As the nationwide high temperature warning is extended into Saturday, and the mercury continues to rise across the Continent, it can be easy to bask in the summer temperatures.But these high temperatures can also pose a risk.Several hospitals in Europe have declared critical incidents. The London Ambulance Service (LAS) responded to its highest number of life-threatening emergencies, and emergency services had reached full capacity as the number of serious heat-related illnesses rose.While similar demands have not been placed on the health service in Ireland, as temperatures didn’t reach such heights, experts said it is still important to take measures to stay safe and healthy during the heatwave.How does heat affect the body?Dr Suzanne Kelly, deputy medical director of the Irish College of GPs, said the first thing is “you dehydrate much faster”.“Your fluids are balanced very carefully in your body. You’re losing fluid off your skin and you don’t feel it. If you’re young and healthy, you’re going to feel thirsty,” she said.“If you’re older, those responses are blunted. You’re less aware that you’re dehydrating and then you become confused. We use a lot of diuretics to control blood pressure. They will continue to force fluids and electrolytes through your kidneys and they can’t adapt; they can’t retain that fluid.”Kelly added the heat also puts additional pressure on your organs, and there is typically an increase in cardiac events during these periods.“In order to maintain your body temperature, everything has to work harder,” she added.Should I be concerned about heat exhaustion?According to Kelly, heat exhaustion is a very real thing and members of the public should listen to their bodies for any symptoms.“What you are physically able to do at 20 degrees is very different from what you’re able to do at 30 degrees,” she added. “You will find you’re more tired in the heat.”Who is most vulnerable in high temperatures?Older people, babies, and people with intellectual disabilities should be particularly cared for during this time, Kelly said, as they may not be aware or are unable to say they are overheating, dehydrating or undereating.[ Why is it so hot and when will Ireland’s ‘exceptionally warm weather’ end?Opens in new window ]People cooling off at the Forty Foot in Sandycove, Dublin. Photograph: Niall Carson/PA Wire