The Dangers of Heat Waves on the Body – and How to Defend Yourself

Send in e-mailSend in e-mail
Send in e-mailSend in e-mail
Go to comments
The Jaffa flea market during a heat wave in Israel, July 2021
A sweltering day in the Jaffa flea market, last week. Heat waves like those slamming Israel at present can also cause higher incidences of illness and deaths in indirect ways, such as by heart attack.Credit: Hadas Parush
Lee Yaron
Yaron Kelner
Lee Yaron
Yaron Kelner

It’s hot outside. Very hot, and anyone who can is seeking shelter with an air conditioner and complaining. The bad news is that it’s likely to get worse. Israel’s Health Ministry warned Sunday that the current heat wave sweeping the country will last until the middle of next week, and will gradually worsen. On such sizzling-hot days everyone knows how to declaim the phrases about how important it is to drink water and to avoid dehydration and heatstroke.

Dehydration is caused by a lack of bodily fluids and can also occur in cool weather when people do not drink enough. Heatstroke occurs when body temperature reaches higher than 41 degrees Celsius (106 degrees Fahrenheit), either due to prolonged exposure to very high temperatures or to illness. Heat waves like those slamming Israel at present can also cause higher incidences of illness and deaths in indirect ways, such as by heart attack.

Dehydration and heatstroke are two of the most dangerous health risks caused by exposure to high temperatures. In real time, however, the number of heat-related cases of illnesses and deaths is not usually reported, and the damage is revealed only in retrospect. But in fact, dehydration, and especially heatstroke, can cause significant damage to the human body, some of it long-term. So, for example, it is only now that the relevant authorities are examining the connection, as reported in Haaretz, between the May 2020 heat wave in country and the deaths of 157 people at around the same time.

Israelis sit nearby a Tel Aviv beach, this week.Credit: Hadas Parush


Dehydration can lead to a drop in blood pressure, which can potentially cause extreme damage to all bodily systems. The kidneys are typically the first to be affected.

“When there is a decrease in fluids there may be direct damage to the kidneys,” explains Michael Drescher, director of the emergency department at Beilinson Hospital, Rabin Medical Center, in Petah Tikva. “All vital organs are damaged, but the kidneys suffer the most. The body knows how to regulate the fluids to maintain blood circulation to vital organs such as the brain and heart, but a little less to the muscles and kidneys.”

According to Prof. Drescher, “dehydration can also lead to a decreased volume in the circulating blood supply to other organs, over time. This eventually causes what is called hypovolemic shock” – meaning, much like what happens with rapid bleeding, dehydration and vomiting also cause a drop in the volume of blood to the point of damaging the body’s systems.


Heatstroke is a condition in which the body becomes overheated and fails to regulate its own temperature. There are two types of heatstroke, the classical kind and one caused by exertion. The first type occurs among people who cannot find a place where they can cool down in time, or who are taking medications that impair the body’s ability to regulate itself. Heatstroke due to exertion is more prevalent in people who engage in sports or other strenuous activity.

The Tel Aviv-Jaffa promenade at the beginning of the heat wave, last Thursday. The actual number of heat-related cases of illnesses and deaths is not reported in real time.Credit: Hadas Parush

Following are the symptoms of heatstroke: body temperature higher than 39.5 degrees; red, hot and dry skin but no sweating; rapid pulse; severe headache, dizziness; nausea; confusion and decreased alertness. Under such conditions, without immediate treatment, the body’s systems are at grave risk.

Drescher: “In cases of heatstroke we see direct damage from the high temperature, especially to the brain. We begin to notice confusion, and disorientation, and this can be a life-threatening condition.” A change in the structure of proteins in the body occurs in such cases, as part of a process called denaturation, which is actually what takes place to an egg’s proteins while it’s being boiled.

“When this happens to our proteins, it can cause damage,” Drescher continues. “There may be a condition where a muscle breaks down and then swells, and becomes damaged. Usually, it does not just happen because of the heat, but heat along with other physical damage may lead to permanent disability.”

The breakdown of muscle tissue can have additional consequences. The molecules of the muscle enter the bloodstream and can reach the kidneys and impair them. Such breakdown can also release salts such as potassium into the bloodstream, which can cause arrhythmia.

How to protect yourself from the heat

The best way to deal with the hazards of summer is to avoid exposure to high temperatures and humidity. The Health Ministry recommends remaining inside in an air-conditioned environment during peak hours, whether at home or in a public place. According to the ministry, electrical fans can reduce the oppressiveness of heat, but when the temperature tops 35 degrees, they can’t keep the body cool enough to guard against health risks.

The Health Ministry also recommends closing curtains and shutters to reduce the penetration of the sun’s rays, bathing in cool water, wearing light and comfortable clothes, and reducing physical activity.

It is also recommended to drink plenty of water, wear a wide-brimmed hat, apply sunscreen and wear sunglasses. In cases of possible heatstroke, seek medical assistance, leave the affected person in a shady area and try to cool them down as much as possible. The Health Ministry warns that the person should be prevented from drinking unless medical personnel administer fluids by infusion.

What should be done?

Hagai Levine – a former chairman of the Israeli Association of Public Health Physicians and an epidemiologist who teaches at the Hebrew University-Hadassah Braun School of Public Health and Community Medicine, explained that the dangers of heat to our bodies are mounting as the climate crisis worsens.

“Climate change impacts human health in a myriad ways, through all stages of life, from the womb, through infancy, puberty, adulthood and old age,” Prof. Levine explains. Exposure to extreme heat can have harmful effects already during pregnancy, and can “lead to various risks to the fetus such as intrauterine growth retardation, pre-term birth, low birth weight and birth defects.”

According to Levine, such heat also impacts health in the broadest sense – in terms of “nutritional insecurity, mental illness, impaired fertility, occupational and economic insecurity, increased exposure to allergens and infectious diseases.”

Nadav Davidovitch, the current chairman of the public health physicians organization and director of the School of Public Health at Ben-Gurion University, points out that the climate crisis has a more serious impact on the health of poorer communities, the elderly, and children. “These populations are less protected from climate damage,” the professor says. “We see significantly higher temperatures in neighborhoods where there are fewer trees, less shade and less investment in examining the connections between health and the environment. “

The bigger problem is that this situation is only likely to get worse. The climate crisis is sparking an increase in the frequency and intensity of heat waves throughout the world, including in Israel. In fact, Israel is warming faster than the rest of the world. As early as 2016, the Israeli Meteorological Service found that there was a “significant and sharp increase” in heat waves – defined as periods in which the daily temperature is 6 degrees above average for three consecutive days.

Palestinian construction workers continue working in scorching weather, in Tel Aviv, today.Credit: Hadas Parush

“Israel is in a hot spot for climate change,” Prof. Levine says. “The impacts on health, especially due to the rise in average temperature, are already being felt. According to valid climatic models, we will see longer summers in the coming years.” Therefore, he predicts, “climatic conditions that currently prevail, for example, only in Eilat, will be experienced in other cities.”

Levine’s remarks are backed up research. A study was published in March in the journal Climate and Atmospheric Science, according to which by the end of the century about half the inhabitants of North Africa and the Middle East will be exposed to an extreme heat event of 56 degrees Celsius or above. According to an analysis of the models, these events will occur frequently and for periods that may last for weeks.

Another study, published last month in Nature Climate Change, found that more than one-third of global heat-related fatalities can be attributed to the climate crisis. The researchers call for concerted efforts to adapt to the mounting, intense heat by taking measures such as setting up cooling centers and preparing action plans for vulnerable populations, especially the elderly and others who have no ways to cool off, such as people of low socioeconomic status without air conditioning.

A man tries to cool down in Tel Aviv-Jaffa.Credit: Hadas Parush

Monitoring climate impact

One way to deal with the hazards of heat, along with taking measures to combat climate change, is to gather information about it. What is needed, Levine suggests, “is better monitoring of the impacts of climate change and global warming on the health of Israeli residents, while cross referencing with environmental and health information sources.” Thus, he says, the health care system can be better prepared for extreme weather events that could lead to widespread harm to people, especially weaker communities such as the elderly.

For his part, Prof. Davidovitch says the country’s health system is not prepared in any systematic way for the global climate crisis: “We must raise the awareness of it among health and medical personnel. They hardly teach this issue during their training.”

The Health Ministry says in response that they receive “regular updates regarding weather fluctuations, such as extreme heat waves” from the meteorological service and that relevant information is uploaded to the ministry’s website. They also report that “as part of an inter-ministerial collaboration, a document has been prepared that identifies at-risk populations, explaining the health-related consequences of exposure to high temperatures and the importance of using shade, wearing protective equipment such as clothing and sunglasses, proper drinking habits, and so on.”

Click the alert icon to follow topics: