Extreme heat is a health emergency: what Pakistan’s cities can do now

Extreme heat is no longer only a weather story. It is a public-health emergency that can push the human body beyond its ability to cool itself, worsen chronic disease and place sudden pressure on hospitals, power systems and water supplies.

The World Health Organization’s updated heat-and-health guidance says the danger builds when unusually hot days are followed by hot nights. Without cooler overnight temperatures, the body has less time to recover. High humidity, weak airflow, direct sunlight, heavy clothing and physical work can increase the strain even when the air temperature alone does not tell the full story.

How heat harms the body

The body normally releases heat through sweating and increased blood flow to the skin. During severe heat, especially when humidity is high, sweat evaporates less effectively. Core temperature can rise while the heart works harder to move blood toward the skin.

That strain can cause dehydration, dizziness, cramps and heat exhaustion. It can also worsen cardiovascular, respiratory and kidney disease, diabetes and some mental-health conditions. Heatstroke — marked by very high body temperature, confusion, seizures or loss of consciousness — is a medical emergency.

The risk is not shared equally. Older adults, infants, pregnant women, people with chronic illness, people living alone and those without reliable cooling are more vulnerable. Outdoor workers, including construction workers, farmers, delivery riders and traffic staff, face additional risk because physical activity generates body heat while the environment makes it harder to lose.

Why cities need a plan

WHO recommends heat-health action plans that connect forecasts to specific action. A warning should trigger clear responsibilities: health departments alert hospitals, local authorities identify cooling spaces, employers adjust strenuous outdoor work, and community networks check on people most at risk.

For Pakistan’s dense cities, preparation also means treating heat as an infrastructure problem. Tree cover, shade at public-transport stops, reflective roofs, ventilation, dependable electricity and access to safe drinking water can reduce exposure. Health facilities need backup power and staffing plans for periods when heat-related illness rises quickly.

Public messages should be simple and repeated before temperatures peak. Residents should follow official forecasts, avoid strenuous activity during the hottest hours, use shade, wear light loose clothing and drink water regularly. Homes can be cooled by blocking direct sunlight during the day and using cooler night air when outdoor temperatures fall below indoor levels.

WHO cautions that electric fans should not be treated as a complete solution in extreme temperatures. When the air is hotter than the body, a fan may add heat unless it is paired with other cooling measures. People with medical conditions should follow advice from their clinician, particularly where fluid intake or medication may need special consideration.

What to do in an emergency

Warning signs of heat exhaustion include heavy sweating, weakness, headache, nausea, dizziness and fainting. Move the person to a cooler place, loosen clothing, cool the skin and offer water if they are conscious and able to drink.

Confusion, hot dry skin, convulsions or unconsciousness can indicate heatstroke. Call emergency medical services immediately and begin rapid cooling while help is on the way. Do not wait for symptoms to improve on their own.

The science is clear that many heat-related illnesses and deaths are preventable. The most effective response combines personal precautions with early warnings, protected workers, prepared hospitals and cities designed to stay safer as extreme heat becomes more frequent.