Regulations last checked for updates: Nov 22, 2024

Title 40 - Protection of Environment last revised: Nov 20, 2024
§ 61.03 - Units and abbreviations.

Used in this part are abbreviations and symbols of units of measure. These are defined as follows:

(a) System International (SI) units of measure:

A = ampere g = gram Hz = hertz J = joule K = degree Kelvin kg = kilogram m = meter m 2 = square meter m 3 = cubic meter mg = milligram = 10−3gram mm = millimeter = 10−3meter Mg = megagram = 10 6gram mol = mole N = newton ng = nanogram = 10−9gram nm = nanometer = 10−9meter Pa = pascal s = second V = volt W = watt Ω = ohm µg = microgram = 10−6gram

(b) Other units of measure:

°C = degree Celsius (centigrade) cfm = cubic feet per minute cc = cubic centimeter Ci = curie d = day °F = degree Fahrenheit ft 2 = square feet ft 3 = cubic feet gal = gallon in = inch in Hg = inches of mercury in H2O = inches of water l = liter lb = pound lpm = liter per minute min = minute ml = milliliter = 10−3liter mrem = millirem = 10−3 rem oz = ounces pCi = picocurie = 10−12 curie psig = pounds per square inch gage °R = degree Rankine µl = microliter = 10−6liter v/v = volume per volume yd 2 = square yards yr = year

(c) Chemical nomenclature:

Be = beryllium Hg = mercury H2O = water

(d) Miscellaneous:

act = actual avg = average I.D. = inside diameter M = molar N = normal O.D. = outside diameter % = percent std = standard [42 FR 51574, Sept. 29, 1977, as amended at 54 FR 51704, Dec. 15, 1989]
authority: 42 U.S.C. 7401
source: 38 FR 8826, Apr. 6, 1973, unless otherwise noted.
cite as: 40 CFR 61.03