Health Risks
Heatwaves occur when there is a spate of very high temperatures for several consecutive days, often associated with high humidity levels, strong sunlight and little or no wind. These climatic conditions can pose a risk to the health of the general population.
Heat causes health problems when it alters the body’s temperature regulation system. Normally, the body cools down by sweating, but under certain physical and environmental conditions this is not enough. If, for example, the humidity is very high, sweat does not evaporate quickly and body heat is not effectively eliminated. As a result, the body’s temperature rises rapidly and this can damage several vital organs including the brain.
Prolonged exposure to high temperatures can cause such mild disorders as cramps, fainting, and swelling of the limbs, or more serious ones, such as digestive congestion, heatstroke, and dehydration. Extreme heat conditions can also lead to a worsening of the health conditions of people with pre-existing chronic diseases.
Sunstroke
This is caused by an increase in body temperature due to inadequate thermoregulation. It occurs due to prolonged exposure to sunlight, particularly on very hot summer days with no wind and intense solar radiation. Reddening of the skin or burns may occur, with or without symptoms of heatstroke.
Cramps
These are caused by a loss of sodium, due to sweating, and a consequent change in the water-salt balance, or can come from venous diseases of the lower limbs. Cramps can occur in the elderly who drink insufficient fluids and in people – even young people – who perform physical activity without sufficiently replenishing the fluids lost through sweating.
Swelling of the legs and feet
This is caused by fluid retention in the lower extremities as a consequence of prolonged peripheral vasodilation.
A simple and effective remedy is to keep the legs elevated and perform gentle movements from time to time to promote venous reflux, or to take cold showers on the lower limbs, from the feet up and from the inside to the outside as far as the top of the thigh.
Digestive Congestion
This is caused by an intake of iced drinks in an overheated body, during or immediately after meals, causing excessive blood supply to the abdomen, which can in turn slow down or block the digestive processes. The first symptoms are sweating and chest pain.
Dehydration
Caused by a loss of water from the body greater than that introduced.
The body becomes dehydrated and begins to function poorly when:
- a greater amount of water is required, as in the case of high ambient temperatures due to sweating
- a lot of fluids are lost due to fever, vomiting, or diarrhoea
- a person does not drink enough water of their own volition due to the absence of a thirst response
- taking drugs to promote the elimination of fluids (e.g. diuretics, laxatives).
The main symptoms are thirst, weakness, dizziness, palpitations, anxiety, dry skin and mucous membranes, muscle cramps, and low blood pressure.
Effects on blood pressure
People with high blood pressure and heart conditions, especially if elderly – but even many healthy people – can experience episodes of low blood pressure, especially when standing up from a lying position.
In such cases, it is advisable to:
- avoid any abrupt transitions from a horizontal to a vertical position, which could even result in fainting
- never get out of bed abruptly, especially during the night, but to stop in intermediate positions (e.g.: sitting on the edge of the bed for a few minutes) before standing up.
Heat Stress
This is caused by a collapse of peripheral vessels with insufficient blood supply to the brain.
Symptoms may arise during physical activity in an excessively hot environment, especially in non-acclimatized subjects, with reduced cardiac efficiency (insufficient compensation in the case of widespread peripheral vasodilation) due to decreased blood volume from dehydration. Heat Stress presents with heavy sweating, a sense of slight disorientation, general malaise, weakness, nausea, vomiting, headache, tachycardia and hypotension, an abnormally small amount of urine, confusion, and irritability.
If not diagnosed and treated immediately, it can progress to heatstroke. Emergency treatment consists of moving the person to a cool environment and, as long as there is no nausea, replenishing fluids and taking steps to cool the body. In severe cases, get the patient to a hospital emergency room.
Heatstroke
Heatstroke occurs when the physiological ability to thermoregulate is compromised and presents with a wide range of signs and symptoms depending on the severity of the condition.
It can occur when someone has been exposed to too high a temperature, in conjunction with high humidity and little or no wind. It can occur outdoors, indoors, or even in a place where there is no direct sunlight.
The first symptom is a sudden general malaise, followed by headaches, nausea, vomiting and a feeling of dizziness, and may even result in states of anxiety and confusion. The person may faint. Body temperature rises rapidly (in 10-15 minutes) up to 40-41° C [104-106° F] and this may be followed by a malfunction of the internal organs, which can lead to death. If you have symptoms of heatstroke, contact the emergency services without delay.
Worsening of pre-existing diseases
Intense heat can lead to a worsening of pre-existing diseases. These may be symptoms which do not attract clinical attention (e.g. reduction in physical capacity), to more severe symptoms, (e.g., requiring a checkup by the family doctor), up to more serious effects which can prompt a visit to the emergency room and hospitalization, or be so severe as to lead to death.
The effect of heatwaves is relatively immediate, with a latent period of 1-3 days between the occurrence of a rapid rise in temperature and a consequent increase in the number of deaths. That said, the heatwaves associated with a more profound effect on health are the most intense and prolonged ones and those which occur at the beginning of the summer months, when the population has not yet physiologically adapted to the arrival of the heat.
If the increase in mortality associated with heatwaves is a well-known and well-documented phenomenon, the biological mechanisms underlying it are still not completely clear. Potentially, all chronic diseases expose us to a higher risk of mortality in the presence of extreme heat conditions. In particular, studies conducted in various Italian cities have shown that certain pathologies (cardio- and cerebrovascular diseases, chronic lung diseases, mental disorders, diseases of the central nervous system, liver and kidney diseases and metabolic diseases such as diabetes) significantly increase the risk of death during heatwaves, especially among the elderly.
Other chronic diseases which involve an impairment of the thermoregulation mechanism can increase the risk during periods of high temperatures: for example, scleroderma, in which sweating is blocked due to a thickening of the skin, and cystic fibrosis, in which excessive sweating can lead to dehydration and circulatory failure.
Finally, in general, any disease or condition that leaves people bedridden or reduces people’s ability to take care of themselves and react by implementing protective behaviour, is to be associated with an increased risk from exposure to heat.
Pay particular attention to fever and related symptoms; they are not always due to rising temperatures
It is important to distinguish between fever and a temporary rise in body temperature due to heat (hyperthermia). It is hyperthermia if, after a break of at least half an hour in a cool place, the body temperature decreases.
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