Heat stress training is for frontline workers, warehouse staff and safety managers in hot environments. Indoor workplaces such as commercial laundries, bakeries and warehouses count, since machinery adds radiant heat. New employees and workers new to the heat are at highest risk. The 10-minute video is in English, with Spanish and French closed captions.

OSHA has proposed a federal heat illness prevention standard, but no final rule is in effect yet. Meanwhile, OSHA enforces heat hazards through the General Duty Clause, Section 5(a)(1) of the OSH Act. OSHA also runs a National Emphasis Program on heat. Some states, such as California, already have their own heat rules.

Heat exhaustion causes heavy sweating, weakness, dizziness, nausea and headache, and usually improves with rest, shade and fluids. Heat stroke is a medical emergency in which body temperature climbs dangerously, causing confusion, slurred speech, seizures or collapse, sometimes with sweating stopped. Call 911 immediately for suspected heat stroke.

The 20 percent rule for heat acclimatization limits a new worker to 20 percent of normal heat exposure time on day one. Exposure then increases by no more than 20 percent each day. Full acclimatization generally takes 7 to 14 days and fades after time away from the heat.

The OSHA-NIOSH Heat Safety Tool is a free smartphone app that calculates the heat index for your location and shows the current risk level. For each level, the app lists protective measures such as water, rest, shade and monitoring. The app also reviews heat illness symptoms and first aid.