A warm home should also be a safe and healthy home. During the winter, people spend more time indoors with windows closed, which means the way a home is heated can have a significant impact on safety and indoor air quality. Understanding common heating-related risks can help you keep your home warm while protecting the health of everyone inside.
Heating systems that burn fuel, such as gas, propane, and oil furnaces and boilers, produce combustion gases, including carbon monoxide. Carbon monoxide is a colorless, odorless gas that can cause headaches, dizziness, nausea, and, at high levels, serious illness or death. Wood stoves and fireplaces also produce carbon monoxide, along with smoke and fine particulate matter.
If your home has any fuel-burning equipment, it's important to install carbon monoxide alarms on every level of the home and near sleeping areas, and to test them regularly. Fuel-burning heating equipment should also be properly vented to the outdoors and inspected by a professional every year.
Ovens, stovetops, grills, and generators should never be used to heat a home. These devices are not designed for space heating and can quickly produce dangerous levels of carbon monoxide indoors.
Electric heating systems, such as heat pumps, do not burn fuel and therefore do not produce carbon monoxide or other combustion pollutants inside the home.
Portable space heaters can provide quick warmth in a single room, but they are also a leading cause of home heating fires. A few practices can help keep space heater use safe:
Because space heaters use electric resistance heating, they are also expensive to operate. They work best for warming a small space for a short period of time, rather than as a home's main heat source.
Cold outdoor air holds very little moisture. When that air leaks into a home and is heated, its relative humidity drops, often leaving indoor air very dry. Relative humidity measures how much moisture is in the air compared to how much moisture the air could hold at its current temperature. Dry indoor air can irritate the skin, eyes, nose, and throat, and can make respiratory symptoms worse.
Dry air can also affect your health in less obvious ways. Research suggests that some respiratory viruses, such as the flu, survive longer and spread more easily in very dry air, while dry air can weaken the natural defenses in your nose and airways.
In winter, indoor relative humidity levels between about 30% and 50% are generally comfortable while limiting moisture problems. If the air is too dry, a humidifier can help. However, too much humidity can cause condensation on cold windows and walls, which can lead to mold growth. Regular condensation on windows is often a sign that indoor humidity is too high.
Air sealing can also help, since it reduces the amount of cold, dry outdoor air that leaks into the home.
While sealing air leaks helps a home hold onto heat, every home still needs fresh air. Cooking, cleaning products, furniture, and even breathing release moisture and pollutants into the air, and these can build up indoors when a home is closed up for the winter.
Kitchen and bathroom exhaust fans that vent to the outdoors can remove moisture and pollutants at the source while cooking and showering. In well-sealed homes, mechanical ventilation systems such as energy recovery ventilators (ERVs) or heat recovery ventilators (HRVs) can bring in fresh outdoor air while capturing much of the heat from the outgoing indoor air. This allows the home to stay well ventilated without wasting the energy used to heat it.