Extreme Temperatures: Workplace Hazards and Health Effects

Workplaces are not always confined to climate-controlled offices. From construction sites under the scorching May sun to glacier patrols in Ladakh and cold storage units in food processing plants, millions of workers face temperature extremes as part of their daily routine. Both heat and cold are recognised as significant physical hazards in occupational health because they push the body’s thermoregulation system beyond its limits, triggering illnesses that range from mild discomfort to fatal collapse. Understanding how these temperature extremes injure the body, who is most at risk, and how exposure can be managed is now more urgent than ever, especially as heat-related deaths in India increased by 55% between 2000-2004 and 2017-2021.

How the body regulates temperature 🔗

The human body works best at a core temperature of around 37°C. The hypothalamus acts as a built-in thermostat, balancing heat production with heat loss through sweating, blood flow shifts, and shivering. When external temperatures swing too far in either direction, this balance collapses. In cold environments, blood is pulled away from the hands, feet, and skin to protect vital organs, which is why toes, fingers, ears, and the nose are at greatest risk because they lack major heat-producing muscles. In hot environments, sweating becomes the main cooling mechanism, but when humidity is high or fluids are not replaced, the system fails. Once the body cannot maintain its core temperature, the resulting cascade of effects is called thermal stress.

Cold temperature risks at work 🔗

Workers in cold storage warehouses, fisheries, defence postings in the Himalayas, and outdoor winter occupations face a group of illnesses collectively called cold stress. The four main types of cold stress recognised by occupational safety authorities are trench foot, frostbite, hypothermia, and chilblains. Each has its own trigger, mechanism, and warning signs.

Hypothermia 🔗

Hypothermia sets in when the body loses heat faster than it can produce it, dropping the core temperature below 35°C. Although it sounds like a problem only of icy regions, hypothermia can occur even at cool temperatures above 4°C if a person becomes chilled from rain, sweat, or cold water. Early signs include uncontrolled shivering, slurred speech, clumsy movements, and confusion. As the condition worsens, shivering may stop entirely, the pulse weakens, and the worker may lose consciousness. Hypothermia is a medical emergency that affects judgement, so the affected worker often cannot help themselves.

Frostbite 🔗

Frostbite is the actual freezing of skin and underlying tissues. It typically attacks extremities such as fingers, toes, the nose, and the earlobes. The affected area first turns red, then pale or waxy, and finally numb. In severe cases, ice crystals damage cells beyond repair and gangrene may set in, sometimes requiring amputation. Safety guidelines stress that a frostbitten area should not be rubbed, massaged, or warmed with heating pads, since affected skin is numb and easily burned. Rewarming is best done under medical supervision because thawing and refreezing causes worse tissue damage than the original injury.

Trench foot 🔗

Trench foot, also called immersion foot, gets its name from soldiers who stood for days in waterlogged World War I trenches. It is a non-freezing injury caused by prolonged exposure of feet to wet and cold conditions. A striking feature is that trench foot can occur at temperatures as high as 15.5°C if the feet remain wet, because wet feet lose heat about 25 times faster than dry feet. Symptoms include numbness, swelling, blisters, leg cramps, and tingling pain. Workers in agriculture during monsoon, fishery workers, and rescue personnel wading through floodwater are at especially high risk.

Chilblains 🔗

Chilblains are the mildest form of cold injury. They appear as red, itchy, swollen patches of skin caused by repeated exposure to cold but non-freezing temperatures. While not as dangerous as frostbite, recurrent chilblains can scar the skin and lead to long-term sensitivity to cold.

Heat-related ailments at work 🔗

India sits at the front line of occupational heat stress. A study profiling Indian workplaces found that 82% of workers were exposed to higher than recommended Wet Bulb Globe Temperatures during the hotter season. The National Institute for Occupational Safety and Health (NIOSH) recognises four main heat-related illnesses: heat rash, heat cramps, heat exhaustion, and heat stroke. They form a spectrum, with each more serious than the last.

Heat rash 🔗

Heat rash, often called prickly heat, is a clutter of small red bumps that appear when sweat ducts become blocked. It is common in humid environments where sweat cannot evaporate. Although it usually heals on its own, it can become infected if scratched. Workers in textile mills, kitchens, and brick kilns frequently complain of heat rash during the summer months.

Heat cramps 🔗

Heat cramps are painful muscle spasms, usually in the arms, legs, or abdomen, that strike workers performing hard physical labour. They are caused by an electrolyte imbalance after heavy sweating. According to OSHA, cramps are driven by an electrolyte imbalance from sweating and develop when water lost through sweat is not adequately replaced. Plain water alone is often not enough; oral rehydration solutions or salted lemon water are commonly recommended in Indian work settings.

Heat exhaustion 🔗

Heat exhaustion is the body’s response to losing large amounts of water and salt. Symptoms include heavy sweating, weakness, dizziness, headache, nausea, and a fast but weak pulse. The skin often feels cool and clammy despite the heat. Without prompt cooling and fluid replacement, heat exhaustion can quickly progress to the most dangerous form of heat illness.

Heat stroke 🔗

Heat stroke is the most serious heat-related disorder. It happens when the body’s thermoregulation system fails completely, sweating stops, and the core temperature rises above 40°C. The CDC warns that heat stroke can cause permanent disability or death without emergency treatment. The affected worker may show confusion, slurred speech, seizures, or unconsciousness, with hot, dry, or profusely sweating skin. Heat stroke is a medical emergency: the worker must be moved to a shaded area, cooled immediately with wet cloths or ice packs to the neck, armpits, and groin, and rushed to hospital.

Workers most at risk 🔗

Although anyone exposed to temperature extremes can fall ill, certain occupations carry far greater risk. Outdoor labourers in construction, agriculture, road building, and brick kilns work for long hours under direct sun. Indoor workers in steel plants, glass factories, bakeries, laundries, and boiler rooms face high radiant heat throughout their shifts. On the cold side, soldiers posted at high-altitude border areas, cold storage workers, ice factory employees, and deep-sea fishermen face prolonged low-temperature exposure.

Women, older workers, and those with pre-existing heart, kidney, or respiratory conditions are particularly vulnerable. Research has found that women in informal sectors of India face a double burden, since heat exposure at work combines with domestic responsibilities and often inadequate sanitation facilities, which discourages drinking water during work hours. The informal sector, which employs the majority of India’s workforce, often lacks the cooling infrastructure, scheduled breaks, and protective equipment available in organised industries.

Long-term and economic consequences 🔗

The effects of extreme temperature are not limited to acute illness. Repeated exposure to heat has been linked to chronic kidney disease, cardiovascular problems, and mental health issues. Cold injuries can leave permanent nerve damage, sensitivity to future cold, and amputation scars. The economic cost is equally heavy. The Lancet Countdown estimated that 167.2 billion potential labour hours were lost in India alone due to heat exposure. As mean temperatures continue to rise, this burden is expected to worsen.

Protective measures and prevention 🔗

Reducing the risk of temperature-related illness requires a layered approach involving the worker, the employer, and the wider regulatory framework.

Hydration and nutrition 🔗

For heat exposure, frequent water breaks are non-negotiable. NIOSH recommends drinking water often enough that you never become thirsty, since thirst is already a sign of mild dehydration. Salted buttermilk, lemon water, and oral rehydration mixtures help replace electrolytes. For cold exposure, warm sweetened drinks help maintain blood sugar and core temperature, while alcohol must be avoided because it accelerates heat loss by dilating skin blood vessels.

Appropriate clothing 🔗

In hot conditions, light-coloured, loose-fitting cotton clothing allows sweat to evaporate. In cold conditions, layered clothing works best: a wicking inner layer, an insulating middle layer such as wool or fleece, and a wind- and water-resistant outer shell. Keeping the head, hands, and feet covered prevents disproportionate heat loss from these areas. Wet clothing should be changed immediately, since damp fabric loses its insulating capacity.

Work scheduling and rest breaks 🔗

Scheduling heavy outdoor work for the cooler hours of early morning or late afternoon dramatically reduces heat exposure. Mandatory rest periods in shaded or air-conditioned areas help the body recover. Acclimatisation, the process of gradually building tolerance over 7 to 14 days, is especially important for new workers, returning workers, and those moving between climates. The Indian government’s National Disaster Management Authority publishes Heat Action Plans that recommend rescheduling outdoor work, mandatory water breaks, and shade arrangements during heat waves.

Engineering and administrative controls 🔗

Employers can install ventilation, exhaust fans, cool roofs, reflective shields, and insulation in hot worksites. In cold environments, heaters, windbreaks, and warm-up shelters protect workers. Training supervisors and workers to recognise early warning signs of heat or cold stress in themselves and coworkers ensures that mild symptoms do not turn into emergencies.

Medical surveillance and policy 🔗

Pre-employment medical screening helps identify workers with conditions like uncontrolled hypertension or heart disease who may need adjusted duties. Regular health check-ups, prompt first aid facilities, and accessible drinking water are basic requirements. India’s regulatory framework, however, has gaps. The Factories Act, 1948 lays down general provisions for ventilation, temperature, and worker welfare, but enforcement is uneven, especially in unorganised sectors. Strengthening these standards and aligning them with WBGT-based international guidelines is increasingly recognised as essential.

The growing climate connection 🔗

Extreme temperatures at work are no longer just a seasonal worry. Climate change is making heat waves longer, more frequent, and more intense, while unpredictable cold snaps catch workers off guard. Public health, occupational safety, and climate adaptation are now intertwined. Protecting workers from temperature extremes is therefore not only a matter of individual welfare but a national public health priority that affects productivity, healthcare costs, and economic growth.

What do you think? If you observed a roadside construction worker showing signs of dizziness on a hot afternoon, what immediate steps would you take, and what longer-term changes would you want to see in workplace policies to prevent such situations from arising in the first place?

References

1. https://pmc.ncbi.nlm.nih.gov/articles/PMC10334395/
2. https://www.ccohs.ca/oshanswers/phys_agents/cold/cold_health.html
3. https://www.osha.gov/winter-weather/cold-stress
4. https://www.osha.gov/emergency-preparedness/guides/cold-stress
5. https://www.cdc.gov/niosh/cold-stress/about/related-illness.html
6. https://pmc.ncbi.nlm.nih.gov/articles/PMC4730480/
7. https://www.cdc.gov/niosh/heat-stress/about/illnesses.html
8. https://www.osha.gov/emergency-preparedness/guides/heat-stress
9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5025522/
10. https://www.cdc.gov/niosh/docs/2010-114/default.html
11. https://ndma.gov.in/Natural-Hazards/Heat-Wave
12. https://labour.gov.in/sites/default/files/the_factories_act1948.pdf