The glossary
was created by a combination of
resources, including the Georgia Department
of Natural Resources, Air Protection
Branch, LouisvilleKy.gov Air Pollution
Control, the National Association of
Clean Air Agencies (NACAA), and EPA's
Plain English Guide to Clean Act Act,
and edited for use in this web
site.
Abatement -- The reduction or elimination of pollution.
Acid rain -- Air pollution
produced when acid chemicals are incorporated into rain, snow, fog
or mist. The "acid" in acid rain comes from sulfur oxides and
nitrogen oxides, products of burning coal and other fuels and from
certain industrial processes. The sulfur oxides and nitrogen oxides
are related to two strong acids: sulfuric acid and nitric acid. When
sulfur dioxide and nitrogen oxides are released from power plants
and other sources, winds blow them far from their source. If the
acid chemicals in the air are blown into areas where the weather is
wet, the acids can fall to Earth in the rain, snow, fog, or mist. In
areas where the weather is dry, the acid chemicals may become
incorporated into dusts or smokes. Acid rain can damage the
environment, human health, and property.
Acute Exposure --
One or a series of short-term exposures
generally lasting less than 24 hours.
Aerosol -- Particles
of solid or liquid matter than can
remain suspended in air from a few
minutes to many months depending on the
particle size and weight.
Air Quality Index (AQI)
-- A numerical index used for reporting
severity of air pollution levels to the
public. It replaces the formerly
used Pollutant Standards Index (PSI).
AQI incorporates five criteria
pollutants - ozone, particulate matter,
carbon monoxide, sulfur dioxide, and
nitrogen dioxide - into a single index.
AQI also incorporates the 8-hour ozone
standard and the 24-hour PM2.5 standard
into the index calculation. AQI
levels range from 0 (Good air quality)
to 500 (Hazardous air quality).
The higher the index, the higher the
level of pollutants and the greater the
likelihood of health effects.
Air Toxic -- Any air pollutant for which a
national ambient air quality standard does not exist (i.e.,
excluding ozone, carbon monoxide, PM10, sulfur dioxide, and nitrogen
dioxide) that may reasonably be anticipated to cause cancer,
developmental effects, reproductive dysfunctions, neurological
disorders, heritable gene mutations or other serious or irreversible
chronic or acute health effects in humans.
Alternative fuels -- Fuels that
can replace ordinary gasoline. Alternative fuels may have
particularly desirable energy efficiency and pollution reduction
features. Alternative fuels include compressed natural gas,
alcohols, liquefied petroleum gas (LPG), and electricity. The 1990
Clean Air Act encourages development and sale of alternative fuels.
Area Sources --
Those sources for which a methodology is
used to estimate emissions. This can
include area-wide, mobile and natural
sources, and also groups of stationary
sources (such as dry cleaners and gas
stations). The federal air toxics
program defines a source that emits less
than 10 tons per year of a single
hazardous air pollutant (HAP) or 25 tons
per year of all HAPs as an area source.
Attainment area -- A geographic
area in which levels of a criteria air pollutant meet the
health-based primary standard (national ambient air quality
standard, or NAAQS) for the pollutant. An area may have on
acceptable level for one criteria air pollutant, but may have
unacceptable levels for others. Thus, an area could be both
attainment and non-attainment at the same time. Attainment areas are
defined using federal pollutant limits set by EPA.
BACT -- Best available control
technology. It is an emission limitation that considers the cost of
energy, environment, and economics in developing a degree of
emission reduction that is achievable through application of good
production processes, control systems, and techniques. In no event
can BACT allow emissions of a pollutant in excess of a NSPS or a
NESHAPS. BACT is determined on a case-by-case basis, is applied to
each pollutant regulated under the Clean Air Act (federal) and is
used mostly in PSD permit work.
BP -- Barometric
pressure: ambient atmospheric pressure.
Btu -- British
thermal unit, a unit of energy: 1 Btu =
1060 J.
Carbon dioxide (CO2)
-- A colorless, odorless gas that occurs
naturally in the Earth's atmosphere.
Significant quantities also are emitted
into the air by fossil fuel combustion.
Carbon monoxide (CO) -- A
colorless, odorless, poisonous gas, produced by incomplete burning
of carbon-based fuels. including gasoline, oil, and wood. Carbon
monoxide is also produced from incomplete combustion of many natural
and synthetic products. For instance, cigarette smoke contains
carbon monoxide. When carbon monoxide gets into the body, the carbon
monoxide combines with chemicals in the blood and prevents the blood
from bringing oxygen to cells, tissues, and organs. The body's parts
need oxygen for energy, so high-level exposures to carbon monoxide
can cause serious health effects. Massive exposures to CO can cause
death. Symptoms of exposure to carbon monoxide can include vision
problems, reduced alertness, and general reduction in mental and
physical functions. Carbon monoxide exposures are especially harmful
to people with heart, lung, and circulatory system diseases.
CAS registry number
-- The Chemical Abstracts Service
Registry Number (CAS) is a numeric
designation assigned by the American
Chemical Society's Chemical Abstract
Service and uniquely identifies a
specific compound. This entry allows one
to conclusively identify a material
regardless of the name or naming system
used.
CEM -- Continuous
emission monitoring (at stationary
sources).
Chlorofluorocarbons (CFCs) --
These chemicals and some related chemicals have been used in great
quantities in industry, for refrigeration and air conditioning, and
in consumer products. CFCs and their relatives, when released into
the air, rise into the stratosphere, a layer of the atmosphere high
above the Earth. In the stratosphere, CFCs and their relatives take
part in chemical reactions which result in reduction of the
stratospheric ozone layer, which protects the Earth's surface from
harmful effects of radiation from the sun. The 1990 Clean Air Act
includes provisions for reducing releases (emissions) and
eliminating production and use of these ozone-destroying chemicals.
Chronic exposure --
Long-term exposure, usually lasting one
year to a lifetime.
Clean Air Act (CAA) -- The
original Clean Air Act was passed in 1963, but our national air
pollution control program is actually based on the 1970 version of
the law. The 1990 Clean Air Act Amendments are the most far-reaching
revisions of the 1970 law. In this glossary, we refer to the 1990
amendments as the 1990 Clean Air Act.
Clean fuels -- Low-pollution
fuels that can replace ordinary gasoline. These are alternative
fuels, including gasohol (gasoline-alcohol mixtures), natural gas,
and LPG (liquefied petroleum gas).
Code of federal regulations
(CFR) -- The body of
regulations written by federal
government agencies, such as the EPA.
Regulations relating to air pollution
are found in Title 40 of the CFR,
sections 50-99.
Combustion -- Burning. Many
important pollutants, such as sulfur dioxide, nitrogen oxides, and
particulates (PM-10) are combustion products, often products of the
burning of fuels such as coal, oil, gas, and wood.
Compliance Advisory Panel (CAP)
-- A seven member panel appointed by the governor state legislature
and the Air permitting agency. The panel is composed of 4 small
business owners, one permitting representative, and two people to
represent the public at large. The CAP provides oversight to the
Small Business Assistance Program (SBAP).
Continuous emission monitoring systems
(CEMS) -- Machines which measure, on a continuous basis,
pollutants released by a source. The 1990 Clean Air Act requires
continuous emission monitoring systems for certain large sources.
Control technology; control measures
-- Equipment, processes, or actions used to reduce air pollution.
The extent of pollution reduction varies among technologies and
measures. In general, control technologies and measures that do the
best job of reducing pollution will be required in the areas with
the worst pollution. For example, the best available control
technology/best available control measures (BACT, BACM) will be
required in serious non-attainment areas for particulates, a
criteria air pollutant. A similar high level of pollution reduction
will be achieved with maximum achievable control technology (MACT)
which will be required for sources releasing hazardous air
pollutants.
Criteria air pollutants -- A
group of very common air pollutants regulated by EPA on the basis of
criteria (information on health and/or environmental effects of
pollution). Criteria air pollutants are widely distributed all over
the country. A National Ambient Air Quality Standard exists for each
criteria pollutant (particulate matter, sulfur dioxide, nitrogen
dioxide, ozone, carbon dioxide, and lead).
CTG -- Control
Techniques Guidelines issued by the EPA
on ways to reduce pollutant emissions
from stationary sources.
De Minimis -- In
general, a level of emissions, etc.,
below which a particular process or
activity is exempted or not regulated.
Diesel engine -- A
type of internal combustion engine that
uses low-volatility petroleum fuel and
fuel injectors and initiates combustion
using compression ignition (as opposed
to spark ignition that is used with
gasoline engines).
Dose -- The amount
of a pollutant that is absorbed. A level
of exposure that is a function of a
pollutant's concentration, the length of
time a subject is exposed, and the
amount of the pollutant that is
absorbed. The concentration of the
pollutant and the length of time that
the subject is exposed to that pollutant
determine dose.
Dust -- Solid
particulate matter that can become
airborne.
Emission -- Release of
pollutants into the air from a source. We say sources emit
pollutants. Continuous emission monitoring systems (CEMS) are
machines, which some large sources are required to install, to make
continuous measurements of pollutant release.
Emission inventory
-- An estimate of the amount of
pollutants emitted into the atmosphere
from major mobile, stationary,
area-wide, and natural source categories
over a specific period of time such as a
day or a year.
Enforcement -- The legal methods
used to make polluters obey the Clean Air Act. Enforcement methods
include citations of polluters for violations of the law (citations
are much like traffic tickets), fines, and even jail terms. EPA and
the state and local governments are responsible for enforcement of
the Clean Air Act, but if they don't enforce the law, members of the
public can sue EPA or the states to get action.
Ethanol --
Ethyl-alcohol, a volatile alcohol
containing two carbon groups (CH3CH2OH).
For fuel use, ethanol is produced by
fermentation of corn or other plant
products.
Exceedance -- A
measured level of an air pollutant
higher than the national or state
ambient air quality.
Exposure -- The
concentration of the pollutant in the
air multiplied by the population exposed
to that concentration over a specified
time period.
Fly ash -- Air-borne
solid particles that result from the
burning of coal and other solid fuel.
Formaldehyde -- A
chemical compound, the simplest
aldehyde, chemical symbol
CH2O. Formaldehyde is
a common pollutant, a VOC.
Fossil fuels --
Fuels such as coal, oil, and natural
gas; so-called because they are the
remains of ancient plant and animal
life.
Fugitive dust --
Dust particles that are introduced into
the air through certain activities such
as soil cultivation, or vehicles
operating on open fields or dirt
roadways.
Fugitive emissions
-- Emissions not caught by a capture
system that are often due to equipment
leaks, evaporative processes, and
windblown disturbances.
Fume -- Solid
particles less than 1 micron in diameter
formed as vapors condense, or as
chemical reactions take place.
Global warming -- An
increase in the temperature of the
Earth's troposphere. Global warming has
occurred in the past as a result of
natural influences, but the term is most
often used to refer to the warming
predicted by computer models to occur as
a result of increased emissions of
greenhouse gases.
Greenhouse effect --
The warming effect of the Earth's
atmosphere. Light energy from the sun
that passes through the Earth's
atmosphere is absorbed by the Earth's
surface and re-radiated into the
atmosphere as heat energy. The heat
energy is then trapped by the
atmosphere, creating a situation similar
to that which occurs in a car with it's
windows rolled up.
Greenhouse gases --
Atmospheric gases such as carbon
dioxide, methane, chlorofluorocarbons,
nitrous oxide, ozone, and water vapor
that slow the passage of re-radiated
heat through the Earth's atmosphere.
Hazardous air pollutants (HAPs)
-- Toxic chemicals that cause serious health and environmental
effects. Health effects include cancer, birth defects, nervous
system problems, and death due to massive accidental releases such
as occurred at the pesticide plant in Bhopal, India. Hazardous air
pollutants are released by sources such as chemical plants, dry
cleaners, printing plants, and motor vehicles (cars, trucks, buses,
etc.)
Hydrocarbons --
Compounds containing various
combinations of hydrogen and carbon
atoms. They may be emitted into the air
by natural sources (e.g., trees) and as
a result of fossil and vegetative fuel
combustion, fuel volatilization, and
solvent use. Hydrocarbons are a major
contributor to smog.
Hydrochlorofluorocarbon
(HCFC) -- A chemical compound
that would be a hydrocarbon except that
one or more hydrogen atoms in each
molecule is replaced by a chlorine atom
and one or more hydrogen atoms is
replaced by a fluorine atom. Some HCFCs
are implicated in the destruction of
stratospheric ozone.
Hydrofluorocarbon (HCA)
-- A chemical compound that would be a
hydrocarbon except that one or more
hydrogen atoms in each molecule is
replaced by a fluorine atom.
IAQ -- Indoor Air
Quality.
Indirect source control
program -- Rules, regulations,
local ordinances and land use controls,
and other regulatory strategies of air
pollution control districts or local
governments used to control or reduce
emissions associated with new and
existing indirect sources. Indirect
source control programs include
regulatory strategies such as
transportation control measures; parking
charges; land use controls that reduce
the need for vehicle travel and increase
transit, bicycle, and pedestrian access;
and source-specific regulations such as
truck idling and travel schedule
requirements.
Indoor air pollution
-- Air pollutants that occur within
buildings or other enclosed spaces, as
opposed to those occurring in outdoor,
or ambient air. Some examples of indoor
air pollutants are nitrogen oxides,
smoke, asbestos, formaldehyde, and
carbon monoxide.
Inhalable particles
-- All dust capable of entering the
human respiratory tract.
Inspection and maintenance program (I/M
program) -- Auto inspection programs are required for some
polluted areas. These periodic inspections, usually done once a year
or once every two years, check whether a car is being maintained to
keep pollution down and whether emission control systems are working
properly. Vehicles which do not pass inspection must be repaired.
Under the 1990 Clean Air Act, some especially polluted areas will
have to have enhanced inspection and maintenance programs, using
special machines that can check for such things as how much
pollution a car produces during actual driving conditions.
Internal combustion engine
-- An engine in which both the heat
energy and the ensuing mechanical energy
are produced inside the engine. Includes
gas turbines, spark ignition gas, and
compression ignition diesel engines.
Interstate air pollution -- In
many areas, two or more states share the same air. We say these
states are in the same air basin defined by geography and wind
patterns. Often, air pollution moves out of the state in which it is
produced into another state. Some pollutants, such as the power
plant combustion products that cause acid rain, may travel over
several states before affecting health, the environment, and
property. The 1990 Clean Air Act includes many provisions, such as
interstate compacts, to help states work together to protect the air
they share. Reducing interstate air pollution is very important
since many Americans live and work in areas where more than one
state is part of a single metropolitan area.
Inversion -- A layer
of warm air in the atmosphere that
prevents the rise of cooling air and
traps pollutants beneath it.
Irritant -- A
substance that causes irritation of the
skin, eyes, or respiratory system.
Effects may be acute from a single
high-level exposure, or chronic from
repeated low-level exposures to such
compounds as chlorine, nitrogen dioxide,
and nitric acid.
Kyoto Protocol -- An
international agreement adopted in
December 1997 in Kyoto, Japan. The
Protocol sets binding emission targets
for developed countries that would
reduce the emissions on average 5.2
percent below 1990 levels.
Local emergency planning
committee (LEPC) -- Established
under the Superfund Reauthorization
Amendments, represent local governments,
emergency response officials,
environmental and citizen groups,
industry, and other interested parties
is established in each planning
district.
Lowest achievable emission rate (LAER) -- Considered to be the lowest rate of emissions from a
source category which is contained in the State Implementation Plan,
or which is achieve in practice by such category of sources. This
term is most often associated with a nonattainment area.
Major source -- Under the PSD
regulations it is a facility, belonging to one or more of 28 source
categories, having the potential to emit 100 tons per year of a
pollutant regulated under the federal Clean Air Act (CAA). For
categories other than the 28 sources, the potential emission level
can not exceed 250 tons per year. A major source for the purpose of Title V in
the CAA is a stationary source that has the potential to emit 100
tons per year a pollutant regulated under the CAA and/or a source
that has the potential to emit 10 tons per year for a single
hazardous air pollutant or 25 tons per year of a combination of all
hazardous air pollutants.
Material safety data sheets (MSDSs)
-- Product safety information sheets prepared by manufacturers and
marketers of products containing toxic chemicals. These sheets can
be obtained by requesting them from the manufacturer or marketer.
Some stores, such as hardware stores, may have material safety data
sheets on hand for products they sell.
Maximum achievable control
technology (MACT) -- Federal
emissions limitations based on the best
demonstrated control technology or
practices in similar sources to be
applied to major sources emitting one or
more federal hazardous air pollutants.
micro-
(µ) --
The metric prefix for one millionth of
the unit that follows.
microgram
(µg) -- One millionth
of a gram:
1 µg = 10-6 g = 0.001 mg.
micrograms per cubic meter
(µg/m3)
-- The mass in micrograms of a substance
contained within a cubic meter of
another substance or vacuum. This is the
standard unit of measure for the mass
density (concentration) of particles
suspended in air; also sometimes used
for the concentration of gases in air.
micrometer (µm), micron
-- One millionth of a meter: 1 µm = 10-6 m.
Mobile sources -- Motor vehicles
and other moving objects that release pollution; mobile sources
include cars, trucks, buses, planes, trains, motorcycles and
gasoline-powered lawn mowers. Mobile sources are divided into two
groups: road vehicles, which includes cars, trucks, and buses, and
non-road vehicles, which includes trains, planes, and lawn mowers.
Monitoring (monitor) --
Measurement of air pollution is referred to as monitoring. EPA,
state, and local agencies measure the types and amounts of
pollutants in community air. The 1990 Clean Air Act requires states
to monitor community air in polluted areas to determine if the areas
are being cleaned up according to schedules set by law.
Multimedia exposure
-- Exposure to a toxic substance from
multiple pathways such as air, water,
soil, food, and breast milk.
NAICS (North American Industry Classification System)
-- A system developed jointly by the U.S., Canada, and Mexico, for
classifying industries and other businesses. NAICS replaced SIC.
They system assigns two-digit numbers to broad categories and adds
more digits for increasingly finer classes within those categories.
National ambient air quality standards (NAAQS) -- Ambient standards developed by EPA that must be
attained and maintained to protect public health. "Secondary" NAAQS
are necessary to protect the public welfare. NAAQS exist for
particular matter, sulfur dioxide, nitrogen dioxide, ozone, carbon
dioxide, and lead.
National emissions inventory
-- The new EPA database system for
inventories of calculated emissions from
point sources in the U.S. that
incorporates data from the National
Emissions Trends Inventory and National
Toxics Inventory.
National emission standards for hazardous air pollutants (NESHAPs) -- National emission
standards for hazardous air pollutants.
New source performance standards (NSPS) -- These are federal EPA emission standards for certain air
pollutants that are emitted from new, modified, or reconstructed
stationary emission sources which reflect the use of best available
control technology
New source review (NSR) -- New source review. NSR
typically means any new source locating in a, e.g., ozone
nonattainment area that will emit volatile organic compounds (VOCs)
and/or oxide of nitrogen (NO) in certain amounts. These sources
must: undergo a new source review that provides for offsetting
emissions for any increases in the emissions of these two
pollutants; use the lowest achievable emissions technology to
control emissions; apply for a construction permit; and meet other
state requirements before the new emission from the source can be
permitted. Existing sources, located in the ozone nonattainment
area, that emit these two pollutants and plan to change their
operational methods that will cause an increase in the emissions of
these two pollutants must apply for a modification permit and under
go a review similar to a new source.
Nitrogen oxides (NOx) -- A
criteria air pollutant. Nitrogen oxides are produced from burning
fuels, including gasoline and coal. Nitrogen oxides are smog
formers, which react with volatile organic compounds to form smog.
Nitrogen oxides are also major components of acid rain.
Non-attainment area -- A
geographic area in which a criteria air pollutant level is higher
than allowed by the federal standards. A single geographic area may
have an acceptable level for one criteria air pollutant, but have
unacceptable levels of one or more other criteria air pollutants.
Thus, an area can be both an attainment and non-attainment area at
the same time. Sixty percent of Americans are estimated to live in
non-attainment areas.
Non-point sources --
Diffuse pollution sources that are not
recognized to have a single point of
origin.
Octane number -- A
numerical measure of the antiknock
properties of gasoline used as a motor
fuel. The higher the octane number, the
greater the antiknock properties.
Offset -- A method used in the
1990 Clean Air Act to give companies, which own or operate large
(major) sources in non-attainment areas, flexibility in meeting
overall pollution reduction requirements when changing production
processes. If the owner or operator of the source wishes to increase
releases of a criteria air pollutant, an offset (reduction of a
somewhat greater amount of the same pollutant) must be obtained
either at the same plant or by purchasing offsets from another
company.
Opacity -- The
amount of light obscured by particle
pollution in the atmosphere. Opacity is
used as an indicator of changes in
performance of particulate control
systems.
Organic compounds --
A large group of chemical compounds
containing mainly carbon, hydrogen,
nitrogen, and oxygen. All living
organisms are made up of organic
compounds.
Ozone -- A gas which is a
variety of oxygen. The oxygen gas found in the air consists of two
oxygen atoms stuck together; this is molecular oxygen. Ozone
consists of three oxygen atoms stuck together into an ozone
molecule. Ozone occurs in nature; it produces the sharp smell you
notice near a lightning strike. High concentrations of ozone gas are
found in a layer of the atmosphere - the stratosphere -high above
the Earth. Stratospheric ozone shields the Earth against harmful
rays from the sun, particularly ultraviolet B. Smog's main component
is ozone; this ground-level ozone is a product of reactions among
chemicals produced by burning coal, gasoline and other fuels, and
chemicals found in products such as solvents, paints, and hair
sprays.
Ozone depletion --
The reduction in the stratospheric ozone
layer. Stratospheric ozone shields the
Earth from ultraviolet radiation. The
breakdown of certain chlorine and/or
bromine-containing compounds that
catalytically destroy ozone molecules in
the stratosphere can cause a reduction
in the ozone layer.
Particulates: particulate matter (PM-10)
-- Particulate matter is a criteria air pollutant and is a finely
divided particle with an aerodynamic diameter of 10 micrometers or
less. Particulate matter includes dust, soot and other tiny bits of
solid materials that are released into and move around in the air.
Particulates are produced by many sources, including burning of
diesel fuels by trucks and buses, incineration of garbage, mixing
and application of fertilizers and pesticides, road construction,
industrial processes such as steel making, mining operations,
agricultural burning (field and slash burning), and operation of
fireplaces and wood stoves. Particulate pollution can cause eye,
nose, and throat irritation and other health problems.
Particulates: particulate
matter (PM2.5) -- Includes tiny
particles with an aerodynamic diameter
less than or equal to a nominal 2.5
microns. This fraction of particulate
matter penetrates most deeply into the
lungs.
Parts per billion (ppb)/parts
per million (ppm) -- Units
commonly used to express contamination
ratios, as in establishing the maximum
permissible amount of contaminant in
water, land, or air.
Peak levels -- A
level of airborne pollutants that is
much higher than average. They can occur
over a short period of minutes or hours
in response to sudden releases, or they
can occur due to a longer term build-up
over several days.
Permit -- A document that
resembles a license that is required by the Clean Air Act for big
(major) sources of air pollution, such as power plants, chemical
factories and, in some cases, smaller polluters. Usually permits are
issued by states, but if EPA has disapproved part or all of a state
permit program, EPA will issue the permits in that state. The 1990
Clean Air Act includes requirements for permit applications,
including provisions for members of the public to participate in
state and EPA reviews of permit applications. Permits contain
information on all the regulated pollutants at a source. Permits
include information on which pollutants are presently released, how
much pollution the source is allowed to release, and the control
measures necessary to meet pollutant release requirements. Permits
are required both for the operation of plants (operating permits)
and for the construction of new plants. The 1990 Clean Air Act
introduced a nationwide permit system for air pollution control.
Permit fees -- Fees paid by
businesses required to have a permit. Permit fees are like the fees
drivers pay to register their cars. Money from permit fees helps pay
for state air pollution control activities.
Plume -- A visible
or measurable discharge of a contaminant
from a given point of origin that can be
measured according to the Ringelmann
scale.
Pollutants (pollution) --
Unwanted chemicals or other materials found in the air. Pollutants
can harm health, the environment and property. Many air pollutants
occur as gases or vapors, but some are very tiny solid particles:
dust, smoke, or soot.
Prevention of significant deterioration (PSD) -- This term refers to regulations that requires a major
new source or an existing source making majoring modifications to be
permitted by the state before construction is started if they are
located in an attainment area.
Primary standard -- A pollution
limit based on health effects. Primary standards are set for
criteria air pollutants.
PTE (Potential to Emit)
-- Capacity (usually measured in tons
per year) of a pollution source to
release a particular pollutant or class
of pollutants.
Quality assurance/quality
control (QA/QC) -- A system of
procedures, checks, audits, and
corrective actions to ensure that all
research design and performance,
environmental monitoring and sampling,
and other technical and reporting
activities achieve the program's desired
data quality objectives (DQOs).
Reasonably available control technology (RACT) -- It is usually an emission limit set by a state
air program and is the basis for emission rates used in their SIP.
It usually applies to sources in attainment areas and in most cases
is less stringent than the NSPS level of control.
Reciprocating internal
combustion engine (RICE) -- An
engine in which air and fuel are
introduced into cylinders, compressed by
pistons, and ignited by a spark plug or
by compression. Combustion in the
cylinders pushes the pistons
sequentially, transferring energy to the
crankshaft, causing it to rotate.
Reformulated gasoline --
Specially refined gasoline with low levels of smog-forming volatile
organic compounds (VOCs) and low levels of hazardous air pollutants.
The 1990 Clean Air Act requires sale of reformulated gasoline in the
nine smoggiest areas. Some reformulated gasolines were sold in
several smoggy areas before passage of the 1990 Clean Air Act.
Ringelmann chart --
A series of charts, numbered 0 to 5,
that simulate various smoke densities by
presenting different percentages of
black. A Ringelmann No. 1 is equivalent
to 20 percent black; a Ringelmann No. 5
is 100 percent black. They are used for
measuring the opacity or equivalent
obscuration of smoke arising from stacks
and other sources by matching the actual
effluent with the various numbers, or
densities, indicated by the charts.
Risk assessment --
An evaluation of risk that estimates the
relationship between exposure to a
harmful substance and the likelihood
that harm will result from that
exposure.
SBA -- Small Business
Administration.
SBEAP -- Small Business
Environmental Assistance Program.
SBDC -- Small Business
Development Center.
Scrubber -- An air
pollution control device that uses a
high energy liquid spray to remove
aerosol and gaseous pollutants from an
air stream. The gases are removed either
by absorption or chemical reaction.
Secondary particulate
-- Particles that usually form over
several hours or days and attain
aerodynamic diameters between 0.1 and 1
µm. Several of these particles,
particularly those containing ammonium
nitrate, are volatile and transfer mass
between the gas and particle phase to
maintain a chemical equilibrium.
Secondary standard -- A
pollution limit based on environmental effects such as damage to
property, plants, or visibility. Secondary standards are set for
criteria air pollutants.
SIC (Standard Industrial
Classification) -- An old
federal system of classifying industries
and other businesses. They system
assigned two-digit numbers to broad
categories and 4-digit numbers beginning
with those 2-digit numbers to finer
classes within those categories. SIC has
been replaced by NAICS, but SIC numbers
are still in common use.
State implementation plan (SIP)
-- A detailed description of the programs a state will use to carry
out its responsibilities under the Clean Air Act. This includes such
things as rules and regulations, plans to control ozone, and ambient
air standards used by a state to reduce air pollution. The Clean Air
Act requires that EPA approve each state implementation plan.
Smog -- A mixture of pollutants,
principally ground-level ozone, produced by chemical reactions in
the air involving smog-forming chemicals. A major portion of
smog-formers comes from burning petroleum-based fuels such as
gasoline. Other smog-formers, volatile organic compounds, are found
in products such as paints and solvents. Smog can harm health,
damage the environment and cause poor visibility. Major smog
occurrences are often linked to heavy motor vehicle traffic,
sunshine, high temperatures and calm winds, or temperature inversion
(weather condition in which warm air is trapped close to the ground
instead of rising).
Source -- Any place or object
from which pollutants are released. A source can be a power plant,
factory, dry cleaning business, gas station, or a farm. Cars,
trucks, and other motor vehicles are sources. Consumer products and
machines used in industry can also be sources.
Stationary source -- A place or
object from which pollutants are released which stays in place.
Stationary sources include power plants, gas stations, incinerators,
and houses.
Sulfur dioxide -- A criteria air
pollutant. Sulfur dioxide is a gas produced by burning coal, most
notably in power plants. Some industrial processes, such as
production of paper and smelting of metals, produce sulfur dioxide.
Sulfur dioxide is closely related to sulfuric acid, a strong acid.
Sulfur dioxide plays an important role in the production of acid
rain.
Synthetic minor permit -- A
permit with practically, enforceable conditions issued to a
facility. These conditions limit the amount of regulated pollutant
emissions so the permitted amount of actual emissions from the
facility is below potential major source emission levels. These
major source thresholds are usually 100 tons per year under Title V,
50 tons per year VOC/NO in the nonattainment area for ozone; 100/250
tons per year for P.D; 10 tons per year for a single hazardous air
pollutant; 25 tons per year for a combination of all hazardous air
pollutants; and 50 tons per year for a new source review.
Title V permit -- Is a federal
operating permit program adopted and implemented by the state. The
basic program elements typically specify that major sources will
submit an operating application to the specified state environmental
regulatory agency according to a schedule. EPA and the affected
states will review the permit issuance. The pubic also has an
opportunity to comment on the permit, which is renewable every five
years. Minor changes to the permit can be made without opening the
permit for public participation.
Total suspended particulates
-- Particles of solid and liquid matter
suspended in air. TSP is collected on
filtration media and analyzed by weight
only. Particle sizes represented by the
method are up to 100
µm in aerodynamic diameter.
Toxic release inventory (TRI)
-- Database of toxic releases in the
U.S. compiled from SARA Title II Section
313 reports.
Ultraviolet B (UVB) -- A type of
sunlight. The ozone in the stratosphere filters out ultraviolet B
rays and keeps them from reaching the Earth. Ultraviolet B exposure
has been associated with skin cancer, eye cataracts, and damage to
the environment. Thinning of the ozone layer in the stratosphere
results in increased amounts of ultraviolet B reaching the Earth.
Vapor -- The gaseous phase of liquids or solids at
atmospheric temperature and pressure.
Vapor recovery nozzles --
Special gas pump nozzles that reduce the release of gasoline vapor
into the air gas is pumped into car tanks. There are several types
of vapor recovery nozzles. Therefore, nozzles may not look the same
at all gas stations. The 1990 Clean Air Act requires the
installation of vapor recovery nozzles at gas stations in smoggy
areas.
Vapor recovery systems
-- Mechanical systems that collect and
recover chemical vapors resulting from
transfer of gasoline from operations
such as tank-to-truck systems at
refineries, tanker-to-pipeline systems
at offshore oil operations, and
pump-to-vehicle systems at gasoline
stations.
Variance --
Permission granted for a limited time
(under stated conditions) for a person
or company to operate outside the limits
prescribed in a regulation.
Visibility -- A
measurement of the ability to see and
identify objects at different distances.
Visibility reduction from air pollution
is often due to the presence of sulfur
and nitrogen oxides, as well as
particulate matter.
Volatile organic compounds (VOCs)
-- Organic chemicals all contain the element carbon (C). Organic
chemicals are the basic chemicals found in living things and in
products derived from living things, such as coal, petroleum, and
refined petroleum products. Many of the organic chemicals we use do
not occur in nature, but were synthesized by chemists in
laboratories. Volatile chemicals readily produce vapors at room
temperature and normal atmospheric pressure. Vapors escape easily
from volatile liquid chemicals. Volatile organic chemicals include
gasoline, industrial chemicals such as benzene, solvents such as
toluene and xylene, and tetrachloroethylene (perchloroethylene, the
principal dry cleaning solvent). Many volatile organic chemicals,
such as benzene, are also hazardous air pollutants.
Zero Air -- Pure
air, used for calibrating air monitoring
instruments. The EPA requires zero air
to have less than 0.1 ppm of
hydrocarbons.