During hot summer days, we sweat, and often complain about being exhausted "just from the heat". This discomfort reflects a process that the human body is using to keep its core temperature at a safe level. The body is like a machine, and as every machine creates heat when it uses energy to run, so too does the human body. The body generates heat when it runs its inner metabolic processes. Real is also supplied by the outside environment as hot and humid weather, by hot objects (like furnaces) or hot places (like being inside a chemical suit or firefighter's turnout gear). There are times and situations when heat is not just a discomfort, but dangerous.
Just checking the thermometer is not an accurate measure of potential heat hazards. A number of factors work together to make heat in the workplace a hazard. These include humidity, air temperature, air movement and radiant heat. Additional factors to consider are the physical condition of workers, work load and pace, and worker acclimatization to heat. Common sense will tell you that working moderately in a well- ventilated setting, with low humidity at 80 degrees is very different from working in the same temperature with high humidity and a heavier work load.
The most accurate measurement of heat hazards can be done with a Wet Bulb Globe Thermometer (WBGT), which takes humidity and radiant heat into account as well as the air temperature. Its readings are often lower than the readings of a regular thermometer. Any testing should be done under normal working conditions as close to the work as possible.
The body's internal core temp must be maintained within a fairly rigid range of temperature. This core temperature, is 99.5 degrees, plus or minus 1.8 degrees. Determined to maintain that core temperature, the body strives to strike a balance between the amount of heat produced internally and the amount of beat lost (or gained) to the outside environment. This is done largely through sweat. As sweat evaporates, it takes heat with it. Work harder and the body will crank up the heat exchange system: you sweat more. The internal core temperature stays within safe ranges as long as this heat/cooling mechanism functions properly. But, if it is very hot or humid, if work is near a furnace or other heat source, or workers wear chemical protective clothing, the mechanism of heat exchange can be altered dramatically. When that happens you can get sick.
HEAT CRAMPS are painful cramps in the legs, arms or stomach muscles. It is the same problem that athletes suffer during a game. Cramps may occur later, after work. The key is to replace the salt lost through sweating. Once it was common to take salt tablets, but that practice has been discouraged. Usually a normally salted diet will help. If not, lightly salted fluids can help.
HEAT STROKE results when your body's cooling system breaks down under stress and sweating stops. A heat stroke victim's skin is hot, dry and usually red or spotted. Body temperature is 105 degrees or higher. The worker may be mentally confused, irritable and complain of feeling chilled. If the person is not removed from the heat and cooled down, severe symptoms will appear, such as unconsciousness or convulsions. Death may result In three out of four beat stroke fatalities, the victims had left the job site and were on their way home when they collapsed.
Treatment for heat stroke: remove from heat, soak clothes thoroughly with water and fan the body to increase cooling.
HEAT EXHAUSTION victims have clammy skin, pale or flushed complexion and a normal or slightly high body temperature. They experience extreme weakness, fatigue, nausea or headache. In extreme cases they may vomit or pass out. Treatment, move to a cool place and administer lots of liquids.
HEAT FATIGUE, resulting from prolonged heat exposure, causes a decline in coordination, alertness, and performance. With so much blood going to the periphery of the body, less is available for muscles. Strength drops and fatigue kicks in sooner than otherwise. Accidents are more likely to happen. For example, accident rates for heavy machine operators double when they work in hot environments.
SUSCEPTIBILITY TO OTHER TOXINS. Heat stress can aggravate the effect of other toxins. Dehydration and loss of minerals through sweat decreases the body's ability to detoxify chemicals. Because the circulatory system is under strain other hazards increase. Carbon monoxide, which reduces oxygen supply to the tissues, is of particular concern. Because of this, standards for other substances should be adjusted downward for workers in hot environments.
An inspection of the workplace, taking stock of the following considerations, can help determine in advance if heat is likely to be a hazard:
Are ventilation systems adequate?
Are "hot" work processes isolated, insulated and ventilated?
Does management have a heat stress training program?
Does management have a heat wave emergency plan?
Does management have heat emergency first aid procedures on line?
Are there steam leaks or other sources of water vapor in the air?
Is work uncomfortable under "normal" temperature conditions?
If it is, what will it be like in higher temperatures?
Michigan OSHA has not set a limit (or any regulations) on heat exposure. The only recourse available under the regulations is the General Duty Clause of your union contract.
Two other agencies, the American Conference of Governmental Industrial Hygienists (ACGIH), and the National Institute on Occupational Safety and Health (NIOSH) have made heat exposure recommendations (see chart for NIOSH recommendations). Although these are not enforceable, you may find them useful ammunition in the fight against heat hazards.
More work slowdowns, walkouts and similar job actions occur over heat problems than any other workplace hazard. Many of these are effective in getting short run solutions. But getting a permanent solution to heat hazards is more time consuming and difficult. Planning ahead and developing an organizing plan around this issue could help. Here are some things to work for:
Better ventilation, to draw heat and steam away from work areas, and person- cooling fans to increase air speed and increase sweat evaporation. Fans do not work effectively above 95 degrees (dry bulb thermometer).
Training programs for management and workers that target recognition of heat hazards, symptoms, first aid, engineering controls, use of protective equipment and other procedures.
Revised work schedules during heat waves. Increasing breaks and reducing exposure should be seen as the number one control of heat hazards. Heavier work can be done during cooler times. Overtime should be reduced during heat waves and slower work pace during hot weather.
Cool rest areas (76 degrees) near the work area for breaks.
Isolation or insulation of hot equipment. Shielding between workers and heat sources.
Cool drinking water, near the work area, up to 2 gallons per worker per day.
"Cool down periods" after work shifts.