Heat Stress
This document will go over Heat Stress and Illness prevention basic information.
1. Heat Stress Causes & Symptoms
When can heat stress occur?
- Primary Trigger: Prolonged exposure to temperatures above 80°F combined with continuous physical movement or work.
- Aggravating Factors: High exertion, high humidity, low airflow, radiant heat sources, dehydration, alcohol or caffeine use, certain medications, and non-breathable clothing or heavy PPE.
Remember: Air temperature is only one factor. Work intensity, humidity, clothing, PPE, and hydration can significantly increase heat stress risk.
What are the symptoms of heat illness?
Heat Exhaustion
- Pale skin
- Muscle cramps
- Headache
- Dizziness
- Weakness or fatigue
- Hyperventilation
- Elevated heart rate
- Body temperature between 101°F and 104°F
- Nausea or vomiting
Heat Stroke — Medical Emergency
- Red or dry skin
- Excessive sweating or inability to sweat
- Body temperature above 104°F
- Confusion
- Slurred speech
- Aggression or agitation
- Hallucinations
- Seizures
- Fainting
Immediate Response: Move the person to a shaded or cooler area, begin cooling measures, and provide water when appropriate.
2. Worksite Temperature Protocols
What actions are required as temperatures increase?
80°F and Higher
- Use a buddy system or check in frequently with a supervisor.
- Monitor yourself and coworkers for signs of heat illness.
- Maintain access to clean drinking water.
- Take preventative cool-down breaks when overheated.
- Report symptoms immediately.
90°F and Higher
- Participate in pre-shift safety briefings on heat illness prevention.
- Maintain hydration and buddy-system monitoring.
- Take a mandatory 10-minute cool-down break every two hours.
100°F and Higher
- Continue all high-heat precautions.
- Increase monitoring for heat illness symptoms.
- Take a mandatory 10-minute cool-down break at least every hour.
Preventative Breaks Matter: Employees should not wait until symptoms develop before taking a cool-down break.
Hydration & Cool-Down Guidance
- Hydration: Drink water regularly throughout the shift rather than waiting until you feel thirsty.
- Water Access: Employees must have access to clean drinking water during the shift.
- Cool-Down Areas: Use open-air shade or air-conditioned spaces for recovery breaks.
- Symptom Reporting: Any heat-illness symptom should be reported to a supervisor immediately.
3. Acclimatization & Supervision
What is acclimatization and why is it important?
Acclimatization is the process of gradually adapting the body to work in hot environments over approximately 7 to 14 days.
New Workers
Limit initial heat exposure to a maximum of 20% of a full shift on Day 1, increasing exposure by no more than 20% on each subsequent day.
Experienced Workers
- Day 1: Up to 50% exposure
- Day 2: Up to 60%
- Day 3: Up to 80%
- Day 4: Up to 100%
Medical Adjustments: The acclimatization period should be extended when relevant medical conditions or other risk factors require additional adjustment.
What supervision is required during hot-weather work?
- New employees must be closely observed by a buddy or supervisor during their first 14 days of employment.
- Previously exposed employees must be observed using the buddy system whenever temperatures exceed 80°F.
- Supervisors should monitor workers for changes in behavior, coordination, speech, or physical condition.
Do Not Leave a Symptomatic Worker Alone: Heat illness can progress quickly. Maintain observation and escalate medical response when needed.
4. EHS Contact & Support
Who can I contact with questions about heat illness prevention?
Contact Environment, Health & Safety (EHS) or Environmental & Occupational Health (EOH) for support.