Typical air vs. spike days
- Annual average PM2.5 (9.43 µg/m³) reflects usual daily exposure.
- Worst-day peak PM2.5 (42.84 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 Dearborn without contradicting EPA-aligned thresholds.
Seasonal Load and Local Factors
Seasonal changes in Wayne County create a heavy biological load that stresses HVAC systems. Spring brings a surge of tree pollen, followed by grass and weed pollen through the fall. The proximity to the Rouge River and local park systems means mold spores are a constant presence, especially during the humid days of summer. These allergens are physically larger than PM2.5 but can overwhelm a filter through sheer volume. When your filter gets coated in pollen and mold, it forces your blower motor to work harder, increasing your energy bills and reducing the lifespan of your equipment. This physical debris also provides a surface for smaller particulates to stick to, further restricting airflow.
Technician's Filter Recommendations
Given that PM2.5 peaks in Dearborn exceed 40 µg/m³, a MERV 13 filter is the minimum requirement for effective whole-home protection. Standard fiberglass or MERV 8 filters will not capture the fine particulates present during these spikes. Because ozone levels also peak at 0.076 ppm, I strongly suggest a filter with an integrated activated carbon layer. Carbon is essential for adsorbing gaseous pollutants and odors that standard mechanical filters miss. In this climate, change your filters every 60 days. The high particulate load on peak days, combined with seasonal pollen and Michigan humidity, can lead to rapid filter bypass or airflow restriction. If you have a high-velocity system, ensure the MERV 13 filter is a high-capacity pleated version to maintain proper static pressure and avoid damaging your furnace motor. Regular replacement is the cheapest way to avoid expensive blower motor repairs.