Document Archives Glossary

A

Access, Accessibility

The opportunity to reach jobs, services, housing, recreation, shopping, and entertainment within a reasonable time frame, and without being impeded by physical, social, or economic barriers. Enhancing mobility is one way of providing improved access.

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Aerosol

Tiny particles dispersed in gases. Often used synonymously with particulate matter (PM).

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Air Pollution Control Division

A subset of the Colorado Department of Public Health and Environment.

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Air Quality Control Commission (AQCC)

Established in 1973 under section 25-7-109 of the Colorado Air Quality Control Act, the AQCC is an eight-member elected commission with authority to adopt, promulgate, modify. or repeal emission control regulations which require the use of effective practical air pollution controls.

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AirCare Colorado

The emissions testing program for the state of Colorado. See www.aircarecolorado.com for more details.

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Alternative Fuels

Any motor fuel other than ordinary gasoline, especially those that result in lower levels of air pollutants (e.g. reformulated gasoline, natural gas, and liquid propane).

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AQI

Acronym for Air Quality Index. The EPA (Environmental Protection Agency) developed the AQI to make reading ambient air data more understandable to the general public. When ambient air data is collected, the numbers are converted from their concentration levels into numbers on a scale. That scale is the pollutant’s AQI value.

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AQS

Acronym for EPA’s Air Quality System – the system records air quality data and makes it available for public review.

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Area Source

A collection of similar seemingly small sources of pollution from throughout the non-attainment area. Examples include lawn mowers, barbecue grills, and fireplaces.

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Attainment Area

An area with air quality that meets or exceeds the U.S. Environmental Protection Agency (EPA) health standards used in the Clean Air Act. An area may be an attainment area for one pollutant and a non-attainment area for others. Non-attainment areas are those that have not met the standards for designated pollutants.

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B

BACT

Acronym for Best Available Technology.

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Brown Cloud

The Brown Cloud — a pollutant-related visibility problem — is caused by tiny particles smaller than 10 microns in size, carbon-containing particles and the chemical reactions of certain gases, including NOx, NH3, and SO2. The collective pollutants block light, causing the distinctive Brown Cloud and impeding visibility.

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Build/No-Build

Conformity requirement that Metropolitan Planning Organizations must show that “building” or implementing a long-range plan or Transportation Improvement Program will provide more emissions reductions that “not building” or not implementing than same long-range plan and program.

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C

Carbon Monoxide (CO)

A colorless, odorless, tasteless gas that impedes the oxygenation of blood. CO is formed in large part by incomplete combustion of fuel.
Clean Air Act Amendments (CAAA)
The 1990 Clean Air Act is a piece of United States environmental policy relating to the reduction of smog and air pollution. It follows the Clean Air Act in 1963, the Clean Air Act Amendment in 1966, the Clean Air Act Extension in 1970, and the Clean Air Act Amendments in 1977. It was enacted by the 101st United States Congress (Pub.L. 101-549).

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Colorado Dept. of Public Health and Environment (CDPHE)

A state agency responsible for the implementation of air quality programs such as oxygenated fuels and the enhanced inspection and maintenance program, the monitoring of daily ambient pollutant levels, and the compliance of industrial and area sources with state and federal law.

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Colorado Dept. of Transportation (CDOT)

A state agency responsible for a 9,161 mile highway system, including 3,775 bridges. Each year, this system handles over 28.6 billion vehicle miles of travel. Although the Interstate system accounts for only about 10 percent (915 miles) of the total mileage on the state system, 40 percent of all travel takes place on our Interstate highways.  CDOT’s highway construction program attracts  private contractors and the low bidder is awarded the project and in turn is responsible for construction of that project. This partnership between government (CDOT) and business works well as we improve and expand our transportation system.

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Conformity

Process to assess the compliance of any transportation plan, program or project with air quality control plans. The conformity process is defined by the Clean Air Act. Federal Highway funds are tied to the region’s conformity determination.

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Congestion Management and Air Quality Improvement Program (CMAQ)

Federal funding for projects that contribute to meeting national air quality standards. CMAQ funds generally may not be used for projects that result in the construction of new capacity available to single-occupant vehicles. Part of the Intermodal Surface Transportation Efficiency Act of 1991.

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D

Demand Management Activities

Activities designed to reduce the need for transportation systems. An example of demand management strategy is telecommuting. By contrast, supply-side activities address meeting the needs of the traveling population rather than diminishing the need to travel.

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Denver Regional Council of Governments (DRCOG)

Since 1955, DRCOG has provided local governments with technical and planning assistance for regional issues of transportation and air quality. In 1991, with passage of ISTEA and CMAQ, DRCOG was given the authority to match federal transportation funds to regional air quality objectives. For more information, see http://www.drcog.org.

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DMA/NFR

Acronym for Denver Metro Area/North Front Range.

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E

Emission Budget

The part of the State Implementation Plan (the state air quality plan or SIP) that identifies allowable emissions levels for specific pollutants emitted from mobile sources. The emissions levels in the budget are used for meeting emission reduction milestones, attainment or maintenance demonstrations.

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Enhanced Inspection and Maintenance Program (I/M)

Program passed by the Colorado State Legislature that requires 1982 and newer vehicles to be inspected with a new high-tech treadmill test called I/M 240. Because the new test simulates actual driving conditions, it is more efficient than previous stagnant inspection and maintenance programs at identifying tailpipe emissions.

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EnviroFlash

EnviroFlash is an e-mail and pager notification system that provides subscribers with instant air quality information that can be customized for individual needs. Denver-metropolitan area residents can sign up for this free service at: https://enviroflash.epa.gov/airnow/subscriber/Subscriber.do?method=start

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Environmental Protection Agency (EPA)

EPA leads the nation’s environmental science, research, education and assessment efforts. The mission of the Environmental Protection Agency is to protect human health and the environment. Since 1970, EPA has been working for a cleaner, healthier environment for the American people.

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Envirotest

Envirotest Systems Corp., a subsidiary of Environmental Systems Products, Inc.     (ESP), operates the Air Care Colorado emissions testing centers under contract to     the State of Colorado.

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F

FHWA

Acronym for Federal Highway Administration.  This federal agency carries out the Federal highway programs in partnership with the State and local agencies to meet the Nation’s transportation needs. FHWA adds value to the delivery of the Federal highway programs by administering and overseeing these programs to ensure that Federal funds are used efficiently. In administering these Federal funds, we apply flexible and innovative financing techniques permissible under the law, and use efficient administrative processes, such as electronic signatures, online processing, Web information dissemination, and videoconferencing.

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FTA

Acronym for Federal Transit Authority. As authorized by the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users of 2005 (SAFETEA-LU), the FTA supports locally planned and operated public mass transit systems throughout the United States.

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G

Greenhouse Gases (GHG)

Greenhouse gases are gases in an atmosphere that absorb and emit radiation within the thermal infrared range. Greenhouse gases greatly affect the temperature of the Earth; without them, Earth’s surface would be on average about 15°C (59°F) colder than at present.

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H

Hot-Spot Analysis

Analysis of particulate matter and/or carbon monoxide emissions at particularly polluted or high-emission areas or intersections.

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I

Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA)

Congressional initiative that restructured funding for transportation programs. ISTEA authorized increased levels of highway and transportation funding and an enlarged role for regional planning commissions (DRCOG in the Denver region) in funding decisions. The Act also requires comprehensive regional long-range transportation plans extending to the year 2015 and places an increased emphasis on public participation and alternatives to the automobile.

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L

Land Use

Refers to the manner in which portions of land or the structures on them are used, e.g., commercial, residential, retail, industrial, etc.

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M

Metropolitan Planning Organization (MPO)

A metropolitan planning organization is a transportation policy-making organization made up of representatives from local government and transportation authorities. In 1962, the United States Congress passed legislation that required the formation of an MPO for any Urbanized Area (UZA) with a population greater than 50,000. Congress created MPOs in order to ensure that existing and future expenditures for transportation projects and programs are based on a continuing, cooperative, and comprehensive (“3-C”) planning process. Federal funding for transportation projects and programs are channeled through this planning process. Statewide and metropolitan transportation planning processes are governed by Federal law (23 USC 134 and 135). As of 2005, there are 385 MPOs in the U.S.

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Mobile Source

A source of pollution that is mobile such as automobile, plane, and train.

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Mode, Intermodal, Multimodal

Form of transportation, such as automobile, transit, bicycling, and walking. Intermodal refers to the connections between modes and multimodal refers to the availability of transportation options within a system or corridor.

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Model

A mathematical and geometric projection of activity and the interactions in the transportation system in an area. This projection must be able to be evaluated according to a given set of criteria which might include land use, economics, social values, and travel patterns.

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N

National Ambient Air Quality Standards (NAAQS)

Federal standards that set allowable concentrations and exposure limits for various pollutants.

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NH3

Ammonia Gas.

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Northern Front Range Air Quality Study (NFRAQS)

A major measurement effort aimed at enhancing our understanding of the sources and processes which influence the Brown Cloud.

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NOx

The sum of nitric oxide, and nitrogen dioxide. The primary nitrogen pollutant emitted for the combustion process.

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O

Oxidation Catalyst

A catalytic converter designed to reduce particulate emissions from diesel vehicles.

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Oxygenated Fuels

 Gasoline blended with alcohol or ether containing oxygen. Use of such fuels reduces carbon monoxide production and other emissions.

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Ozone

Ozone is a colorless gas with a sweet odor. Ozone is not a direct emission from transportation sources. It is a secondary pollutant formed when hydrocarbons (HC) and nitrogen oxides (NOx) combine in the presence of sunlight. Ozone is associated with smog or haze conditions.

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Ozone Action Plan

A State plan proposed to the AQCC reduce ozone levels in the Denver/North Front Range area by 2010.

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P

Particulate Matter (PM), (PM10) (PM2.5)

Any material that exists as solid or liquid in the atmosphere. Particulate matter may be in the form of fly ash, soot, dust, fog, fumes, etc. Small particulate matter, or PM10, is less than 10 microns in size (about one-eighth the diameter of a human hair) and is too small to be filtered by the nose and lungs. PM2.5 is small particulate matter that is less than 2.5 microns in size).

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ppb

Abbreviation for parts per billion.  A unit of concentration used to measure     pollutant levels.

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ppm

Abbreviation for parts per million.  A unit of concentration used to measure pollutant levels.

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Primary Pollutant

Pollutant gases or particle directly emitted from a pollutant source.

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Q

Quality Assurance Process

A process for determining the accuracy of emissions information. Examples of activities include checking with specific industrial firms concerning the information reported on the Air Pollution Emission Notifications, and reviewing the body of literature regarding the best methods for estimating emissions.

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R

RACT

Acronym for Reasonably Available Control Technology.

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RAQC

Acronym for the Regional Air Quality Council, metro Denver’s lead air quality planning agency.

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Re-entrained Road Dust

Particulate emissions that are kicked-up from movement of vehicles on paved roadway surfaces.

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Reformulated Gasoline

Gasoline that is reformulated (refined and blended) to burn more efficiently and cleanly in motor vehicles.

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Reid Vapor Pressure (RVP)

A measure which indicates how volatile a fuel is (how easily it evaporates).

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RICE

Acronym for Reciprocating Internal Combustion Engines.

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S

Secondary Pollutant

A pollutant formed in the atmosphere through the chemical or physical interaction between primary pollutants.

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Single-Occupant Vehicles (SOVs)

A single-occupant vehicle refers to an automobile that is used to get just one person to a destination.

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SO2

Sulfur Dioxide.

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Stage II Controls

Mechanisms on gasoline pumps designed to control and capture vapors during vehicle fueling.

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State Implementation Plan (SIP)

Required air quality planning documents prepared by states and submitted to EPA for approval. SIPs identify actions and programs to show how the various non-attainment areas of the state will attain and maintain air quality standards.

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T

Telecommuting

Telecommuting is a work arrangement in which employees enjoy flexibility in working location and hours. In other words, the daily commute to a central place of work is replaced by telecommunication links.

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Transportation Control Measures (TCMs)

Local actions to adjust traffic patterns or reduce vehicle use in order to reduce air pollutant emissions. These may include High-Occupancy Vehicle lanes, provision of bicycle facilities, ridesharing, telecommuting, etc.

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Transportation Demand Management (TDM)

TDM is the application of strategies and policies to reduce automobile travel demand, or to redistribute this demand in space or in time.

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Transportation Improvement Program (TIP)

Document prepared by states and regional planning commissions (i.e., DRCOG) identifying projects to be funded under federal transportation programs for a full-year period. If it is not included in a conforming TIP, a project is ineligible for federal funding.

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Transportation Management Organization (TMO)

A voluntary association of public and private agencies and firms joined to cooperatively develop transportation-enhancing programs in a given area. TMOs typically manage transportation demand in congested urban and suburban communities. The first Denver region TMO formed Downtown in early 1995.

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V

Vehicle Miles of Travel (VMT)

A standard areawide measure of travel activity. Most conventional VMT calculation is to multiply the average length of trips by the total number of trips.

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Visibility Standard

Established by the Colorado State Legislature, the visibility standard requires that not more than 7.6 percent of the light in a kilometer of air be blocked, averaged over four daylight hours. The standard is equivalent to a visual range of 32 miles and was established by the Colorado Department of Public Health and Environment after assessing public perception and values on visual aesthetics.

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Volatile Organic Compound (VOC)

Natural (Organic) Emissions from plant material or related solvents from industrial processes. Combine in the atmosphere with NOx to form ozone.

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