Health Effects of Heat.
With the highest ever recorded temperature on Earth this year, and heat warnings across much of Canada this past summer, let’s take time to reflect on how heat can affect the human body.
Heat stress on the body can increase our risks of illness and dying. It can affect our mental health, our ability to get our work done, and increase the chances of adverse pregnancy and birth outcomes. Those older than 65 years of age, the very young and those with chronic diseases, like chronic lung disease, are most at risk.
Our bodies have mechanisms in place to make sure our core temperature doesn’t fluctuate too much, this ensures that the cells in our bodies can function as they’re meant to. The two main ways our body does this are by widening the blood vessels (vasodilation) so that heat moves from our muscles to the skin, and by secreting sweat which removes heat from our body as it evaporates.
So, if our bodies have protective ways to prevent us from overheating, how exactly does heat stress affect our bodies in such a dramatic way? Well, there are a couple of factors at play:
There is more demand on the heart - in order to have more blood flow to the skin surface (vasodilation), less blood comes back to the heart to be pumped, so the heart needs to pump faster and harder than usual. In order for the heart to do this, it requires more oxygen. If you have pre-existing heart or lung conditions, these organs might not be up for the extra challenge and this could lead to damage of the heart, including a heart attack. Research tells us that during heatwaves the primary cause of death relates back to the heart and the blood vessels.
Dehydration - sweating can lead to dehydration especially if we don’t replenish the sweat we’ve lost by drinking fluids. This dehydration creates more work for the heart and kidneys. Again, those with pre-existing conditions in these organs are at risk. Often, we can be at risk of dehydration before we start to feel thirsty, so drink non-dehydrating (non-caffeinated) beverages throughout the day.
Illness due to heat stroke - this can occur with high internal temperatures (>39 degrees celsius). The cells in our bodies do not receive the oxygen they need due to the redistribution of blood (vasodilation), and this results in cell, tissue and organ damage. In the lungs, this results in edema (swelling) of the lungs with trapped fluid and this can lead to acute respiratory distress syndrome. Those with underlying lung conditions are at risk.
Be sure to read our tips on how to stay cool and exercise tips for when it’s hot, so that you can minimize the health effects of heat stress.