Manage an Outdoor Work Crew on a Hot Day
OSHA's heat exposure rule sets specific water, rest, and shade requirements indexed to heat index. Here is the operational version of the rule.
- 1
Read the heat index every two hours
Bring a digital weather station to the job site, or use the calculator on this page. Air temperature alone is not enough, humidity changes the math substantially. Read at 8 AM, 10 AM, noon, 2 PM, 4 PM. Log the values; if OSHA audits a heat illness incident, this log is the first thing they ask for.
- 2
Apply the water-rest-shade schedule
Heat index 80 to 90 F: 1 cup water every 20 minutes available, shade access at break time. Heat index 90 F+: 1 cup water every 15 minutes, mandatory 15-minute shade rest every hour. Heat index 105 F+: stop nonessential work, mandatory 30-minute rest each hour, two workers paired (no solo work).
- 3
Acclimatize new workers progressively
Workers in their first 14 days on a hot job have 70% of OSHA heat fatality risk. Day 1: 20% of full workload. Day 2: 40%. Day 3: 60%. Day 4: 80%. Day 5: full. This applies to actual new hires and to seasonal returners who have been on an indoor or cool job for over 2 weeks.
- 4
Brief the crew on symptom recognition
5-minute toolbox talk at start of day during hot conditions. Cover: heat exhaustion (heavy sweating, weakness, nausea) needs immediate shade and water; heat stroke (confusion, dry hot skin, slurred speech) needs 911 and aggressive cooling. Workers should buddy up and call out symptoms in each other.