Glossary & Terms

Environmental Consulting – Air Pollution Control


acfm = actual cubic feet per minute

acid rain = a condition resulting from combination of atmospheric water vapor with pollutants such as SO x and NOx

AGRE = Acid Gas Removal Efficiency, % AGRE = (ASC-AST)(100)(ASC)

Air Pollution Index = an arbitrarily derived, mathematical combination of air pollutants which give a single number attempting to describe the ambient air quality. The formula API = 20 [SO+1(CO)+2(smoke shade)] has no scientifically derived basis. Experience indicates that the average value of this index in 12.0. An index reading of 50.0 is considered adverse and a cause for alarm.

Ambient air quality standards = those specified as for the general atmosphere in outdoor areas frequented by people, as opposed to stack or source emission standards.

ANPR = advance note of proposed rulemaking

APC = Air Pollution Control

APCD = Air Pollution Control District

AQCR = Air Quality Control Region Top of Page icon

AQMD = Air Quality Management District, as SCAQMD = South Coast (of California) AQMD.

AQMP = Air Quality Maintenance Plan

ARB = Air Resources Board, e.g. CARB for California ARB

ARIP = Accidental Release Information Program

AS = Area Source

ASC = Acid gases exiting on SCC, volume concentration

AST = Acid Stack Gases, volume concentration

ATERIS = Air Toxics Exposure and Risk Information System

Atmosphere fixation = thermal fixation – see thermal NO

Attainment area = region considered clean within the definition of clean air established by the NAAQS

BACT = Best Available Control Technology (process, not burner)

CAA = Clean Air Act

CAAA = Clean Air Act Amendments

CAP = Criteria Air Pollutant

CAPH = Combustion Air Preheat

CAS = Chemical Abstracts Service (of American Chemical Society)

CE = Combustion Efficiency, %CE=(CO 2)(100)/(CO 2+CO) where CO 2 & CO are stack volume concentrations (dgb) [per TSCA only – see DRE for RCRA].

CEM = Continuous Emission Monitoring (CEMS = …System)

CERCLA = Comprehensive Environmental Response, Compensation and Liabilities Act = “Superfund” (See also SARA)

cf = cubic foot or cubic feet, assumed stp, unless specified otherwise

CFCs = chlorofluorocarbons = refrigerants, propellant gases (deplete stratosphere ozone)
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CFR = Code of Federal Regulations

CFR40 = Code of Federal (US) Regulations #40 on “Protection of Environment” (available from government book stores)

CGVI = Combustion Gas Velocity Indication

COH = Coefficient of Haze

C p = specific heat at constant pressure

credits = (see offsets)

criteria pollutants = CO (carbon monoxide, Pb (lead), NO (nitrogen dioxide), O (ozone), particulates, SO (sulfur dioxide).

CTG = Control Techniques Guidelines (see RACT)

da = dry air

DEC = Department of Environmental Conservation ( New York State)

Delta p = pressure difference or pressure drop (Δp)

De-NOx = (See Thermal De-NOx)

dgb = dry gas basis

DOD, E, J, L, T = Department of Defense, …Energy, Justice, Labor, Transportation

DOP = DiOctylPhthalate – for testing HEPA

dp = dew point

DRE = Destruction Rate Efficiency, per p 588, 40CFR#264 = (100%) (W in – W out)/(W in)

dscf = dry standard cubic feet (at 29.9” Hg and 60˚F)

EFSP = Equivalent fan static pressure

ehs = Extremely hazardous substance
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ei = Emissions inventory

eis = environmental impact statement

EKMA = Empirical Kinetic Modeling Approach

EOP = Emission Offset Policy

EPA = Environmental Protection Agency. The US EPA was established by Clean Air Acts of 1967 and 1970.

FEMA = Federal Emergency Management Agency

FFIC = fuel flow indicating controller

FIP = Federal Implementation Plan

Fixed nitrogen = nitrogen combined in fuels

FM = Factory Mutual insurance system

FO = fuel oil

fps = feet per second (scfs = standard cubic feet per second)

FR = Federal Register

FRP = fiberglass reinforced plastic

Fuel NOx = nitrogen oxides from N atoms in the fuel in forms other than N 2; i.e. from fixed nitrogen

FY = ration control device

GACT = Generally Available Control Technology

GAO = General Accounting Office
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GEP = Good Engineering Policy

Global warming = a currently suspected trend to warmer climatic conditions on planet earth. See greenhouse…

GPO = Government Printing Office

gr = grains (700 gr = 1 pound avoirdupois = 1 lb avdp)

greenhouse effect – trapped heat under the earth’s atmosphere by…

greenhouse gases = principally carbon dioxide, methane, CFCs, nitrus oxide, and ozone, all of which are opaque to re-radiation of infrared heat from earth to space. (They are transparent to the wavelength of solar radiation – hence the thermal build-up as in a greenhouse.)

hap = hazardous air pollutant; HAPPS = …prioritization system

hazmat = hazardous material

HCl = HydroChloric Acid (chemically HCl)

HEPA = High Efficiency Particulate Air Filters

HHV or hhv = Higher Heating Value – gross heating or calorific value

HRS = hazard ranking system

IFB = insulating fire brick

Inversion = an atmospheric phenomenon in which a mass of warm air moves over a mass of cool air, resulting in a stable stagnation that causes accumulation rather than ventilation of warm polluted air rising from the earth.

LAER = Lowest Achievable Emission Rate

LHV or lhv = Lower Heating Value = net heating or calorific value

MACT = Maximum Achievable Control Technology

maf = moisture and ash-free

major stationary source = any plant in a designated list of 28 industries that emits 100 tons/year of a regulated pollutant or any stationary source that emits 250 tons/year

major modification = variance of code resulting in a “significant” emissions increase

msa = metropolitan statistical area; MSA = Mine Safety Appliance Company
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naa = non-attainment area

NAAQS = National Ambient air Quality Standards – those specified as for the general atmosphere in outdoor areas frequented by people as opposed to stack or source emission standards

NaOH = Sodium Hydroxide

NEPA = National Environmental Policy act

NESHAP = National Emission Standards for Hazardous Air Pollutants

NFPA = National Fire Protection Association

NIOSH = National Institute from Occupational Safety and Health

nmhc = non-methane hydrocarbons (reactive gases)

NO = nitric oxide – a compound often formed in combustion reactions at temperatures above 3000˚F

NO 2 = nitrogen dioxide-involved in the photo-oxidation (by sunshine) of Hydrocarbons, forming eye-irritating smog. It usually comes from reaction of NO with oxygen from the air at atmospheric temperature

NOD = Notice of Deficiency

Non-attainment area = region where the air quality is below that established by the NAAQS

NOx = NO x = nitrogen oxides, specifically NO and NO 2. NO (nitric oxide) + NO 2 (nitrogen dioxide) collectively

NPDES = National Pollutants Discharge Elimination System

NPRM = Notice of Proposed Rulemaking

NSPS = New Source Performance Standards
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nsr = new source review

NTIS = National Technical Information Service, US Department of Commerce, Springfield, VA 22161

O = Ozone – a photochemical oxidant

Offsets = emission credits (by purchase or trade) for use when moving an operation into a non-attainment area. Offsets have a time window.

OGT = Off-Gas Treatment

ORD = Office of Research & Development

OSHA = Occupational Safety and Health Administration

PC = Particulate concentration, corrected to 7% O 2 standard, Pc=Pm(21-7)(21-Y) Where Pm = Particulate concentration, measured Y = measured volume % O 2 in the stack (dgb)

PCB = PolyChlorinated Biphenyl

PCC = Primary Combustion Chamber (most often a rotary kiln)

PEL = Permissible Exposure Limits (OSHA)

pH = a chemical term used to define the acidity of a solution. A pH of 0-7 is acid; 7 is neutral; 7-14 is alkaline

photochemical smog (now often called simply “smog”) = haze produced by photochemical oxidation, accompanied by eye irritation, plant damage, ozone formation, and characteristic odor

pic = products of incomplete combustion

PIC = Pressure Indicating Controller

P&ID = Process & Instrument Diagram

PID = Proportional/Integral/Derivative control (gain/rate/reset)

PM 10 = particulate matter nominally < micrometers in diameter (ambient air std)

Pna = poly nuclear aromatics – hydrocarbons containing 2 or more fused rings, including one benzene ring; a product of incomplete combustion

POC = Products of Combustion (often assumed complete combustion)
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POHC = Principle Organic Hazard Constituent

ppb = parts per billion, assumed ppb v (by volume)

ppm = parts per million (assumed by volume, ppm v, unless specified as by weight). 1 ppm = 0.0000001, or 0.0001%

ppmv = parts per million based on volume

Primary Standards = protect public health; secondary standards protect public welfare

Priority 1 areas = places where ambient air pollution already exceeds primary standards

psd = prevention of significant deterioration (in air quality)

psia = pounds per square inch absolute (vs. psig = …gauge)

RACT = Reasonably Available Control Technology; RACM = …Measure

RCRA = Resources Conservation and Recovery Act

rdf = refuse-derived fuel

REL = Recommended Exposure Limits (NIOSH)

rh = relative humidity (%)

RKI = Rotary Kiln Incinerator

rog = reactive organic gases ~ voc

ROM = regional Oxidant Model

RTECS = Registry of Toxic Effects of Chemical Substances

SAB = Science Advisory Board

SARA = Superfund Amendments and Reauthorization Act (See CERCLA)

SBA = Small Business Administration

SCAQMD = South Coast Air Quality Management District (of California)

SCC = Secondary Combustion Chamber
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scr = selective catalytic reduction, a form of de-NOx

SGM = Stack Gas Monitoring

“significant´ increase in emission (potential), in tons/year is

40 tpy for NOx

7 tpy for sulfuric acid mist

3 tpy for fluorides

40 tpy for ozone

10 tpy for total reduced sulfur, including H 2S

10 tpy for hydrogen sulfide

25 tpy for particulates

0.007 for asbestos

0.6 for lead

11 tpy for PM10

0.0004 tpy for beryllium

0.1 tpy for mercury

40 tpy for sulfur dioxide



SIP = State Implementation Plan

SMSA = Standard Metropolitan Statistical Area

Source = any property, real or personal, that emits or may emit any air pollutant; stationary source = fixed, non-movable as utility power plant; mobile source – automobile, train, airplane, ship

SOx = Sulfur Oxides (usually SO 2 and SO 3)

stp = standard temperature and pressure = 60˚F and 14.696 psia or 15.56˚C and 760 mm Hg

TACB = Texas Air Control Board

TCLP = Toxicity Characterization Leaching Procedure

tfn = total fixed nitrogen

THC = Total HydroCarbons

Thermal De-NOx = an after treatment to remove nitrogen oxides from products of combustion, using NH 3 (ammonia), or urea, with our without catalysts. See SCR.

Thermal NO = NO formed by temperature effects as opposed to that by fixed nitrogen from the fuel, fuel NO.

TIC = Temperature Indicating Controller

TLV = Threshold Limit Value

TLCP = Toxic Leach Characterization Procedure

Tpy = tons per year
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TRI = Toxic Release Inventory

TRV® = Thermal Relief Vent, trademark of ACGIH, American Conference of Governmental Industrial Hygienists

TSCA = Toxic Substance Control Act

twa = time-weighted average

TY = temperature control split range device

USC = United States Code

vcm = vinyl chloride monomer

VOC = Volatile Organic Compounds (includes pna); VOL = …Liquid

wb = wet bulb temperature

“wc = inches of water column or “wg = inches of water gauge (pressure)

wesp = wet electrostatic precipitator

wgb = wet gas basis

WHB = Waste Heat Boiler

wte = waste to energy

%XSA = percent excess air


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