{"data":{"id":"us/40-cfr-61.03","jurisdiction":"us","citation":"40 CFR 61.03","heading":"Units and abbreviations.","body":"Used in this part are abbreviations and symbols of units of measure. These are defined as follows:\n(a) System International (SI) units of measure:\nA = ampere\ng = gram\nHz = hertz\nJ = joule\nK = degree Kelvin\nkg = kilogram\nm = meter\nm 2 = square meter\nm 3 = cubic meter\nmg = milligram = 10−3gram\nmm = millimeter = 10−3meter\nMg = megagram = 10 6gram\nmol = mole\nN = newton\nng = nanogram = 10−9gram\nnm = nanometer = 10−9meter\nPa = pascal\ns = second\nV = volt\nW = watt\nΩ = ohm\nµg = microgram = 10−6gram\n(b) Other units of measure:\n°C = degree Celsius (centigrade)\ncfm = cubic feet per minute\ncc = cubic centimeter\nCi = curie\nd = day\n°F = degree Fahrenheit\nft 2 = square feet\nft 3 = cubic feet\ngal = gallon\nin = inch\nin Hg = inches of mercury\nin H2O = inches of water\nl = liter\nlb = pound\nlpm = liter per minute\nmin = minute\nml = milliliter = 10−3liter\nmrem = millirem = 10−3 rem\noz = ounces\npCi = picocurie = 10−12 curie\npsig = pounds per square inch gage\n°R = degree Rankine\nµl = microliter = 10−6liter\nv/v = volume per volume\nyd 2 = square yards\nyr = year\n(c) Chemical nomenclature:\nBe = beryllium\nHg = mercury\nH2O = water\n(d) Miscellaneous:\nact = actual\navg = average\nI.D. = inside diameter\nM = molar\nN = normal\nO.D. = outside diameter\n% = percent\nstd = standard","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER C—AIR PROGRAMS","PART 61—NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS","Subpart A—General Provisions"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-40.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:04Z","sha256":"06e1cd6ff25dcfc2dc31b57897264065f34bad1ab9e4cc7b7fc203a853acad02","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-61.02","next":"us/40-cfr-61.04"},"notice":"GroundRules: Original legal text. Not legal advice."}