A doctor writes: how to survive the heat

Met Éireann has issued a status yellow weather warning as temperatures are expected to reach 29 degrees in parts of the midlands and the west today. What might this mean for your health?

Our adaptation to heat is dependent on the body’s ability to act as a natural cooling system. Human beings maintain an internal temperature within a narrow range of about 37 degrees Celsius.

The main ways in which the body eliminates heat during thermal stress are through sweat production, increased cardiac output and redirection of blood flow to the skin. These responses can be diminished or delayed in older people or in those taking certain drugs such as diuretics.

Is overheating dangerous?

Signs of heat-related illness begin with heat exhaustion, which can progress to heatstroke. This is defined as a core body temperature of at least 40.6 degrees. Progression to death in an individual with heatstroke can happen within hours. Rates of heat-related mortality and morbidity are high in older people and in those with pre-existing illnesses such as heart attack, stroke and chronic lung problems.

How do we know when someone is overheating dangerously?

The first sign is heat exhaustion which produces symptoms such as excessive thirst, nausea and vomiting and muscle cramps. Remedies for heat exhaustion include removing yourself to a cool room and resting; drinking plenty of fluids but not coffee or alcohol; and changing into loose clothing.

Untreated heat exhaustion progresses to heatstroke. Watch out for heavy sweating that suddenly stops; a rapid heart rate and rapid breathing; and neurological symptoms such as confusion and a loss of co-ordination. Heatstroke is a medical emergency: even with prompt medical care some 15 per cent of heatstroke cases are fatal.

There is something of an urban-rural divide when it comes to the health effects of extreme heat. In what is known as the “heat island effect” asphalt and concrete store heat during the day and gradually release it at night, resulting in higher night temperatures. Once the relative humidity rises above 60 per cent or so it interferes with sweat evaporation, thereby depriving the body of a key defence mechanism.

What can you do to prevent heat-related health problems?

Try the following preventive measures: increase your fluid intake - older people especially should drink water often without waiting to feel thirsty; stay in a cool or air-conditioned environment and wear loose-fitting clothes; and reduce your normal activity levels.

That way we can continue to enjoy the mood enhancing benefits of prolonged sunshine while our bodies stock up on Vitamin D.