Typical air vs. spike days
- Annual average PM2.5 (9.78 µg/m³) reflects usual daily exposure.
- Worst-day peak PM2.5 (26.25 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 Collinsville without contradicting EPA-aligned thresholds.
Seasonal Filtration Challenges
The local environment in Madison County produces heavy seasonal loads of pollen and mold. During the transition into spring and the peak of fall, the outdoor air is thick with allergens that quickly accumulate on HVAC filters. In the summer, the humidity common to the region can cause these captured organic materials to become a breeding ground for odors. Residents near local parks or trails will notice a faster buildup of biological debris, necessitating more frequent filter inspections to prevent airflow restriction and maintain system efficiency.
HVAC Filter Recommendations
For the city homes, I recommend a MERV 13 pleated filter. Because the max PM2.5 exceeds 25 µg/m³, a standard MERV 8 or 10 filter will not capture enough of the fine particulates during peak events. Furthermore, since ozone peaks are a documented issue at 0.0761 ppm, I strongly suggest a filter that includes activated carbon or charcoal. Carbon is the only filter media that can chemically adsorb ozone and other gaseous pollutants, preventing them from circulating through your house.
- Maintenance Schedule: Replace filters every 60 to 90 days. If you have pets or high foot traffic, 60 days is the limit.
- Filter Fit: Ensure there are no gaps around the filter rack. Air will take the path of least resistance, bypassing the filter if it isn't seated properly.
- Airflow: If your system is older, have a technician verify that it can handle the static pressure of a MERV 13 filter.