Extreme heat in the workplace is more than an issue of discomfort. Hot surfaces and steam, sweaty palms and slippery hands, dehydration, the ever-present threat of heat stress — all of this spells danger in the workplace. Here’s how you can stay safe and healthy.

Between 1979 and 2002, exposure to excessive heat caused 8,966 deaths in the United States alone, with more people dying from extreme heat than from hurricanes, lightning, tornadoes, floods and earthquakes combined, according to the Centers for Disease Control and Prevention (CDC).

A record-breaking West Coast heat wave is pushing the mercury past the 110-degree mark, while an excessive-heat warning has been issued for parts of the Northeast, where increasing humidity and temperatures are expected to boost the heat index to 105 degrees Fahrenheit (41 Celsius). Temperatures last week climbed so high that authorities warned residents of southern Nevada, southeastern California and northwestern Arizona that outdoor activities could be dangerous except during the cooler early morning hours.

Working in a hot environment lowers the mental alertness and physical performance of an individual, while increased body temperature and physical discomfort promote irritability, anger and other emotional states that can cause workers to overlook safety procedures or to divert attention from hazardous tasks.

Palms get sweaty and slippery, safety glasses get foggy, personal protective equipment (PPE) becomes unbearable to wear, hot surfaces and steam lead to burns, Plant Services has made clear. And of course, there is the ever-present threat of heat stress.

When the body is unable to cool itself by sweating, several heat-induced illnesses such as heat stress or heat exhaustion and the more severe heat stroke can occur. During unusually hot weather lasting longer than two days, the number of heat illnesses usually increases. This is due to several factors, such as progressive body fluid deficit, loss of appetite (and possible salt deficit), buildup of heat in living and work areas and breakdown of air-conditioning equipment, according to the National Institute for Occupational Safety and Health (NIOSH)’s Working in Hot Environments.

Factors that lead to heat stress include high temperature and humidity; direct sun or heat; limited air movement; physical exertion; poor physical condition; some medicines and inadequate tolerance for hot workplaces, according to the Occupational Safety & Health Administration (OSHA). The effects of heat stress range from simple discomfort to life-threatening illnesses such as heat stroke.

Plant Services provides the following three strategies for assessing and controlling heat stress:

Step 1. Evaluate heat stress to identify personnel who have a high risk of heat strain. The Wet Bulb Globe Temperature (WBGT) screening criteria established by the American Conference for Governmental Industrial Hygienists (ACGIH) is the most commonly used method of monitoring of potential heat stress.

Step 2. Monitor and limit heat strain for high-risk personnel. One option of monitoring heat strain is to use an ear thermometer to monitor the person’s core temperature. Every worker who works in extraordinary conditions that increase the risk of heat stress should be monitored personally.

Step 3. Implement heat-stress control strategies. Consider a combination of engineering controls, administrative and work practice controls, and PPE to manage heat stress. This step should also be incorporated into Steps 1 and 2 as appropriate.

One of the best ways to reduce heat stress on workers is to minimize heat in the workplace, NIOSH’s classic publication advises.

Moreover, OSHA recommends the following:

• Reduce the physical demands of work, such as excessive lifting or digging with heavy objects.

• Provide recovery areas, such as air-conditioned enclosures and rooms.

• Use shifts like the early morning or the cool part of the day, or night work.

• Use intermittent rest periods with water breaks.

• Use relief workers.

• Use worker pacing.

• Assign extra workers and limit worker occupancy, or the number of workers present, especially in confined or enclosed spaces.

However, there are some work environments where heat production is difficult to control, such as when furnaces or sources of steam or water are present in the work area or when the workplace itself is outdoors and exposed to varying warm weather conditions.

If this is the case, a special effort should be made to adhere rigorously to the above preventive measures and to manage heat stress.

Training is the key to good work practices. Unless all employees understand the reasons for using new, or changing old, work practices, the chances of such a program succeeding are reduced greatly.

NIOSH states that a good training program on heat stress should include at least the following components:

• Knowledge of the hazards of heat stress;

• Recognition of predisposing factors, danger signs and symptoms;

• Awareness of first-aid procedures for, and the potential health effects of, heat stroke;

• Employee responsibilities in avoiding heat stress;

• Dangers of using drugs, including therapeutic ones, and alcohol in hot work environments;

• Use of protective clothing and equipment; and

• Purpose and coverage of environmental and medical surveillance programs and the advantages of worker participation in such programs.

Finally, although some high-tech solutions to heat stress are now available — such as thermally conditioned clothing with a self-contained air conditioner, ice vests, wet clothing, water-cooled garments and circulating air — not all employers can afford such products. Nevertheless, OSHA’s Technical Manual suggests other ways to add cool ingredients, recognizing five major types of engineering controls to reduce heat stress: ventilation, air cooling, fans, shielding and insulation.

Earlier: When You Have a Hot Staff, Look Out!

Resources

OSHA’s Technical Manual

Heat Stress Management: Assessment and Control Strategies
Plant Services, 2007

How to Help Workers Stand the Heat
by Caron Mason
Plant Services, 2005

Working in Hot Environments
National Institute for Occupational Safety and Health (NIOSH)

Additional

American Industrial Hygiene Association

OSHA’s Working Outdoors

OSHA’s Heat Stress Card

NIOSH’s Working in Hot Environments

Online Library: Heat Stress
Oklahoma State University

Extreme Heat: A Prevention Guide to Promote Your Personal Health and Safety
Center for Disease Control