Recognize the hazard — There is no exact cut-off point below which work in heat is not a risk. Even work in 70 degrees can be risky if it’s heavy work at high relative humidity, or if workers are wearing protective clothing. With California’s typical relative humidity of 20 percent to 40 percent, employers need to take actions to reduce heat stress when temperatures reach 80 degrees, he says. If it’s above 90 degrees and the work is heavy, that’s a major risk.

Provide plenty of water —There must be an adequate supply of clean, cool, potable water. Workers in the heat need to drink three or four glasses of water per hour, including at the start of the shift, to replace water lost to sweat. That equates to two or more gallons per person in an eight-hour day. Also, thirst isn’t a reliable indicator of dehydration, so workers often have to be reminded to keep drinking water.

Provide shade — Direct sunlight can add as much as 15 degrees to the heat index, so work should be done in the shade if possible, Faber says. If not, where possible, employers need to provide a shaded area for breaks and for when employees need relief from the sun. Wide-brimmed hats are also advised.

Acclimatization is important — People need time for their bodies to adjust to heat, particularly if they’re returning after a prolonged absence, recent illness, or moving from a cool to a hot climate. For hard work in hot conditions, Faber suggests starting with shorter periods and working up to a full shift over 4 days to 10 days.

Provide rest breaks — Breaks reduce internal heat load and provide time for cooling, as well as an opportunity to drink water. They should be taken in cooler, shaded areas.

Recognize illness symptoms — Employers should watch for early warning signs such as headache, muscle cramps, and unusual fatigue, and provide an effective response. Illness can rapidly get more severe and can include unusual behavior, nausea and vomiting, weakness, rapid pulse, excessive sweating or hot, dry skin, seizures and fainting, or loss of consciousness. Any of these symptoms require immediate attention, Faber says, and no employee with any of the symptoms should be sent home or left unattended.

Provide training — Supervisors and employees must learn about the risks of heat illness and measures to protect themselves and their co-workers. This training should include how to contact emergency services, and how to effectively report the work location to 911.