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How hot is too hot for health?
The body responds to heat by dilating blood vessels in the arms and legs and sending blood to the periphery. Heat is then able to leave the body through sweat. However, this means that less blood is flowing to vital organs such as the heart or kidneys. In addition, heavy sweating causes the loss of water as well as salt, which can cause dehydration. When natural cooling mechanisms fail to operate properly, then heat exposure can result in kidney failure, heart attacks, brain damage, and even death. Anyone who can’ t easily get to a cool place is at risk of heat-related illness, including homeless people, workers who labor outdoors, and disabled and elderly people— who are often prescribed medication that predisposes them to dehydration. Also at risk: People with underlying kidney or heart disease, people with mental health conditions whose medications may disrupt the body’ s ability to regulate heat, and children. During heat waves, we also see an increase in pregnancy-related complications because the body has to work harder to cool down the pregnant person as well as the developing baby.
The most important things you can do in a heat wave are staying hydrated and cool. Beware of diuretics like caffeinated or alcoholic beverages— alcohol, especially, can be very dehydrating. Drink water alongside these types of beverages to counteract the fluid loss. When it’ s hot and humid outside, also consider abstaining from high-intensity exercise.
If you start to overheat, you may sweat profusely and feel thirsty; your mouth may become dry. Your urine flow is dark yellow. These red flags can progress to symptoms of heat exhaustion, which include headache, dizziness, a rapid heartbeat, and nausea. Immediately get someplace cool or at least cooler— find shade, go inside where there’ s air conditioning. Drink fluids, and if you can, sip something like Gatorade with electrolytes to replace those that you’ re losing through sweat. Spritz your body with water or take a cool shower. Don’ t exert yourself. You’ ll know you’ re out of danger when you start to feel normal again, but that may take a couple of hours.
Seek medical evaluation if you become confused or develop any other concerning symptoms such as chest pain, persistent muscle cramps, hot and dry skin, or severe headache.
Katelyn Moretti, MD, is an assistant professor of emergency medicine at Brown and an emergency medicine physician at The Miriam and Women & Infants hospitals. She studies the health implications of climate change and cofounded the Rhode Island Medical Society Climate Change and Health Committee. HD @ B
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