Typical air vs. spike days
- Annual average PM2.5 (8.22 µg/m³) reflects usual daily exposure.
- Worst-day peak PM2.5 (28.71 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 Simpsonville without contradicting EPA-aligned thresholds.
Seasonal Filtration Loads
Seasonal shifts in the Upstate bring heavy pollen and mold loads that don't always show up in PM2.5 data but definitely clog filters. Proximity to Heritage Park and surrounding wooded areas means oak, pine, and ragweed cycles are intense. During high humidity months, mold spores become a secondary load on your HVAC system. These biological particles are larger than PM2.5 but far more numerous during the spring and fall. If you notice a musty smell or increased dust on surfaces near vents, your filter is likely saturated by these seasonal cycles. This organic material can accumulate on the cooling coils if the filter is not changed regularly.
Technician's Filter Recommendations
Based on peak PM2.5 levels exceeding 25 µg/m³, I recommend a MERV 13 pleated filter for most modern systems. This rating is high enough to capture the fine particulates that spike during the worst days without excessively restricting airflow, provided your ductwork is sized correctly. Because ozone peaks reach 0.0713 ppm, a filter with an activated carbon layer is highly effective at neutralizing odors and gaseous pollutants that standard filters miss. In this part of South Carolina, humidity and pollen are constant factors. You should inspect your filter every 30 days and replace it at least every 60 to 90 days. If you have pets or high foot traffic, stick to the 60-day mark to prevent your AC coils from becoming a breeding ground for dust and biological growth.