Occupational Safety and Health Administration OSHA


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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.

Other Drinks

Encourage workers to choose water over soda and other drinks containing caffeine and high sugar content. These drinks may lead to dehydration. Drinks with some flavoring added may be more palatable to workers and thereby improve hydration. Encourage workers to avoid drinking alcohol after work shifts, during hot weather events.

Use the protective measures described for each risk level to help you plan ahead, and schedule and train your workers so that everyone is prepared to work safely as the heat index rises.

Actions for Low Risk Conditions: Heat Index Less Than 91°F

Actions for Moderate Risk Conditions: Heat Index is 91°F to 103°F

Actions for High Risk Conditions: Heat Index is 103°F to 115°F

Actions for Very High to Extreme Risk Conditions: Heat Index Greater Than 115°F

Summary of Risk Levels and Associated Protective Measures

The most critical actions employers should take to help prevent heat-related illness at each risk level:

Heat Index Risk Level Protective Measures
Lower (Caution)
  • Provide drinking water
  • Ensure that adequate medical services are available
  • Plan ahead for times when heat index is higher, including worker heat safety training
  • Encourage workers to wear sunscreen
  • Acclimatize workers

If workers must wear heavy protective clothing, perform strenuous activity or work in the direct sun, additional precautions are recommended to protect workers from heat-related illness.*

91°F to 103°F

In addition to the steps listed above:

  • Remind workers to drink water often (about 4 cups/hour)**
  • Review heat-related illness topics with workers: how to recognize heat-related illness, how to prevent it, and what to do if someone gets sick
  • Schedule frequent breaks in a cool, shaded area
  • Acclimatize workers
  • Set up buddy system/instruct supervisors to watch workers for signs of heat-related illness

If workers must wear heavy protective clothing, perform strenuous activity or work in the direct sun, additional precautions are recommended to protect workers from heat-related illness.*

  • Schedule activities at a time when the heat index is lower
  • Develop work/rest schedules
  • Monitor workers closely
103°F to 115°F High

In addition to the steps listed above:

  • Alert workers of high risk conditions
  • Actively encourage workers to drink plenty of water (about 4 cups/hour)**
  • Limit physical exertion (e.g. use mechanical lifts)
  • Have a knowledgeable person at the worksite who is well-informed about heat-related illness and able to determine appropriate work/rest schedules
  • Establish and enforce work/rest schedules
  • Adjust work activities (e.g., reschedule work, pace/rotate jobs)
  • Use cooling techniques
  • Watch/communicate with workers at all times

When possible, reschedule activities to a time when heat index is lower

>115°F Very High to Extreme

Reschedule non-essential activity for days with a reduced heat index or to a time when the heat index is lower

Move essential work tasks to the coolest part of the work shift; consider earlier start times, split shifts, or evening and night shifts.

Strenuous work tasks and those requiring the use of heavy or non-breathable clothing or impermeable chemical protective clothing should not be conducted when the heat index is at or above 115°F.

If essential work must be done, in addition to the steps listed above:

  • Alert workers of extreme heat hazards
  • Establish water drinking schedule (about 4 cups/hour)**
  • Develop and enforce protective work/rest schedules
  • Conduct physiological monitoring (e.g., pulse, temperature, etc)
  • Stop work if essential control methods are inadequate or unavailable.

*The heat index is a simple tool and a useful guide for employers making decisions about protecting workers in hot weather. It does not account for certain conditions that contribute additional risk, such as physical exertion. Consider taking the steps at the next highest risk level to protect workers from the added risks posed by:

  • Working in the direct sun (can add up to 15°F to the heat index value)
  • Wearing heavy clothing or protective gear

**Under most circumstances, fluid intake should not exceed 6 cups per hour or 12 quarts per day. This makes it particularly important to reduce work rates, reschedule work, or enforce work/rest schedules.

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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.

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).

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