Working in Outdoor and Indoor Heat Environments

Millions of U.S. workers are exposed to heat in their workplaces. Although illness from exposure to heat is preventable, every year, thousands become sick from occupational heat exposure, and some cases are fatal. Most outdoor fatalities, 50% to 70%, occur in the first few days of working in warm or hot environments because the body needs to build a tolerance to the heat gradually over time. The process of building tolerance is called heat acclimatization. Lack of acclimatization represents a major risk factor for fatal outcomes.

How Can Heat-Related Illness Be Prevented?
Heat-related illness is preventable, especially with management commitment to providing the most effective controls. An effective heat-related illness prevention program is incorporated in a broader safety and health program and aligns with OSHA’s Recommended Practices for Safety and Health Programs core elements.

Workers who have not spent time recently in warm or hot environments and/or being physically active will need time to build tolerance (acclimatize or, less frequently used, acclimate) to the heat. During their first few days in warm or hot environments, employers should encourage workers to:

1. Consume adequate fluids (water and sport drinks)
2. Work shorter shifts,
3. Take frequent breaks,
4. Quickly identify any heat illness symptoms.