StacksVerified U.S. regulatory reference

40 CFR Part 53, Table C-3

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov
Concentration range equivalent to percentage of NAAQS in µg/m330% to 250%
Minimum number of 24-hr measurements5
Maximum reference method analytical bias, Dq±5%
Maximum precision, PR or PC≤15%
Maximum difference (D)±20%
Estimated Method Detection Limit (MDL), µg/m35% of NAAQS level.

[73 FR 67059, Nov. 12, 2008]