Daily eCFR

Table F-3 to Subpart F of Part 53—Critical Parameters of Idealized Ambient Particle Size Distributions

Critical Parameters of Idealized Ambient Particle Size Distributions

CorpusDaily eCFR

Displayed edition2026-04-27

Last updated2026-04-27

Idealized Distribution	Fine Particle Mode	Coarse Particle Mode	PM _2.5/PM ₁₀ Ratio	FRM Sampler Expected Mass Conc. (µg/m³)
MMD (µm)	Geo. Std. Dev.	Conc. (µg/m³)	MMD (µm)	Geo. Std. Dev.	Conc. (µg/m³)
Coarse	0.50	2	12.0	10	2	88.0	0.27	13.814
“Typical”	0.50	2	33.3	10	2	66.7	0.55	34.284
Fine	0.85	2	85.0	15	2	15.0	0.94	78.539