|
INTRODUCTION
|
|
|
| This glossary provides definitions of terms pertaining to the laws, regulations,
programs, and government agencies involved in assuring healthful air quality for California's citizens. Moreover,
this glossary explains some of the scientific terms used to describe air pollutants, the processes that form
them, and their effects on the environment and the population. The primary focus of this publication is to
help interested citizens understand the most commonly used air pollution terms. |
| Please read an overview that describes what air pollution
is and the regulatory system that has been developed to control it. |
|
Air Pollution Terms
|
|
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
|
|
A
|
| AB
1807 (Tanner):
A California state law (Health and Safety Code section 39650
et seq.) which became effective in January of 1984
and established the framework for California's toxic air contaminant identification and control program. For more information, please see our toxics summary. |
| AB
2588 (Connelly) Air Toxics "Hot Spots" Information and Assessment Program:
A California program (Health and Safety Code Section 44300 et seq.) which requires certain stationary sources to report the type and quantity of specific toxic substances they routinely
release into the air. The program identifies high priority facilities and requires facilities posing significant
risks to notify all exposed individuals. For more information, please go to our AB2588 website. |
| AB 2766 (Sher) Motor Vehicle Fee Program: A program that permits air district and local governments
to allocate vehicle registration surcharge fees to projects that reduce motor vehicle emissions such as zero-emission vehicles, bike lanes, and trip reduction programs. |
| Abatement: The reduction or elimination of pollution. |
| Acceptable
Daily Intake (ADI): The highest daily amount of a substance that
may be consumed over a lifetime without adverse effects. |
| Acid
Deposition: A comprehensive term for the various ways acidic
compounds precipitate from the atmosphere and deposit onto surfaces. It can include: 1) wet deposition by means
of acid rain, fog, and snow; and 2) dry deposition of acidic particles (aerosols). |
| Acid
Rain: Rain which is especially acidic (pH <5.2). Principal
components of acid rain typically include nitric and sulfuric acid. These may be formed by the combination
of nitrogen and sulfur oxides with water vapor in the atmosphere. |
| Acute
Exposure: One or a series of short-term exposures generally lasting
less than 24 hours. |
| Acute
Health Effect:
A health effect that occurs over a relatively short period of
time (e.g., minutes or hours). The term is used to describe
brief exposures and effects which appear promptly after exposure. |
| Add-On
Control Device:
An air pollution control device such as carbon absorber
or incinerator that reduces the pollution in exhaust
gas. The control device usually does not affect the
process being controlled and thus is "add-on" technology, as
opposed to a scheme to control pollution through
altering the basic process itself. See also pollution prevention. |
| Adsorber: An emissions control device that removes VOCs from a gas stream as a result
of the gas attaching (adsorbing) onto a solid matrix such as activated carbon. |
| Adverse
Health Effect: A health effect from exposure to air contaminants
that may range from relatively mild temporary conditions, such as eye or throat irritation, shortness
of breath, or headaches to permanent and serious conditions, such as birth defects, cancer or damage
to lungs, nerves, liver, heart, or other organs. |
| Aerosol: Particles of solid or liquid matter that can remain suspended in air from a few minutes
to many months depending on the particle size and weight. |
| Afterburner: An air pollution abatement device that removes undesirable
organic gases through incineration. |
| Agricultural
Burning: The intentional use of fire for vegetation management
in areas such as agricultural fields, orchards, rangelands, and forests. The regulation of agricultural
burning is described in the Agricultural Burning Guidelines, Title 17, California Code of Regulations. For
more information, please go to our smoke management program website. |
| Air: So called "pure" air is a mixture of gases containing about 78 percent
nitrogen; 21 percent oxygen; less than 1 percent of carbon dioxide, argon,
and other gases; and varying amounts of water vapor. See also ambient air. |
| Air
Basin: A land area with generally similar meteorological and
geographic conditions throughout. To the extent possible, air basin boundaries are defined along political
boundary lines and include both the source and receptor areas. California is currently divided into 15 air
basins. |
| Airborne Toxic Control Measure (ATCM):
A control measure adopted by the ARB (Health and Safety Code Section 39666 et seq.), which reduces emissions
of toxic air contaminants. For more information please see our ATCM top page. |
| Air
District: A political body responsible for managing air quality
on a regional or county basis. California is currently divided into 35 air districts. (See also
air pollution
control district and air quality management district).
For more information, see our local air district directory. |
| Air
Monitoring: Sampling for and measuring of pollutants present
in the atmosphere. |
| Air
Pollutants: Amounts of foreign and/or natural substances occurring
in the atmosphere that may result in adverse effects to humans, animals, vegetation, and/or materials.
(See also air pollution.) |
| Air
Pollution: Degradation of air quality resulting from unwanted
chemicals or other materials occurring in the air. (See also air pollutants.) |
| Air Pollution Control District (APCD):
A county agency with authority to regulate stationary, indirect, and area sources of air pollution
(e.g., power plants, highway construction, and housing developments) within a given county, and governed by a district
air pollution control board composed of the elected county supervisors. (See also air quality management
district). |
| 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). Like the PSI, the AQI incorporates five criteria pollutants -- ozone, particulate matter,
carbon monoxide, sulfur dioxide, and nitrogen dioxide -- into a single index. The new index 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. The AQI incorporates an additional index
category -- unhealthy for sensitive groups -- that ranges from 101 to 150. In addition, the AQI comes with more
detailed cautions. For more information, see our air quality index top page. |
| Air Quality Management District (AQMD):
A group of counties or portions of counties, or an individual county specified in law with authority to regulate
stationary, indirect, and area sources of air pollution within the region and governed by a regional air pollution
control board comprised mostly of elected officials from within the region. (See also air pollution control
district). For more information, please see our local air district directory. |
| Air Quality Management Plan (AQMP):
A plan prepared by an APCD / AQMD, for a county or region designated as a nonattainment area, for
the purpose of bringing the area into compliance with the requirements of the national and / or California
ambient air quality
standards. AQMPs are incorporated into the State Implementation Plan (SIP). |
| Air
Quality Manager: An individual employed by the local, state,
or federal government to manage air quality. |
| Air
Quality Simulation Model: A mathematical relationship between
emissions and air quality which simulates on a computer the transport, dispersion, and transformation
of compounds emitted into the air. For more information, please see our software webpage. |
| Air
Quality Standard (AQS): The prescribed level of a pollutant in
the outside air that should not be exceeded during a specific time period to protect public health. Established
by both federal and state governments. (See also ambient air quality standards.)
For more information please see our ambient air quality standards webpage. |
| Air Quality Working Groups (AQWG):
Advisory groups that provide forums for communication, cooperation, and coordination in the development and implementation
of air quality control measures. They may be comprised of representatives from the ARB, citizen groups, environmental
groups, industry, local air districts, and the U.S. EPA. |
| Air
Resources Board: (See California Air Resources Board.) |
| Airshed: A subset of air
basin, the term denotes a geographical area that shares the same
air because of topography, meteorology, and climate. |
| Air
Toxics: A generic term referring to a harmful chemical or group
of chemicals in the air. Substances that are especially harmful to health, such as those considered under
U.S. EPA's hazardous
air pollutant program or California's AB 1807 and / or AB 2588 air toxics
programs, are considered to be air toxics. Technically, any compound that is in the air and has
the potential to produce adverse health effects is an air toxic. For more information, please visit our toxics website. |
| Alternative
Fuels: Fuels such as methanol, ethanol, natural gas, and liquid
petroleum gas that are cleaner burning and help to meet ARB's mobile and stationary emission standards. These fuels
may be used in place of less clean fuels for powering motor vehicles. For more information, please visit our alternative fuels website. |
| Ambient
Air: The air occurring at a particular time and place outside
of structures. Often used interchangeably with "outdoor air." (See also air.) |
| Ambient Air Quality Standards (AAQS):
Health- and welfare-based standards for outdoor air which identify the maximum acceptable average concentrations
of air pollutants during a specified period of time. (See also CAAQS and NAAQS and Criteria Air Pollutant.)
For more information, please view our ambient air quality standards website. |
|
American Society for Testing and Materials (ASTM): A nonprofit organization that provides a forum for producers, consumers, and representatives
of government and industry, to write laboratory test standards for materials, products, systems, and services.
ASTM publishes standard test methods, specifications, practices, guides, classifications, and terminology.
For more information, please visit the ASTM website. |
| Ammonia
(NH3): A pungent colorless gaseous compound of nitrogen and hydrogen that is very
soluble in water and can easily be condensed into a liquid by cold and pressure. Ammonia reacts with NOx to form
ammonium nitrate -- a major PM2.5 component in the Western United States. |
| 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 California Clean Air Act requires
air districts to include area sources in the development and implementation of the AQMP.
In the California emission inventory all sources which are not reported as individual point sources are included
as area sources. 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. For more information, please visit our area-wide source methodologies website. |
| Area-Wide
Sources: Sources of pollution where the emissions are spread
over a wide area, such as consumer products, fireplaces, road dust and farming operations. Area-wide sources
do not include mobile sources or stationary
sources. |
| Aromatic: A type of hydrocarbon, such as benzene or toluene. Some aromatics are toxic. |
| Asbestos: A mineral fiber that can pollute air or water and cause cancer or asbestosis when inhaled.
The U.S. EPA has banned or severely restricted its use in manufacturing and construction and the ARB
has imposed limits on the amount of asbestos in serpentine rock that is used for surfacing applications. For more
information, please visit our website. |
| Asthma: A chronic inflammatory disorder of the lungs characterized by wheezing, breathlessness,
chest tightness, and cough. |
| Atmosphere: The gaseous mass or envelope of air surrounding the Earth. From ground-level
up, the atmosphere is further subdivided into the troposphere, stratosphere, mesosphere,
and the thermosphere. |
| Attainment
Area: A geographical area identified to have air quality as good
as, or better than, the national and / or California ambient air quality standards
(NAAQS / CAAQS). An area may be an attainment area for one pollutant and a nonattainment area
for others. For more information, please visit our area designations website. |
| Authority to Construct (A/C):
A pre-construction permit issued by an air district. |
|
B
|
| Baghouse: An air pollution control device that traps particulates by forcing gas
streams through large permeable bags usually made of glass fibers. For more information, please go tou our baghouse training website. |
| Banking: A provision in air
district permit regulations that allows a facility to accumulate credits
for reducing emissions beyond regulatory limits (emission reduction credits) and then use or sell those credits
at a later date. For more information, please go to our New Source Review website. |
| Best Available Control Measure (BACM):
A term used to describe the "best" measures (according to U.S. EPA guidance) for controlling small
or dispersed sources of particulate
matter and other emissions from sources such as roadway dust,
woodstoves, and open burning. |
| Best Available Control Technology (BACT):
The most up-to-date methods, systems, techniques, and production processes available to achieve
the greatest feasible emission reductions for given regulated air pollutants and processes. BACT is a requirement of
NSR (New Source Review) and PSD (Prevention
of Significant Deterioration). For more information, please go to our BACT website. |
|
Best Available Retrofit Control Technology (BARCT): An air emission limitation that applies to existing sources and is based
on the maximum degree of reduction achievable, taking into account environmental, energy, and economic impacts
by each class or category of source. (See also Best Available Control Technology.)
For more information, please go to our BARCT website. |
| Biogenic
Source: Biological sources such as plants and animals that emit
air pollutants such as volatile
organic compounds. Examples of biogenic sources include animal
management operations, and oak and pine tree forests. (See also natural sources.) For more information, please go to our Ecosystems Impact website. |
| Bureau of Automotive Repair (BAR):
An agency of the California Department of Consumer Affairs that manages the implementation of the motor
vehicle Inspection
and Maintenance Program. For more information, please go to the smogcheck website. |
| Burn
Day: A day that is not officially determined by meteorologists
and air quality managers to be a no-burn day. Burn days vary by air basin on any given day. For more information, please view our smoke management program website. |
|
C
|
|
California Air Pollution Control Officers Association (CAPCOA): A nonprofit association of the air pollution control officers from all 35 air
quality agencies throughout California. CAPCOA was formed in 1975 to promote clean air and to provide a forum
for sharing of knowledge, experience, and information among the air quality regulatory agencies
around the state. CAPCOA is an organization of air quality professionals -- leaders in their
field -- who promote unity and efficiency, and strive to encourage consistency in methods and practices
of air pollution control. For more information, please go to CAPCOA's website. |
|
California Air Resources Board (ARB):
The State's lead air quality agency consisting of an
eleven-member board appointed by the Governor and
several hundred employees. CARB is responsible for attainment and
maintenance of the state and federal air quality standards, and is fully responsible for motor vehicle pollutioncontrol. It oversees county
and regional air pollution management programs. |
|
California Ambient Air Quality Standard (CAAQS): A legal limit that specifies the maximum level and time of exposure in the
outdoor air for a given air pollutant and which is protective of human health and public welfare
(Health and Safety Code section 39606b). CAAQSs are recommended by the California Office of Environmental Health Hazard Assessment
and adopted into regulation by the CARB. CAAQSs are the standards which must be met per the requirements
of the California Clean Air Act (CCAA). For more information, please view our AAQS website. |
| California Clean Air Act (CCAA):
A California law passed in 1988 which provides the basis for air quality planning and regulation independent
of federal regulations. A major element of the Act is the requirement that local air districts in violation of
the CAAQS must prepare attainment plans which identify air quality problems, causes, trends, and
actions to be taken to attain and maintain California's air quality standards by the earliest practicable
date. |
|
California Environmental Protection Agency (Cal/EPA): A state government agency established in 1991 for unifying environmental
activities related to public health protection in the State of California. There are six boards, departments,
and offices under the organization of Cal/EPA including the California Air Resources Board
(ARB), California Integrated Waste Management Board (IWMB), State Water Resources Control Board (SWRCB)
and its nine Regional Water Quality Control Boards (RWQCB), Department of Pesticide Regulation (DPR), Department
of Toxic Substances Control (DTSC), and Office of Environmental Health Hazard Assessment
(OEHHA). To see links to these Cal/EPA organizations, go to
the bottom of this webpage or any webpage on this website.
The Cal/EPA boards, departments, and offices are directly
responsible for implementing California environmental laws,
or play a cooperative role with other regulatory
agencies at regional, local, state, and federal levels. Please visit Cal/EPA's home page. |
| California Environmental Quality Act (CEQA):
A California law that sets forth a process for public agencies to make informed decisions on discretionary
project approvals. The process aids decision makers to determine whether any environmental impacts are associated
with a proposed project. It requires environmental impacts associated with a proposed project to be eliminated
or reduced, and that air quality mitigation measures are implemented. |
| Cancer: A group of diseases characterized by uncontrolled invasive growth of body cells
leading to the formation of malignant tumors that tend to grow rapidly and spread (i.e., metastasize). |
| Carbon Dioxide (CO2): A colorless, odorless gas
that occurs naturally in the Earth's atmosphere. Significant quantities are also emitted into the air by fossil fuel combustion.
(See also ClimateChange.ca.gov Glossary.) |
| Carbon Monoxide (CO): A colorless, odorless
gas resulting from the incomplete combustion of hydrocarbon fuels. CO interferes with the blood's ability
to carry oxygen to the body's tissues and results in numerous adverse health effects. Over
80 percent of the CO emitted in urban areas is contributed by motor vehicles. CO is a criteria air pollutant. |
| Carcinogen: A cancer-causing substance. (See also cancer.) |
| Carl
Moyer Fund: A multi-million dollar incentive grant program designed
to encourage reduction of emissions from heavy-duty engines. The grants cover the additional cost
of cleaner technologies for on-road, off-road, marine, locomotive and agricultural pump engines, as well
as forklifts and airport ground support equipment. Please visit our Carl Moyer Program website. |
| 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. |
| Catalyst: A substance that can increase or decrease the rate of a chemical reaction between
the other chemical species without being consumed in the process. |
| Catalytic
Converter: A motor vehicle pollution control device designed
to reduce emissions such as oxides
of nitrogen, hydrocarbons, and carbon monoxide. Catalytic converters have been required equipment on all new motor vehicles sold in California
since 1979. |
| Chlorofluorocarbons (CFCs): Any of a
number of substances consisting of chlorine, fluorine, and carbon. CFCs are used for refrigeration, foam packaging,
solvents, and propellants. Visit the Cal/EPA website for more information. |
| Chronic
Exposure: Long-term exposure, usually lasting one year to a lifetime. |
| Chronic
Health Effect: A health effect that occurs over a relatively
long period of time (e.g., months or years). (See also acute health effect.) |
| Cleaner-Burning Gasoline: Gasoline
fuel that results in reduced emissions of carbon monoxide, nitrogen
oxides, reactive organic gases, and particulate matter, in addition to
toxic substances such as benzene and 1,3-butadiene. Visit our cleaner-burning gasoline website or an overview of ARB's fuels program. |
| Climate Change: see ClimateChange.ca.gov Glossary.) |
| Coating: A layer of any substance such as paint, lacquer, or varnish applied over a surface
for protection. For more information, please see our coatings website. |
| Coefficient of Haze (COH): A
measurement of the quantity of dust and smoke in the atmosphere in a theoretical 1,000 linear
feet of air. A COH of less than three is considered clean air and more than five is of some concern.
COH readings of 20 or more can occur in urban areas. |
| Combustion: The act or instance of burning some type of fuel such as gasoline to produce
energy. Combustion is typically the process that powers automobile engines and power plant generators. |
| Compressed Natural Gas (CNG):
(See alternative fuels.) |
| Conformity: A demonstration of whether a federally-supported activity is consistent with the
State Implementation Plan (SIP) -- per Section 176 (c) of the Clean Air Act. Transportation
conformity refers to plans, programs, and projects approved or funded by the Federal Highway Administration
or the Federal Transit Administration. General conformity refers to projects approved or funded by other federal
agencies. |
| Congestion
Management Program: A state-mandated program (California Government
Code Section 65089a) that requires each county to prepare a plan to relieve congestion and reduce air
pollution. |
| Consumer
Products: Products such as hairspray, detergents, cleaning compounds,
polishes, lawn and garden products, personal care products, and automotive specialty products which are part
of our everyday lives and, through consumer use, may produce volatile organic air emissions which contribute
to air pollution. Please view our consumer products website. |
| Continuous Emission Monitor (CEM):
A type of air emission monitoring system installed to operate continuously inside of a smokestack or
other emission source. |
| Continuous
Sampling Device: An air analyzer that measures air quality components
continuously. (See also Integrated
Sampling Device.) |
| Control Techniques Guidelines (CTG):
Guidance documents issued by U.S. EPA
that define reasonably available control technology (RACT)
to be applied to existing facilities that emit excessive quantities of air pollutants; they contain information
both on the economic and technological feasibility of available techniques. |
| Cost-Effectiveness: The cost of an emission control measure assessed in terms of dollars-per-pound,
or dollars-per-ton, of air emissions reduced. |
| Criteria
Air Pollutant: An air pollutant for which acceptable levels of
exposure can be determined and for which an ambient air quality standard has been set. Examples include: ozone,
carbon monoxide, nitrogen
dioxide, sulfur dioxide, and PM10
and PM2.5. The term "criteria air pollutants" derives from the requirement that the U.S. EPA must describe
the characteristics and potential health and welfare effects of these pollutants. The U.S. EPA and CARB
periodically review new scientific data and may propose revisions to the standards as a result. View our health and air pollution website. |
| Cyclone: An air pollution control device that removes larger particles -- generally greater
than one micron -- from an air stream through centrifugal force. |
|
D
|
| Deciview: A measurement of visibility. One deciview represents the minimal perceptible
change in visibility to the human eye. |
| Degreaser: Equipment that removes grease, dirt, or unwanted materials from any part or product.
Degreasers typically use aqueous or nonaqueous solvents, as liquid baths or condensing vapors, to remove
such material. |
| Deposit
Control Additives: Substances added to motor vehicle fuel to
reduce and prevent deposits in the fuel delivery system and engine intake valves. |
| Design
Value: The pollutant concentration used by air quality managers as the
basis for determining attainment of an air quality
standard, generally by using an air quality model. The design
value may or may not be the same as the designation value. |
| Designation
Value: The pollutant concentration used by air quality managers for designating
attainment status of an air district with respect to the state and federal ambient air quality standards.
Generally, the designation value is the highest concentration that remains after excluding certain qualifying
values. For a specific pollutant, the designation value for the state and federal standards may not be the
same. |
| 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). |
| Dispersion
Model: See air quality simulation model
above. |
| Dose: The amount of a pollutant that is absorbed. A level of exposure which 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. |
| Dose-Response: The relationship between the dose of a pollutant and the response (or effect)
it produces on a biological system. |
| Dust: Solid particulate
matter that can become airborne. |
|
E
|
| Electric Vehicle: A motor vehicle
that uses an electric motor as the basis of its operation. Such vehicles emit virtually no air pollutants. (See
also hybrid
electric vehicle.) For more information, please see our zero emission vehicles website. |
| Electrostatic Precipitator (ESP):
An air pollution control device that removes particulate matter
from an air stream by imparting an electrical charge to the particles
for mechanical collection at an electrode. For more information,
please see our associated training class on this subject. |
| Emission
Factor: For stationary sources, the relationship
between the amount of pollution produced and the amount of raw material processed or burned. For mobile sources, the relationship
between the amount of pollution produced and the number of vehicle miles traveled. By using the emission
factor of a pollutant and specific data regarding quantities of materials used by a given source, it is possible
to compute emissions for the source. This approach is used in preparing an emissions inventory. Please also look at
U.S. EPA emission factors, or ARB's emission factors and toxic air contaminants, |
| 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. For more information, please view our emissions inventory website. |
| Emission
Offsets (also known as Emissions
Trading): A rule-making concept whereby approval of a new or
modified stationary source of air pollution is conditional on the reduction of emissions from other existing
stationary sources of air pollution. These reductions are required in addition to reductions required by best available
control technology. For information please go to our New Source Review Emission Reduction Credit Offsets website. |
| Emission
Rate: The weight of a pollutant emitted per unit of time (e.g.,
tons / year). |
| Emission
Standard: The maximum amount of a pollutant that is allowed to
be discharged from a polluting source such as an automobile or smoke stack. |
| Energy
Content: The amount of energy available for doing work. For example,
the amount of energy in fuel available for powering a motor vehicle. |
| Environmental
Justice: The fair treatment of people of all races and incomes
with respect to development, implementation, and enforcement of environmental laws, regulations, and
policies. |
| Environmental
Tobacco Smoke: Primarily a combination of sidestream smoke from the
burning end of a cigarette, pipe or cigar, and exhaled mainstream smoke from the smoker. Other components
include smoke emitted at the mouthpiece during puff drawing. For more information, please see our environmental tobacco smoke website. |
| Epidemiology: The study of the occurrence and distribution of disease within a population. |
| 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. |
| Evaporative
Emissions: Emissions from evaporating gasoline, which can occur
during vehicle refueling, vehicle operation, and even when the vehicle is parked. Evaporative emissions
can account for two-thirds of the hydrocarbon emissions from gasoline-fueled vehicles on hot summer days. |
| Exhaust Gas Recirculation (EGR):
An emission control method that involves recirculating exhaust gases from an engine back into the intake
and combustion chambers. This lowers combustion temperatures and reduces NOx. (See also nitrogen oxides.) |
| Expected Peak Day Concentration (EPDC):
A calculated value that represents the concentration expected to
occur at a particular site once per year, on average.
The calculation procedure uses measured data collected at the site
during a three-year period. Measured concentrations that are
higher thatn the EPDC are excluded from the state area designation
process. |
| Exceedance: A measured level of an air pollutant higher than the national or state ambient air quality
standards. (See also NAAQS and CAAQS.) |
| Exposure: The concentration of the pollutant in the air multiplied by the population exposed
to that concentration over a specified time period. |
| Exposure
Assessment: Measurement or estimation of the magnitude, frequency,
duration and route of exposure to a substance for the populations of interest. |
|
F
|
| Federal Clean Air Act (FCAA):
A federal law passed in 1970 and amended in 1974, 1977 and 1990 which forms the basis for the national air pollution
control effort. Basic elements of the act include national ambient air quality standards
for major air pollutants, mobile and stationary control measures, air toxics standards, acid rain control measures,
and enforcement provisions. For more information, please go to the Federal Clean Air Act. |
| Federal Implementation Plan (FIP):
In the absence of an approved State
Implementation Plan (SIP), a plan prepared by the U.S. EPA which provides
measures that nonattainment areas must take to meet the requirements of the Federal Clean Air Act. |
| Flexible Fuel Vehicle (FFV): Vehicles
that can use a combination of fuels such as alcohol fuel and unleaded gasoline. |
| Fly Ash: Air-borne solid particles that result from the burning of coal and other solid fuel. |
| Fossil
Fuels: Fuels such as coal, oil, and natural gas; so-called because
they are the remains of ancient plant and animal life. |
| Fuel
Cell:
An electrochemical cell which captures the electrical energy of a
chemical reaction between fuels such as liquid
hydrogen and liquid oxygen and converts it
directly and continuously into the energy of a direct
electrical current. For more information, please go to ARB's fuel cell portal page. |
| 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. A subset
of fugitive emissions. |
| Fugitive
Emissions: Emissions not caught by a capture system which are
often due to equipment leaks, evaporative processes and windblown disturbances. |
| Fume: Solid particles under 1 micron in diameter formed as vapors condense, or as chemical
reactions take place. |
| Furnace: A combustion chamber; an enclosed structure in which fuel is burned to heat air or material. |
|
G
|
| Gas
Turbine: An engine that uses a compressor to draw air into the
engine and compress it. Fuel is added to the air and combusted in a combustor. Hot combustion gases exiting
the engine turn a turbine which also turns the compressor. The engine's power output can be delivered
from the compressor or turbine side of the engine. |
| Gasoline
Volatility: The evaporative properties of gasoline. Gasoline
vapor is a volatile organic compound. (See also Reid Vapor Pressure.) |
| 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. For more information, please go to ARB's climate change website or Climate Change:
see ClimateChange.ca.gov Glossary.) |
| Greenhouse
Effect: The warming effect of the Earth's atmosphere. Light energy
from the sun which 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 its windows rolled up. A number of scientists believe that the emission of CO2 and other gases into the atmosphere may increase the greenhouse effect and
contribute to global warming. Climate Change: see ClimateChange.ca.gov
Glossary.) |
| 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. ( See also ClimateChange.ca.gov
Glossary.) |
| Growth
Management Plan: A plan for a given geographical region containing
demographic projections (i.e., housing units, employment, and population) through some specified point
in time, and which provides recommendations for local governments to better manage growth and reduce
projected environmental impacts. |
|
H
|
| Hazardous Air Pollutant (HAP):
An air pollutant listed under section 112 (b) of the federal Clean Air Act as particularly hazardous to health.
Emission sources of hazardous air pollutants are identified by U.S. EPA, and emission standards are set accordingly.
For more information, please go our Title III website area. |
| Haze
(Hazy): A phenomenon that results in reduced visibility due to the scattering
of light caused by aerosols. Haze is caused in large part by man-made air pollutants. |
| Health-Based
Standard (Primary Standard): A dosage of air pollution scientifically
determined to protect against human health effects such as asthma, emphysema, and cancer. |
| Health Risk Assessment (HRA):
A document that identifies the risks and quantities of possible adverse health effects |
