WHO Warns Rising Heat Poses Growing Global Health Threat

Islamabad (GNP): The World Health Organization has renewed its warning that extreme heat is becoming one of the most significant environmental health hazards worldwide, with rising temperatures driving up deaths and worsening chronic illness across regions.

In a fact sheet released this week, the agency said heat stress remains a leading cause of weather-related fatalities and can aggravate conditions such as cardiovascular disease, diabetes, asthma and mental health disorders, while also raising the risk of accidents and the spread of certain infectious diseases.

WHO said the number of people exposed to extreme heat is rising sharply as climate change accelerates, with heat-related deaths among people over 65 increasing by roughly 85 percent between 2000-2004 and 2017-2021. Globally, an estimated 489,000 heat-related deaths occurred annually between 2000 and 2019, with nearly half recorded in Asia and more than a third in Europe.

The agency noted that Europe alone recorded about 61,700 excess heat-related deaths in the summer of 2022, while a 2003 heatwave across the continent killed an estimated 70,000 people and a 2010 heatwave in Russia caused 56,000 excess deaths over 44 days.

According to the agency, vulnerability to heat depends on a combination of physiological factors such as age and underlying health conditions, along with exposure factors including occupation and socio-economic status. WHO said the health impacts of heat are largely predictable and preventable through coordinated public health measures, and it has issued guidance to help institutions identify and manage heat-related risks as part of broader climate action and preparedness planning.

The organization explained that heatwaves occur when unusually high temperatures persist over consecutive days and nights, and said such events are becoming more frequent, longer and more intense due to climate change. Even moderate heatwaves, it added, can affect the health and wellbeing of vulnerable groups, while extreme events can trigger public health emergencies, disrupt healthcare and transport systems during power shortages, and reduce labour productivity.

WHO pointed to population ageing and the rising prevalence of non-communicable diseases, including respiratory and cardiovascular conditions, diabetes and renal disease, as factors increasing susceptibility to heat. It also flagged inadequate urban planning, including the loss of green spaces and the use of heat-retaining building materials, as compounding the problem. The agency said awareness of heat-related health risks remains low among both health workers and the public, and urged professionals to adapt their guidance and planning accordingly.

On who is most affected, WHO said populations in tropical and subtropical regions face chronic heat exposure, while those in mid-to-high latitudes experience seasonal risk. Outdoor and manual labourers, athletes and civil protection workers face heightened exposure due to their work, while low-income urban and rural populations are often disproportionately affected because of substandard housing and limited access to cooling. The agency added that gender can also influence exposure, citing the example of women who are frequently responsible for cooking indoors during hot weather.

Explaining the physiological effects, WHO said the body’s ability to regulate temperature can be overwhelmed by a combination of high heat, humidity, restrictive clothing and limited airflow, increasing the risk of heat exhaustion, heatstroke, and strain on the heart and kidneys. It noted that heat-related deaths and hospitalizations tend to occur rapidly, underscoring the need for swift public health responses once heat alerts are issued.

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The agency outlined a series of protective measures for the public, including avoiding strenuous activity during peak heat hours, staying hydrated, keeping homes cool by managing window use according to indoor and outdoor temperature differences, and taking extra precautions for infants, older adults and people with existing health conditions. It specifically warned against leaving children or animals in parked vehicles under any circumstances.

WHO said it continues to address the issue through its Alliance for Transformational Change in Climate and Health, alongside technical and policy support for national health systems. The agency also co-sponsors the Global Heat Health Information Network and works with the World Meteorological Organization on early warning systems, while its “Beat the Heat” initiative, aligned with a World Health Assembly resolution, focuses on protecting workers and the public from combined risks of extreme heat, air pollution and UV exposure at workplaces and large gatherings.