Heat stress, also known as Hyperthermia, is a raised body temperature where the body has not regulated its heat properly. It occurs when the body produces or absorbs more heat than it dissipates. Heat stress is where the body gains heat faster than it can get rid of it. The most common cause of hyperthermia is heat stroke. An adverse side effect of some drugs can also cause hyperthermia. In relation to the workplace, heat stroke is the main cause of heat stress.
Obviously during the summer months there will be elevated temperatures all around due to the season, but for some jobs the risk of heat stress poses an issue all year around. Some workplaces that pose risk include bakeries, compressed air tunnels, foundries and smelting operations. Other work environments where heat stress may occur include mines, brick-firing and ceramics plants, laundries as well as glass and rubber manufacturing plants. As well as air temperature, other factors like work rate, humidity and clothing may also cause heat stress, either as primary cause or as a combination.
Environmental causes of heat stress include air temperature, air flow, air humidity, radiant heat (sun, kiln). Heat stress caused by the worker themselves can include hydration, clothing and medical conditions. Causes at the work place include work pace and work load. There are personal risk factors associated with developing heat stress. A person that has been acclimatized to working in hot environments routinely will be less susceptible to heat disorders than a person who just enters that environment. Also those that are physically fit can cope better with heat stress. Other stress factors include age, obesity, use of medication and state of health.
Symptoms of heat stress include nausea, dizziness, heat cramps and excessive sweating. Where there has been suspected heat stress, the worker should be moved to a cooler environment. Any restrictive clothing should be loosened. They should not be cooled down too quickly otherwise they may shiver. If the worker is alert they should be given oral fluids like juices, energizing sports drinks. Alcohol and caffeine should not be given. Continued work under conditions where there is heat stress can lead to heat exhaustion. Heat exhaustion is a more serious condition and this is caused by depletion of both water and salt from the body. Signs and symptoms are the same as mild shock and medical attention should be sought immediately. Signs of heat stroke include shallow respiration, fainting, weak pulse, sweating and nausea. Heat stroke is a more serious condition where the body’s core temperature will rise above 41 degrees celcius. This can result in loss of consciousness, brain damage and death.
Prevention of Heat Stress in the Workplace
- The temperature should be controlled as much as possible by air conditioning and fans. There should be physical barriers placed up against radiant heat if possible
- Automated ways of reducing the work rate should be in place where possible
- There should be periodic breaks and cool rest areas
- Workers should be encouraged to drink regularly, ie during and after work
- Personal protective equipment should be in use which would protect workers in certain hot environments. But this protective equipment, whilst protecting from a hazard, may add to heat stress. A balance in the form of breaks from working in these hot environments needs to be followed.
- In the risk assessment, employees should be identified who may be more susceptible, for example, those on medication or where there are mobility challenges
- Employees working in a possible heat stress environment should be trained and given information on how to cope in these hot conditions. Employees health should be monitored.
If a worker is exposed to environmental conditions that could cause heat stress, the employer must mitigate against exposure. An appropriate work rest cycle must be followed and or personal protective equipment if necessary.