DIt’s easy to get sick in winter. Headaches, coughs and sniffles abound. Colds, Covid and flu are probably the culprits. But sometimes these symptoms are exacerbated or even caused by the hot, dry indoor environments we live in during the colder months. Constant heating from boilers, heaters and ovens can make us feel unwell.
Dry air, reduced air circulation and increased exposure to indoor pollutants can leave us feeling exhausted and sore.
When it gets cold outside, “people start coughing more when they’re indoors,” says Dr. Imran Satia, a physician and assistant professor at McMaster University. Coughing, he explains, is a defense mechanism. When Satia sees patients with a cough, the question is: what does the cough protect the lungs against?
It is of course possible that you are ill. Studies like a co-author of Satia show that you have a greater chance of becoming infected with a respiratory virus in winter. In this case, coughing is a spontaneous reflex that clears the lungs of germs and mucus.
But there are other reasons why you might not feel well once your indoor heating kicks in. This is what you need to know about the possible consequences of the heated indoor climate in our homes, offices and other spaces.
How does heated indoor air affect your health?
In short, indoor air quality is not regulated and can vary depending on the type of building you live in, how old it is, how it is heated and how much you can control the temperature.
In an effort to keep your home warm but your heating bills low, you can keep your windows and doors closed in the winter. However, this can cause indoor air quality to deteriorate, explains John Durant, a professor at Tufts University who researches indoor air quality. Pollutants such as allergens, dust and mold can be released when heating systems are turned on. These join other pollutants that end up indoors, such as the chemicals in cleaning products, the byproducts of cooking and the compounds emitted by furniture. If your home is not well ventilated and you keep the windows closed, these particles can cause irritation.
If there is not much air circulation and several people are around, carbon dioxide can also build up, explains Dr. Clayton Cowl, an occupational medicine specialist and pulmonologist at the Mayo Clinic. This can cause “headaches, fatigue and just plain ickiness,” says Cowl.
Meanwhile, hot spaces can cause your heart rate to drop, making you feel less energetic, Durant explains. Heated air is also dry, which can lead to dehydration.
“I think it’s fair to say that you’re simultaneously bombarding yourself with a mixture of environmental insults when you heat your air, close your windows, dehydrate yourself, and expose yourself to whatever’s in your air ducts,” says Durant.
How does dry air affect us?
In winter we are already dealing with drought, because cold air cannot hold as much moisture as warm air. When the indoor air is heated, it becomes even drier. With these two effects combined, you may feel jerky.
“Cold winter air contains less vapor than warm summer air,” says Dr. William Checkley, a physician and professor of medicine at Johns Hopkins University. “When your indoor heater is on, the air is heated, which in turn lowers the relative humidity, making the air in your home even drier.”
Dry air draws moisture from your body and dries out your skin, along with the mucous membranes in your nose, throat and eyes, Checkley explains. These dry mucous membranes make us more susceptible to illness from airborne particles, including allergens, viruses and bacteria.
The drying itself can also feel unpleasant. When you breathe in dry air, the resulting moisture loss can damage hair-like structures called cilia. These are located on the cells lining your airways and propel slime. This can make your throat scratchy. Dryness can also activate the part of the vagus nerve that lines the throat, says Satia. All this can lead to coughing.
Meanwhile, dehydration caused by dry indoor air can affect your blood circulation, causing fatigue. Scientists don’t know exactly why, but dehydration can also cause headaches. It’s possible that the “loss of body water could cause your brain to shrink, pulling it away from the skull and activating pain receptors,” Checkley explains.
How do you know if the warm indoor air is making you sick?
“The first thing I would say to anyone who is coughing and feeling ill in the winter months is to make sure they don’t have the virus,” says Satia. You can take a Covid-19 test at home, and if it is negative and you still feel sick, you can ask your healthcare provider for a multiplex PCR test, which can test for multiple viruses.
For people who can’t make it to the doctor’s office, Durant has a simple solution: get outside.
“If you feel like you’re sick because of the indoor air, you can easily test that hypothesis by going outside for half an hour to see if you feel better,” he says. The walk won’t tell you What indoors makes you feel bad, but it indicates that it has something to do with your home and not a virus.
What can you do to counteract the effects of warm, dry air?
Drink more water – Checkley recommends about six to eight glasses per day. Your skin may also feel very dry; Checkley recommends moisturizing, which reduces skin blemishes evaporation of water of the skin and using a humidifier.
You can reduce your chances of encountering allergens by regularly changing your bed linen and carefully cleaning your floors, carpets and furniture. Technology such as Hepa filters and air purifiers can improve indoor air quality. It’s also vital to regularly maintain the equipment that heats your home, says Cowl.
“People take that part of the house for granted,” he says. “They’ll remember to change the oil in their car, but they won’t get their furnace checked. And it is potentially very important because you are at home a lot, especially if you work from home.”
Turning on a fan or opening a few windows can also help, even if it seems counterintuitive in cold weather. “Anything you can do to increase or improve air movement will undoubtedly make you feel better,” says Durant.