Typical air vs. spike days
- Annual average PM2.5 (8.10 µg/m³) reflects usual daily exposure.
- Worst-day peak PM2.5 (32.50 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 New Orleans without contradicting EPA-aligned thresholds.
River Humidity and Mold Spores
Proximity to the Mississippi River and the Gulf ensures that humidity remains a constant factor for local HVAC systems. This moisture facilitates high mold spore counts and keeps heavy pollen, like that from local live oaks, damp and sticky. These particles adhere to filter fibers more aggressively than dry dust. In the city, the combination of urban particulates and high biological loads means filters can become restricted quickly, even if they don't look completely black with soot.
Technician's Filter Recommendations
Given the PM2.5 spikes above 25 µg/m³, I recommend a MERV 13 pleated filter for the city homes. A MERV 13 is specifically designed to capture the fine particles that make up those 32.5 µg/m³ peaks. Additionally, because ozone levels hit 0.0706 ppm, look for a filter that includes an activated carbon or charcoal layer to help absorb gaseous pollutants. Change these filters every 60 days. The local humidity can cause organic material trapped in the filter to break down, which can lead to odors or even mold growth within the air handler. Ensure your filter fits tightly in the track; any gaps allow the most dangerous fine particles to bypass the filter entirely and coat your evaporator coils.