Typical air vs. spike days
- Annual average PM2.5 (9.15 µg/m³) reflects usual daily exposure.
- Worst-day peak PM2.5 (46.68 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 Savannah without contradicting EPA-aligned thresholds.
Coastal and River Basin Allergens
The coastal environment and proximity to the Savannah River contribute to high humidity levels that sustain mold and heavy pollen counts. From early spring oak pollen to late summer ragweed, the outdoor load on your HVAC system is constant. These allergens are often sticky and can adhere to the internal components of your AC unit, such as the evaporator coil. When combined with the high humidity common in the city, this creates a risk for biological growth inside the system. Managing the indoor environment requires a filter that can handle both the fine PM2.5 spikes and the larger, more frequent seasonal biological particles.
HVAC Filter Recommendations
I recommend a MERV 13 filter for the city homes to address the PM2.5 peaks that reach 46.68 µg/m³. A MERV 13 is dense enough to capture the fine particles that a standard MERV 8 will miss. Since ozone levels also spike to 0.072 ppm, a filter with activated carbon is highly effective at absorbing those gases before they enter your rooms. Do not wait 90 days to change your filter here. The humidity and heavy pollen load will saturate the media, forcing your blower motor to work harder and potentially leading to a frozen coil. Change your filter every 60 days. If you have pets or high foot traffic, check it every 30 days. A secondary HEPA purifier in the bedroom is the best way to supplement your central HVAC system.