That sniffing? That cough? Those watery eyes? Could be a cold. Could be the flu. And it could be air pollution—which is at full strength right now when doors and windows are shut tight against the weather.

While you’re trying to keep cold air out, you’re also trapping bad air in. Without circulation, indoor air quality takes a dive during the winter months. To protect yourself and your family, and improve your health, there are some simple things you can do to improve the air in your home. Here’s how:

1. Every month, replace your air and heating filters.
2. Keep your vents clean, and make sure they’re not blocked by furniture.
3. Clean your chimney so smoke doesn’t back up into your home.
4. Don’t smoke in your home, and don’t permit visitors to do so either.
5. Restrict pets from certain rooms to keep those rooms free of tracked-in dirt.
6. Switch to burning natural candles without chemical components and artificial scents.
7. Use non-toxic cleaning supplies.
8. Take your shoes off at the door so you don’t bring in outdoor pollutants.
9. Vacuum carpets and rugs frequently.

10.  Don’t forget to vacuum your upholstery.

 If you’ve got a green thumb, houseplants can also help filter your indoor air—so you can breathe even easier this winter.