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.

Persistent periods of high temperatures are a problem as they can cause health problems.
During the heatwaves of recent years, the number of hospital referrals and heat-related deaths in Germany increased significantly: in the particularly hot month of August 2003, there were around 7,000 additional deaths related to heat compared with the numbers for August in previous years.

Humans are generally good at adapting to high temperatures. The body tries to cool down in a number of ways. The most important way it does this is by 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. Low fluid and electrolyte levels can also quickly cause heat-related health conditions. This is indicated by headaches and indisposition, circulation problems, confusion and in extreme cases loss of consciousness.
At-risk groups such as older people, children and people with chronic conditions are particularly affected by heat-related conditions.

Maintaining sufficient fluid intake and light meals, as well as handy 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 initial precautions need to be taken when the room and ambient temperature reaches 26°C or your wellbeing is affected. There is a far greater risk to health if extreme hot weather with temperatures above 30°C persists for several days. 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 referred to as the “apparent 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°C higher than the measured air temperature.

Persistent periods of 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.

It is important to give those affected drinks containing salt to avoid exacerbating the electrolyte deficit. Mixing salt in water (1 teaspoon of salt per liter) is a good way to do this.

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.

Too much sun on a person’s (uncovered) head can easily cause sunstroke. Possible signs are restlessness, dizziness, nausea, headaches, 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 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. Drinks containing salt should be administered to people with mild sunstroke. The emergency services should also be called if there are signs of severe sunstroke such as impaired consciousness or a stiff neck.

Temporary loss of consciousness or circulatory collapse are indications of heat collapse. 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 the person lies down in a cool place with their legs raised. They should be given drinks containing salt if they are conscious. The emergency services should be called as a precaution even though the loss of consciousness is mostly brief and not normally dangerous.

Painful muscle cramps, often following severe physical exertion in hot weather, are indications of heat cramp. They occur mostly in the legs and abdomen, sometimes several hours later.

First aid

People with heat cramp should rest in a cool location, carefully stretch and massage the muscles affected and drink beverages containing salt to restore electrolyte levels.

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. Indications of heat exhaustion include debility, indisposition, dizziness, headache, increased sweating, severe thirst and later on dry, pale, cool skin, body temperature of up to 40°C and low blood pressure.

First aid

It’s important to call the emergency services if someone has heat exhaustion. It is also important to cool the body down to 38.5 to 39°C, for example by immersing the body in cold water or taking a shower, spraying with cold water to cool by evaporation or ensuring there is a through draft; other options include cool packs on the neck, groin and armpits. It is also important to place the person in a cool location, remove surplus clothing and administer drinks containing salt. It is advisable to call the doctor if the person is suffering from severe heat exhaustion. 

Indications of heatstroke are a body temperature above 40°C and impaired consciousness, and may include epileptic fits, vomiting, diarrhea and low blood pressure.

Heatstroke in older people, people with chronic conditions and children is mostly caused by high ambient temperatures as well as 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 signs of heatstroke and resuscitation measures initiated if necessary. It is essential to cool down the body as quickly as possible until the emergency services or emergency doctor arrives. The best way to do this is by immersing the body in cold water or taking a shower, spraying with cold water to cool by evaporation or ensuring there is a through draft; other options include cool packs on the neck, groin and armpits. It is also important to place the person in a cool location, remove surplus clothing and give them something to drink if at all possible.

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.

People most at risk are

• people who work outdoors or engage in sports
• older people and people in need of care, particularly if they live alone
• babies and infants
• people with memory problems who are dependent on other people’s help
• people who regularly take certain medication such as diuretic and hypertensive drugs, medical patches
• people with physical and mental impairments or certain chronic conditions such as cardiovascular disease, metabolic disorders, infectious diseases
• people with acute conditions, particularly fever
• people who consume alcohol and psychoactive drugs

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.
• 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 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.
• When the weather is very hot, physical exertion, such as sports, should be limited to mornings and evenings.

Make sure you get enough to eat and drink

• Drink at least 1.5 to 2 liters of fluid per day. 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.de portal of the Federal Center for Health Education (BZgA) provides information on what to do during hot weather as well as suggestions for your everyday routine (in German).