Hot weather

As a result of global warming, heatwaves are becoming longer, more common, and more intense. When the weather is hot, there are more pollutants in the air, the ozone level increases, and airborne microparticles are transported indoors. Heat-related health hazards increase when the temperature exceeds +23–25°C. Those with long-term ill health start noticing increased and aggravated symptoms at around +20°C. Heat can affect health and functional ability negatively in just a few days.

Heat places a great burden on the respiratory and circulatory systems. Physical exertion increases the body’s heat generation by up to ten times. For many people, heat also causes fatigue, poor concentration, disturbed sleep, muscle weakness, and reduced stamina.

The normal human body temperature is around 37°C. If the core body temperature rises by 1°C, the person’s physical performance decreases.

Exposure to heat aggravates the symptoms of long-term illnesses, such as respiratory diseases, especially in elderly people. Heat stress can lead to a respiratory infection and make existing respiratory diseases worse. Elderly people often have poor heat tolerance, which is due to their weaker temperature regulation and delayed perception of thirst and heat stress.

Heatwaves increase the need for hospital care and doctor’s appointments, particularly among the elderly and people with long-term ill health. When the temperature exceeds 30°C, mortality will increase among the elderly, both at home and in care facilities. In the 2010s, heatwaves caused 300–400 premature deaths a year in Finland among people aged over 65 and people with long-term ill health.

Warning signs of heat-related illness

  • thirst
  • dry mouth
  • decreased physical performance
  • faintness and muscle weakness
  • nausea
  • confusion
  • concentration difficulties
  • sleep disturbances and fatigue
  • heart arrhythmia
  • shortness of breath
  • wheezing and excess mucus
  • changes in the effects of medication.

Related content

Other topics that may interest you

How to protect yourself from heat

  • Find a cool place. The temperature inside your apartment should be below 25°C.  Keep in mind that tolerance to heat varies from person to person.
  • To cool the apartment, keep the curtains closed, reduce the amount of heat generated by household appliances, and air out the apartment at night. 
  • When you close the blinds, make sure that the convex side faces the window. This way, the UV rays will be reflected back outside.
  • High indoor temperatures can be reduced with cooling systems and air source heat pumps.
  • Wearing the right kinds of clothes can help cool your body indoors. Damp and thin garments are an effective way to cool your body. 
  • Cold showers also help cool the body down. 
  • Check whether your medication contributes to heat-related symptoms. Certain medications,  particularly medicines that affect the cardiovascular system, can increase heat-related symptoms. Check with your physician to find out how your medication interacts with heat.

How to ensure proper hydration

  • In hot weather, you should drink 1.5 times the normal amount of fluids. 
  • Drink even if you don’t feel thirsty.
  • Eat something salty every now and then.
  • Ask your doctor for advice on hydration.