  • grounding for employee protection
  • work on underground electrical installations and overhead lines
  • line-clearance tree trimming
  • work in substations and generating plants
  • other special conditions and equipment unique to the generation, transmission and distribution of electric energy
This regulation applies to electric power generation, transmission and distribution installations, whether owned by a utility or not. The electric utility, other general industry and associated contract employers must comply with this standard.

Industrial generation, transmission and distribution installations at industrial plants are essentially the same as those of an electric utility, and their operation and maintenance is similar.

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