Heat stress and safety on construction sites

Safety: heat stress

Safety on residential construction sites has changed dramatically over the last couple of decades. Safety is to be thought of before anything else to protect the workers, the equipment they are using and the buildings that they are working on.

Since the warm weather has finally arrived supervisors and workers alike need to be aware of the dangers of working in area’s or environments where the heat is high. They need to aware of what is called “heat stress” on their workers.

Construction sites are very different then normal offices or places of business in that when the weather is nicer and the sun is shining longer they work longer hours to take advantage of this, this is good for the wallet but can be bad for your health if you are not careful. Heat stress is a real concern on today's construction sites.

What is Heat Stress?

Working or playing where it is hot puts stress on your body’s cooling system. When heat is combined with other stresses such as hard physical work, loss of fluids, fatigue or some pre-existing medical conditions, it may lead to heat-related illness, disability and even death.

How do we cope with heat?

Your body is always generating heat and passing it into the environment. The harder your body works, the more heat it has to lose. When the environment is hot and/or humid or has a source of radiant heat (such as a furnace or the sun), your body must work harder to get rid of heat.

If the air is moving (for example, by fans) and it is cooler than your body, it is easier for your body to pass heat into the environment.

Workers on medication or with pre-existing medical conditions may be more susceptible to heat stress because some medication and/or medical conditions may impair the body’s response to heat. Such workers should speak to their personal physicians to see if their medication(s) and/or health condition(s) affect their ability to work in hot environments.

Heat-Stress–related disorders

A summary of heat-stress-related disorders, causes, symptoms, treatment and prevention is presented in the table below.

	Cause	Symptoms	Treatment	Prevention
Heat rash	Hot humid environment; plugged sweat glands.	Red bumpy rash with severe itching.	Change into dry clothes and avoid hot environments. Rinse skin with cool water.	Wash regularly to keep skin clean and dry.
Heat cramps	Heavy sweating from strenuous physical activity drains a person’s body of fluid and salt, which cannot be replaced just by drinking water. Heat cramps occur from salt imbalance resulting from failure to replace salt lost from heavy sweating.	Painful cramps occur commonly in the most worked muscles (arms, legs or stomach); this can happen suddenly at work or later at home. Heat cramps are serious because they can be a warning of other more dangerous heat-induced illnesses.	Move to a cool area; loosen clothing, gently massage and stretch affected muscles and drink cool salted water (1½ to 2½ mL salt in 1 litre of water) or balanced commercial fluid electrolyte replacement beverage. If the cramps are severe or don’t go away after salt and fluid replacement, seek medical aid. Salt tablets are not recommended.	Reduce activity levels and⁄or heat exposure. Drink fluids regularly. Workers should check on each other to help spot the symptoms that often precede heat stroke.
Fainting	Fluid loss, inadequate water intake and standing still, resulting in decreased blood flow to brain. Usually occurs in unacclimatized persons.	Sudden fainting after at least two hours of work; cool moist skin; weak pulse.	GET MEDICAL ATTENTION. Assess need for cardiopulmonary resuscitation (CPR). Move to a cool area; loosen clothing; have the person lie down; and if the person is conscious, offer sips of cool water. Fainting may also be due to other illnesses.	Reduce activity levels and⁄or heat exposure. Drink fluids regularly. Move around and avoid standing in one place for too long. Workers should check on each other to help spot the symptoms that often precede heat stroke.
Heat exhaustion	Fluid loss and inadequate salt and water intake causes a person's body's cooling system to start to break down.	Heavy sweating; cool moist skin; body temperature over 38°C; weak pulse; normal or low blood pressure; person is tired and weak, and has nausea and vomiting; is very thirsty; or is panting or breathing rapidly; vision may be blurred.	GET MEDICAL ATTENTION. This condition can lead to heat stroke, which can cause death quickly. Move the person to a cool shaded area; loosen or remove excess clothing; provide cool water to drink; fan and spray with cool water. Do not leave affected person alone.	Reduce activity levels and⁄or heat exposure. Drink fluids regularly. Workers should check on each other to help spot the symptoms that often precede heat stroke.
Heat stroke	There are two types of heat stroke: Classic heat stroke may occur in older adults and in persons with chronic illnesses exposed to excessive heat. When the body has used up its water and salt reserves, it stops sweating causing a rise in body temperature. Exertional heat stroke generally occurs in young persons, who engage in strenuous physical activity for a prolonged period of time in a hot environment and the body’s cooling mechanism cannot get rid of the excessive heat. Heat stroke may develop suddenly or may follow from heat exhaustion.	High body temperature (over 40°C) and any one of the following: the person is weak, confused, upset or acting strangely; has hot, dry, red skin (classic heat stroke) or profusely sweating (exertional heat stroke); a fast pulse; headache or dizziness. In later stages, a person may pass out and have convulsions.	CALL AMBULANCE. This condition can kill a person quickly. Remove excess clothing; fan and spray the person with cool water; offer sips of cool water if the person is conscious.	Reduce activity levels and/or heat exposure. Drink fluids regularly. Workers should check on each other to help spot the symptoms that often precede heat stroke.

Controlling Heat Stress

Acclimatization

The longer you work in a hot environment, the better your body acclimatizes to the heat. If you are ill or away from work for a week or so you can lose your acclimatization.
To become acclimatized, consider the following progressive approaches:

1. If you are experienced on the job, you should limit your shift time in hot working conditions to 50 per cent on the first day, 60 per cent on the second day, and 80 per cent on the third day. You should be able to work a full shift on the fourth day.
2. If you are not experienced on the job (for example, if you are a new employee), you should start off spending 20 per cent of shift time in hot working conditions on the first day and increase your time by 20 per cent on each subsequent day. You should be able to work a full shift in hot working conditions the fifth day.
3. Instead of progressively increasing the exposure times on the job in a hot environment, you can become acclimatized by gradually increasing the physical demands of the job over a week or two.

If you have health problems or are not in good physical condition, you may need longer periods of acclimatization. Hot spells in Ontario seldom last long enough to allow acclimatization. However, exposure to workplace heat sources may permit acclimatization.

Controlling Heat Stress

Acclimatization

The longer you work in a hot environment, the better your body acclimatizes to the heat. If you are ill or away from work for a week or so you can lose your acclimatization.
To become acclimatized, consider the following progressive approaches:

1. If you are experienced on the job, you should limit your shift time in hot working conditions to 50 per cent on the first day, 60 per cent on the second day, and 80 per cent on the third day. You should be able to work a full shift on the fourth day.
2. If you are not experienced on the job (for example, if you are a new employee), you should start off spending 20 per cent of shift time in hot working conditions on the first day and increase your time by 20 per cent on each subsequent day. You should be able to work a full shift in hot working conditions the fifth day.
3. Instead of progressively increasing the exposure times on the job in a hot environment, you can become acclimatized by gradually increasing the physical demands of the job over a week or two.

If you have health problems or are not in good physical condition, you may need longer periods of acclimatization. Hot spells in Ontario seldom last long enough to allow acclimatization. However, exposure to workplace heat sources may permit acclimatization.
When there is a potential for exposure to heat stress, control measures must be taken to prevent heat exposure in the workplace. These include engineering controls, administrative controls and protective clothing. Selection of appropriate workplace controls will vary, depending on the type of workplace and other factors. Some measures may include:

Engineering controls

• Reduce physical demands of work task through mechanical assistance (hoists, lift–tables, etc.)
• Control the heat at its source through the use of insulating and reflective barriers (e.g. insulate furnace walls)
• Exhaust hot air and steam produced by operations
• Reduce the temperature and humidity through air cooling
• Provide cool, shaded work areas
• Provide air–conditioned rest areas
• Increase air movement if temperature is below 35°C (e.g. use fans).

Administrative and work practice controls

• The employer should:
• Assess the demands of all jobs and have monitoring and control strategies in place for hot days and hot workplaces
• Increase the frequency and length of rest breaks
• Schedule strenuous jobs to cooler times of the day
• Provide cool drinking water near workers and remind them to drink a cup about every 20 minutes, or more frequently, to stay hydrated
• Caution workers to avoid direct sunlight
• Assign additional workers or slow down the pace of work
• Make sure everyone is properly acclimatized
• Train workers to recognize factors which may increase the risk of developing a heat related illness and the signs and symptoms of heat stress and start a “buddy system” since people are not likely to notice their own symptoms
• Investigate any heat–related incidents
• Trained First Aid providers should be available and an emergency response plan should be in place in the event of a heat related illness.
• Pregnant workers and workers with a medical condition – or those taking certain medications – should discuss with their physicians about working in the heat

Protective clothing

• Light summer clothing should be worn to allow free air movement and sweat evaporation
• If working outdoors, wear light-coloured clothing, preferably long-sleeve shirt and pants, and cover the head to prevent exposure to direct sunlight
• In a high radiant heat situation, wearing reflective clothing to shield radiant heat may help
• For very hot environments, consider air, water or ice–cooled insulated clothing
• Vapour-barrier clothing, such as chemical protective clothing, greatly increases the amount of heat stress on the body. Extra caution such as heat strain (physiological) monitoring is necessary, if vapour-barrier clothing is worn

Construction companies should have programs in place so that all employee’s understand the risks and know what to do in these situations.

Rob Abbott

Village Builders

Information gathered for this post was taken from the ministry of labour webstie. To see more about this here is the link to it.

http://www.labour.gov.on.ca/english/hs/pubs/gl_heat.php