Typical air vs. spike days
- Annual average PM2.5 (8.05 µg/m³) reflects usual daily exposure.
- Worst-day peak PM2.5 (33.79 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 Mundelein without contradicting EPA-aligned thresholds.
Local Allergen Loads
In Lake County, the proximity to the Des Plaines River and various forest preserves creates a heavy seasonal load of tree and ragweed pollen. Mold spores also become a factor during humid Illinois summers. These biological particles are much larger than PM2.5, but they clog standard fiberglass filters in weeks. When these allergens combine with the fine particulate spikes seen in local data, the dust load on your HVAC system increases. This isn't just about sneezing; it’s about maintaining the airflow your furnace needs to operate without overheating or burning out the blower motor.
Technician's Filter Recommendation
Based on the peak PM2.5 levels exceeding 25 µg/m³, I recommend a MERV 13 pleated filter for most homes. A MERV 13 is dense enough to capture the fine particles seen during those 33.79 µg/m³ spikes without severely restricting airflow in modern systems. Because ozone peaks reach 0.084 ppm, look for filters that include an activated carbon layer. Carbon is the only effective way to neutralize ozone gas as it passes through your ducts. Change these filters every 60 to 90 days. If you pull out a filter and it’s gray or bowed inward, you’ve waited too long. The high humidity in Illinois can also cause moisture to settle on captured dust, potentially leading to biological growth if filters are left in place for an entire season.