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Protective Measures to Take at Each Risk Level

Drinking Water

Water should have a palatable (pleasant and odor-free) taste and water temperature should be 50°F to 60°F, if possible.

Sanitation standard 29 CFR 1910.141 requires that employers provide "potable water" at work sites, which is water that meets the drinking water standards of the state or local authority having jurisdiction, or water that meets the quality standards prescribed by the U.S. EPA’s drinking water regulations (40 CFR Part 141).

Actions for Lower (Caution) Risk Conditions:
Heat Index is Less Than 91 degrees F

Most people can work safely when the heat index is <91°F with only basic measures for worker safety and health, as required by the OSH Act. As minimum measures, employers have a duty to:

  • Provide adequate amounts of drinking water in convenient, visible locations close to the work area.
  • Ensure that adequate medical services are available. Where medical services (e.g., emergency medical services, clinic, hospital) are not available within 3-4 minutes, have appropriately trained personnel and adequate medical supplies on site. The trained personnel should have a valid certificate in first aid training from the American Red Cross or equivalent training. (A first aid certificate is required at maritime and construction worksites.)

Additional precautions are advisable based on site conditions, work load, and protective clothing use:

  • Take actions described for Moderate Risk Conditions (91°F - 103°F) if heat index is close to 91°F OR work is being conducted in direct sunshine or without a light breeze.
  • Follow additional precautions for workers wearing heavy or non-breathable clothing or impermeable chemical protective clothing because they are at greater risk even when the risk to other workers is lower. Workers in heavy, non-breathable or "impermeable" protective clothing can experience heat-related illness at temperatures as low as 70°F. Monitor them closely for signs of heat-related illness and see the section on Taking Added Precautions for High Risk Conditions.
  • Acclimatize new and returning workers performing strenuous work. These individuals may be at high risk for heat-related illness, even when the heat index is low.
  • Check the weather forecast regularly in warm seasons to learn if more extreme hot weather conditions are predicted. Make sure your hot weather plans are in place and that workers are trained before hot outdoor work begins. Train workers on how to recognize symptoms of heat-related illness, individual risk factors for heat-related illness, how to prevent it, and what to do if someone has symptoms so they are prepared when hotter, higher-risk work conditions arise.
  • Encourage workers to wear sunscreen and use other protections from direct sunlight. Provide shade, hats, and sunscreen, when possible. Sunburn reduces the skin's ability to release excess heat, making the body more susceptible to heat-related illness.

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Heat Index Risk Level Protective Measures
Less than 91°F Lower (Caution) Basic heat safety and planning
91°F to 103°F Moderate Implement precautions and heighten awareness
103°F to 115°F High Additional precautions to protect workers
Greater than 115°F Very High to Extreme Triggers even more aggressive protective measures


OSHA is a Weather-Ready Nation Ambassador committed to working with NOAA and other Ambassadors to strengthen national preparedness for and resilience against extreme weather
OSHA is a Weather-Ready Nation Ambassador committed to working with NOAA and other Ambassadors to strengthen national preparedness for and resilience against extreme weather.


How can OSHA help? Workers have a right to a safe workplace. If you think your job is unsafe or have questions, visit OSHA's Worker's Page or call 1-800-321-6742 (OSHA). It's confidential. For other valuable worker protection information, such as Workers' Rights, Employer Responsibilities, and other services OSHA offers, visit OSHA's Workers' page.

OSHA also provides help to employers. OSHA's On-site Consultation Program offers free and confidential advice to small and medium-sized businesses in all states across the country, with priority given to high-hazard worksites. For more information or for additional compliance assistance contact OSHA at 1-800-321-6742 (OSHA).