This Glossary is compiled from several glossaries that are inserted individually. Therefore there are three sets, each in alphabetical order. This table allows you to skip to the start of each. Also, some links to outside glossaries.

Internal glossaries:
Perkins Miscellaneous OSHA - Air Contaminants EPA \Indoor Air Quality (IAQ)
Bay Area Air Quality Management District Air Pollution    
External Glossaries
EPA Law    

Acute: Acute exposure is exposure for a short time, hours or days. Acute effect. An effect that shows up shortly after exposure.

Chronic: Chronic exposure is exposure for a longer time, weeks or months. Chronic effect, an effect that lasts for a long time. (Contract with latent effect, that dose not show up for a long time.)

Narcosis: Stupor or unconsciousness produced by chemical substances.

Asphyxia : Suffocation from lack of oxygen. Simple asphyxia oxygen is displaced by another gas. Chemical asphyxia, like carbon monoxide poisoning, proper utilization of oxygen is blocked.

Fog. Fog rolls in little cats feet...a large mass of condensed water vapor, at or just above, the earth's surface.

Vapor. The gas phase of a substance that is normally liquid or solid at standard temperature and pressure.

Water loving. Substance that has strong polar groups that readily interacts with water.

Hydrophobic: water hating. A substance that does not dissolve in water. Also called lipophilic (fat loving).

Flammable liquid. Any liquid with a flash point below 100 F (37.8 C).


From OSHA Preambles - Air Contaminants (29 CFR 1910_1000) - IV_ Overview of Rulemaking.htm

ACGIH - The American Conference Governmental Industrial Hygienists is a professional society devoted to the development of administrative and technical aspects of worker health protection. Membership is limited to professional personnel in governmental agencies or educational institutions engaged in occupational safety and health programs. The ACGIH issues guidelines and recommendations in the form of Threshold Limit Values (TLVs(R)) which are published annually.

CAS - The Chemical Abstracts Service (CAS) Registry Number is a numeric designation assigned by the American Chemical Society's Chemical Abstracts Service which uniquely identifies a specific chemical compound. This entry allows one to conclusively identify a substance regardless of the name or naming system used.

CHRIS - The Chemical Hazards Response Information System was developed by the U.S. Coast Guard in cooperation with the National Academy of Sciences to provide information on the handling and disposal of toxic substances. CHRIS consists primarily of the Hazardous Chemical Data Manual which contains chemical, physical and health hazard data on approximately 600 hazardous chemicals and substances; and a Hazard Assessment Computer System is an extensive data base of the information contained in the Hazardous Chemical Data Manual.

HSDB - The Hazardous Substances Data Bank, a part of the National Library of Medicine System, will soon be available on OSHA's Computerized Information System (OCIS). This data bank, currently available through TOXNET, contains health and safety profiles for over 4100 chemicals. It includes 144 data elements in 10 categories including use information, substance identification, animal and human toxicity, environmental fate, standards, personal protective equipment, fire, physical and chemical properties.

IARC - The International Agency for Research on Cancer (IARC) is a research organization authorized by the World Health Organization in 1965. IARC's mission is to study the causes of cancer in the human environment. IARC has published (and continues to update) a series of monographs on a substantial number of toxic chemicals and substance in which the carcinogenic risk of these chemicals is evaluated.

ILO - The International Labour Organization (ILO) is a specialized agency associated with the United Nations. Established in 1919 as part of the Versailles Peace Treaty, the ILO serves to band together governments, employers, and workers of 145 nations in an international effort to improve overall working conditions and to protect the life and health of workers.

IMIS - The Integrated Management Information System (IMIS) is a data base developed by OSHA in 1979 with sampling information on more than 70,000 individual measurements. The IMIS contains exposure measurements obtained by OSHA compliance officers during thousands of health inspections; it is the most extensive data base of its kind.

MSDS - The Material Safety Data Sheet (MSDS) is a compilation of data and information on individual hazardous chemicals produced by the manufacturers and importers of that chemical, as required by OSHA's Hazard Communication Standard, 29 CFR 1910.1200. An MSDS contains data on chemical identification, current exposure limits, chemical reactivity, fire and explosion limits, and information on health hazards and emergency procedures, spill, leak, and disposal procedures, and any needed special protection or precautions.

NIOSH - The National Institute for Occupational Safety and Health (NIOSH) was created by the Occupational Safety and Health Act of 1970. NIOSH is part of the Centers for Disease Control under the Department of Health and Human Services. Its mandate includes conducting research in developing criteria and/or recommendations to be used in setting occupational exposure standards, identifying and evaluating workplace hazards, measurement techniques, and control technologies, and providing professional education as well as health and safety information.

NOES - The National Occupational Exposure Survey (NOES) is a data base completed in 1982 by NIOSH. NOES is the successor to the first such data base, completed by NIOSH in 1974, and known as the National Occupational Hazard Survey (NOHS). The NOES data base contains a sample of the number of persons exposed by substance and industry from approximately 4500 businesses in 98 geographic areas in the U.S. These surveys provide national estimates of potential exposure to workplace hazards, by industry and occupational group.

OCIS - The OSHA Computerized Information System is a comprehensive data base that contains information and data on standards interpretation, chemical information, hazardous waste activity, 5(a)(1) citations, a health hazard evaluation index, training materials, and other information compiled by OSHA on subjects related to occupational safety and health.

OSHA HS Number - A Health Standard (HS) number is a 4-digit code assigned, for ease in reference, to each of the hazardous substances or chemicals considered for change of PEL in this rulemaking.

PEL - Permissible Exposure Limits (PELs) are limits developed by OSHA to indicate the maximum airborne concentration of a contaminant to which an employee may be exposed over the duration specified by the type of PEL assigned to that contaminant.

REL - Recommended Exposure Limits (RELs) are issued by NIOSH to aid in controlling hazards in the workplace. These limits are generally expressed as 8 - or 10 - hour TWAs for a 40-hour workweek and/or ceiling levels with time limits ranging from instantaneous to 120 minutes. RELs are published in a variety of NIOSH documents.

RTECS - The Registry of Toxic Effects of Chemical Substances (RTECS) is a data base that lists an identification number, synonyms, Department of Transportation (DOT) hazard label information, EPA Toxic Substances Control Act (TSCA) information, OSHA and Mine Safety and Health Administration (MSHA) air exposure limits, and animal and human toxicologic data.

TLV® - The Threshold Limit Value (TLV®) is a registered trademark for an exposure limit developed by the American Conference of Governmental Industrial Hygienists (ACGIH). A listing of TLVs may be found in the ACGIH's "Documentation of the Threshold Limit Values and Biological Exposure Indices for 1988-1989." TLVs may be stated as a time-weighted average (TLV-TWA), a Short-Term Exposure Limit (TLV -STEL), or a Threshold Limit Value Ceiling (TLV-C). OSHA utilized the 1987-88 TLV's as a starting point for this rulemaking.

TSCA - The Toxic Substances Control Act (TSCA), administered by the Environmental Protection Agency (EPA), was passed by Congress to protect human health and the environment by requiring testing and necessary use restrictions to regulate the commerce of certain chemical substances.

WHO - The World Health Organization (WHO) is part of the United Nations. WHO's programs in occupational health include development of an occupational health information system, criteria for early detection of health impairment, and the development of internationally recommended health-based permissible exposure limits for occupational exposure to toxic substances.

From EPA \Indoor Air Quality (IAQ) - Glossary of Terms.htm

ACID AEROSOL: Acidic liquid or solid particles that are small enough to become airborne. High concentrations of acid aerosols can be irritating to the lungs and have been associated with some respiratory diseases, such as asthma.

ACTION LEVEL: A term used to identify the level of indoor radon at which remedial action is recommended. (EPA's current action level is 4 pCi/L.)

ACTION PACKET: In reference to the IAQ Tools for Schools Kit - contains three components - an introductory memo, IAQ Backgrounder, and IAQ Checklist - to assist school personnel to implement an effective yet simple IAQ program in their school.

AHU: See "Air Handling Unit."

AIR CLEANING: An IAQ control strategy to remove various airborne particulates and/or gases from the air. The three types of air cleaning most commonly used are particulate filtration, electrostatic precipitation, and gas sorption.

AIR EXCHANGE RATE: The rate at which outside air replaces indoor air in a space. Expressed in one of two ways: the number of changes of outside air per unit of time air changes per hour (ACH); or the rate at which a volume of outside air enters per unit of time - cubic feet per minute (cfm).

AIR HANDLING UNIT (AHU): For purposes of this document refers to equipment that includes a blower or fan, heating and/or cooling coils, and related equipment such as controls, condensate drain pans, and air filters. Does not include ductwork, registers or grilles, or boilers and chillers.

AIR PASSAGES: Openings through or within walls, through floors and ceilings, and around chimney flues and plumbing chases, that permit air to move out of the conditioned spaces of the building.

ANIMAL DANDER: Tiny scales of animal skin.

ALLERGEN: A substance capable of causing an allergic reaction because of an individual's sensitivity to that substance.

ALLERGIC RHINITIS: Inflammation of the mucous membranes in the nose that is caused by an allergic reaction.

ANTIMICROBIAL: Agent that kills microbial growth. See "disinfectant," "sanitizer," and "sterilizer."

BIOLOGICAL CONTAMINANTS: Agents derived from, or that are, living organisms (e.g., viruses, bacteria, fungi, and mammal and bird antigens) that can be inhaled and can cause many types of health effects including allergic reactions, respiratory disorders, hypersensitivity diseases, and infectious diseases. Also referred to as "microbiologicals" or "microbials."

BREATHING ZONE: Area of a room in which occupants breathe as they stand, sit, or lie down.

BUILDING ENVELOPE: Elements of the building, including all external building materials, windows, and walls, that enclose the internal space.

BUILDING-RELATED ILLNESS (BRI): Diagnosable illness whose symptoms can be identified and whose cause can be directly attributed to airborne building pollutants (e.g., Legionnaire's disease, hypersensitivity pneumonitis). Also: A discrete, identifiable disease or illness that can be traced to a specific pollutant or source within a building. (Contrast with "Sick building syndrome").

CEILING PLENUM: Space below the flooring and above the suspended ceiling that accommodates the mechanical and electrical equipment and that is used as part of the air distribution system. The space is kept under negative pressure.

CENTRAL AIR HANDLING UNIT (Central AHU): This is the same as an Air Handling Unit, but serves more than one area.

CFM. Cubic feet per minute. The amount of air, in cubic feet, that flows through a given space in one minute. 1 CFM equals approximately 2 liters per second (l/s).

CHEMICAL SENSITIZATION: Evidence suggests that some people may develop health problems characterized by effects such as dizziness, eye and throat irritation, chest tightness, and nasal congestion that appear whenever they are exposed to certain chemicals. People may react to even trace amounts of chemicals to which they have become "sensitized."

CO: Carbon monoxide.

CO2:. Carbon dioxide.

COMBINATION FOUNDATIONS: Buildings constructed with more than one foundation type; e.g., basement/crawlspace or basement/slab-on-grade.

COMMISSIONING: Start-up of a building that includes testing and adjusting HVAC, electrical, plumbing, and other systems to assure proper functioning and adherence to design criteria. Commissioning also includes the instruction of building representatives in the use of the building systems.

CONDITIONED AIR: Air that has been heated, cooled, humidified, or dehumidified to maintain an interior space within the "comfort zone." (Sometimes referred to as "tempered" air.)

CONSTANT AIR VOLUME SYSTEMS: Air handling system that provides a constant air flow while varying the temperature to meet heating and cooling needs.

DAMPERS: Controls that vary airflow through an air outlet, inlet, or duct. A damper position may be immovable, manually adjustable or part of an automated control system.

DIFFUSERS AND GRILLES: Components of the ventilation system that distribute and return air to promote air circulation in the occupied space. As used in this document, supply air enters a space through a diffuser or vent and return air leaves a space through a grille.

DISINFECTANTS: One of three groups of antimicrobials registered by EPA for public health uses. EPA considers an antimicrobial to be a disinfectant when it destroys or irreversibly inactivates infectious or other undesirable organisms, but not necessarily their spores. EPA registers three types of disinfectant products based upon submitted efficacy data: limited, general or broad spectrum, and hospital disinfectant.

DRAIN TILE LOOP: A continuous length of drain tile or perforated pipe extending around all or part of the internal or external perimeter of a basement or crawlspace footing.

DRAIN TRAP: A dip in the drain pipe of sinks, toilets, floor drains, etc., which is designed to stay filled with water, thereby preventing sewer gases from escaping into the room.

ENVIRONMENTAL AGENTS: Conditions other than indoor air contaminants that cause stress, comfort, and/or health problems (e.g., humidity extremes, drafts, lack of air circulation, noise, and over-crowding).

ENVIRONMENTAL TOBACCO SMOKE (ETS): Mixture of smoke from the burning end of a cigarette, pipe, or cigar and smoke exhaled by the smoker (also secondhand smoke (SHS) or passive smoking).

ERGONOMICS: Applied science that investigates the impact of people's physical environment on their health and comfort (e.g., determining the proper chair height for computer operators).

EXHAUST VENTILATION: Mechanical removal of air from a portion of a building (e.g., piece of equipment, room, or general area).

FLOW HOOD: Device that easily measures airflow quantity, typically up to 2,500 cfm.

FUNGI: Any of a group of parasitic lower plants that lack chlorophyll, including molds and mildews.

GAS SORPTION: Devices used to reduce levels of airborne gaseous compounds by passing the air through materials that extract the gases. The performance of solid sorbents is dependent on the airflow rate, concentration of the pollutants, presence of other gases or vapors, and other factors.

GOVERNMENTAL: In the case of building codes, these are the State or local organizations/agencies responsible for building code enforcement.

HEPA: High efficiency particulate arrestance (filters).

HUMIDIFIER FEVER: A respiratory illness caused by exposure to toxins from microorganisms found in wet or moist areas in humidifiers and air conditioners. Also called air conditioner or ventilation fever.

HVAC: Heating, ventilation, and air-conditioning system.

HYPERSENSITIVITY DISEASES: Diseases characterized by allergic responses to pollutants. The hypersensitivity diseases most clearly associated with indoor air quality are asthma, rhinitis, and hypersensitivity pneumonitis. Hypersensitivity pneumonitis is a rare but serious disease that involves progressive lung damage as long as there is exposure to the causative agent.

HYPERSENSITIVITY PNEUMONITIS: A group of respiratory diseases that cause inflammation of the lung (specifically granulomatous cells). Most forms of hypersensitivity pneumonitis are caused by the inhalation of organic dusts, including molds.

IAQ: Indoor air quality.

IAQ BACKGROUNDER: A component of the IAQ Tools for Schools Kit that provides a general introduction to IAQ issues, as well as IAQ program implementation information.

IAQ COORDINATOR: An individual at the school and/or school district level who provides leadership and coordination of IAQ activities.

IAQ CHECKLIST: A component of the IAQ Tools for Schools Kit containing information and suggested easy-to-do activities for school staff to improve or maintain good indoor air quality. Each Activity Guide focuses on topic areas and actions that are targeted to particular school staff (e.g., Teacher's Checklist, Administrative Staff Checklist, Health Officer's Checklist, Ventilation Checklist, Building Maintenance Checklist, Food Service Checklist, Waste Management Checklist, Renovation and Repair Checklist and Walkthrough Checklist) or specific building functions (e.g., HVAC system, roofing, renovation, etc.). The Checklists are to be completed by the staff and returned to the IAQ Coordinator as a record of activities completed and assistance as requested.

IAQ MANAGEMENT PLAN: A component of the IAQ Tools for Schools Kit, specifically, a set of flexible and specific steps for preventing and resolving IAQ problems.

IAQ TEAM: People who have a direct impact on IAQ in the schools (school staff, administrators, school board members, students and parents) and who implement the IAQ Action Packets.

IPM: Integrated pest management.

INDICATOR COMPOUNDS: Chemical compounds, such as carbon dioxide, whose presence at certain concentrations may be used to estimate certain building conditions (e.g., airflow, presence of sources).

INDOOR AIR POLLUTANT: Particles and dust, fibers, mists, bioaerosols, and gases or vapors.

MAKE-UP AIR: See "Outdoor Air Supply."

MAP OF RADON ZONES: A U.S. EPA publication depicting areas of differing radon potential in both map form and in state specific booklets.

MCS: See "Multiple Chemical Sensitivity."

MECHANICALLY VENTILATED CRAWLSPACE SYSTEM: A system designed to increase ventilation within a crawlspace, achieve higher air pressure in the crawlspace relative to air pressure in the soil beneath the crawlspace, or achieve lower air pressure in the crawlspace relative to air pressure in the living spaces, by use of a fan.

MICROBIOLOGICALS: See "Biological Contaminants."

MODEL BUILDING CODES: The building codes published by the 4 Model Code Organizations and commonly adopted by state or other jurisdictions to control local construction activity.

MODEL CODE ORGANIZATIONS: Includes the following agencies and the model building codes they promulgate:

Building Officials and Code Administrators International, Inc. (BOCA National Building Code/1993 and BOCA National Mechanical Code/1993);
International Conference of Building Officials (Uniform Building Code/1991 and Uniform Mechanical Code/1991);
Southern Building Code Congress, International, Inc. (Standard Building Code/1991 and Standard Mechanical Code/1991);
Council of American Building Officials (CABO One- and Two-Family Dwelling Code/1992 and CABO Model Energy Code/1993).

MULTIPLE CHEMICAL SENSITIVITY (MCS): A condition in which a person reports sensitivity or intolerance (as distinct from "allergic") to a number of chemicals and other irritants at very low concentrations. There are different views among medical professionals about the existence, causes, diagnosis, and treatment of this condition.

NEGATIVE PRESSURE: Condition that exists when less air is supplied to a space than is exhausted from the space, so the air pressure within that space is less than that in surrounding areas. Under this condition, if an opening exists, air will flow from surrounding areas into the negatively pressurized space.

ORGANIC COMPOUNDS: Chemicals that contain carbon. Volatile organic compounds vaporize at room temperature and pressure. They are found in many indoor sources, including many common household products and building materials.

OUTDOOR AIR SUPPLY: Air brought into a building from the outdoors (often through the ventilation system) that has not been previously circulated through the system. Also known as "Make-Up Air."

PELs: Permissible Exposure Limits (standards set by the Occupational, Safety and Health Administration - OSHA).

PICOCURIE (pCi): A unit for measuring radioactivity, often expressed as picocuries per liter (pCi/L) of air.

PLENUM: Air compartment connected to a duct or ducts.

PM: Preventive Maintenance.

POLLUTANT PATHWAYS: Avenues for distribution of pollutants in a building. HVAC systems are the primary pathways in most buildings; however all building components interact to affect how air movement distributes pollutants. Also - a term used in the IAQ Tools for Schools: IAQ Coordinator's Guide.

POSITIVE PRESSURE: Condition that exists when more air is supplied to a space than is exhausted, so the air pressure within that space is greater than that in surrounding areas. Under this condition, if an opening exists, air will flow from the positively pressurized space into surrounding areas.

Potentially Responsible Party (PRP): Any individual or company--including owners, operators, transporters or generators--potentially responsible for, or contributing to a spill or other contamination at a Superfund site. Whenever possible, through administrative and legal actions, EPA requires PRPs to clean up hazardous sites they have contaminated.

PPM: Parts per million.

PRESSED WOOD PRODUCTS: A group of materials used in building and furniture construction that are made from wood veneers, particles, or fibers bonded together with an adhesive under heat and pressure.

PRESSURE, STATIC: In flowing air, the total pressure minus velocity pressure. The portion of the pressure that pushes equally in all directions.

PRESSURE, TOTAL: In flowing air, the sum of the static pressure and the velocity pressure.

PRESSURE, VELOCITY: In flowing air, the pressure due to the velocity and density of the air.

PREVENTIVE MAINTENANCE: Regular and systematic inspection, cleaning, and replacement of worn parts, materials, and systems. Preventive maintenance helps to prevent parts, material, and systems failure by ensuring that parts, materials and systems are in good working order.

PSYCHOGENIC ILLNESS: This syndrome has been defined as a group of symptoms that develop in an individual (or a group of individuals in the same indoor environment) who are under some type of physical or emotional stress. This does not mean that individuals have a psychiatric disorder or that they are imagining symptoms.

PSYCHOSOCIAL FACTORS: Psychological, organizational, and personal stressors that could produce symptoms similar to those caused by poor indoor air quality.

RADIANT HEAT TRANSFER: Radiant heat transfer occurs when there is a large difference between the temperatures of two surfaces that are exposed to each other, but are not touching.

RADON (Rn) AND RADON DECAY PRODUCTS: Radon is a radioactive gas formed in the decay of uranium. The radon decay products (also called radon daughters or progeny) can be breathed into the lung where they continue to release radiation as they further decay.

RE-ENTRAINMENT: Situation that occurs when the air being exhausted from a building is immediately brought back into the system through the air intake and other openings in the building envelope.

RE-ENTRY: Situation that occurs when the air being exhausted from a building is immediately brought back into the system through the air intake and other openings in the building envelope.

RELs: Recommended Exposure Limits (recommendations made by the National Institute for Occupational Safety and Health (NIOSH)).

SANITIZER: One of three groups of anti-microbials registered by EPA for public health uses. EPA considers an anti-microbial to be a sanitizer when it reduces but does not necessarily eliminate all the microorganisms on a treated surface. To be a registered sanitizer, the test results for a product must show a reduction of at least 99.9% in the number of each test microorganism over the parallel control.

SHORT-CIRCUITING: Situation that occurs when the supply air flows to return or exhaust grilles before entering the breathing zone (area of a room where people are). To avoid short-circuiting, the supply air must be delivered at a temperature and velocity that results in mixing throughout the space.

SICK BUILDING SYNDROME (SBS): Term that refers to a set of symptoms that affect some number of building occupants during the time they spend in the building and diminish or go away during periods when they leave the building. Cannot be traced to specific pollutants or sources within the building. (Contrast with "Building related illness").

SOIL GAS: The gas present in soil which may contain radon.

SOIL-GAS-RETARDER: A continuous membrane or other comparable material used to retard the flow of soil gases into a building.

SOURCES: Sources of indoor air pollutants. Indoor air pollutants can originate within the building or be drawn in from outdoors. Common sources include people, room furnishings such as carpeting, photocopiers, art supplies, etc.

STACK EFFECT: The overall upward movement of air inside a building that results from heated air rising and escaping through openings in the building super structure, thus causing an indoor pressure level lower than that in the soil gas beneath or surrounding the building foundation.

STATIC PRESSURE: Condition that exists when an equal amount of air is supplied to and exhausted from a space. At static pressure, equilibrium has been reached.

STERILIZER: One of three groups of anti-microbials registered by EPA for public health uses. EPA considers an anti-microbial to be a sterilizer when it destroys or eliminates all forms of bacteria, fungi, viruses, and their spores. Because spores are considered the most difficult form of a microorganism to destroy, EPA considers the term sporicide to be synonymous with "sterilizer."

SUB-SLAB DEPRESSURIZATION SYSTEM (ACTIVE): A system designed to achieve lower sub-slab air pressure relative to indoor air pressure by use of a fan-powered vent drawing air from beneath the slab.

SUB-SLAB DEPRESSURIZATION SYSTEM (PASSIVE): A system designed to achieve lower sub-slab air pressure relative to indoor air pressure by use of a vent pipe routed through the conditioned space of a building and connecting the sub-slab area with outdoor air, thereby relying solely on the convective flow of air upward in the vent to draw air from beneath the slab.

SUB-MEMBRANE DEPRESSURIZATION SYSTEM: A system designed to achieve lower sub-membrane air pressure relative to crawlspace air pressure by use of a fan-powered vent drawing air from under the soil-gas-retarder membrane.

TRACER GASES: Compounds, such as sulfur hexaflouride, which are used to identify suspected pollutant pathways and to quantify ventilation rates. Trace gases may be detected qualitatively by their odor or quantitatively by air monitoring equipment.

TLVs - Threshold Limit Values (guidelines recommended by the American Conference of Governmental Industrial Hygienists).

TVOCs. Total volatile organic compounds. See "Volatile Organic Compounds (VOCs)"

UNIT VENTILATOR: A fan-coil unit package device for applications in which the use of outdoor- and return-air mixing is intended to satisfy tempering requirements and ventilation needs.

VARIABLE AIR VOLUME SYSTEM (VAV): Air handling system that conditions the air to constant temperature and varies the outside airflow to ensure thermal comfort.

VENTILATION AIR: Defined as the total air, which is a combination of the air brought inside from outdoors and the air that is being re-circulated within the building. Sometimes, however, used in reference only to the air brought into the system from the outdoors; this document defines this air as "outdoor air ventilation."

VENTILATION RATE: The rate at which indoor air enters and leaves a building. Expressed in one of two ways: the number of changes of outdoor air per unit of time (air changes per hour, or "ach") or the rate at which a volume of outdoor air enters per unit of time (cubic feet per minute, or "cfm").

VOLATILE ORGANIC COMPOUNDS (VOCs): Compounds that vaporize (become a gas) at room temperature. Common sources which may emit VOCs into indoor air include housekeeping and maintenance products, and building and furnishing materials. In sufficient quantities, VOCs can cause eye, nose, and throat irritations, headaches, dizziness, visual disorders, memory impairment; some are known to cause cancer in animals; some are suspected of causing, or are known to cause, cancer in humans. At present, not much is known about what health effects occur at the levels of VOCs typically found in public and commercial buildings.

ZONE: The occupied space or group of spaces within a building which has its heating or cooling controlled by a single thermostat.


From Bay Area Air Quality Management District Air Pollution Glossary.htm

Abatement-the reduction in degree or intensity, or elimination, of pollution.

Acid Deposition-a term for the conversion of sulfur oxide and nitrogen oxide emissions into acidic compounds which precipitate in rain, snow, fog, or dry particles.

Acute-occurring over a short period of time; used to describe brief exposures and effects which appear promptly after exposure.

Adverse Health Effects-health effects from exposure to air contaminants that may range from relatively mild temporary conditions, such as minor 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-particle of solid or liquid matter that can remain suspended in the air because of its small size (generally under one micron).

Afterburner-an air pollution abatement device that removes undesirable organic gases through incineration.

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 inert gases; and varying amounts of water vapor.

Air Basins-areas defined by geographical or administrative boundaries; used for air pollution control programs.

Air Monitoring-sampling for and measuring of pollutants present in the atmosphere.

Air Pollution-the presence of polluting gases and suspended particles in the atmosphere in excess of air quality standards.

Air Quality Criteria-the varying amounts of pollution and lengths of exposure at which specific adverse effects to health and comfort take place.

Air Quality Plan (AQP)-a plan developed to attain and maintain an air quality standard.

Air Quality Management District (AQMD)-local agency charged with controlling air pollution and attaining air quality standards. The Bay Area Air Quality Management District is the regional AQMD that includes all of seven counties (Alameda, Contra Costa, Marin, Napa, San Francisco, San Mateo and Santa Clara) and the southern halves of Solano and Sonoma counties.

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.

Airshed-a term denoting a geographical area of which, because of topography, meteorology, and climate, shares the same air (see Air Basins).

Ambient Air-outside air; any portion of the atmosphere not confined by walls and a roof.

Aromatic-a hydrocarbon that consists of one or more benzenoid rings (i. e., benzene).

Asbestos-a mineral fiber that can pollute air or water and cause cancer or asbestosis when inhaled. EPA has banned or severely restricted its use in manufacturing and construction.

Association of Bay Area Governments (ABAG)-a voluntary joint-powers comprehensive regional planning agency for the cities and counties of the Bay Area.

Asthma-a medical condition characterized by abnormal restriction of breathing, especially in response to allergens or air contaminants.

Atmosphere-the layer of life-supporting gases (air) that surrounds the earth.

Attainment-a designation used when an area meets an air quality standard.

Authority to Construct (A/C)-a pre-construction permit issued by the District.

Baghouse-an air pollution abatement device that traps particulates (dust) by forcing gas streams through large permeable bags usually made of glass fibers.

Banking-a provision in District permit regulations that allows a facility to obtain credits for reducing emissions beyond regulatory limits and use those credits at a later date, similar to how a savings account works.

Bay Area '94 Clean Air Plan-the planning document produced by the District identifying all feasible measures for the reduction of ground-level ozone in the Bay Area as mandated by the California Clean Air Act.

Best Available Control Technology (BACT)-an emission limitation based on using the most up-to-date methods, systems, techniques, and production processes available to achieve the greatest feasible emission reductions. These are the most stringent requirements for new or modified sources and are determined on a case-by-case basis as part of New Source Review.

Best Available Retrofit Control Technology (BARCT) - an emission limitation based on the maximum degree of reduction achievable for existing sources taking into account environmental, energy, and economic impact.

British Thermal Unit (BTU)-a unit of heat used to describe the capacity of boilers and furnaces. One BTU equals the amount of heat required to raise the temperature of one pound of water one degree Farenheit at sea level.

California Air Resources Board (CARB)-the state of California agency responsible for air pollution control.

California Clean Air Act (CCAA)-legislation enacted in 1988, and amended in 1992 and 1996, mandating a planning process to attain state ambient air quality standards.

Cal-EPA-the state agency created in 1991 to oversee the various state environmental agencies.

Carbon Dioxide (CO2)-a colorless, odorless, non-poisonous gas that results from fossil fuel combustion and is a normal constituent of ambient air.

Carbon Monoxide (CO)-a colorless, odorless, toxic gas produced by the incomplete combustion of carbon-containing substances. One of the major air pollutants, it is emitted in large quantities by exhaust from gasoline-powered vehicles.

Carcinogen-any substance that can cause or contribute to the production of cancer.

Catalytic Converter-an air pollution abatement device used primarily on motor vehicles and other sources. It removes organic contaminants by oxidizing them into carbon dioxide and water through chemical reaction. May convert nitrogen dioxide to nitrogen and oxygen or promote other similar reactions.

Chlorofluorocarbons (CFCs)-a family of inert, nontoxic, and easily liquified chemicals used in refrigeration, air conditioning, packaging, insulation, or as solvents and aerosol propellants. Because CFCs are not destroyed in the lower atmosphere they drift into the upper atmosphere where their chlorine components destroy the ozone layer.

Chronic-marked by long duration or frequent recurrence, as with a chronic disease.

Clean Air Act (CAA)-long standing federal legislation that is the legal basis for the national clean air programs, last amended in 1990 .

Clean Air Vehicle- a vehicle that does not use gasoline or diesel as its primary fuel and is certified by CARB to meet very stringent tailpipe emission standards.

Coefficient of Haze (COH)-a measurement of the quantity of dust and smoke in the atmosphere in a theoretical 1000 linear feet of air. A COH of less than 1 is considered clean air and more than 3 is considered dirty air.

Combustion-burning, that is, the production of heat and light energy through chemical change, such as the oxidation of hydrocarbon fuel.

Continuous Emission Monitor (CEM)-a type of air emission monitoring device installed to operate continuously inside of a smoke stack or other emission source.

Criteria Air Pollutants-as required by the Clean Air Act, the EPA identifies and set standards to protect human health and welfare for six pollutants: ozone, carbon monoxide, particulate matter (PM10), sulfur dioxide, lead, and nitrogen oxide. The term "criteria pollutants" derives from the requirement that the EPA must describe the characteristics and potential health and welfare effects of these pollutants. EPA periodically reviews new scientific data and may propose revisions to the standards as a result.

Cyclone-an air pollution abatement device that removes heavy particles from an air stream through centrifugal force.

Degreaser-equipment which removes grease, dirt or unwanted materials from any part or product. Degreasers typically use solvents, as liquid baths or condensing vapors, to remove such material.

Dew Point-the temperature at which droplets of water condense from air (dependent on the prevailing humidity).

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, which is used with gasoline engines.)

Dust-solid particulate matter that can become airborne.

Ecology-the interrelationship of organisms and their environment and the science that is concerned with that interrelationship.

Electrostatic Precipitator-an air pollution abatement device that removes particulate matter from a gas stream by imparting an electrical charge to the particles for mechanical collection on an electrode.

Emission Factor-the relationship between the amount of pollution produced and the amount of raw material processed or burned. For example, the emission factor for oxides of nitrogen from fuel oil combustion in an industrial boiler would be the number of pounds of oxides of nitrogen emitted per 1000 gallons of fuel oil burned. By using the emission factor of a pollutant and specific data regarding quantities of material used by a given source, it is possible to compute emissions for the source. This approach is used in preparing an emissions inventory.

Emission lnventory-a list of air pollutants emitted into a community's atmosphere, in amounts (commonly tons) per day or year, by type of source.

Emission Standard-the maximum amount of pollution that is permitted to be discharged from a polluting source - for example, the number of pounds of dust that may be emitted per hour from an industrial process.

Environment-the aggregate of all the external conditions and influences affecting the life, development, and ultimately the survival of an organism. More commonly, the earth's crust, water resources, life forms, and atmosphere.

Environmental Protection Agency (EPA)-the federal agency responsible for control of air and water pollution, toxic substances, solid waste, and cleanup of contaminated sites.

Equivalent Opacity-the application of the Ringelmann system to the evaluation of the density of other than black smoke (see Ringelmann).

Ethanol-ethyl alcohol, a volatile alcohol containing two carbons (CH3CH2OH). For fuel use, it would be produced by fermentation of corn or other plant products. away.

Evaporation-the physical transformation of a liquid to a gas at any temperature below its boiling point.

Exceedance-a measured level of an air pollutant higher than the national or state ambient air quality standard.

Flexible Fuel Vehicle-vehicles that can use either alcohol fuels (methanol or ethanol) or a combination of alcohol fuel and unleaded gasoline.

Fluorocarbon-an organic compound that contains fluorine. Some of these compounds may affect health but they are non-reactive and therefore not smog forming.

Fossil Fuels-coal, oil, and natural gas; so-called because they are the remains of ancient plant and animal life.

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.

Greenhouse Effect-the warming of the earth's atmosphere caused by a buildup of carbon dioxide and other trace gases. This buildup allows light from the sun's rays to heat the earth but prevents a counterbalancing loss of heat.

Ground Level Monitor (GLM)-a type of air pollution monitoring device located around major industrial facilities to measure ambient levels of certain pollutants.

Halogen-a family of chemical elements that includes fluorine, chlorine, bromine, and iodine.

Halogenated Organic Compounds-organic compounds containing one or more atoms of a halogen. These compounds tend to be stable and non-reactive, and therefore have low smog-producing potential.

Health Risk-the probability that exposure to a given set of toxic air contaminants will result in an adverse health effect. The health risk is affected by several factors: the amount and toxicity of emissions; the weather; how far sources are from people; the distance between sources; and the age, health and lifestyle of the people living and working at the receptor location. The term "risk" usually refers to the increased chance of contracting cancer as a result of an exposure and is expressed as a probability, e.g., chances-in-a-million.

Health Risk Assessment-a document that identifies the risks and quantities of possible adverse health effects that may result from exposure to emissions of toxic air contaminants. A health risk assessment cannot predict specific health effects; it only describes the increased possibility of adverse health effects based on the best scientific information available.

"Hot Spot"-a location where emissions from specific sources may expose individuals and population groups to elevated risks of adverse health effects, including but not limited to cancer, and contribute to the cumulative health risks of emissions from other sources in the area.

Hydrocarbon-any of a vast number of compounds containing carbon and hydrogen in various combinations; found especially in fossil fuels. Some of the hydrocarbon compounds are major air pollutants; they may be active participants in the photochemical process or affect health.

Hydrogen Sulfide (H2S)-a gas characterized by a "rotten egg" smell that is often produced by and found in the vicinity of oil refineries, chemical plants and sewage treatment plants.

Incineration-the burning of household or industrial waste in a combustion chamber.

Inert Gas-a gas such as helium, neon, or argon that does not react with other substances under ordinary conditions.

Inorganic Gaseous Pollutant-a gaseous pollutant that is not an organic compound. Examples are: sulfur dioxide, hydrogen sulfide and nitrogen oxides.

Internal Combustion Engine (ICE)-an engine in which both the heat energy and the ensuing mechanical energy are produced inside the engine.

Inversion-the phenomenon of a layer of warm air pressing down on cooler air below it. Inversions are a special problem because they prevent the natural dispersion and dilution of air contaminants.

LAER (lowest achievable emission rate)- under the Clean Air Act, the rate of emissions that reflects (a) the most stringent emissions limitation in the state implementation plan identified for a source unless the owner or operator demonstrates such limitations are not achievable or (b) the most stringent emissions limitation achieved in practice, whichever is more stringent.

Maximum Achievable Control Technology(MACT) - EPA standards mandated by the 1990 amendments to the federal Clean Air Act for the control of toxic emissions from various industries. Industries range from dry cleaners to petroleum refineries.

Manual of Procedures (MOP)-a manual of District enforcement, permitting, source testing, laboratory and monitoring procedures used by the staff and industry to determine whether industries are meeting Air District regulations. Also contains guidelines for environmental processes under the California Environmental Quality Act (CEQA), and procedures for calculating and generating mobile source emission credits.

Major Source-a source that emits or has the potential to emit more than 100 tons of any pollutant regulated under the federal Clean Air Act, more than 10 tons of any hazardous air pollutants or 25 tons of all hazardous air pollutants.

Methanol-a single carbon alcohol, generally produced from natural gas (methane).

Metropolitan Transportation Commission (MTC)-the regional agency that provides comprehensive regional transportation planning for the Bay Area and distributes federal and state transportation assistance funds.

Micro-a prefix meaning 1/1,000,000. Abbreviated by the Greek letter µ.

Micron-a unit of length equal to one thousandth of a millimeter, or about 1/25,000 of an inch.

Milli-a prefix meaning 1/1,000.

Mist-liquid particles up to 100 microns in diameter.

Mixing Depth-the expanse in which air rises from the earth and mixes with the air above it until it meets air of equal or warmer temperature.

Mobile Source-a moving source of air pollution; includes cars, trucks, motorcycles, and airplanes.

National Ambient Air Quality Standards (NAAQS)-health-based pollutant concentration limits established by EPA that apply to outside air (see Criteria Pollutants).

National Emissions Standards for Hazardous Air Pollutants (NESHAPS)-emissions standards set by EPA for air pollutants not covered by NAAQS that may cause an increase in deaths or in serious, irreversible, or incapacitating illness; includes. toxic emissions such as benzene.

New Source Performance Standards (NSPS)-pollutant emission limits for newly constructed sources; defined in the BAAQMD's Regulation 10.

New Source Review (NSR)-a permitting procedure for new or modified stationary sources found in the BAAQMD's Regulation 2. NSR applies if the emissions from the new source are above a trigger level.

Nitric Oxide (NO)-precursor of ozone, NO2, and nitrate; usually emitted from combustion processes. Converted to nitrogen dioxide (NO2) in the atmosphere, it then becomes involved in the photochemical process and/or particulate formation.

Nitrogen Oxides (NOx)-gases formed in great part from atmospheric nitrogen and oxygen when combustion takes place under conditions of high temperature and high pressure; considered a major air pollutant and precursor of ozone.

Nonattainment Area-defined geographic area that does not meet one or more of the federal air quality standards for the criteria pollutants.

Open Burning-the uncontrolled burning of waste materials in the open, in outdoor incinerators, or in an open dump, either intentionally or accidentally. Open burning is regulated in the Bay Area.

Organic Compounds-a large group of chemical compounds that contain carbon. All living organisms are made up of organic compounds. Some types of organic gases, including olefins, substituted aromatics and aldehydes, are highly reactive -- i.e., have high ozone-producing potential. Standards to control organic compounds are found in the BAAQMD's Regulation 8.

Oxidant-an air pollutant containing oxygen that can react chemically with other substances. Ozone, and nitrogen compounds are examples of oxidants.

Ozone (O3)-a pungent, colorless, toxic gas. Close to the earth's surface it is produced photochemically from hydrocarbons, oxides of nitrogen and sunlight and is a major component of smog. At very high altitudes, it protects the earth from harmful ultraviolet radiation.

Ozone Depletion-destruction of the stratospheric ozone layer, which shields the earth from ultraviolet radiation. This destruction is caused by the breakdown of certain chlorine and/or bromine-containing compounds (chlorofluorocarbons or halons) that catalytically destroy ozone molecules in the stratosphere.

Particulate-a particle of solid or liquid matter; soot, dust, aerosols, fumes and mists.

Parts Per Million (PPM)-the number of parts of a given pollutant in a million parts of air.

Permit to Operate (P/O)-an operational permit issued yearly by the District to sources that meet District regulations.

Photochemical Process-the process by which sunlight acts upon various compounds, causing a chemical reaction to occur.

Photochemical Smog -produced when hydrocarbons and oxides of nitrogen combine in the presence of sunlight to form ozone.

Plume-a visible or measurable discharge of a contaminant from a given point of origin that can be measured according to the Ringelmann scale.

PM2.5 (Particulate Matter less than 2.5 microns) -tiny solid or liquid particules, generally soot and aerosols. The size of the particles (2.5 microns or smaller, about 0.0001 inches or less) allows them to easily enter the air sacs deep in the lungs where they may cause adverse health effects; PM2.5 also causes visibility reduction.

PM10 (Particulate Matter less than 10 microns)-tiny solid or liquid particles of soot, dust, smoke, fumes, and aerosols. The size of the particles (10 microns or smaller, about 0.0004 inches or less) allows them to easily enter the air sacs in the lungs where they may be deposited, resulting in adverse health effects. PM10 also causes visibility reduction and is a criteria air pollutant.

Pollutant Standards Index (PSI)-a system developed by the federal government for reporting air pollution concentrations to the public as numerical values between 0 and 500.

Precipitators-any number of devices using mechanical, electrical, or chemical means to collect particulates. Used to measure, analyze, or control particulates.

Precursor-compounds that change chemically or physically after being emitted into the air and eventually produce air pollutants. For example, organic compounds are precursors for ozone.

Prevention of Significant Deterioration (PSD)-an EPA program in which state and/or federal permits are required to restrict emissions in areas that meet federal standards for criteria pollutants.

Radon-a colorless, naturally occurring, radioactive, inert gaseous element formed by the radioactive decay of radium atoms in soil or rocks.

Reactive Organic Gases (ROG)-classes of organic compounds, especially olefins, substituted aromatics and aldehydes, that react more rapidly in the atmosphere to form photochemical smog or ozone.

Reasonable Further Progress (RFP)-specified rate of progress towards meeting an air quality standard, as set forth in law or in a plan.

Reasonably Available Control Technology (RACT)- air pollution abatement equipment that is both technologically feasible and cost effective.

Ringelmann Chart-actually 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.

Saturated Hydrocarbon-an organic compound consisting of only carbon and hydrogen atoms with no double or triple bonds. Examples are ethane, methane and propane. They are relatively unreactive, (i.e., do not form photochemical smog as rapidity as other organics).

Scrubber-a 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.

Smog-a term used to describe many air pollution problems. Smog is a contraction of smoke and fog; in California, it describes the irritating stagnant haze resulting from the sun's effect on pollutants in the air.

Soot-very fine carbon particles that appear black when visible.

State Implementation Plan (SIP)-EPA-approved state plans for attaining and maintaining national ambient air quality standards.

Stationary Source-a fixed, non-mobile producer of pollution, usually at industrial or commercial facilities.

Storage Tank -any stationary container, reservoir, or tank used for the storage of liquids. District regulations usually only apply to the storage of organic liquids.

Stratosphere-the portion of the atmosphere that is 10 to 25 miles above the earth's surface.

Sulfur Oxides-pungent, colorless gases formed primarily by the combustion of sulfur-containing fossil fuels, especially coal and oil. Considered major air pollutants, sulfur oxides may impact human health and damage vegetation.

Title III-a section of the 1990 amendments to the federal Clean Air Act that deals with the control of toxic air emissions.

Title V-a section of the 1990 modifications to the federal Clean Air Act that requires a federally enforceable operating permit for major sources of air pollution.

Topography-the configuration of a surface, especially the earth's surface, including its relief and the position of its natural and man-made features.

Total Organic Gases (TOG)-gaseous organic compounds, including reactive organic gases and relatively unreactive organic gases such as methane.

Total Suspended Particulates (TSP)-particles of solid or liquid matter - such as soot, dust, aerosols, fumes and mist - up to approximately 30 microns in size.

Toxic Air Pollutants-air pollutants that may cause or contribute to an increase in mortality or in serious illness or which may pose a present or potential hazard to human health.

Toxic Best Available Control Technology(TBACT) - similar to BACT standards except applies to sources of toxic emissions. In many cases, it is the same as BACT. The standards are based on using the most up-to-date methods, systems, techniques, and production processes available to achieve the greatest feasible emission reductions. These are the most stringent requirements for new or modified sources and are determined on a case-by-case basis.

Transportation Control Measures (TCMs)-strategies to reduce vehicle trips, vehicle use, vehicle miles traveled, vehicle idling or traffic congestion for the purpose of reducing motor vehicle emissions.

Transportation Fund for Clean Air(TFCA) - Air District grants to public agencies for eligible transportation projects that reduce emissions from motor vehicles.

Troposphere-the layer of the atmosphere nearest the earth's surface. The troposphere extends outward about 5 miles at the poles and 10 miles at the equator.

Underground Storage Tank-a tank located completely or partially under ground that is designed to hold gasoline or other petroleum products or chemical solutions.

Variance-permission granted for a limited time under stated conditions for a person or company to operate outside the limits prescribed in a regulation.

Volatile Organic Compound (VOC)-an organic compound that evaporates readily at atmospheric temperatures. A major precursor of ozone.

Woodburning Pollution-air pollution caused by emissions of particulate matter, carbon monoxide, and odorous and toxic substances from woodburning stoves and fireplaces.