Healthy living Hot weather: risks and preventive measures

Heatwaves and very hot summers have become frequent in Germany since 2000. And extremely hot summers are likely in the future, too.

Persistently high temperatures are a problem as they can cause health problems. This affects people living in city centers in particular. Heat gets trapped between buildings in heavily built-up areas and, as a result, the air cannot cool down sufficiently even at night. During the heatwaves that occurred in Germany in recent years, the number of hospital admissions and heat-related deaths have increased significantly. Around 8,000 people are known to have died as a result of the heat during the particularly hot summer of 2018.

Humans are generally able to adapt to high temperatures. The body tries to cool down in a number of ways. The most important way it does this is by producing sweat, which then evaporates. The body increases the circulation of the blood to give off as much heat through the skin as possible. It does this by widening the blood vessels.

It is harder for this natural cooling system to maintain normal body temperature during periods of extreme heat. This is often because people do not drink enough for the body to produce enough sweat. Increased sweating also causes the body to lose important electrolytes. Loss of fluids and electrolytes can lead to heat-related conditions. These are indicated by headaches and a general feeling of being unwell, in addition to circulation problems, confusion and, in extreme cases, loss of consciousness. Certain risk groups are affected more than others by heat-related conditions – these include older people, children and people with chronic illnesses.

Maintaining sufficient fluid intake, eating light meals and observing easily implemented tips and precautions all help to protect your health. These include for example adjusting your daily routine and keeping your home environment as cool as possible. 

If you spend time outdoors in summer it’s also important to protect your skin and eyes from UV radiation.

People react differently to high temperatures. However, precautions need to be taken at the latest when the room and ambient temperature reaches 26 degrees Celsius or your wellbeing is affected. When extreme temperatures of 30 degrees or higher during the day and 20 degrees or higher at night persist for several days, the health risk increases significantly. In these situations it is extremely important to take precautions, particularly for at-risk groups. But healthy people should not underestimate the risk either.

The temperature reading on the thermometer is not the only factor: wind speed, air pressure and relative humidity all affect how the temperature is perceived. This is known as the “apparent temperature”.

Commonly referred to as the “felt temperature” or “feels-like temperature”, this refers to how the average adult perceives heat outdoors. The apparent temperature may be higher than the thermometer reading, particularly on sunny summer days with little wind or high relative humidity. In extreme cases, it can be up to 15 degrees higher than the measured air temperature.

Persistently high temperatures can cause a number of heat-related conditions, particularly when people do not drink enough or during physical exertion. These include sunstroke, heat collapse, heat cramp, heat exhaustion and heatstroke.

Cardiovascular and respiratory conditions also occur more frequently in periods of hot weather. Ozone levels, for example, also increase at high temperatures. This causes respiratory problems for many people and can also cause irritations of the eyes and mucous membranes as well as headaches.

With heat-related conditions, it is always important to avoid further exposure to heat and to accompany the person affected to a cooler location. They should also drink plenty of fluids. Water, tea or highly diluted fruit juices are suitable. To counteract electrolyte loss, salty foods or broths can also be eaten. Many fruits and vegetables also have a high water content and also contain various minerals.

Too much sun on a person’s (uncovered) head can easily cause sunstroke. Possible signs are restlessness, dizziness, nausea, headaches, a very red and hot head, impaired consciousness and a stiff neck.

First aid

People with sunstroke must be moved to a shady, well-ventilated spot and placed in a position with their head elevated. It is important to cool the head, for example with damp, cold towels or compresses covering the whole of the head. For mild sunstroke, it is important to drink plenty of fluids. The emergency services should also be called if there are signs of severe sunstroke such as impaired consciousness or a stiff neck.

Heat collapse causes loss of consciousness because the brain is temporarily deprived of an adequate supply of oxygen. Heat collapse can occur at relatively low levels of overheating, frequently after long periods spent standing up. People with heat collapse typically feel better when they are lying down.

First aid

Following heat collapse, it’s important to ensure that the person affected lies down in a cool place with their legs raised. Once they regain consciousness, they should drink plenty of fluids. Although people usually only become unconscious for a short period with heat collapse, it is important to always call emergency services to rule out heatstroke or other possible causes for the loss of consciousness.

Painful muscle cramps, often following severe physical exertion in hot weather, are indications of heat cramp. The cramps usually occur in the arms and legs, but can also occur in the lower abdomen. The cramps sometimes only begin after several hours. Heat cramps may also be an indication of heat exhaustion.

First aid

People with heat cramp should rest in a cool location, carefully stretch and massage the muscles affected and drink plenty of fluids to restore electrolyte levels. If the muscle cramps last longer than one hour, a doctor should be consulted.

Physical exertion at high temperatures and severe sweating cause a sharp drop in fluid and electrolyte levels and can increase the likelihood of heat exhaustion. Symptoms include severe thirst, weakness, cold and damp skin, circulatory problems (such as a high pulse and low blood pressure), fast but shallow breathing, loss of appetite, nausea, dizziness and lethargy.

First aid

With heat exhaustion, it’s important to accompany the person affected to a cooler, shady location. Warm clothing should be removed and restrictive clothing loosened. It’s also important to cool the body down. This can be done, for example, using damp cloths or by spraying the body with cold water. The person can also be fanned. This cools the body via evaporation. Cool packs can be placed on the forehead, neck, arms and legs. If the person is still fully conscious, they should drink plenty of fluids.

If their body temperature rises above 38 degrees Celsius or symptoms last for more than one hour, a doctor should be consulted.

The signs of heatstroke are a body temperature above 40 degrees Celsius and circulatory problems, as well as impaired consciousness and possibly seizures, vomiting and diarrhea.

Heatstroke in older people, people with chronic conditions and children is mostly caused by high ambient temperatures as well as a severe drop in fluid and electrolyte levels. Most cases of heatstroke in healthy people, however, are due to excessive physical exertion at high temperatures such as sport or working outdoors.

First aid

The emergency services must be called at the first sign of heatstroke. If cardiac arrest is suspected, resuscitation measures should be started. It is essential to cool down the body as quickly as possible until the emergency services or emergency doctor arrive. The most effective way to do this is by using damp cloths or spraying the body with cold water. The person can also be fanned. This cools the body via evaporation. Cool packs can be placed on the forehead, neck, arms and legs. It is also important to bring the person to a cool location and remove warm clothing or loosen restrictive clothing. If the person is still fully conscious, they can be offered something to drink. 

People in at-risk groups respond particularly sensitively to heat, or are unable to make sufficient adjustments to their behavior. Persistent periods of hot weather can also exacerbate certain pre-existing conditions.

The following groups in particular are at risk:

• people aged 65 and older
• older people who live alone and have restricted mobility
• people in need of care
• babies and infants
• people with pre-existing conditions
• people with acute illnesses
• people who work outdoors and are engaged in strenuous physical labor
• people in certain living situations (for example, homeless people or people with an addiction)

If you know a person who is particularly at risk, offer to help them.

Here are some handy tips to help you increase wellbeing and protect yourself from heat-related conditions at high temperatures.

Adjust your daily routine

• Avoid being outside in the midday sun if at all possible and limit outdoor activities to the mornings and evenings.
• When the weather is very hot, physical exertion, such as sports, should also be limited to mornings and evenings.
• If you have to perform physical work, drink two to four glasses of a cool non-alcoholic drink per hour.
• When outside, keep to the shade as much as possible, wear light clothing and sunglasses and keep your head covered if it’s sunny.
• Never leave children or people in poor health in a parked vehicle or in direct sunlight, even for brief periods.

Make sure you get enough to eat and drink

• Drink at least 1.5 to 2 liters of fluid per day. Sodium-rich mineral water or tap water, fruit juice mixed with mineral water and tea without sugar are best. Avoid drinks that contain alcohol, caffeine or lots of sugar. If you have pre-existing conditions such as cardiovascular disorders or kidney diseases you should talk to the doctor treating you about the right amount to drink.
• Whilst it’s true that people often feel less hungry at high temperatures, it’s important to stick to light meals. Soups, broths and fruit and vegetables with a high water content keep the body supplied with sufficient fluids and restore electrolyte levels.

Cool yourself and your living areas down

• Air the rooms at night and early in the mornings. Windows should be kept shut with the curtains drawn during the day. Stay in the coolest rooms, particularly at night-time.
• Cool down by taking a shower or bathing your arms and feet. Wet compresses or a water atomizer are also a good way to cool down. Dry yourself down as little as possible. 

There are further recommendations for older people and people in need of care that can stop hot weather from harming their health.

The “Klima Mensch Gesundheit” (Climate People Health) portal of the Federal Institute for Public Health (Bundesinstitut für Öffentliche Gesundheit) provides information about what to do during hot weather as well as suggestions for your everyday routine (in German).

The Heat Protection Plan for Health (Hitzeschutzplan für Gesundheit) developed by the Federal Ministry of Health (Bundesministerium für Gesundheit) is designed to make people more aware of the topic of heat protection. It includes specific heat protection strategies for municipalities, care facilities, hospitals and individuals (in German).