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OSHA’s National Emphasis Program – Outdoor & Indoor Heat-Related Hazards

As Originally Seen in the July/August Issue of Industrial Hygiene in the Workplace


On a warm, summer day in July, a 42-year-old man was on his way to work for his new job as a roofer. When he arrived, there was plenty of water, ice and drinks available at the site for him to hydrate throughout the day. It was only his third day on the job, and he got straight to work. The high temperature was about 86°F and a relative humidity of 57%, for a heat index of 90°F. Later that afternoon, the man told his colleagues he wasn’t feeling well. He climbed down from the roof and sat out of the sun. When his co-workers checked on him a few minutes later, he had developed symptoms of heat stroke. He was taken to nearby hospital where he died shortly after. (See OSHA’s case studies link, below.)

Cases like the one above demonstrate why the new Outdoor and Indoor Heat-Related Hazards standard and the National Emphasis Program (NEP) are so important to keeping workers safe. The NEP protects employees from heat-
related hazards and the resulting injuries and illnesses in outdoor and indoor workplaces. The standard expands on the agency’s ongoing heat-related illness prevention initiative and campaign by setting forth targeted enforcement components and reiterating its compliance assistance and outreach efforts. This tactic is intended to urge early interventions by employers to prevent illnesses and deaths among workers during high heat conditions, such as working outdoors in a local area experiencing a heat wave. Early prevention measures include implementing water, rest, shade, training and acclimatization procedures for new/returning employees.

Why the Standard Matters

Millions of American workers are subjected to heat in their work environment and, even though illness from heat exposure is preventable, every year thousands become sick from occupational heat exposure. And, as noted in the above case study, some exposures can be fatal. According to OSHA, “Most outdoor fatalities, 50-70%, 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.” This process is called heat acclimatization, and the lack of acclimatization represents a major risk factor for fatal outcomes.

Occupational risk factors for heat illness include heavy physical activity; warm or hot environmental conditions; lack of acclimatization; and wearing clothing that holds in body heat.

Hazardous heat exposure can occur indoors or outdoors—and during any season, if the conditions are right—not only during heat waves.

Some outdoor industries where workers have suffered heat-related illnesses include:

  • Agriculture
  • Construction—road, roofing and other outdoor work
  • Landscaping
  • Mail and package delivery
  • Oil and gas well operation

And, some indoor industries where workers have suffered heat-related illnesses include:

  • Bakeries, kitchens and laundries (businesses with heat-generating appliances)
  • Electrical utilities (boiler rooms)
  • Fire service
  • Iron/steel mills and foundries
  • Manufacturing with hot local heat sources, like furnaces (i.e., paper products and concrete)
  • Warehousing

Key Compliance Requirements:

All industries that could potentially deal with heat-related illnesses and conditions should note the following:

  • Compliance safety and health officers (CSHOs), who are investigating for other purposes, shall open or refer a heat-related inspection for any hazardous heat conditions observed, or where an employee brings a heat-related hazard(s) to the attention of the CSHO (such as, employees or temporary workers being exposed to high-temperature conditions without adequate training, acclimatization, or access to water, rest and shade).
  • When the weather is hot or a heat alert is issued for an area where the WHD, (Wage and Hour Division) is investigating, the WHD is encouraged to coordinate with OSHA by providing information on heat-related hazards.
  • CSHOs should inquire during inspections regarding the existence of any heat-related hazard prevention programs on heat priority days. A heat priority day follows when the heat index for the day is anticipated to be 80°F or more.
  • Programmed inspections could occur on any day that the NWS (National Weather Service) has announced a heat warning or advisory for the local area.


For more information about how to properly access high temperatures in correlation with safe working practices, visit:

For Employers Administrating Heat Illness Prevention Training, read:

For Specifics on planning and supervision, visit:

To read up on more case studies, visit:

For general heat exposure guidelines, visit:

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