Why Indoor Air Quality Gets Worse During Washington Winters
Rodger Brown • February 27, 2026

Why Indoor Air Quality Gets Worse During Washington Winters

When you think of air pollution, you probably think of smog or pollen. But the air inside your home can often be of lower quality than outside. Sealing up your environment, never-ending rain and moisture, and higher heating system usage create the perfect storm for the poor indoor air quality winter in Happy Valley is known for.


“Trapping” Particles in Your Home

Homeowners should seal their home before winter. It’s one of the most effective ways to ensure comfort and prevent the HVAC from overworking itself. It keeps your utility bills low at a cost to your air quality by sealing you in with whatever contaminants were already inside your home.


Other seasons give you breathing room to open windows and let fresh air in. Winter is the worst time for natural ventilation. Without the fresh air coming in, you’ll keep circulating particles throughout your living space over and over again.


Humidity and Condensation

Washington winters are wet. Even if it isn’t raining, the ambient humidity is at an all-time high. The combination of damp air and heat from inside your home can cause condensation, especially in older homes or those with aging insulation.


Mold and mildew love this excess moisture. These spores significantly lower your home’s air quality and often trigger allergy symptoms that you might mistake for a cold that won’t quit.


If you notice a musty smell in your basement or see lots of condensation on your windowpanes, this is the poor indoor air quality winter in Washington is unfortunately infamous for.


Try keeping the indoor humidity levels between 30% and 50%. This means it’s too dry for mold but not so dry that you end up with itchy skin and more sinus issues than you started with. Whole-home dehumidifiers (or humidifiers) are excellent for regulating humidity levels.


The Kind of Indoor Air Quality Winter in Washington Should Have

Despite the uphill battle, winter doesn’t have to be a time when you feel suffocated by the air in your living room. Contact The Clean Air Act today to learn more about your options and schedule an indoor air quality assessment with one of our technicians.

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