This document provides guidance on managing heat stress in the workplace. It discusses factors that influence heat stress like temperature, humidity, and physical activity. It also outlines the symptoms of heat-related illnesses like heat rash, sunburn, and heat cramps. The document recommends a 5 step process to control heat stress which includes training workers, selecting proper clothing, measuring temperature and humidity throughout the workplace, adjusting for radiant heat sources, and using a heat stress calculator and action chart to determine appropriate actions based on the level of risk. The overall goal is to recognize symptoms, assess risk, and implement controls to help workers stay cool and safe in hot environments.

1. Heat Stress
A guide to
keeping your cool
!!!!
August 27, 2023

2. Is Heat Stress a concern in your workplace?
 Has anyone been affected by heat in your workplace?
 Are fans needed to keep workers cool?
 Is work done in direct sunlight?
 Do workers wear extra clothing/protective equipment
that can make them hot?
 Have workers ever expressed concern about heat in the
workplace?
 Chances are that you have answered YES to one or more
of theses questions. Actually “Heat Stress” is something
most workplaces must deal with – not just those who
work in the hot sun or beside heat producing machinery.

3. The purpose of this tool kit is to provide workplace parties with
strategies to:
 Recognize the symptoms
 Assessing the risk
 Putting together an effective control program
Purpose of this heat stress
tool kit

4. Factors that Influence Heat
Stress
 The heating and cooling of the body depends on the
following factors:
 Air temperature
 Humidity
 Radiant heat load
 Physical activity
 Cooling
 Body adjustments

5. Heat Exposure
 There are two sources of heat exposure, the outside
environment and internal muscle activity. 80% of the
muscle activity is converted into body heat.
 High temperatures and high levels of physical activity
create heat stress.
 The body cools itself by evaporating sweat.
 High humidity hinders sweat from evaporating

6. Can you get used to heat?
 Yes
 The body will get used to working in a hot environment
gradually over time.
 This process of the body becoming more efficient at
cooling itself down is known as “acclimatization”
 The body redirects blood to the skin’s surface
 The heart becomes more efficient
 Sweating starts sooner and there is more of it
 Sweat contains less salt

7. Heat Rash, Sunburn and Heat
Cramps

8. Causes, Symptoms and
Treatment

9. 5 Steps to Managing Heat
Stress
1. Training: measurements by themselves cannot
guarantee a worker protection from heat stress. It is
essential that workers learn to recognize the early signs
and symptoms of heat stress and know how to prevent
them.
 If it is possible, workers need to be able to alter their
pace of work, take rest breaks, and drink in response to
early symptoms (a cup of water every 20 minutes.)
 The ideal heat stress response plan would let workers
regulate their own pace by “listening” to their bodies.

10. 2. Clothing;
 The heat stress action chart on next slide assumes
workers are wearing regular summer clothes
 If the workers wear a double layer of woven clothing
add 50 of Humidex to the workplace measurement
 Estimate the correction factor for other types of
clothing/protective equipment by comparing them with
cotton overalls.
 If completely encapsulating suits are worn, heat stress
should be managed by monitoring vital signs as
recommended

11. Humidex Action Recommended
Low
30 - 37
Post heat stress alerts
Drink water
Medium
38 - 39
Reduce physical activity
Drink a cup of water every 20 minutes
Moderate
40-41
Further reduce physical activity
Drink a cup of water every 15 – 20 minutes
High
42 - 44
Severely curtail physical activity
Ensure sufficient rest/recovery time
Drink a cup of water every 10 – 15 minutes
Extreme
45+
Hazardous to continue physical activity

12. 3. Select a measurement location
 Divide the workplace into zones that have similar heat
exposures
 Select a representative location in each zone where you
can take measurements.

13. 4. Measure workplace temperature and humidity.
5. Adjust for radiant heat
Look at heat stress
calculator on next slide

14. www.ohcow.on.ca/menuweb/heat_stress_calculator.htm

15. KEEP YOUR
COOL !!!