CONTROLLING THE STRESS OF THERMAL EXTREMES

1
CONTROLLING THE STRESSOF THERMAL EXTREMES

• preventing adverse effects ofexposure 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
• 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 StressEngineering Controls

• general ventilation
• local exhaust ventilation
• enclosure/isolation
• shielding
• area cooling/air conditioning
• fans
• dehumidification
• equipment modification
• others

7
Control of Heat StressAdministrative
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

• http//www.osha.gov/SLTC/heatstress/standards.html
  
• ACGIH