Typical air vs. spike days
- Annual average PM2.5 (8.16 µg/m³) reflects usual daily exposure.
- Worst-day peak PM2.5 (32.14 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 Adrian without contradicting EPA-aligned thresholds.
Local Pollen and Mold Loads
Seasonal allergens represent the heaviest physical load on local HVAC filters. The proximity to the River Raisin and the surrounding agricultural landscape ensures a steady supply of tree pollen in the spring and ragweed in the late summer. High humidity levels in southern Michigan also contribute to mold spore activity. These biological particles are much larger than PM2.5 but are produced in massive volumes, often matting across filter media and reducing airflow. This restricted airflow forces your blower motor to work harder, increasing wear and energy costs if the filter isn't swapped regularly.
Technician's Filter Recommendations
Because Adrian sees PM2.5 spikes exceeding 25 µg/m³, I recommend a MERV 13 pleated filter for your central HVAC system. A standard MERV 8 or 11 filter is sufficient for dust, but it lacks the density required to capture the fine combustion particles seen during those 32.14 µg/m³ peaks. Additionally, since ozone levels reach 0.0705 ppm, look for a filter that includes an activated carbon layer to help neutralize gaseous pollutants. In this climate, filters should be replaced every 60 to 90 days. If you notice a gray or heavy brown film on the filter surface before the 60-day mark, it is a sign of high local dust or pollen infiltration, and you should move to a more frequent replacement schedule.