Europe heat wave puts focus on dehydration and heatstroke risks

A severe heat wave in Europe is straining hospitals and underscoring how quickly extreme temperatures can threaten human health. AFP reported that at least 150 million people across the continent were expected to face temperatures above 35°C, or 95°F, on Friday, based on its calculations from forecasts.

Hundreds of deaths have been reported during the prolonged hot spell, according to AFP. Scientists cited by AFP said the event would have been “virtually impossible” without human-caused climate change.

Heat becomes dangerous because the body must work harder to keep its internal temperature near 37°C, AFP reported. The heart pumps faster, blood vessels in the skin widen to release heat, and sweating helps cool the skin’s surface.

Those defenses can fail when temperatures stay high or when the body loses too much fluid, according to AFP. Early signs of heat stress can include tiredness, headaches, fever and disrupted sleep.

Why dehydration raises the risk

AFP reported that dehydration develops when the body loses or uses more water than it replaces. Once that happens, circulation can suffer, which can reduce the oxygen reaching organs.

Severe dehydration can contribute to failure of vital organs, including the kidneys, according to AFP. Older people face added danger because they may feel less thirsty, while infants and children depend on others to keep them hydrated.

Pregnant women also face higher risk during extreme heat, AFP reported. The news agency cited links between very high temperatures and increased rates of premature birth and other complications.

Heatstroke can become life-threatening

Heatstroke occurs when the body can no longer keep its temperature from climbing above 40°C, AFP reported. The condition is considered the most serious heat-related illness and can be fatal.

As the body tries to conserve water, sweating can stop and urine can become darker, according to AFP. Poor health, diarrhea, fever, some medications and alcohol can raise the risk.

Older adults, children under 5 and people with weakened immune systems are among the groups most at risk, AFP reported. Healthy adults can also develop heatstroke after intense or prolonged exertion, such as running or manual work, in hot conditions.

French emergency department doctor Agnes Ricard-Hibon told AFP that young people had arrived at French emergency hospitals with heatstroke during the current heat wave. “We are seeing young athletes in critical condition, in intensive care, or even suffering cardiac arrest after exercise-induced heatstroke,” she said.

AFP reported that people without housing are especially vulnerable because they may have no place to cool down. The news agency also said heat can worsen existing illnesses, including heart and breathing problems, chronic kidney disease, COPD and type 2 diabetes.

Hot nights add to the strain

Researchers cited by AFP warned that nights can be dangerous when temperatures do not fall below 20°C. Parts of Europe experienced repeated warm nights this week, and AFP reported that France recorded its hottest night on record.

Heat stress researcher Rebecca Emerton told AFP that nights without relief can prevent the body from cooling down. Scientists cited by AFP said heat stress measurements also account for humidity, radiation and wind, and that climate change has sharply increased heat stress worldwide.

AFP reported that people should drink plenty of water during heat waves, avoid going outside during the hottest part of the day, keep homes cool by closing windows and shutters, and use cold showers or air-conditioned spaces when possible. The advice cited by AFP also says people should avoid physical exertion and alcohol during extreme heat.

This story draws on original reporting from Medical Xpress.