Photo: Adobe Stock | Anna Baburkina

Spring in the Midwest can be unpredictable, with frigid temperatures at the start of the week and unseasonably high temperatures at the end of the week. Conditions like this can make outdoor workers more susceptible to heat-related illnesses because they do not have time to acclimatize to heat and humidity.

According to the U.S. Occupational Safety and Health Administration (OSHA), employees who are new to working outdoors also are more likely to experience heat-related illnesses. The agency suggests gradually increasing these employees’ workloads or allowing for more frequent breaks as they build up their tolerance to the heat.

While OSHA does not have a specific standard for working in hot environments, the agency says that under the Occupational Safety and Health (OSH) Act of 1970, “employers have a duty to protect workers from recognized serious hazards in the workplace, including heat-related hazards.”

With this duty in mind, companies should have hot weather plans in place, and they should go into effect when the heat index reaches 80 F, OSHA advises.

Monitor the heat index

Overheating can occur for two reasons: environmental conditions and internal heat generated by labor.

To understand the risk present to outdoor workers from the environment, employers should consult the heat index, which takes into account temperature and humidity.

The U.S. National Oceanographic and Atmospheric Administration (NOAA) says it developed the heat index for shady conditions with light winds present. Working in direct sunlight also increases workers’ risk for developing heat-related illnesses, increasing the heat index by up to 15 F.

“The higher the heat index, the hotter the weather feels since sweat does not readily evaporate to cool the skin,” OSHA says.

While high humidity interferes with sweat evaporation and the natural cooling process, low humidity also poses a risk because of the high evaporation rate, which can result in dehydration if workers don’t drink enough water, OSHA warns.

NOAA’s National Weather Service says it issues alerts when the index is expected to exceed 105 F to 110 F for at least two consecutive days.

In addition to taking extra precautions for new workers when the heat index is elevated, OSHA also advises doing so for workers who are engaged in strenuous activity and for those wearing heavy or nonbreathable clothing.

To help with monitoring heat index values, OSHA offers its Heat Smartphone App, available at The app also offers reminders about protective measures to take at the risk level specified.

Have a response plan in place

OSHA says employers should take the same steps to respond to an elevated heat index as they would to other workplace hazards:

  • Develop an illness prevention plan.
  • Train workers to recognize and prevent heat-related illnesses.
  • Track the workplace heat index daily, communicating it to employees as well as required precautions.
  • Implement your plan, reviewing it and revising it throughout the summer.

According to OSHA, a company’s illness prevention plan should include a number of measures:

  • ensuring adequate water and other supplies, such as cold compresses and ice packs, as well as provisions for rest areas;
  • emergency planning and response;
  • worker acclimatization that includes increasing workloads gradually and allowing more frequent breaks;
  • modified work schedules (This only becomes necessary when the threat ranges from moderate to very high or extreme.);
  • training that enables workers to recognize heat-related illnesses and preventive measures; and
  • physiological, visual and verbal monitoring for signs of heat-related illnesses. (This step becomes necessary when the heat index ranges from moderate to very high or extreme.)

The agency suggests training employees on the plan before temperatures start to rise and reinforcing training on hot days.

Take protective measures

Workers should be encouraged to wear sunscreen and to stay hydrated by drinking water and not soda or other drinks that contain sugar or caffeine, OSHA advises; sugary and caffeinated drinks may lead to dehydration. Employees should aim for 32 fluid ounces of water per hour when the heat index ranges from moderate to very high or extreme. The agency also suggests discouraging employees from drinking alcohol after work during extended periods of hot weather.

OSHA recommends a range of other protective measures as the heat index rises:

With these protective measures in mind, a company can engage in its most essential tasks while safeguarding its employees from heat-related illnesses.

The author is managing editor of Recycling Today and can be contacted at