Heat Stress in the Workplace

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Many people are at risk from heat stress while on the job. Operations involving high heat, direct sunlight or heavy exertion can all expose workers to heat stress, and put them at risk for heat-related illness. According to the Centers for Disease Control, an estimated 6 million workers are exposed to occupational heat stress, resulting in tens of thousands of injuries and hundreds of deaths each year. Heat stress can occur both indoors and outdoors. With many places experiencing record temperatures in recent years, working outside in the summer months carries obvious risks. However, working around equipment that gives off lots of heat or partaking in very strenuous workplace tasks can create or enhance the risk of heat stress. Because the effects of heat stress can be severe, OSHA requires employers to take steps to protect workers from heat stress. There are four broad levels of heat stress:

  • Early symptoms – dehydration, fatigue, reduced mental alertness, hot skin
  • Heat Rash – blocked sweat glands, redness, itchiness
  • Heat Exhaustion – heavy sweating with cool skin, extreme thirst, nausea, weakness, cramping
  • Heat Stroke – Severe dehydration, confusion, slurred speech, headache, rapid heart rate, seizures, coma, death

Normal Body Conditions

Under normal conditions, the human body maintains a core temperature of around 98°F, or 37°C. The body is very good at self-regulating this temperature and does so primarily by sweating and circulating blood to the skin. Both processes allow heat to be released from the body into the air. When working in high heat – especially when humidity levels are high – these natural cooling processes can be disrupted, leading to heat stress. Poor health, advanced age, and drug and alcohol use can also reduce a person’s natural ability to cool down.

As with most things in life, prevention is better than cure. Even mild heat stress is unpleasant and distressing. The best way to reduce heat and humidity is with air conditioning, which is usually available in buildings and vehicles, as well as some other heavy equipment used outdoors. If air conditioning isn’t available, portable fans with built in air-chillers, or fans paired with water misters, can effectively reduce worker body heat. Even a fan on its own is better than nothing, because air circulation will help in transferring heat away from the skin. Added ventilation, particularly above points of high heat production such as cooking or laundry equipment, can quickly remove heat from buildings and bring in cooler air. Finally, simple barrier protection, such as using tarps or screens to reflect heat back towards the source, can be effective both indoors and outdoors.

Recognizing the Signs

Cooling, ventilation and barrier protection won’t always eliminate risk of heat stress. Workers must be trained to recognize the signs of heat stress early and to know what protective actions to take. They need to know when they are most at risk, and understand the importance of drinking plenty of water, taking breaks in the shade or designated cool areas, acclimating to hot environments, reducing strenuous tasks, and dressing appropriately. Training should cover recognizing signs of heat stress in themselves and others, and understanding how to follow company policies and procedures. Workers should have means to monitor the heat and the heat index, which is easily tracked using mobile apps such as this one provided by OSHA.

Selecting Personal Protective Equipment (PPE) Related to Heat Stress

As with all safety issues, personal protective equipment (PPE) should be considered as a last resort, but it can still provide essential protection when other options aren’t available or effective. Simply wearing a wide-brimmed hat when out in the sun considerably reduces personal heat exposure. If a worker must wear additional PPE such as a hard hat, gloves or coveralls, workers should purchase articles made from reflective and insulating materials, particularly if working with point heat sources such as furnaces. Breathable materials may be an option to improve air circulation if chemical protection isn’t a requirement of the PPE. Personal cooling systems can be utilized in some cases, but these have drawbacks and are usually reserved for extreme situations.

Symptoms and Treatment

Heat fatigue – Take rest breaks in a cool, shady area and drink water or other cool beverages; if cramps occur, avoid strenuous work for a few hours. Seek medical attention if conditions don’t improve.

Heat rash – Keep affected areas dry, and wear loose clothing that breathes easily; creams or lotions worn during heavy exertion under tight clothing or in high heat may aggravate the problem.

Heat exhaustion – The victim should lie down in a cool, shady area and drink water or a sports drink containing electrolytes; remove heavy or tight clothing, and use cold compresses, ice packs, wet clothing or other methods to cool down. See urgent medical attention if symptoms worsen or do not improve within 60 minutes.

Heat stroke – Heat stroke is a medical emergency that requires immediate treatment in a hospital setting; if you suspect heat stroke, call 911 or a local emergency number. While waiting, efforts to cool the victim should be made.

Symptoms of heat stress vary and will depend on the severity of the condition. Dehydration and heat rash are milder forms of heat stress and can be treated easily if caught in time. Heat exhaustion and heat stroke are more severe, with heat stroke being considered a medical emergency. Dehydration can stop sweating and cause raised skin temperature, but cramps, sudden tiredness, goosebumps and blurred vision are all clear signs of heat stress in hot conditions. Heat exhaustion and stress can lead to severe fatigue, confusion, rapid heart rate and can lead to seizures and unconsciousness. Coma and death can result in severe cases if not treated correctly. If you detect any signs in yourself or others, quick action is key. Sit or lie down, apply cold wet compresses, remove or loosen clothing and take fluids which contain electrolytes. Of course if symptoms don’t improve or worsen then seek medical attention immediately. In the event of an emergency, call 911.

There is plenty of information online about heat stress such as this from the Centers for Disease Control and Prevention. You can also check out the SafetySkills Heat Stress course for more details on how to prevent and deal with it.

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