Indoor Air Quality in Winter: Your Windows Are Closed and It Shows

From November to March, most Victoria homes seal up tight. Windows stay closed, so less fresh air comes in. The furnace runs. Indoor air isn't only a winter concern, though. EPA studies of human exposure found levels of about a dozen common organic pollutants to be 2 to 5 times higher inside homes than outside.

Pollutants that build up in sealed winter homes

Dust settles on every flat surface. Fine particles from cooking settle on your kitchen walls and cabinets. Pet dander collects on furniture and in carpet fibres. Mould spores grow in dark, damp spots—especially bathrooms. Dead skin cells from you and your family accumulate in bedding. Cleaning product fumes have nowhere to escape, so they recirculate through your home.

None of this is dramatic. None of it smells bad (usually). But when you add it all up over four months of closed windows, your home's air quality deteriorates.

Why do dust mites thrive in winter?

Dust mites live in your bedding and carpet. They don't actually cause allergy problems for most people, but their droppings do. Winter is breeding season for them because your home stays sealed. They multiply fast.

The fix: wash bedding weekly in hot water (at least 55°C / 130°F). Vacuum carpet twice a week with a HEPA filter. Both help keep their numbers down.

The easiest ways to improve indoor air quality

You don't need an expensive system to improve your air. Start here:

• Dust with damp cloths, not dry ones. Dry dusting just moves particles into the air.
• Vacuum with a HEPA filter twice a week. Standard filters miss fine particles.
• Open windows for 10 minutes on milder days (even in January, Victoria has some mild stretches).
• Clean your range hood filters monthly. Most are clogged and not working.
• Wash bedding in hot water every week.

That's it: five habits to work into your week.

Do air purifiers actually help in winter?

Air purifiers are worth it for your bedroom and living room if you have pets or severe allergies. A good HEPA purifier pulls particles out of the air. But here's the catch: they're not a replacement for cleaning. If you don't dust, vacuum, and wash bedding, the purifier is just working harder.

Think of it this way: a purifier manages what's already in the air. Cleaning stops new dust from accumulating. You need both.

Bathroom exhaust fans and your air quality

Most bathroom fans are clogged. You flip the switch and feel no real suction. That's the problem. Moisture from showers stays in your bathroom and migrates into walls and attic spaces, creating mould conditions.

Check yours. Open the cover and look for dust buildup. If it's thick, it needs cleaning. Keep the fan running after every shower; Health Canada and HealthLinkBC give specific guidance. It helps keep moisture down.

Beyond the bathroom fan, the window condensation checklist also looks at the range hood, the furnace and HRV filters, and the dryer vent.

Can houseplants really clean your air?

You've heard that houseplants clean air. They do remove some pollutants, but not enough to matter in a closed house. Don't buy 20 plants thinking they'll fix your air quality.

That said, they look nice and improve your mood. If you like plants, get them. Just don't count on them as an air quality solution.

What's the best way to maintain clean air in winter?

Winter air quality isn't about buying the right product. It's about cleaning consistently. Dust twice a week. Wash bedding weekly. Clean range hood filters. Open windows when you can. Run bathroom fans.

Those habits cost almost nothing. Want a head start before the windows close? Our fall seasonal clean includes dusting heating vents and radiators.