Typical air vs. spike days
- Annual average PM2.5 (8.80 µg/m³) reflects usual daily exposure.
- Worst-day peak PM2.5 (33.00 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 Henderson without contradicting EPA-aligned thresholds.
The Hidden Load on Your Filters
Pollen and mold represent a constant, invisible load on local HVAC filters. The Ohio River geography traps moisture and airborne irritants, leading to high mold counts during humid months and heavy tree pollen in the spring. These biological particles are often larger than PM2.5 but occur in much higher volumes, physically clogging filter media and reducing airflow. If you notice a musty smell when the air conditioner starts, it is usually a sign that the evaporator coil or the filter has captured enough organic material to support microbial growth. Regular filter changes are the only way to prevent these allergens from recirculating through your living space.
Technician's Filter Recommendations
Because PM2.5 peaks in Henderson exceed 25 µg/m³, I recommend a MERV 13 pleated filter for most modern HVAC systems. A MERV 13 is dense enough to capture the fine combustion particles and smoke that characterize those 33.0 µg/m³ days. However, these filters create more resistance, so you must change them every 60 to 90 days to avoid stressing the blower motor. If your system is older and struggles with the thickness of a MERV 13, use a MERV 11 and supplement it with a standalone HEPA unit in the main living area. Given the ozone peaks, look for filters with a layer of activated carbon to help neutralize odors and gaseous pollutants that standard fiberglass filters miss entirely. Always check your filter monthly during the peak humidity of summer.