Typical air vs. spike days
- Annual average PM2.5 (8.85 µg/m³) reflects usual daily exposure.
- Worst-day peak PM2.5 (27.91 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 Irving without contradicting EPA-aligned thresholds.
Seasonal Load on HVAC Systems
Beyond the measured PM2.5, seasonal allergens like mountain cedar and elm create a heavy physical load on HVAC systems. Near the Trinity River corridors, mold spores can also spike during humid transitions between seasons. These larger particles do not always show up on fine particulate sensors, but they are the primary cause of dirty filter calls. When pollen counts are high, the dust load in a typical home increases significantly. This material settles in the ductwork and on the cooling coils if the filter is not seated properly or if the MERV rating is too low to catch fine biological dust. Regular filter changes are required to prevent these allergens from recirculating.
Technician's Filter Recommendations
Since PM2.5 peaks exceed 25 µg/m³, I suggest a MERV 13 filter. This is the sweet spot for capturing fine particulates without causing excessive backpressure on most residential blowers. Given the ozone peaks of 0.0803 ppm, a filter with an activated carbon layer is highly effective at absorbing the gases that cause smog smells and lung irritation. In Irving, you should plan to swap these filters every 60 days. If you have pets or high foot traffic, 45 days is safer to maintain airflow. For those with asthma, a MERV 13 in the furnace plus a portable HEPA air cleaner in the bedroom is the most effective setup. Avoid the cheap, see-through fiberglass filters; they are designed to stop large debris, not the fine dust and ozone-related particles we see in local data. Standard baseline is MERV 11, but the MERV 13 is necessary for peak protection.