‘Heatwaves are one of the most deadly natural hazards,’ climate scientist says as high temperatures scorch parts of US, Asia and Europe.

Asia, Europe and the United States are baking under extreme heat, forcing millions of people to suffer through scorching temperatures.

Temperatures were expected to reach record highs in Italy on Tuesday, and the World Meteorological Organization warned of an increased risk of deaths as extreme weather gripped parts of three continents.

Experts are warning of the many ways heat can affect people’s health and livelihoods.

What are the health hazards?

Heat exhaustion is a common risk when temperatures are high. It causes dizziness, headaches, shaking and thirst. It is not usually serious, provided that the person cools down within 30 minutes.

A more serious medical emergency is heatstroke when the body’s core temperature rises above 40.6 degrees Celsius (105 degrees Fahrenheit). The condition can lead to long-term organ damage and death. Symptoms include rapid breathing, confusion, nausea and seizures.

Who is at risk?

Babies, seniors, active people and those more exposed to high temperatures, such as the homeless, are usually more susceptible to heat-related health risks

Existing conditions, including respiratory and cardiovascular diseases and diabetes, can also heighten risks and be exacerbated by heat.

According to a 2021 study in The Lancet medical journal, heat is the cause for almost half a million deaths a year although data are lacking from many low-income countries.

As many as 61,000 people may have died in Europe due to heatwaves last summer, and a repetition is feared this season as intense heat grips the continent.

“Heatwaves are a silent and invisible killer,” said Professor Liz Stephens, a researcher on climate risk and resilience at Britain’s University of Reading.

“We don’t often see the impact that they have had on human health until the mortality statistics are published many months later.”

Overlooked risks

Air pollution also poses a health risk, and smoke from heat-fed wildfires can cause inflammation and tissue damage.

A number of studies have shown that heat could also lead to low birthweights and premature births for pregnant women exposed to high temperatures.

Vikki Thompson, a climate scientist at the Royal Netherlands Meteorological Institute, said extreme heat can contribute to a wide variety of issues, including poorer mental health, car crashes and drownings.

“Heatwaves are one of the most deadly natural hazards,” she said.

Timing matters

Experts say more deaths occur earlier in the summer when people’s bodies have yet to had time to acclimatise.

Location matters, too. People are at higher risk in places where they are not used to such heat, including parts of Europe.

But hot weather poses risks to people all around the world, particularly those who work in physically demanding jobs.

“It is more important than ever that we put in place measures to limit the harm on our health,” said Dr Modi Mwatsama, head of capacity at Wellcome, a London-based global health charity.

These actions can range from providing shade and painting buildings white to investing in early warning systems for climate-sensitive infectious diseases, like cholera, she said.

Safety measures

Public health agencies from Italy to the US have issued advice on keeping cool, including avoiding exertion when possible and staying hydrated.

Workers should think about taking more breaks and changing their clothing too, scientists said. It is also important to check on the vulnerable, including older and isolated people, and to remember that heatstroke is a medical emergency and requires immediate professional attention.