When heat is applied to the body, it reacts by pumpimg more blood to the skin’s surface, and increasing perspiration. This results in cooling as heat is diverted to the surface of the body and sweat evaporates from the body’s surface. From the Skin surface, heat can be lost by convection and radiation..

In hot and humid conditions a person could be at risk of heat stress if doing heavy work and wearing  protective clothing.

How does this Happen?

1. Heat will be produced within the body due to the work rate and, if insufficient heat is lost, deep body temperature will rise.
2. Sweat evaporation is restricted by the type of clothing and the humidity of the environment.
3. Heart rate also increases which puts additional strain on the body.
4. As deep body temperature rises the body reacts by increasing the amount of sweat produced,which may lead to dehydration.
5. If the body is gaining more heat than it can lose the deep body temperature will continue to rise.

After a while, the body’s control mechanism begins to fail.
If the individual continues to work in this environmemt, symptoms will worsen.
How does heat Stress affect us?
Some people are more susceptible than others and the effects will vary.

Typical Heat Stress Symptoms are:

1. Unable to concentrate;
2. Heat rash;
3. Severe thirst – a late symptom of heat stress;
4. Fainting;
5. Muscle cramps;
6. Headaches,
   moist skin
7. Heat exhaustion – fatigue, giddiness, nausea,
8. Heat stroke – hot dry skin, confusion, convulsions and eventual loss of consciousness. This is the most severe effects and death can result if not picked up early.

Heat Stress occur in industry where the environment is too hot and thereby creating the problem or if  the workplace is restricted.

Areas at Risk are:

• Boiler Room
• Brick-firing and ceramics plants
• Bakeries and Catering Kitchens
• Laundries
• Glass and Rubber Manufacturing Plants
• Mines
• Compressed Air Tunnels
• Conventional and Nuclear Power Plants;
• Foundries and Smelting Operations

In addition, seasonal changes such a hot sunny day can increase air temperature and may contribute to the cause of heat stress.

How do you cope with the risk of heat stress?

The first thing to do is change behaviour. The body adapts to environmental changes but you can help by removing unnecessary clothing, take cool drinks regularly and make conscious efforts to cool down or reduce your work rate. In circumstances that make it difficult to reduce heat stress such as Asbestos removal, an accurate risk assessment must be carried out.

When carrying out a risk Assessment look at these things.

• Working climate – this includes air temperature, humidity, air movement and effects of working near a heat source.
• Work rate – the harder someone works the greater the amount of body heat generated.
• Worker’s age, build and medical factors – may affect an individual’s tolerance.
• Worker clothing and respiratory protective equipment – may impair the efficiency of sweating and other means of temperature regulation.

If you are concerned about heat stress at your workplace, talk to nurse, doctor or occupational hygienist. This way you can determine your risk and find a way around it.

Ways to reduce risk of heat stress:

• Control the temperature using engineering solutions, eg- change the processes, use fans or air conditioning,  use physical barriers that reduce exposure to radiant heat.
• Remove or reduce the sources of heat where possible:
• Provide mechanical aids where possible to reduce the work rate.
• Regulate the length of exposure to hot environments by:- allowing workers to enter only when the temperature is below a set level or at cooler times of the day, – issuing permits to work that specify how long your workers should work in situations where there is a risk, – providing periodic rest breaks and rest facilities in cooler conditions.
• Prevent dehydration. Working in a hot environment causes sweating which helps keep people cool but means losing vital water that must be replaced. Provide cool water in the workplace and encourage workers to drink it frequently in small amounts before, during (this is not possible in some situations eg respiratory protective equipment use or asbestos removal) and after working.
• Provide personal protective equipment-protective clothing is available which incorporates, for example, personal cooling systems or breathable fabrics. This may help protect workers in certain hot environments. Protective clothing or respiratory protective equipment is often required when there will be exposure to some other hazard at work eg asbestos. This type of equipment, while protecting from the other hazard, may increase the risk of
  heat stress.
• Provide training for your workers, especially new and young employees, telling them about the risks of heat stress associated with their work,

Strategy to Employ.

Allow workers to acclimatise to their environment and identify which workers are acclimatised/assessed as fit to work in hot conditions.

Identify employees who are more susceptible to heat stress either because of an illness/condition or medication that may encourage the early onset of heat stress, eg
pregnant women or those with heart conditions. You may need to seek help from a health professional.
Monitor the health of workers at risk. If there is a residual risk remains after implementing as many control measures as practicable, you may need to monitor the health of exposed workers. You need to all the facts when working in heat stress situations.