There are several reasons why older people have particular difficulty when the temperature is high:

• They are not as able as younger people to gradually adjust (acclimate) to long periods of high temperatures and humidity.

• They tend to have difficulty increasing the flow of blood to all skin surfaces because of reduced circulation, and thus their body does not cool itself as readily.

• They tend to lose sweat glands with age.

• They have delayed perception of heat and are, therefore, slow to respond to temperature change.

• They may have mobility problems that make it difficult for them to move out of hot environments.

Certain disorders that are more common among older people, such as heart and kidney failure, can interfere with the body’s ability to cool itself. People with high blood pressure are often on low-salt diets, which may prevent them from consuming enough salt to replace the salt they lose in sweat.

Aging also affects thirst. Older people do not get thirsty as readily as younger people. Thus, older people tend to get dehydrated, which in turn means they are less able to sweat in warm surroundings.