A University of São Paulo study led by Dr. Alessandra Carvalho Goulart reveals that each additional day under a heat wave significantly elevates acute stroke risk in adults aged 65 and older, with the risk rising 40.4% per day when high temperatures combine with fine particulate matter pollution. Meanwhile, nearly 150 international researchers in the Lancet Countdown report are urging the UN to declare climate change a global health emergency as extreme heat caused $1.07 trillion in economic losses.
São Paulo study findings on heat waves and stroke
- ▪When a heat wave combines with fine particulate matter pollution (PM10), the risk of acute stroke in adults aged 65 and older increases by 40.4% per additional day.
- ▪The University of São Paulo study analyzed 769 acute stroke patients from the Stroke Mortality and Morbidity Study (EMMA) database between 2006 and 2018, of whom 65.5% were aged 65 or older.
- ▪A University of São Paulo study found that each additional day spent under a heat wave in São Paulo increases the risk of acute stroke in adults aged 65 and older.
Physiological mechanisms linking heat to stroke risk
- ▪Thermal overload from heat waves causes changes in human thermoregulation and cardiovascular function, altering blood pressure and blood flow to act as a direct trigger for acute stroke.
- ▪Exposure to intense heat causes dehydration that reduces blood liquid volume and increases blood viscosity, according to University of São Paulo Medical School professor Alessandra Carvalho Goulart.
Health effects of fine particulate matter air pollution
- ▪Inhalation of fine particulate matter, such as PM2.5, damages blood vessel linings and contributes to high blood pressure, circulation problems, and atherosclerosis, according to Fortis Hospital's Dr. Vinit Banga.
- ▪Prolonged exposure to air pollutants triggers systemic inflammation and oxidative stress, affecting cardiovascular function and elevating risks for ischemic stroke, hemorrhagic stroke, and cognitive impairment.
Global Mortality and economic impacts of heat waves
- ▪Climate change caused more than half a million heat-related deaths in 2023 alone and nearly 3 million heat-related deaths between 2016 and 2023, according to the Lancet Countdown report.
- ▪Extreme heat resulted in an estimated $1.07 trillion in lost potential income globally in 2023, according to the annual Lancet Countdown report.
- ▪Extreme heat wiped out 573 billion potential working hours globally in 2025, with vulnerable economies in Africa and South-East Asia losing up to 5% of GDP.
Calls for global health action
- ▪To save lives and protect human health, experts called for a new World Health Organization instrument to help countries share information, coordinate responses, monitor threats, and disburse funds.
- ▪Nearly 150 researchers from over 30 countries called for climate change to be declared a global health emergency in the 2026 Lancet Countdown report.
Story comments
Loading comments…