This summer has been one of the hottest summers since records began. As many of us revel in the hot summer sunshine, others are at risk of getting sunstroke and heatstroke – so why, exactly, can we be at risk in hot weather?
Our bodies fight hard to keep internal conditions pretty much the same, so that our cells and organs operate in optimum circumstances. For our core temperature deep inside, that’s around 37.5 degrees C, and we have a range of reflexes that kick in to keep this stable, even before it changes. This happens whether we are hot because of being in the sun, or just indoors in a hot room.
To cope, firstly our bodies change the amount blood flow. When it’s hot, more blood flows close to the skin and we lose heat to the outside world. This requires the heart to work harder to get the blood moving closer to the skin which can put it under strain.
This heat loss is helped by sweating - when sweat evaporates off our body, it cools us down. Sweating, or wet skin, can increase the amount of heat lost from the body by as much as ten times, thereby reducing the strain on the heart. But we need to keep well hydrated to keep the sweat flowing.