[Code of Federal Regulations]
[Title 40, Volume 2]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR50.3]

[Page 6]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 50--NATIONAL PRIMARY AND SECONDARY AMBIENT AIR QUALITY STANDARDS--Table 
of Contents
 
Sec. 50.3   Reference conditions.

    All measurements of air quality that are expressed as mass per unit 
volume (e.g., micrograms per cubic meter) other than for the particulate 
matter (PM10 and PM2.5) standards contained in 
Sec. 50.7 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 PM10 and PM2.5 for purposes of 
comparison to the standards contained in Sec. 50.7 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.

[62 FR 38711, July 18, 1997]