Typical air vs. spike days
- Annual average PM2.5 (10.32 µg/m³) reflects usual daily exposure.
- Worst-day peak PM2.5 (38.72 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 Houston without contradicting EPA-aligned thresholds.
Local Biological Load
Beyond the measured pollutants, the local humidity and proximity to the Buffalo Bayou contribute to a persistent mold and pollen load. In this region, oak and cedar seasons are particularly aggressive, often coating outdoor surfaces in yellow dust. This biological material doesn't stay outside; it enters through open doors and settles in your ductwork. High humidity levels also mean that mold spores are a year-round concern for local HVAC systems. These particles are often larger than PM2.5 but are numerous enough to clog standard filters quickly, reducing airflow and forcing your system to work harder than necessary to cool your home.
Technician's Filter Recommendations
Based on a PM2.5 max of 38.72 µg/m³, I recommend a MERV 13 filter for most modern HVAC systems. This rating is high enough to capture the fine particulates seen during peak pollution days without excessively restricting airflow. Because ozone peaks reach 0.0898 ppm, look for filters that include an activated carbon layer. Carbon is the only effective way to neutralize gaseous pollutants like ozone that pass straight through standard fiberglass filters. In this climate, do not wait 90 days to swap filters. Between the high humidity and seasonal pollen, most filters in the area are spent by the 60-day mark. If you have pets, check them every 30 days. Keeping a fresh filter is the simplest way to protect your blower motor and your lungs.