1. CONTROLLING THE STRESS OF THERMAL EXTREMES
…preventing adverse effects of exposure to heat stress

2. Background/Overview
Humans function within a narrow range of temperature
Examples of heat exposures in industry
Extent of the heat stress problem
among the earliest of OSHA targets, but…
most industries have learned how to cope

3. Modes of Heat Transfer conduction convection radiation
direct contact
convection
surrounding air
radiation
from hot surfaces
metabolism/metabolic heat
due to activity

4. Factors Affecting Heat Exchange
temperature of solid surroundings
air temperature
skin temperature
amount of sweat on exposed skin
humidity
air speed
clothing
time of exposure

5. Purpose of Engineering Controls
reduce air temperature
reduce air humidity
reduce radiant heat
increase air movement/circulate air
reduce physical work demand

6. Control of Heat Stress Engineering Controls
general ventilation
local exhaust ventilation
enclosure/isolation
shielding
area cooling/air conditioning
fans
dehumidification
equipment modification
others

7. Control of Heat Stress Administrative Controls/Work Practices
hydrate
training/education
rest periods
scheduling
acclimatization

8. Control of Heat Stress PPE
primary considerations:
insulation value of clothing
permeability
ventilation of clothing
reflective clothing
auxiliary body cooling
Wetted clothing, water-cooled garments, circulating air, ice packs, etc.

9. The current situation... Heat stress is a common potential risk.
Environmental limits have been suggested by NIOSH, ACGIH, etc.
There is no regulatory standard, i.e., OSHA.
Industries have developed their own ways of “dealing with” the heat stress problem.
“Worker is his/her own best control!”

10. Resources
ACGIH