The dangers of the heatwave in the big city

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Cement has higher thermal conductivity and heat capacity than other materials, while heat tends to flow from a warmer to a colder environment.

When the apartment does not cool down even at night, when we warm ourselves by leaning on the hot cement, when even inactivity exhausts us, then the peak of summer has come. Even if we are still in June. The first heatwave has already hit Berlin and other German cities. Scientists warn that the heatwave is not just tiring, but poses a risk to our health or even our lives, especially in big cities. Experts speak of a “slow death”.

Of particular concern is the fact that hospitals, nursing homes and other care facilities are not prepared to deal with this extreme phenomenon. In Berlin, an informal alliance of doctors, health executives and the Health and Climate Change Initiative (KLUG) on Monday unveiled its own proposals to protect the most vulnerable. Some of them are more or less known: light diet, foods with high water content, a lot of fluids, transport of particularly vulnerable patients to cooler rooms. But there are other ideas. Some suggest storing medicines at lower temperatures, but also construction work or related interventions for a cooler environment.

Increased risk in the big city

But why are people in big cities at greater risk of being affected by high temperatures? Jürgen Krop, a researcher at the Potsdam-based Climate Institute (PIK), points out that, among other things, the dangers are due to the “urban heat island” phenomenon. Cement has higher thermal conductivity and heat capacity than other materials, while heat tends to be channeled from a warmer to a colder environment. So at night, when the temperatures in the city fall, the cement releases into the atmosphere the heat it has absorbed during the day. Thus, in the urban environment the temperatures remain much higher than in the countryside.

Under these conditions the body does not find time to rest and replenish lost energy. The “thermal island phenomenon” is certainly not something new. But when more frequent and more intense heat waves occur, the health risks multiply, according to a recent French study published in the International Journal of Environmental Research and Public Health. All of these are direct consequences of climate change.

More victims in the future

The German Environmental Protection Agency (UBA) lists on its website specific computational models, according to which “a one degree rise in temperature on an annual basis could cause a 1 to 6% increase in mortality”. The Robert Koch Epidemiological Institute points out that in Germany there are no official statistics on the victims of a heat wave, but in 2018 the local governments in Berlin and the state of Hesse conducted an unofficial assessment / registration and the result was alarming: 4 in Vero people are estimated to have lost their lives due to the extreme heat, while in Hesse the corresponding number reached 740 dead.

The elderly are certainly at increased risk, says Natalie Needens, a member of the Berlin-based initiative “Health and Climate Change”. The feeling of thirst in the elderly is not so strong, while their circulatory system can not withstand excessive stress. But there are also social reasons that aggravate their situation: many elderly people live alone and do not have anyone to help them in the heat. Even more dangerous are the many homeless people in Berlin or other big cities. Of course, special precautionary measures are needed for pregnant women, minors and those who have a burdensome medical history.

Correcting the mistakes of the past

How can the body be affected by heat? There are many possible effects. “From dizziness and exhaustion to swelling in the legs,” says Natalie Needens, “at periods of very high temperatures, the risk of heart attacks also increases, which can even cause permanent damage to health.”

“Certainly a useful measure would be to increase the number of green spaces in the city,” says scout Jürgen Krop. He proposes the wider use of natural materials, such as wood, which can even be used to build office buildings up to 100 meters high. Beyond that, wider urban planning interventions are needed. Jelka Wickham, also a member of the “Health and Climate Change” group, reminds of course that one can help with smaller interventions, for example by installing drinking water coolers. “But whatever we do now,” says Jelka Wickham, “we are just correcting the wrong texts of the past. We caused the climate change, now we have to find solutions to fight the consequences … “

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