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Turning Heat Illness Best Practices into an Enforceable Standard

LHSFNA Management Co-Chairman Noel C. Borck

Every year, as temperatures start regularly reaching well into the 80s and 90s – and even breaking 100 in parts of the country – workers suffer. While OSHA has done a lot of campaigning and outreach urging employers to protect their workers from the dangers of heat illness, there is still no enforceable federal OSHA standard. A bill in Congress has been proposed that would require federal OSHA to issue a heat stress standard, but it is far from passage.

Heat stress standards only exist in three states (CAWAMN); two others (VAMD) are working to develop them, and several more (NC, FL and NY) are considering bills to require heat stress rules. More and more states and legislators understand that workers need to be protected from heat illness on the job.

“Without a national heat illness standard, we must continue encouraging employers to provide adequate water, rest and shade on construction jobsites,” says LHSFNA Management Co-Chairman Noel C. Borck. “Another important step is training both supervisors and workers to look for the signs of heat illness, so affected workers can be treated immediately.”

While it may seem that protecting workers from heat is relatively straightforward through the use of water, rest and shade, there are a number of important questions that need to be answered to turn these best practices into an enforceable OSHA standard.

Trigger Point

At what point is the risk high enough that employers should be required to act? How do we measure that risk? The actual temperature is an important factor, but risk for heat illness stems from many other factors as well:

  • Humidity
  • Direct exposure to sunlight (radiant heat)
  • Workload (as you work harder, your body generates heat, adding to risk)
  • Type and amount of clothing (which reduces the body’s ability to cool itself through sweating)
  • Ventilation (e.g., there is no breeze)

The OSHA-NIOSH Heat Safety app uses the NOAA heat index, which considers temperature and humidity. NIOSH’s recommended heat illness standard suggests the more sophisticated wet bulb globe temperature (WBGT), which measures temperature, humidity, radiant heat and air velocity. It can then be adjusted for workload and clothing. Working at temperatures below 90°F can often pose a risk if these other factors are high. The WBGT is more accurate than the NOAA heat index for assessing risk to workers, but it has to be calculated, unlike the daily NOAA heat index which can easily be looked up on the Internet.

Preparing to Work in the Heat

The first few days working in the heat are the most dangerous. The body has to adjust to the heat – a process called acclimatization. To protect workers, the first few days in the heat should involve less work or less intense work. For example, the Mine Safety and Health Administration (MSHA) recommends only working 50 percent of the time in the heat on Day 1, 60 percent in the heat on Day 2, and so on, so a worker wouldn’t have a full day in the heat until Day 6. They also recommend taking four days to work up to a full day following a break of nine or more days.

The California heat illness standard requires acclimatization for work at 80°F or above and “close supervision” for 14 days or during a “heat wave.” These aren’t easy provisions for employers, which may expect workers to work at full capacity on Day 1, but they are essential to prevent heat illness among new workers in hot environments.


Working in hot weather causes the body to lose a lot of water from sweating, and if it isn’t replaced, workers can quickly become dehydrated and sick. Generally, heat illness standards require cool, clean drinking water to be readily available on site. The Department of Defense recommends drinking 0.5-1 quart of water per hour, depending on the temperature and your workload. NIOSH recommends one cup of water (8 oz.) every 15-20 minutes when doing moderately heavy work in the heat. This is another very important element that must be part of any heat illness prevention rule, because the body’s thirst mechanism is insufficient to make us drink enough water to stay safe.


Working in the heat causes the body to tire more quickly, which is why it’s important to incorporate sufficient rest into the workday. Work/rest schedules developed by the EPA in the 1990s recommended resting 15 minutes each hour during moderate work in 100°F weather. For heavy work, work in Tyvek suits or work in very hot environments (e.g., boiler repair), workers would need even more rest each hour. Current recommendations also suggest that workers be able to rest in the shade or that employers provide artificial shade areas such as tents so workers can take a break from the sun. The specific provisions around rest in a heat-illness standard could be among the most difficult to determine, since some workers may require more rest than others to work safely, and this area is likely to face significant scrutiny from employers.

Waiting for a Federal Standard

Hopefully, federal OSHA and more individual states will issue a heat illness prevention standard sooner than later to protect workers from a known hazard that’s becoming more prevalent with every passing year. There are difficult issues to address given the need to maintain production, especially in an industry like construction where work is strenuous and mostly outdoors. But preventing heat illness requires that we follow these steps if we want to keep workers safe as temperatures climb.

[Scott Schneider]

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