Typical air vs. spike days
- Annual average PM2.5 (8.76 µg/m³) reflects usual daily exposure.
- Worst-day peak PM2.5 (112.82 µg/m³) is what filtration must handle during bad-air events.
Sections below reference one or both metrics on purpose — that is how HVAC vs. portable guidance differs for Renton without contradicting EPA-aligned thresholds.
Local Allergen Loads
The moisture levels around Lake Washington contribute to high mold spore counts, while regional tree pollen creates a heavy seasonal load on your HVAC filters. This biological material acts as a sticky base for other pollutants. When pollen counts rise, they do more than trigger allergies; they physically clog the surface of your air filter, reducing airflow and forcing the blower motor to work harder. In the Pacific Northwest, keeping a clean filter is less about the visible dust and more about managing the organic debris that hitches a ride into your home during the damp spring and fall months.
Technician's Filter Recommendation
Because PM2.5 maxes out well above 25 µg/m³, I recommend a MERV 13 pleated filter for your central air system. A MERV 13 is dense enough to catch the fine particulates seen during those 112.82 µg/m³ spikes without causing excessive static pressure, provided it is changed regularly. Given the ozone peaks of 0.077 ppm, a filter with an activated carbon layer is a smart addition to help neutralize gaseous pollutants and odors. Change these filters every 60 to 90 days. If you live in a high-humidity pocket near the water, check the filter every 45 days for signs of graying or moisture, which indicates it has reached its holding capacity and needs immediate replacement.