Typical air vs. spike days
- Annual average PM2.5 (8.03 µg/m³) reflects usual daily exposure.
- Worst-day peak PM2.5 (25.36 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 Charlotte without contradicting EPA-aligned thresholds.
Pollen and Regional Factors
Seasonal pollen is a major factor for local filtration systems. The proximity to the Catawba River basin and the heavy tree canopy in the region leads to high concentrations of oak, pine, and grass pollen. This biological load clogs filters quickly and can lead to mold growth within the HVAC cabinet if indoor humidity is not strictly managed. In the city, these natural allergens often combine with fine particulates, creating a heavy load on your home's air return.
Technician's Filter Recommendation
Because PM2.5 peaks in the city exceed 25 µg/m³, I recommend a MERV 13 filter for most homes. This rating is dense enough to capture the fine particulates seen during peak days without overly restricting airflow in modern HVAC systems. Given the ozone max of 0.0789 ppm, a carbon-infused filter is a smart upgrade to help strip out gaseous irritants and odors. Replace these filters every 60 days during peak pollen or high-heat months to ensure the blower motor does not overheat while pushing air through a dirty medium.