40 CFR 97.203 - Measurements, abbreviations, and acronyms.

Regulations last checked for updates: Feb 08, 2026

Title 40 - Protection of Environment last revised: Dec 22, 2026

§ 97.203 - Measurements, abbreviations, and acronyms.

Measurements, abbreviations, and acronyms used in this subpart and subparts BBB through III are defined as follows:

Btu—British thermal unit.

CO2—carbon dioxide.

H2O—water.

Hg—mercury.

hr—hour.

kW—kilowatt electrical.

kWh—kilowatt hour.

lb—pound.

mmBtu—million Btu.

MWe—megawatt electrical.

MWh—megawatt hour.

NOX—nitrogen oxides.

O2—oxygen.

ppm—parts per million.

scfh—standard cubic feet per hour.

SO2—sulfur dioxide.

yr—year.

authority: 42 U.S.C. 7401,7403,7410,7426,7491,7601,and,

source: 65 FR 2727, Jan. 18, 2000, unless otherwise noted. 71 FR 25396, 25422, and 25443, Apr. 28, 2006

cite as: 40 CFR 97.203