40 CFR § 50.3Chapter I

§ 50.3 Reference conditions.

Primary source

Verbatim text below is from the Electronic Code of Federal Regulations (eCFR), a public-domain U.S. government work. Always verify the current version with the eCFR before relying on it for any legal matter.

Full Text

e.g.,2.52.5All measurements of air quality that are expressed as mass per unit volume ( micrograms per cubic meter) other than for particulate matter (PM) standards contained in §§ 50.7, 50.13, 50.18, and 50.20, and lead standards contained in § 50.16 shall be corrected to a reference temperature of 25 (deg) C and a reference pressure of 760 millimeters of mercury (1,013.2 millibars). Measurements of PM for purposes of comparison to the standards contained in §§ 50.7, 50.13, 50.18, and 50.20, and of lead for purposes of comparison to the standards contained in § 50.16 shall be reported based on actual ambient air volume measured at the actual ambient temperature and pressure at the monitoring site during the measurement period.

[89 FR 10365, Dec. 19, 2024]

eCFR data current as of: June 10, 2026

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