Hot weather can overwhelm an outdoor worker’s physical ability to stay cool, resulting in heat related illness. When temperatures increase suddenly, workers have not yet acclimated and are more susceptible to heat related illness. To better acclimate during the first hot days of spring or summer and during heat waves, drink lots of water (one quart per hour) and take breaks in the shade or a cool place to prevent overheating. Remember, personal factors also contribute to heat tolerance, such as age, fitness, medical conditions, water consumption, alcohol, caffeine use, nicotine use, previous heat related illness, pregnancy, and use of medications. Workers must self-monitor for personal factors, hydrate, and take cool-down rest periods when needed. Remove extra clothing and personal protective equipment during breaks to cool-down.
When outdoor temperatures reach the following action levels, employers/supervisors must adhere to the following requirements:
| Temperature Fo | Requirements |
| 52o Wearing non-breathable clothing, e.g. Tyvek™
80o All other clothing |
· Provide at minimum 1 quart of suitably cool drinking water per hour.
· Encourage preventative cool down breaks to prevent overheating. · Provide an air-conditioned location or shade1, for cool down breaks near the work area. |
| 90o | · Provide at minimum 1 quart of suitably cool drinking water per hour.
· Encourage preventative cool down breaks to prevent overheating. · Provide an air-conditioned location or shade1, for cool down breaks near the work area. · Mandatory 10-minute cool down breaks every 2-hours – may be incorporated into lunch break.2 · Closely observe employees for signs and symptoms of heat related illness (see next section). |
| 100o | · Provide at minimum 1 quart of suitably cool drinking water per hour.
· Encourage preventative cool down breaks to prevent overheating. · Provide an air-conditioned location or shade1, for cool down breaks near the work area. · Mandatory 15-minute cool down breaks every hour – may be incorporated into lunch break.2 · Closely observe employees for signs and symptoms of heat related illness (see next section). |
Note 1. Shade is defined as a location where objects won’t cast a shadow and must be located away from other heat sources such as radiant heat from hot objects.
Note 2. Cool down breaks must be paid, unless incorporated into unpaid meal break.
Close Observation
Employers (supervisors) must closely observe employees for signs of heat related illness under the following conditions:
- When temperatures meet or exceed 90o,
- When new employees start work, or when employees return from an absence of 7-days or more, and for 14 days thereafter,
- During heat waves.3
Note 3. Heat waves are defined as any day when temperatures meet or exceed 80o and are 10o Fahrenheit higher than the previous 5 day’s average high temperature.
Implement one or more of the following methods to closely observe employees for signs of heat related illness:
- Regular cell phone or radio communication, or
- Implement a buddy system, or
- Some other means of effective observation.
Supervisors must inform employees of the following:
- The means of observation during acclimatization periods,
- Where to cool down during encouraged or required breaks,
- Where to cool down or take a coworker to cool down when suffering from symptoms of heat related illness.
When possible, supervisors should schedule outdoor work during the cooler hours of the day.
Employees assigned to work outdoors for more than 15 minutes in any given hour must complete Heat Stress training each year before it gets hot. That training will familiarize employees with the following signs and symptoms of heat related illness and the actions to take when experiencing those symptoms or observing them in a coworker.
| Illness | Symptoms | Treatment: What to Do |
| Heat Rash | · Red clusters of small blisters that look like pimples on the neck, chest, groin or in elbow creases | · Stay in a cool dry place
· Keep rash dry |
| Sunburn | · Painful red and warm skin
· Blisters on the skin |
· Stay out of the sun until your sunburn heals
· Put cool cloths on sunburned areas or take a cool bath · Do not break blisters |
| Heat Cramps | · Heavy sweating
· Muscle pain or spasms |
· Stop physical activity and move to a cool place
· Drink water or a low sugar sports drink · Wait for cramps to go away before resuming activity Get medical help immediately if: · Cramps last longer than 1 hour · You’re on a low sodium diet · You have heart problems |
| Heat Exhaustion | · Heavy sweating
· Cold, pale, and clammy skin · Fast, weak pulse · Nausea or vomiting · Muscle cramps · Tiredness or weakness · Dizziness · Headache · Fainting |
· Move to a cool place
· Loosen your clothes · Put cool, wet cloths on your body, or take a cool bath · Sip water Get medical help immediately if: · You are throwing up · Your symptoms get worse · Your symptoms last longer than 1 hour |
| Heat Stroke | · High body temperature (103oF or higher
· Hot, red, dry, or damp skin · Fast, strong pulse · Headache · Dizziness · Nausea · Confusion · Losing consciousness |
· Call 911 immediately
· Move the person to a cooler place · Help lower the person’s temperature with cool cloths or a cool bath · Do not give the person anything to drink |