Abbreviations and Symbols

Abbreviations and Symbols

Air pollution science and engineering employs basic and derived information from the physical, chemical, biological, and social sciences. As such, the abbreviations and symbols used in equations, reactions, and descriptions of properties and mechanisms vary according to the specific aspect of air pollution being discussed. The following abbreviations and symbols are used in this text and/or other air pollution writings. The same symbol or abbreviation may be applied differently in different chapters. Thus, the specific context must be understood. D v V he DG0 f K1aG=A s or s s or SD s2 Fg Fm sn D / dy dx SA

y g

vy vx

[C]

[ V V y z h / 4 C F K  lat  long R m or mv

dispersion tensor (length time
1) average linear velocity (length time
1) average speed (length time
1) effective porosity (dimensionless) free energy formation at steady state global volumetric mass transfer coefficient (time
1) single bond surface tension (forces length
1) standard deviation variance microgram micron or micrometer normal shear stress (mass length
1 time
2) energy (heat) required for reaction ordinary derivative of x with respect to y substrate concentration at the gaseaqueous interface sample mean source mean partial derivative of x with respect to y molar concentration mean or average (capped symbol or letter) double bond (nabla) gradient of a scalar field, especially in NaviereStokes equations (nabla) water table approximately equal to almost equal to triple bond kinetic reaction equilibrium reaction degrees Celsius or Centigrade (temperature) degrees Fahrenheit (temperature) degrees Kelvin (temperature) latitude (degrees) longitude (degrees) degrees Rankine (temperature) dynamic viscosity (mass length
1 time
1)

m mE mg mm mM 0 A a A A A A A/C AA Aaw ABL abs ABT AC AC ACGIH AChE ACM ACS ACToR ADAF ADD ADME ADP AF AF Afabric AFO AIHA AIRS ALAD amu Ap ap AP-1 APCD APCD APCS APE APG aq AQCD AQI AQMA AQS ASCE ASME

963

chemical potential (mass length2 time
2) microenvironment gas viscosity (mass length
1 time
1) arithmetic mean micromole initial (subscript) area, surface area (length2) acceleration (length time2) activity rate (in emission calculation) air (subscript) aqueous phase atomic weight air-to-cloth ratio (filtration; length time
1) atomic absorption detection airway surface area (length2) atmospheric boundary layer absorbed averaging, banking, and trading activated carbon alternating current (electricity) American Conference of Governmental and Industrial Hygienists acetylcholine esterase asbestos-containing material American Cancer Society Aggregated Computational Toxicology Resource age-dependent adjustment factor (cancer risk) average daily dose absorption, distribution, metabolism, and excretion (or elimination) adenosine diphosphate absorption factor atrial fibrillation fabric surface area (length2) animal feeding operation American Industrial Hygiene Association Aerometric Information Retrieval System (U.S.) aminolevulinic acid dehydratase atomic mass unit pd2 cross-sectional area of the particle (length2) ¼ 4 p particle acceleration activator protein-1 air pollution control device air pollution control district air pollution control system alkylphenolethoxylates assigned protection factor aqueous phase Air Quality Criteria Document (U.S.) air quality index air quality maintenance area Air Quality System (part of AIRS; U.S.) American Society of Civil Engineers American Society of Mechanical Engineers

964 ASPECT AT or taveraging atm ATP ATSDR ATUS aw AWMA B B(a)P B/C BACT BAF bag bap BCF BCR bext BF BOEM BOF BP BPA brg bscat Btu or BTU BW C c Ca CA CAA CAAA90 CAFO cal CAM CARB Cc CCA CD CDC CDD CDF CEM CEQ CERCLA

CFC CFR CHAD CHIEF CI Ci Cij CMAQ

ABBREVIATIONS AND SYMBOLS

airborne spectral photometric environmental collection technology averaging time for exposure (time) atmosphere (unit of pressure) adenosine triphosphate Agency for Toxic Substances and Disease Registry (U.S.) American Time Use Survey airway (subscript) Air and Waste Management Association background pollutant concentration (rollback model) benzo(a)pyrene benefit-to-cost ratio best available control technology bioaccumulation factor absorption of light by NO2 gas absorption of light by particles bioconcentration factor benefit/cost ratio light extinction coefficient bioavailability (percent of substance absorbed per day) Bureau of Energy Management (U.S.) basic oxygen furnace blood pressure Bonneville Power Administration scattering of light by gaseous molecules (Rayleigh scattering) scattering of light by particles British Thermal Unit (power) ¼ 1060 J body weight (mass) chemical concentration ([mass mass
1], [volume volume
1], or [mass volume
1]) speed of light (3  108 m s
1) airborne chemical concentration (mass volume
1 of air in breathing zone) carbonic anhydrase Clean Air Act (U.S.) Clean Air Act Amendments of 1990 (U.S.) confined animal feeding operation calorie compliance assurance monitoring California Air Resources Board Cunningham slip correction factor chromated copper arsenate drag coefficient (dimensionless) Centers for Disease Control and Prevention (U.S.) chlorinated dibenzodioxin chlorinated dibenzofruan continuous emissions monitoring Council on Environmental Quality (U.S.) Comprehensive Environmental Response, Compensation and Liability Act (Also known as Superfund; U.S.) chlorofluorocarbon Code of Federal Regulations (U.S.) Consolidated Human Activity Database Clearinghouse for Inventories and Emission Factors (U.S.) confidence interval curie (radioactivity unit) concentration of exposure by person i in microenvironment j Community Multi-scale Air Quality Model (U.S.)

CMB CNG CNS COE COHb COPD Corg cos COX2 cp cps CS CSF CTEPP cv CVD CWA CWS CxHyOx CYP450 d D d D d D D D D D D d0 DA DANT DAS DC DC DCE DD DDD DDE DDT DES DfD DfE DfR DHHS DHS di DI DIAL dL DNA DNAPL DNT DO DOAS DOC DOE

chemical mass balance (model) compressed natural gas central nervous system U.S. Army Corps of Engineers (also USACE) carboxyhemoglobinemia chronic obstructive pulmonary disease substrate organic matter (mass of organic carbon per mass of substrate) cosine cyclooxygenase-2 specific heat at constant pressure cycles per second (1 cps ¼ 1 Hz) equilibrium concentration of the solute in the solid phase cancer slope factor ([mass mass
1 time
1]
1) Children’s Total Exposure to Persistent Pesticides and Other Persistent Organic Pollutants Study specific heat at constant volume cardiovascular disease Clean Water Act (U.S.) Canada-wide standards organic compound (hypothetical or representative) cytochrome P450 enzyme membrane thickness (length) air quality standard (rollback model) day destroyed diameter (length) dose index of community diversity inside diameter of cyclone intermedia or intercompartmental transport term (fugacity models) mass of pollutant per body mass transfer coefficient or compartmental rate constant (for fugacity) proportionality constant (diffusion) nondiffusive transfer coefficient for fugacity diaminonitrotoluene data acquisition system diameter of the collection object (length) direct current (electricity) dichloroethene diffusive transfer coefficient for fugacity dichlorodiphenyldichloroethane dichlorodiphenyldichloroethylene dichlorodiphenyltrichloroethane diethylstilbestrol design for disassembly design for the environment design for recycling Department of Health and Human Services (U.S.) Department of Homeland Security (U.S.) percentage difference (precision) daily intake differential absorption lidar deciliter (volume) deoxyribonucleic acid dense (high density) nonaqueous phase liquid dinitrotoluene dissolved oxygen differential optical absorption spectroscopy diesel oxidation catalyst Department of Energy (U.S.)

ABBREVIATIONS AND SYMBOLS

DOI DOI DOS DOT DP dp Dpa or dpa DPF Dps or dps DQO DRE DWH e E E E E E e E E E E E0 E10 E85 EC EC ECA ECD ED EDC EDD EDS EDSP EF EF EGR EH EIA Eing Einh EIS EIS EJ EL ELF EMEP

EMR EPA or U.S. EPA ER ERDEM erg EROEI ERPG ESP ETS EVT exp(x) Ey

Department of the Interior (U.S.) digital object identifier Department of State (U.S.) Department of Transportation (U.S.) degradation product physical particle diameter (length) aerodynamic diameter of a particle (length) diesel particulate filter Stokes particle diameter (length) data quality objective destruction removal efficiency Deepwater Horizon charge of electron (4.8  10
10 statcoulombs) electrical field strength (potential; voltage length
1) bulk modulus (fluid stress divided by strain) element (chemical) emission energy required in a reaction Euler’s number ¼ 2.71,828,183. event (probability and statistics) exposure extractive particle collection efficiency; inverse of penetration (filtration) strength of electrical field (volts length
1) Fuel mix of 90% gasoline and 10% ethanol Fuel mix of 15% gasoline and 85% ethanol average exposure concentration elemental carbon European Chemicals Agency electron capture detection exposure duration (time) endocrine disrupting compound electronic data delivery energy dispersive spectroscopy endocrine disruptor screening program emission factor (in emission calculation) exposure frequency (time) exhaust gas recirculation epoxide hydrolase Energy Information Administration (U.S.) ingestion exposure (mass per time) inhalation exposure (mass per time) Emission Inventory System (U.S.) environmental impact statement environmental justice exposure length (time per time) extremely low frequency Cooperative Program for Monitoring and Evaluation of Long-range Transmission of Air Pollutants in Europe electromagnetic radiation Environmental Protection Agency (U.S.) percent overall emission reduction efficiency (in emission calculation) Exposure Related Dose Estimating Model energy and work unit (10
7 J) energy return on energy investment Emergency Response Planning Guidelines (U.S.) electrostatic precipitator environmental tobacco smoke extreme value theory exponential (ex) energy at frequency y

f F F F F f f FB FC FD FE FFDCA FGD FHWA FID FIFRA FOARAM fOC FONSI FQPA FR FRM ft FTIR g G G g g g g G g0 GAC gal GC gc GDP GHG GHz Gi GI GIS GLP GPS grad GSP GST GT h or hr h H H H H H H h HAP HC HCB

965 Coriolis parameter energy flux favorable force (mass length time
2) frequency (probability and statistics) fugacity fugacity (subscript) buoyancy force (mass length time
2) centrifugal force (mass length time
2) drag force (mass length time
2) electrostatic charge (force) Federal Food, Drug and Cosmetic Act (U.S.) flue gas desulfurization Federal Highway Administration (U.S.) flame ionization detection Federal Insecticide, Fungicide and Rodenticide Act (U.S.) Federal Ocean Acidification Research and Monitoring Act (U.S.) weight fraction of organic carbon in compartmental matrix (dimensionless) finding of no significant impact Food Quality Protection Act (U.S.) Federal Register (U.S.) federal reference method (U.S.) foot (length) Fourier-transform infrared gas or vapor phase (subscript or parenthetic) gas-phase emissions (mass time
1) Gibbs free energy gram gravitational force gravitational gas hold-up growth factor (rollback model) nondiffusive flow rate (for fugacity) standard gravitational field granulated activated carbon gallon (volume) gas chromatography
2 m $ft gravitational constant ¼ 32:2 lb lbf $s2 ¼ 980 cm s gross domestic product global greenhouse gas gigahertz (109 Hz) advection rate (fugacity models) gastrointestinal geographic information system good laboratory practice global positioning system gradient; grad f ¼ Vfðx; yÞ in a plane and Vfðx; y; zÞ in space global warming potential glutathione S-transferase glucosyltransferases hour elevation enthalpy hazard headspace height heat (subscript [mass length
1 time
2]) Henry’s Law (subscript) horizontal (subscript) Planck’s constant (6.62  10
27 erg s) hazardous air pollutant hydrocarbon hexachlorobenzene

966 HCFC HCH HEDS HEPA HHM HI HMIWI HON hPa HPG HPLC HPV HQ HR HRS HRV HSWA HVAC HYSPLIT Hz hy i I I I I I/M IAEA ICRP ID IDL IDLH IF IMPROVE in Hg IN IOGAPS IOM IPCC IQ IR IR IR-DIAL IRIS ISCLT IUR J J k K k k1 k2 Ka KAW Kb KD ke KF kg

ABBREVIATIONS AND SYMBOLS

hydrochlorofluorocarbon hexachlorocyclohexane Human Exposure Database System (U.S.) high efficiency particulate air (filter) hierarchical holographic modeling hazard index hospital/medical/infectious waste incinerators hazardous organic NESHAPs hectopascal (unit of pressure) hypothalamic-pituitary-gonadal (axis) high performance liquid chromatography high production volume (chemical class) hazard quotient hazard ratio Hazard Ranking System (U.S.) heart rate variability Hazardous and Solid Waste Amendments (U.S.) heating, ventilation, and air conditioning Hybrid Single Particle Lagrangian Integrated Trajectory (model) hertz (cycles s
1) photon group, species, subgroup of total (subscript) immobilized in situ intake dose intensity inspection and maintenance program International Atomic Energy Agency International Commission on Radiological Protection interior diameter instrument detection limit immediately dangerous to life or health intermediate frequencies interagency monitoring of protected visual environments (U.S.) inches of mercury (unit of pressure) mass or energy inflow to control volume; influent (subscript) integrated organic gas and particulate sampler Institute of Medicine (U.S.) Intergovernmental Panel on Climate Change intelligence quotient intake rate ([mass time
1] or [volume per time) infrared infrared-differential absorption lidar Integrated Risk Information System Industrial Source Complex Long Term (model) inhalation unit risk Joule (energy unit) soil-to-air flux Boltzmann’s constant (1.37  10
16 erg K
1) partitioning coefficient reaction rate constant filter media resistance constant filter dust cake resistance constant acid equilibrium constant Airewater partitioning coefficient base equilibrium constant Soil sorption partitioning coefficient rate at which the producers use energy (via respiration) Freundlich isotherm constant kilogram (mass)

KG/A KH kinh km Koa Koc Kow kp kPa Ksp Kw kWh L or l l LADD LAER lb lbf lbm LC LC50 LCA LCI LD50 LEL LEV lidar ln(x) LNAPL LOAEC LOAEL LoD log LoQ LOSU LPG LRTAP LTP Lv m m M M MACT max MCE MCL Me MEI MFAA mg MHz MIC min min MIR mm Hg mm mM

partition coefficient between the gaseous and aqueous phases Henry’s Law partitioning coefficient inhalation rate (volume of air per unit time) kilometer (length) Octanoleair partitioning coefficient Organic-carbon partitioning coefficient Octanolewater partitioning coefficient rate of chemical energy storage by primary producers kilopascal (unit of pressure) solubility product constant water dissociation equilibrium constant kilowatt-hour liter liquid phase (subscript or parenthetic) lifetime average daily dose lowest achievable emission rate pound (weight) foot-pound (force) international avoirdupois pound (weight) liquid chromatography lethal concentration-50 (lethal to 50% of tested organisms) life cycle analysis or life cycle assessment life cycle inventory lethal dose-50 (lethal to 50% of tested organisms) lower explosive limit low emissions vehicle remote sensing of distance using a laser (combination of light and radar) natural log of x light (low density) nonaqueous phase liquid lowest observed adverse effect concentration lowest observed adverse effect level limit of detection (also known as DL, detection limit) logarithm limit of quantitation level of scientific understanding liquefied propane gas long-range transboundary air pollutants local temperature and pressure distance at which a black object is just barely visible mass meter mole (gram molecular weight) relatively nonreactive molecule in a reaction maximum achievable control technology maximum (subscript) mixed cellulose ester maximum contaminant level (drinking water) metal maximum exposed individual Millipore cellulose ester membrane mass of displaced gas megahertz (106 Hz) methylisocyanate minimum (subscript) minute (time) maximum individual risk millimeters of mercury (unit of pressure) millimeter millimole

ABBREVIATIONS AND SYMBOLS

mmBTU MMT mmt MOA mol mp MQO MRL MS MSAT MSDS Mt MT MTBE MUC mV MW MW n N N N n N N-100 NA NA NAA NAAQS NAD NADP NADP+ NADPH NAE NAMS NAPL NAS NASA NAT NATA ND, n.d. NDIR NEA NEI NEPA NESHAP ng NHANES NHATS NHEXAS NHIS Nin NIOSH NIST NLEV nM

106 BTU methylcyclopentadienyl manganese tricarbonyl million metric tons mode of action mole (gram molecular weight) particle mass model quality objective minimum risk level mass spectroscopy mobile source air toxic material safety data sheet malonyltransferases metallothionein methyl tertiary-butyl ether maximum use concentration millivolts (potential) megawatt molecular weight number of charges (electrostatics) concentration (number) Newton (unit of force) not significant number (e.g. number of moles) transport process rate (fugacity  compartmental rate constant) respirator protection efficiency against particulate aerosols (99.97%), but not resistant to oil nonaqueous phase nonattainment neutron activation analysis National Ambient Air Quality Standard (U.S.) nicotinamide adenine dinucleotide National Atmospheric Deposition Program (U.S.) nicotinamide adenine dinucleotide phosphate reduced form of NADP+ National Academy of Engineering (U.S.) national air monitoring station (U.S.) nonaqueous phase liquid National Academy of Sciences (U.S.) National Aeronautics and Space Administration (U.S.) N-acetyltransferase National Air Toxics Assessment (U.S.) not detected nondispersive infrared Nuclear Energy Agency National Emissions Inventory (U.S.) National Environmental Policy Act (U.S.) National Standard for Hazardous Air Pollutants (U.S.) nanogram National Health and Nutrition Examination Survey (U.S.) National Human Adipose Tissue Survey (U.S.) National Human Exposure Assessment Survey (U.S.) National Health Interview Survey (U.S.) number of particles (count) entering a system (e.g. filter) National Institute for Occupational Safety and Health National Institute of Standards and Technology (U.S.) National Low Emissions Vehicle Program (U.S.) nanomole

NMDA NMHC NMMAPS NMOG NMVOC NOAA NOAEC NOAEL NOES Nout NOx NOy NOz NPL NPL NPP NPRI NR NRC NRp NSF NSR NTP NTSIP NVOC O O&M O(1D) OA OC OC/EC OECD OMI OP OP-FTIR OSHA OUT P or p p p p P P P P P0 P1 P-100 pa pa Pa PA PAD PAH

967 N-methyl-D-aspartate nonmethane hydrocarbon National Mortality and Morbidity Air Pollution Study (U.S.) nonmethane organic gases nonmethane volatile organic compound National Oceanic and Atmospheric Administration (U.S.) no observed adverse effect concentration no observed adverse effect level National Occupational Exposure Survey (U.S.) number of particles (count) exiting a system (e.g. filter) oxides of nitrogen; specifically NO and NO2 oxides of nitrogen; specifically NOx and NOz HNO3 + HONO + N2O5 + HO2NO3 + PAN + organic nitrates National Physics Laboratory (UK) National Priorities List (U.S.) net primary product (or productivity) National Pollutant Release Inventory (Canada) Reynolds number National Research Council (U.S.) dimensionless particle Reynolds number National Science Foundation (U.S.) new source review National Toxicology Program (U.S.) National Toxic Substance Incidents Program (U.S.) nonvolatile organic compound octanol (subscript) operation and maintenance O atom in an excited singlet state organic acid organic carbon (subscript) organic carbon-to-elemental carbon ratio Organisation for Economic Co-operation and Development ozone monitoring instrument organophosphorous (pesticide class) open path Fourier transform infrared Occupational Safety and Health Administration (U.S.) mass or energy outflow from control volume; effluent (subscript) pressure momentum partial particle (subscript) particle penetration; inverse of efficiency (filtration) particulate matter emissions (mass time
1) present air quality (rollback model) probability vapor pressure net primary productivity (or production) oil-proof respirator protection efficiency against particulate aerosols (99.97%) partial pressure of chemical substance gas in inhaled air partial pressure of gas a pascal (unit of pressure) preliminary assessment population adjusted dose polycylic aromatic hydrocarbon (sometimes polyaromatic hydrocarbon)

968 PAL PAL-DS PAMS PAN pb PBDE PBPD PBPK PBT PC PC PC PCB PCDD/F PCE pCi PCM PDF PFOA PFOS pH PHED PIC PID pKa pL PLM PM PM10 PM2.5 pMC PMF PMN PNS pOH POM POP ppb ppbv PPE ppm ppmv ppt PQAO PQL PRTR PSD PSI psi PTFE PUF Pv PVC Q q Q QA QAPP QC Qg QM-A QSAR R or r r

ABBREVIATIONS AND SYMBOLS

point, area and line (model) point, area, and line model with deposition and settling photochemical assessment monitoring station peroxyacyl nitrate partial pressure of chemical substance gas in blood pentabromodiphenyl ether physiologically-based pharmacodynamic physiologically-based pharmacokinetic persistent, bioaccumulating, and toxic particle concentration polycarbonate polycarbonate polychlorinated biphenyl pentachlorodibenzodioxins and furans tetrachloroethene picocurie (radioactivity unit)) phase contrast microscopy probability density function perfluorooctanoic acid perfluorooctane sulfonate negative log of H+ or H3O+ concentration Pesticide Handlers Exposure Database (U.S.) product of incomplete combustion photoionization detector negative log of the acid dissociation constant supercooled liquid vapor pressure polarized light microscopy particulate matter Particulate matter, <10 micron diameter Particulate matter, <2.5 micron diameter percent modern carbon positive matrix factorization premanufacture notification peripheral nervous system negative log of OH
concentration polynuclear organic material persistent organic pollutant parts per billion parts per billion by volume personal protection equipment parts per million parts per million by volume parts per trillion primary quality assurance organization practical quantitation limit Pollutant Release and Transfer Register (Mexico) prevention of significant deterioration (U.S.) pollution standard index (replaced by AQI) pounds per square inch (pressure) polytetrafluoroethylene polyurethane foam velocity pressure polyvinyl chloride airflow electric charge on particle ionic product quality assurance quality assurance project plan quality control gas flow rate (length2 time
1) Whatman QM-A, quartz micro-fiber filter quantitative structureeactivity relationships correlation coefficient chemical production or degradation rate

R R R r R R R r R(t) R0 R-100 R2 or r RACT RAT RCRA Re REACH REL REL-TWA Rep RF RfC RfD RIOPA RNA RO2 ROD ROS RR RT RT RX s or sec S S s S S S S S/N S2 s2 SA SAR SARA SATB SCR SD or s SDWA SE SEM SES Sf SF SG Sh

gas constant percentage emission reduction (rollback model) radial position of particle (centrifugal force calculation) radius remote removed risk thermodynamic loss term reliability function universal gas constant (8.315 J K
1 mol
1) oil-resistant respirator protection efficiency against particulate aerosols (99.97%) coefficient of determination reasonably available control technology rapid assessment tool Resource Conservation and Recovery Act (U.S.) Reynolds number Registration, Evaluation, Authorisation, and Restriction of Chemicals (Europe) recommended exposure limit recommended exposure limit (time-weighted average) dimensionless particle Reynolds number radio frequency reference concentration reference dose Relationship Between Indoor, Outdoor and Personal Air Study (U.S.) ribonucleic acid radical made of a chain of organic compounds with O2 substituted for H record of decision reactive oxygen species relative risk residence time retention time organic compound second (time) entropy severity of risk solid or sorbed phase (subscript or parenthetic) solid phase concentration solubility Sorption source or sink signal-to-noise ratio variance variance of the source substrate concentrations in the aqueous phase structureeactivity relationships Superfund Amendments and Reauthorization Act (U.S.) surface area of the tracheobronchial region selective catalytic reduction standard deviation Safe Drinking Water Act (U.S.) standard error scanning electron microscopy socioeconomic status filter drag force slope factor substrate concentrations in the bulk gas phase horizontal surface

ABBREVIATIONS AND SYMBOLS

SHEDS SHS sin SIP SLAMS SMR SMR SNCR SOF SOM SOP SOx SPMS SS ST Stk STP SVOC T t T t0 t1/2 TAGA tan TC TCDD TCDF TCE TCLP TCM TDL TDS TEAM TEL TEM Tf Tij TL TLV TLV-C TLV-STEL TNT TOMS TPTH tpy T-R TRI TRS TS TSCA TSP TVA TWA TWA U U U UAM UEL UFinter UFintra UFother

Stochastic Human Exposure and Dose Simulation (model) second-hand smoke sine State Implementation Plan (U.S.) state and local air monitoring station (U.S.) standard morbidity ratio standard mortality ratio selective noncatalytic reduction soluble organic fraction soil organic matter standard operating procedure oxides of sulfur special purpose monitoring station steady state (subscript) sulfotransferase Stokes number standard temperature and pressure semivolatile organic compound temperature tonne total (subscript) initial time half-life trace atmospheric gas analyzer tangent total carbon tertrachlorodibenzo-para-dioxin tertrachlorodibenzofuran trichloroethene toxicity testing leaching procedure tetrachloromercurate tunable diode laser total dissolved solids Total Exposure Assessment Methodology Study tetraethyl lead transmission electron microscopy time of failure time spent in microenvironment j by person i typical lifetime threshold limit value threshold limit value (ceiling) TLV threshold limit value-short-term exposure limit trinitrotoluene total ozone mapping spectrometer triphenyltin hydroxide tons per year transformer-rectifier Toxic Release Inventory (U.S.) total reduced sulfur total sulfur Toxic Substances Control Act (U.S.) total suspended particulate Tennessee Valley Authority T wave alternans time-weighted average epistemic uncertainty internal energy unknown urban airshed model upper explosive limit interspecies uncertainty intraspecies uncertainty RfC or RfC uncertainty other than UF or UFintra

UFP UGT UNEP UNFCCC UNICEF USCG USDA USF&W USGS UST UV UVCB

UV-DOAS UVF V V V v V Vaw VC VD Ve vf Vff vg vg vis vmax VMT VOC vp Vp Vtotal W W W WHO WOE WWT WWTP x x XAD XRD XRF y y Y y yp z Z z Z Z a g D

969 ultrafine particles UDP-glucuronyltransferase United Nations Environmental Program United Nations Framework Convention on Climate Change United Nations Children’s Fund United States Coast Guard U.S. Department of Agriculture U.S. Fish and Wildlife Services U.S. Geological Survey underground storage tank ultraviolet chemical substances of unknown or variable composition, complex reaction products, and biological materials (U.S.) differential optical absorption spectroscopy in UV range ultraviolet fluorescence fluid velocity speed stochastic or aleatory uncertainty vapor phase (subscript or parenthetic) volume airway volume (length3) vinyl chloride volume of distribution minute volume (volume time
1) velocity through the filter (length time
1) filter fiber volume gas velocity geostrophic velocity visible light range frequency of maximum radiation intensity (Wien’s displacement law) vehicle miles traveled volatile organic compound particle velocity particle volume total filter volume body weight water (subscript) watt (unit of power; J s
1) World Health Organization weight of evidence wastewater treatment wastewater treatment plant at distance x from x ¼ 0 (subscript) distance (horizontal) sorbing material; ion exchange resin X-ray diffraction spectrometry X-ray fluorescence at distance y from y ¼ 0 (subscript) distance (width) modeling result/outcome year (time) difference in velocity between the particle and collection object (length time
1) at distance z from z ¼ 0 (subscript) atomic number distance (vertical) fugacity capacity zenith angle (degrees) packing density (solidity) specific weight (mass length
3) change

970 d DG* DPdust-cake DPmedia DPtotal 30 h q l l l np ns p r r0 rg rp

ABBREVIATIONS AND SYMBOLS

solar declination (degrees) standard change in Gibbs free energy pressure drop across dust cake on filter pressure drop across filter media total pressure drop permittivity of free space (8.85  10
12 F m
1) hour angle (degrees) potential temperature average or expected counts or events per unit time (Poisson equation) degradation term in chemical decay wavelength (length, often nm) relative velocity between the particle and the target object tangential velocity of gas 3.14159. density (volume length
3) standard density (1 g m
3) gas density (mass length
3) particle density (volume length
3)

s s ss y or yv y 4 4 4 4 4 X Xp j JD U U u u

StefaneBoltzmann constant tortuosity shear stress (mass length
1 time
2) kinematic viscosity (length2 time
1) ¼ dynamic viscosity divided by density (m r
1) specific volume (reciprocal of density; length3 mass
1) angle (degrees or radians) filter porosity fugacity coefficient latitude (degrees) fraction, ratio or coefficient leaving group from organic compound particle diffusivity (length2 time
1); surface deposition diffusional collection parameter (dimensionless) migration velocity (electrostatics) angular speed of the Earth’s rotation solar azimuth (degrees) spherical particle mass