Physical Inactivity Due To Heat May Cause Up To 700,000 Deaths Annually By 2050, Study Finds

Rising temperatures caused by climate change could lead to 470,000 to 700,000 deaths worldwide and $3.68 billion in productivity losses each year by 2050, a new study published in the journal The Lancet Global Health has found. Analysing data from 156 countries between 2000 and 2022, the researchers found that for each additional month with average temperatures above 27.8 degrees Celsius, physical inactivity increased by 1.4 percentage points worldwide.

The researchers explained that heat elevates skin blood flow and sweating, increases cardiovascular strain, dehydration risk, and exertion, which contributes to a lack of physical activity.

"Furthermore, air-conditioned indoor environments provide thermal refuge but often promote sedentary behaviour, reinforcing a feedback loop between heat and physical inactivity," the study highlighted.

Currently, approximately one-third of the global adult population does not adhere to WHO guidelines, which stipulate a minimum of 150 minutes of moderate intensity or 75 minutes of vigorous intensity physical activity on a weekly basis. If the trend continues, reduced muscular strength, impaired cognition, and poor sleep due to heat-driven physical inactivity may translate into lower on-the-job performance and higher absenteeism.

The study also pointed out a link between climate and physical inactivity. Warm regions, i.e., South Asia, the Middle East and Africa show higher rates of physical inactivity, whereas milder climates (Central Asia and Australia) show lower rates. Meanwhile, colder areas such as North America, Argentina, and South Africa also report high rates of physical inactivity.

The study data projected that by 2050, India's mortality rate linked to physical inactivity is projected to reach 10.62 deaths per 100,000 population

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'Climate-Sensitive Necessity'

The International Labour Organization projects that, by 2030, heat stress alone will erase around 2.2 per cent of total working hours worldwide (approximately 80 million full-time jobs), with losses concentrated in agriculture (around 60 per cent) and construction (around 19 per cent) and approaching approximately five per cent of working hours in South Asia and Western Africa.

The researchers stated that instead of treating physical activity as a discretionary lifestyle choice, it should be classified as a climate-sensitive necessity. Doing so will help prevent a heat-driven sedentary population and its unintended health consequences and economic losses.

"Integrating heat-risk messages into exercise guidelines, directing climate finance towards shade-rich active transport corridors, subsidising cooled exercise facilities for at-risk populations, and enforcing robust occupational heat safety standards are highly cost-effective actions that deliver concurrent public health, urban liveability, and emissions-reduction benefits," it stated.