Why You Should Open A Window (Especially When It's Cold Outside)

It's counterintuitive, but according to the U.S. Environmental Protection Agency, indoor air is often more polluted than outdoor air, even in urban environments. Keeping windows closed during winter months may provide warmth and save on household energy use, but it also traps in pollutants. The simple act of opening a window—even in cold weather—can reduce this pollution.

In fact, opening a window for at least five minutes a day should be enough to decrease the concentration of indoor air pollutants. Most home heating and cooling systems, including forced air heating systems, do not mechanically bring fresh air into the house, so manual really is the way to go.

If you're wondering where all of this indoor air pollution comes from, it's a long list of offenders that includes building materials, furnishings, air fresheners, unvented or malfunctioning stoves, furnaces, paints, cleaning products, personal care products, pesticides, and more. The top classes of chemicals to look out for at home include volatile organic compounds (VOCs), nitrogen dioxide, flame retardants, and phthalates.