UK cold weather: what are the health risks and who is most affected?

With weather forecasters warning of low temperatures and potentially severe overnight frosts across the UK from Wednesday, the UK Health Security Agency is urging people to keep warm and look out for others most at risk from the cold. But what are the dangers that cold weather poses?

How does the cold weather hit health directly?

Public health officials are most concerned about the predictable and preventable impact of cold weather. When temperatures plummet, hospitals see more patients with heart attacks, strokes and respiratory infections, including influenza. There is also a greater risk of hypothermia – when prolonged exposure to the cold causes body temperature to drop below 35C – and when conditions are icy, more falls and related injuries.

What other health problems arise in the cold?

Beyond the direct impact of chilly weather on health, the cold has indirect effects in wellbeing, too. Cold temperatures are linked to more mental health problems, such as depression. Other risks include carbon monoxide poisoning from badly maintained or poorly ventilated boilers, and cooking and heating appliances that burn fuels.

Who is most at risk?

There are many ways to be vulnerable to the cold. Children and older people are clearly at risk, though for different reasons. Children, particularly those younger than five, have small bodies, meaning they lose heat quickly. Older people, especially those over 75, are more likely to be frail, and if they are socially isolated, may not have people checking in on them, for instance, to make sure their home is warm enough.

Among the hardest hit are the most deprived. Homeless people, or those sleeping rough, are far more exposed to the cold than others and many will die on the streets this winter. People without enough fuel to warm their homes, or who live in homes with mould, are also on the higher-risk list. So are those with mental health problems, including dementia, which can prevent people from looking after themselves.

A great swathe of others are vulnerable, too. Pregnant women need to be careful, primarily because of the potential impact of the cold on their foetus. Extreme cold, like extreme heat, has been linked to lower birth weight in babies. People with underlying health problems, such as heart disease, stroke, asthma, chronic obstructive pulmonary disease (COPD) and diabetes can all experience worse symptoms. Cholesterol and blood pressure both tend to rise in the colder months, raising the risk of heart attack and stroke. With diabetes, blood sugar tends to creep up in the cold weather, and if people’s hands get cold, it can make blood testing harder.

At what temperature do the risks ramp up?

Official figures on excess winter deaths suggest that the impact on health starts to rise when average temperatures fall below 12C, but there are regional differences, and factors such as how well a person’s home is insulated come into play. Research from UCL and the University of Bristol found that cold snaps, when the temperature drops for a few days, doubled the risk of heart attack and stroke.

What about indoor temperature?

The UKHSA advise people with pre-existing medical conditions to heat their homes to a comfortable temperature, aiming for at least 18C in the rooms used most, such as the living room and bedroom, and to keep bedroom windows closed at night.