Heat waves make even nights dangerous


If you thought that health risks from heat waves subside with the setting of the sun, you are wrong. Sultry nights during summer, especially in a heatwave are equally dangerous to your wellbeing.

Heat waves are especially dangerous, and could even prove deadly, to vulnerable populations like infants, small children, and older people. But people usually tend to protect themselves and their families only from the scorching daytime heat, with some even deferring strenuous activities to the evenings. But medical experts now say that you also need to be aware of the dangers that heat waves bring after the sun sets.


Evenings might feel relatively cooler after a day spent suffering a heatwave, but outside temperatures still may not be cool enough for people who have been exposed to extreme heat all day. The core body temperature of those exposed to a heatwave could keep increasing at night and pose a threat to their health.


Doctors recommend that whenever possible people should avoid any strenuous activity, like exercising or lifting heavy objects, during these nighttime hours when your body has not been able to cool down. In particular, small children, elderly folks and those suffering chronic illness should be monitored while they are asleep at night in a heatwave. While asleep, people may not realize their core temperature is rising, as opposed to during the day when they are awake and could take precautions against the threat.


These risks can be particularly stark for people in densely populated urban environments. The Environmental Protection Agency (EPA) in the United States explains that built-up cities are basically ‘heat islands’ and hotter than nearby rural areas.


Dense urban areas of at least 1 million people can be 1.8 to 5.4 degrees hotter than surrounding areas. This is even more pronounced at night. In the evenings, these heat islands can be as much as 22 degrees higher than the countryside and impair city energy grids, raise air-conditioning expenses, and result in more heat-related illnesses.


Research published in 2012 looked at the impact these heat islands had on the high death rates in Paris during a deadly heat wave that hit Europe in the summer of 2003. Nearly 15,000 people died in France alone during that summer’s heat wave. Many of those who died were older people.


The study found that high night temperatures had a significant impact on people’s health. The researchers concluded that at night, urban areas slowly release the heat absorbed during the day, which prevents the human body from recovering from daytime high-heat exposure.