Title: Heat Hazards
Headings: 
Heat Hazards
Protecting Workers in Hot Environments

Content: High temperatures and humidity, direct sun exposure or radiant heat sources, limited air movement, not drinking enough fluids, physical exertion, PPE and clothing, physical condition, health problems, medications, lack of acclimatization, advanced age, previous heat-related illness—all of these can increase risk of heat-related illness. Lack of acclimatization is one risk factor that can be eliminated with some planning and effort. Acclimatization can be described as the physiological changes that occur in response to a succession of days of exposure to environmental heat stress. These changes reduce the strain caused by heat stress and enable a person to work with greater effectiveness and with less chance of heat-related illness. A recent article in Morbidity and Mortality Weekly Report showed that most OSHA citations involving heat-related illness or death of workers involved work sites with no program (or with a deficient program) to prevent heat illness. Of these programs, acclimatization was the element most commonly missing. Unacclimatized workers readily show signs of heat stress when exposed to hot environments and have difficulty replacing the water lost in sweat. Acclimatized workers have increased sweating efficiency, stabilized circulation, the ability to perform work at lower core body temperature and heart rate, and increased skin blood flow, all of which aid in heat loss. Knowing whether workers are acclimatized or not is also essential when determining an appropriate NIOSH recommended limit. Figure 3.