Hourly average
Hourly average means the arithmetic average of at least four CMS data values representing the four 15-minute periods in an hour, or at least two 15-minute data values during an hour when CMS calibration, quality assurance, or maintenance activities are being performed.
Source
40 CFR § 63.7575
Scoping language
Terms used in this subpart are defined in the Clean Air Act, in 63.2 (the General Provisions), and in this section as follows: