Working in the Heat

When is hot too hot?

Legislation is not always specific about the acceptable temperature range for working in the heat, especially when working outdoors. Some jurisdictions have adopted Threshold Limit Values for heat stress from the American Conference of Governmental Industrial Hygienists, while others use them as guidelines.

You can take measures to protect workers from heat stress and related disorders by avoiding extreme heat, sun exposure, high humidity, and heavy work, when possible.

• Provide breaks to rest and cool off, preferably in the shade or an air-conditioned space.
• Set up shade structures. Umbrellas, buildings, and trees can also shield workers from sun exposure. Note: You can still get sunburn on a cloudy day.
• Provide plenty of water. Workers should drink a cup every 15 to 20 minutes, thirsty or not, and avoid caffeine and alcohol.
• Gradually increase workload and heat exposure to give workers time to adjust.
• Schedule less strenuous tasks between 11 a.m. and 4 p.m. when the sun's rays are strongest.
• Make sure outdoor workers wear light, loose-fitting clothing, UV-rated sunglasses and a wide-brim hat. Provide sunscreen with a sun protection factor (SPF) of at least 30 and UVA/UVB protection. Allow workers to re-apply every two hours and after sweating.
• Be aware that protective clothing or personal protective equipment may increase the risk of heat-related illnesses.
• Provide education and training about heat-related illnesses, including how to recognize symptoms and seek medical help. Encourage workers to watch for symptoms in others.

When working in the heat, workers may feel

• Increased irritability
• Loss of concentration and ability to do mental tasks
• Loss of ability to do skilled tasks or heavy work

Symptoms of heat exhaustion

• Nausea
• Heavy sweating
• Headache
• Cold, pale, moist skin
• Muscle cramps
• Dizziness
• Fatigue

How to respond
Move the worker to a cooler, shaded location.
Remove as much clothing as possible, including socks and shoes.
Apply cool wet cloths or ice to the head, face or neck. Spray with cool water.
Give the worker water, clear juice or a sports drink.
Provide medical aid if the worker does not start to feel better.
Stay with the worker until help arrives.

Symptoms of heat stroke

• Nausea
• Hot, dry skin
• Loss of consciousness
• Confusion
• Strange behaviour
• High body temperature
• Headache

Call 911 immediately. This is a medical emergency. Stay with the worker until help arrives.