Understanding Airborne Particle Scale
Airborne pollution is categorized by aerodynamic diameter, measured in micrometers (microns, µm). For perspective, a single strand of human hair measures roughly 50 to 70 microns across. The smaller the particle, the deeper it travels into human pulmonary tissue.
| Fraction | Particle Size | Common Sources | Health Mechanism |
|---|---|---|---|
| PM10 | 2.5 to 10 µm | Coarse dust, mold spores, ragweed pollen | Trapped in nasal mucous; coughing, sneezing |
| PM2.5 | 0.1 to 2.5 µm | Wildfire smoke, vehicle exhaust, pet dander | Penetrates deep lung alveoli; cardiovascular inflammation |
| PM1.0 | < 1.0 µm | Ultrafine aerosols, virus droplets, diesel soot | Crosses alveolar-capillary barrier directly into bloodstream |
Filtration Requirements by Fraction
Standard MERV 8 filters capture PM10 effectively but capture less than 20% of PM1.0. To eliminate sub-micron PM1.0 particles, residential systems require MERV 13+ central media or standalone H13 True HEPA purifiers, which achieve 99.97% arrestance down to 0.3 microns.
About ClariSelect Editorial & Research Standards:
Sizing measurements, static pressure curves, and filtration ratings referenced across our educational guides are compiled from published ANSI/ASHRAE Standard 52.2 engineering data, AHAM AC-1 verified ratings, and manufacturer technical documentation. ClariSelect provides objective editorial research and analysis with zero sponsored placements.