Cold Weather Can Be Dangerous for the Human Body. This Winter Worries Experts

A particularly nasty trifecta of influenza, COVID-19, and respiratory syncytial virus (RSV) is already portending a rough winter. But there’s another factor contributing to a potentially tough season for health: a colder-than-average season, which is forecast in the northern U.S. and the U.K.

Even an ordinary cold season can pose a threat to human health and safety. One 2015 study published in the Lancet analyzed over 74 million deaths around the world found that more than 7% of deaths were attributed to exposure to cold temperatures. “There is conclusive evidence that there is increased risk for many health outcomes related to cold,” says Antonio Gasparrini, lead author of the study and professor at the London School of Hygiene & Tropical Medicine.

Surging natural gas costs mean that many families will struggle to afford to heat their homes, compounding the issue. “I’m extremely worried. Especially in Europe, [many] homes are heated by natural gas,” says Tiina Ikäheimo, a professor at the University of Tromsø, known as the Arctic University of Norway. “[I’m especially worried] for those who cannot afford to purchase energy needed for their homes, and for elderly people.”

Here’s what to know about how cold temperatures affect health.

How cold weather can be dangerous

One of the most dangerous things about cold temperatures is that they come with an increased risk of cardiac issues, like heart attack and stroke, particularly for people with conditions like heart disease. This is the result of the body’s natural defense system that kicks in as the temperature drops: to avoid losing heat to the environment, blood vessels by the skin contract, leading to a natural increase in blood pressure. This happens suddenly when the body gets cold, but the effect lasts; people’s blood pressure tends to stay higher throughout the cold season, says Ikäheimo. This constriction of blood vessels also leads to more urination, which can cause dehydration if lost liquid isn’t replaced by drinking more water. These changes can cause blood to thicken, which raises the risk of blood clots and forces the cardiovascular system to work harder.

Cold can also have harsh effects on the respiratory system and aggravate respiratory diseases like asthma and chronic obstructive pulmonary disease (COPD). Breathing in cold air can irritate the airway and trigger symptoms like trouble breathing, coughing, and mucus production.

Read More: RSV Cases Are Rising in Kids and Babies. What Parents Should Know

Respiratory diseases like influenza and COVID-19 also circulate more in the winter. People tend to spend more time inside and gather more often in homes and other indoor spaces in the winter, which facilitates the spread of viruses. Some evidence also suggests that cold, dry weather may be ideal for rhinovirus and flu virus to spread, which may mean that viruses can remain viable longer and spread more efficiently, says Ikäheimo.

Who is most vulnerable to the health effects of low temperatures?

Being exposed to cold temperatures is more dangerous for people with chronic conditions, including cardiovascular disease, respiratory disease, and diabetes. Older people tend to have a combination of other related risk factors that may increase their risk for cold-related health effects. For instance, during aging, metabolic systems slow down, the layer of fat under the skin thins, and organ systems are more likely to get stressed from a sudden shift in temperature.

Lower income communities are also at graver risk than other people. In the U.S., lower income households spend three times the share of their income on energy than more affluent households, said Lanikque Howard, director of the Office of Community Services in the Administration for Children and Families, which is part of the U.S. Department of Health and Human Services, in a Nov. 2 press release.

On the same day, the Biden Administration announced $4.5 billion in assistance to help lower-income Americans cover their heating costs this winter.

Age UK, a charity that provides elder services, said in a statement in Sept. that 2.8 million households with people over 60 in the U.K. are expected to live in energy poverty this cold season—meaning that they won’t be able to afford to properly heat their home. That’s 1.8 million more households than in 2021.

“We have in the U.K. the oldest housing stock in Europe,” which means homes are difficult to heat, says Caroline Abrahams, director of Age UK. “People’s energy bills tend to be high in the best of times.” But because of surging energy costs, especially as Russia has reduced exports to Europe, “our bills have gone up so much so quickly, that they’re overwhelming people. Even people who would normally never expect to have to worry about things like how much it was costing them to turn on the heating now have to worry about it.”

How to protect yourself

One surprising finding in Gasparrini’s study is that some countries have many more deaths attributable to the cold—but not necessarily because they’re colder places. For instance, in Sweden (which has colder winters than the U.K.), the rate of deaths attributable to cold is lower than in the U.K. Part of the reason is the U.K.’s old housing stock, which is poorly suited to cold weather. Sweden, meanwhile, has high thermal standards in buildings, and enforces a rule in which heating costs are typically fixed and part of the rent, unlike in the U.K. and other E.U. member states. Ikäheimo also points out that people who live in places that are accustomed to cold have learned to adapt their behavior to protect themselves.

One modifiable way to protect yourself from the cold is to dress warmly. When you’re outside, Ikäheimo says it’s important to dress in adjustable layers: first, don a base layer that can wick away moisture; then, put on an inner layer to insulate you; and finally, wear a waterproof outer layer that can guard you from wind, snowfall, and rain. In cold indoor environments, she says, add layers to protect your extremities—like warm socks and scarves—and make sure your bedding is warm enough to keep you comfortable at night.