As temperatures rise in southern British Columbia this week, so will health risks for seniors.

Environment Canada is forecasting temperatures in the Southern Interior in the mid to high 30s this week and up to 39 C for the weekend.

"I don't think that people take [heat waves] as seriously as they probably should," said Sarah Henderson, senior environmental scientist with the B.C Centre for Disease Control.

Henderson studied the effects of a week-long extreme heat event in the Lower Mainland in 2009 which caused an estimated 110 premature deaths and found many of those victims were between 65 and 75 years old.

"Can you imagine what it would look like if 110 people died of the flu in a week?" said Henderson, "It would be insane."

She said researchers think older seniors might be less at risk because more of them are in care facilities with access to air conditioners or health care practitioners than their younger peers.

Hard on the heart

The human body loses the ability to regulate temperature as it ages for a number of reasons, putting people without access to shelter, shade or air conditioning at a higher risk of heat-related illness or death.

On top of that, older bodies have a delayed thirst response. "By the time they think they're thirsty, they are really dehydrated," according to Gareth Jones, assistant professor at the School of Health and Exercise Sciences at the University of British Columbia Okanagan.

When a person becomes dehydrated, their blood thickens and it puts more stress on the heart, according to Jones. For seniors, dehydration can be deadly, because they're already dealing with a weakened circulatory system.

"The veins and arteries get a little bit softer and harder to move blood through. It's just a compounding effect. Basically, the heat puts stress on the body and it can knock people over the edge," said Henderson.

"Staying cool is staying safe"

Theoretically, it's easy to stay safe during a heat wave if you have access to shelter and water, according to Henderson.

"Staying cool is staying safe," she said.

Jones suggested a number of ways for seniors to keep their cool through the hot spell; first of all, by avoiding strenuous activity.

He also suggests checking in on friends, family and neighbours who are at risk or live alone.

Seniors should eat crackers or try drinking tomato juice, which has much needed potassium and sodium that is lost through sweating, said Jones.

Other ways to keep cool include misting skin with a spray bottle and wearing light, loose fitting clothing,.

It's also important to be aware that some drugs can affect the body's temperature-regulating ability, including pharmaceuticals used to treat psychosis, epilepsy and Parkinson's disease, according to Henderson.

Children and poor at risk

Seniors aren't the only group at an increased risk of mortality during an extreme weather event.

Henderson said her research showed an increase in heat-related illness and death as well as an up-tick in suicides in low-income neighbourhoods during the 2009 heat wave in Vancouver.

Very young children from infancy to early grade school are also at an increased risk. Because their temperature regulation isn't fully developed until later in life, they should be given extra attention to ensure they stay cool and hydrated, said Ian Pike, a pediatrician at B.C. Children's Hospital.

Pike suggested parents keep children's skin covered using hats and clothing and sunscreen, but most importantly, make sure kids are drinking water throughout the day and keep them inside when possible.

With files from CBC Radio One's Daybreak South