Heat Stress Locations

Workplaces involving heavy physical work in hot, humid environments can put considerable heat stress on workers.

Hot and humid conditions can occur either indoors or outdoors.

Indoors

– Steel mills and foundries.

– Boiler rooms.

– Pulp and paper mills.

– Generation plants.

– Petrochemical plants.

– Smelters.

– Furnace operations.

– Oil and chemical refineries.

– Electrical vaults.

– Interior construction and renovation.

Outdoors

– roadbuilding.

– homebuilding.

– work on bridges.

– trenching.

– pouring and spreading tar or asphalt.

– working on flat or shingle roofs.

– excavation and grading.

– electrical utilities .

Asbestos removal, work with hazardous wastes, and other operations that

require workers to wear semipermeable or impermeable protective clothing can contribute significantly to heat stress.

Heat stress causes the body’s core temperature to rise.

Effect on the Body

The human body functions best within a narrow range of internal temperature.

This “core” temperature varies from 36°C to 38°C.

A worker performing heavy work in a hot environment builds up body heat.

To get rid of excess heat and keep internal temperature below 38°C, the body uses two cooling mechanisms:

• The heart rate increases to move blood—and heat—from heart, lungs, and other vital organs to the skin.

• Sweating increases to help cool blood and body. Evaporation of sweat is the most important way the body gets rid of excess heat.

When the body’s cooling mechanisms work well, core temperature drops or stabilizes at a safe level (around 37°C).

But when too much sweat is lost through heavy labour or working under hot, humid conditions, the body doesn’t have enough water left to cool itself.

The result is dehydration. Core temperature rises above 38°C.

A series of heatrelated illnesses, or heat stress disorders, can then develop.

Heat Stress Disorders

They range from minor discomforts to life-threatening conditions, such as the following:

Heat rash, Heat cramps, Heat exhaustion, and Heat stroke.

for more details, read this article.

Controlling Heat Stress

Heat stress can be controlled through education, engineering, and work procedures. Controls will:

Protect health: Illness can be prevented or treated while symptoms are still mild.

Improve safety: Workers are less likely to develop a heatrelated illness and have an accident.

Heat stress often creeps up without warning.

Many heatinduced accidents are caused by sudden loss of consciousness.

Increase productivity: Workers feel more comfortable and are likely to be more productive as a result.

Training and Education

According to the U.S. National Institute of Occupational Safety and Health (NIOSH), heat stress training should cover the following components:

• Knowledge of heat stress hazards.

• Recognition of risk factors, danger signs, and symptoms.

• Awareness of first-aid procedures for, and potential health effects of, heat stroke.

• Employee responsibilities in avoiding heat stress.

• Dangers of using alcohol and/or drugs (including prescription drugs) in hot work environments.

Engineering Controls

Engineering controls are the most effective means of preventing heat stress disorders and should be the first method of control.

Also, engineering controls seek to provide a more comfortable workplace by using:

• Reflective shields to reduce radiant heat.

• Fans and other means to increase airflow in work areas.

• Mechanical devices to reduce the amount of physical work.

When engineering controls are not feasible or practical, work procedures are required to prevent heat stress disorders.

Work Procedures

The risks of working in hot environments can be diminished if workers and management cooperate to help control heat stress.

Management

Give workers frequent breaks in a cool area away from heat.

The area should not be so cool that it causes cold shock—around 25°C is ideal.

Increase air movement by using fans where possible.

This encourages body cooling through the evaporation of sweat.

Provide unlimited amounts of cool (not cold) drinking water conveniently located.

Allow sufficient time for workers to become acclimatized.

A properly designed and applied acclimatization program decreases the risk of heat-related illnesses.

Such a program exposes employees to work in a hot environment for
progressively longer periods.

NIOSH recommends that for workers who have had previous experience in hot jobs, the regimen should be:

• 50% exposure on day one
• 60% on day two
• 80% on day three
• 100% on day four.

For new workers in a hot environment, the regimen should be 20% on day one, with a 20% increase in exposure each additional day.

Make allowances for workers who must wear personal protective clothing and equipment that retains heat and restricts the evaporation of sweat.

Schedule hot jobs for the cooler part of the day; schedule routine maintenance and repair work in hot areas for the cooler seasons of the year.

Consider the use of cooling vests containing ice packs or ice water to help rid bodies of excess heat.

Workers

Wear light, loose clothing that permits the evaporation of sweat.

Drink small amounts of water—8 ounces (250 ml)—every half hour or so.

Don’t wait until you’re thirsty.

Avoid beverages such as tea, coffee, or beer that make you pass urine more frequently.

Where personal PPE must be worn,

• use the lightest weight clothing and respirators available
• wear light-colored garments that absorb less heat from the sun
• use PPE that allows sweat to evaporate.

Avoid eating hot, heavy meals.

They tend to increase internal body temperature by redirecting blood flow away from the skin to the digestive system.

Don’t take salt tablets unless a physician prescribes them.

Natural body salts lost through sweating are easily replaced by a normal diet.

Responsibilities of Workplace Parties Employers

The Occupational Health and Safety Act (OHSA) and its regulations do not specifically cover worker exposure to heat.

However, under the OHSA employers have a general obligation to protect workers exposed to hot environments.

Employers should develop a written health and safety policy outlining how workers in hot environments will be protected from heat stress.

As a minimum, the following points should be addressed.

Adjust work practices as necessary when workers complain of heat stress.

Make controlling exposures through engineering controls the primary means of control wherever possible.

Oversee heat stress training and acclimatization for new workers, workers who have been off the job for a while, and workers with medical conditions.

Provide worker education and training, including periodic safety talks on heat stress during hot weather or during work in hot environments.

Monitor the workplace to determine when hot conditions arise.

Determine whether workers are drinking enough water.

Determine a proper work/rest regime for workers.

Arrange first-aid training for workers.

When working in a manufacturing plant, for instance, a contractor may wish to adopt the plant’s heat stress program if one exists.

Workers

Follow instructions and training for controlling heat stress.

Be alert to symptoms in yourself and others.

Avoid consumption of alcohol, illegal drugs, and excessive caffeine.

Find out whether any prescription medications you’re required to take can increase heat stress.

Get adequate rest and sleep.

Drink small amounts of water regularly to maintain fluid levels and avoid dehydration.