K – O – BUILT ENVIRONMENT & PUBLIC HEALTH CLEARINGHOUSE

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Kids Walk-To-School: A CDC-supported community-based program that aims to increase opportunities for daily physical activity by encouraging children to walk to and from school in groups accompanied by adults. At the same time, the program advocates for communities to build partnerships with the school, PTA, local police department, department of public works, civic associations, local politicians, and businesses to create an environment that is supportive of walking and bicycling to school safely. By creating active and safe routes to school, walking to school can once again be a safe, fun, and pleasant part of children’s daily routine. The goals of KidsWalk-to-School are to: 1) Encourage children to walk and bicycle to and from school; 2) Increase awareness of the importance of regular physical activity for children, improved pedestrian safety, and healthy and walkable community environments; and 3) Mobilize communities to work together to create safe routes to school. Source: Centers for Disease Control and Prevention
Kitchen: Any room used for the storage and preparation of foods and containing the following equipment: sink or other device for dishwashing, stove or other device for cooking, refrigerator or other device for cold storage of food, cabinets or shelves for storage of equipment and utensils, and counter or table for food preparation. Source: U.S. Department of Housing and Urban Development
Kitchenette: A small kitchen or an alcove containing cooking facilities. Source: U.S. Department of Housing and Urban Development

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Land Trust: (Conservation) A conservation group that maintains a revolving fund for quickly buying land that is in danger of being developed inappropriately or without regard to proper environmental considerations. Source: American Society of Landscape Architects
Land Use: Refers to the manner in which portions of land or the structures on them are used, i.e. commercial, residential, retail, industrial, etc. Source: Federal Highway Administration
Landscape Architecture: The design profession focused on exterior spaces, including interior courtyards, gardens, campuses, public spaces, river corridors, and entire ecological regions. Source: Making Healthy Places
Land-use Mix: The different types of uses for physical space, including residential, office, retail/commercial, and public space. Source: Making Healthy Places
Land Use Plan: A plan which establishes strategies for the use of land to meet identified community needs. Source: U.S. Department of Transportation Federal Highway Administration
Landscape: The traits, patterns, and structure of a specific geographic area, including its biological composition, its physical environment, and its anthropogenic or social patterns. An area where interacting ecosystems are grouped and repeated in similar form. Source: EPA Terms and Acronyms
Landscape Contractor: A trained builder or installer of landscapes, retained to implement the plans of landscape architects. Source: American Society of Landscape Architects
Lane Management Tools: Lane Management Tools include: 1) Access Limiting or metering vehicle ingress to the lane or spacing access so that demand cannot overwhelm HOT lane capacity. See also Limited Access; 2) Eligibility Limiting lane use to specific types of users, such as HOVs, motorcycles, low emission vehicles, or trucks. For most typical HOT lane settings, eligibility requirements would be used during selected hours or at specific access ramps; and 3) Pricing Imposing a user fee on a lane that helps regulate demand by time of day or day of week. The fee increases during periods of highest demand. Source: U.S. Department of Transportation
Latency Period: Duration of time from first exposure to first symptoms or signs of a disease. Source: Agency for Toxic Substances and Disease Registry
Leadership in Energy and Environmental Design (LEED): An internationally recognized green building certification system, developed by the U.S. Green Building Council, providing third-party verification that a building or community was designed and built using strategies aimed at improving performance in energy savings, water efficiency, CO2 emissions reduction, indoor environmental quality, and stewardship of resources and sensitivity to their impacts. Source: Making Healthy Places
LEED for Neighborhood Development (LEED-ND): A certification system that integrates the principles of smart growth, New Urbanism, and green building with a focus on neighborhood design. Source: Making Healthy Places
Legislation: A proposed or enacted law or group of laws, as well as the act or process of making laws
Leisure-time physical activity: Physical activity that is done for recreation, enjoyment, sports, hobbies, health, or exercise during leisure time (cf. utilitarian physical activity). Source: Making Healthy Places
Level of Service (LOS): 1) A qualitative assessment of a road’s operating conditions. For local government comprehensive planning purposes, level of service means an indicator of the extent or degree of service provided by, or proposed to be provided by, a facility based on and related to the operational characteristics of the facility. Level of service indicates the capacity per unit of demand for each public facility. 2) This term refers to a standard measurement used by transportation officials which reflects the relative ease of traffic flow on a scale of A to F, with free-flow being rated LOS-A and congested conditions rated as LOS-F. Source: U.S. Department of Transportation Federal Highway Administration
Life cycle: A continuum for a product (“cradle to grave”) from raw materials extraction through manufacturing, consumer use, transport, and disposal. Source: Making Healthy Places
Life cycle assessment: A technique for assessing the environmental aspects and potential impacts associated with a product, process, or system throughout its life cycle and for making determinations about the environmental ramifications of a material or design choice. Source: Making Healthy Places
Lifelines: Systems or networks that provide for the circulation of people, goods, services, and information upon which health, safety, comfort, and economic activity depends. Source: Making Healthy Places
Lifelong Communities: Places where individuals can live throughout their lifetime; they provide a full range of options to residents, insuring a high quality of life for all. Lifelong Communities work to achieve three major goals: 1) Promoting Housing and Transportation Options; 2) Encouraging Healthy Lifestyles; and 3) Expanding Information and Access to Services. Source: Atlanta Regional Commission Lifelong Communities
Lifestyle: a way of living based on identifiable patterns of behavior which are determined by the interplay between an individual’s personal characteristics, social interactions, and socioeconomic and environmental living conditions. Source: A Healthy Lifestyle
Light Rail: A streetcar-type vehicle operated on city streets, semi-exclusive rights-of-way, or exclusive rights-of-way. Service may be provided by step-entry vehicles or by level boarding. Source: Federal Highway Administration
Light Truck: Trucks of 10,000 pounds gross vehicle weight rating or less, including pickups, vans, truck-based station wagons, and sport utility vehicles. Source: U.S. Department of Transportation Federal Highway Administration
Light-Duty Vehicle: A vehicle category that combines light automobiles and trucks. Source: Federal Highway Administration
Limited Maintenance Plan: A maintenance plan that EPA has determined meets EPA’s limited maintenance plan policy criteria for a given NAAQS and pollutant. To qualify for a limited maintenance plan, for example, an area must have a design value that is significantly below a given NAAQS, and it must be reasonable to expect that a NAAQS violation will not result from any level of future motor vehicle emissions growth. Source: Federal Highway Administration
Livable Communities: 1) Provides affordable, appropriate, accessible housing; 2) Ensures accessible, affordable, reliable, safe transportation; 3) Adjusts the physical environment for inclusiveness and accessibility; 4) Provides work, volunteer, and education opportunities; 5) Ensures access to key health and support services; and 6) Encourages participation in civic, cultural, social, and recreational activities. Within each of these six areas, a livable community strives to maximize people’s independence, assure safety and security, promote inclusiveness, and provide choice. Source: National Council on Disability
Local Street: A street intended solely for access to adjacent properties. Source: U.S. Department of Transportation Federal Highway Administration
Local/Community Food System: A community food system, also known as a local food system, is a collaborative effort to integrate agricultural production with food distribution to enhance the economic, environmental, and social well-being of a particular place (i.e. a neighborhood, city, county or region). Source: (Gail Feenstra and Dave Campbell, Steps for Developing a Sustainable Community Food System)
Location-Efficient Mortgages: Competitive rates and low down payments to those who want to live in location-efficient communities that are convenient to resources and reduce the need to drive. Source: Centers for Disease Control and Prevention
Logistics: All activities involved in the management of product movement; delivering the right product from the right origin to the right destination, with the right quality and quantity, at the right schedule and price. Source: U.S. Department of Transportation Federal Highway Administration
Long Range Transportation Plan (LRTP): A document resulting from regional or statewide collaboration and consensus on a region or state’s transportation system, and serving as the defining vision for the region’s or state’s transportation systems and services. In metropolitan areas, the plan indicates all of the transportation improvements scheduled for funding over the next 20 years. Source: U.S. Department of Transportation Federal Highway Administration
Long Term: In transportation planning, refers to a time span of, generally, 20 years. The transportation plan for metropolitan areas and for States should include projections for land use, population, and employment for the 20-year period. Source: U.S. Department of Transportation Federal Highway Administration
Low Emission & Energy-Efficient Vehicles: A vehicle that has been certified as meeting the Tier II emission level under section 202(i) of the Clean Air Act for that make and model year and is certified by EPA to have achieved not less than a 50-percent increase in city fuel economy or not less than a 25 percent increase in combined city-highway fuel economy relative to a comparable vehicle that is an internal combustion gasoline fueled vehicle; or is an alternative fuel vehicle. Source: U.S. Department of Transportation Federal Highway Administration
Low-impact development (LID): Land development that uses land planning and design practices and technologies to conserve and protect natural resource systems and reduce infrastructure costs. Source: Making Healthy Places
Low Physical Effort: Principle six of Universal Design: The design can be used efficiently and comfortably and with a minimum of fatigue. Source: The Center for Universal Design (1997). The Principles of Universal Design, Version 2.0. Raleigh, NC: North Carolina State Univ
Lowest-Observed-Adverse-Effect Level (LOAEL): The lowest tested dose of a substance that has been reported to cause harmful (adverse) health effects in people or animals. Source: Agency for Toxic Substances and Disease Registry

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Maintenance Area: Maintenance area is any geographic region of the United States previously designated nonattainment pursuant to the CAA Amendments of 1990 and subsequently redesignated to attainment subject to the requirement to develop a maintenance plan under section 175A of the CAA, as amended. Source: Federal Highway Administration
Maladaptive Behavior: Behavior or response to an environment, policy, or situation that is damaging or counterproductive to the individual and to his or her health, safety, or quality of life. Source: Making Healthy Places
Maladaptive Response: Behaviors that take place when environmental press and personal competence are out of balance, resulting in less than optimal well-being. Source: Glaas and Balfour
Managed Lane: A lane or lanes designed and operated to achieve stated goals by managing access via user group, pricing, or other criteria. A managed lane facility typically provides improved travel conditions to eligible users. Source: U.S. Department of Transportation
Mass Transportation: Another name for public transportation. Source: Federal Highway Administration
Material Safety Data Sheet (MSDS): Printed material concerning a hazardous chemical, or Extremely Hazardous Substance, including its physical properties, hazards to personnel, fire and explosion potential, safe handling recommendations, health effects, firefighting techniques, reactivity, and proper disposal. Originally established for employee safety by OSHA. Source: Environmental Protection Agency
Means of Transportation: A mode used for going from one place (origin) to another (destination). Included are private and public modes, as well as walking. For all travel day trips, each change of mode constitutes a separate trip. Source: Federal Highway Administration
Mega City: A metropolitan area with a population of 10 million or more. Source: Making Healthy Places
Memorandum of Understanding (MOU): A document providing a general description of the responsibilities that are to be assumed by two or more parties in their pursuit of some goal(s). More specific information may be provided in an associated SOW. Source: Federal Highway Administration
Mental Health: A state of well-being in which the individual realizes his or her own potential, can cope with the normal stresses of life, can work productively and fruitfully, and is able to make a contribution to her or his community. Source: Making Healthy Places
Meta-analysis: The process of synthesizing, using statistical methodologies, research results from similar independent studies that have addressed a shared hypothesis. Source: Making Healthy Places
Metabolic syndrome: A cluster of medical disorders such as obesity, hypertension, and elevated cholesterol that occur together and increase the risk of heart disease, stroke, and diabetes. Source: Making Healthy Places
Metropolitan Planning Area: The geographic area in which the metropolitan transportation planning process required by 23 U.S.C. 134 and section 8 of the Federal Transit Act (49 U.S.C. app. 1607) must be carried out. Source: Federal Highway Administration
Metropolitan Planning Organization (MPO): 1) Regional policy body, required in urbanized areas with populations over 50,000, and designated by local officials and the governor of the state. Responsible in cooperation with the state and other transportation providers for carrying out the metropolitan transportation planning requirements of federal highway and transit legislation. 2) Formed in cooperation with the state, develops transportation plans and programs for the metropolitan area. For each urbanized area, a Metropolitan Planning Organization (MPO) must be designated by agreement between the Governor and local units of government representing 75% of the affected population (in the metropolitan area), including the central cities or cities as defined by the Bureau of the Census, or in accordance with procedures established by applicable State or local law (23 U.S.C. 134(b)(1)/Federal Transit Act of 1991 Sec. 8(b)(1)). Source: Federal Highway Administration
Metropolitan Statistical Area (MSA): Areas defined by the U.S. Office of Management and Budget. A Metropolitan Statistical Area (MSA) is 1) A county or a group of contiguous counties that contain at least one city of 50,000 inhabitants or more, or 2) An urbanized area of at least 50,000 inhabitants and a total MSA population of at least 100,000 (75,000 in New England). The contiguous counties are included in an MSA if, according to certain criteria, they are essentially metropolitan in character and are socially and economically integrated with the central city. In New England, MSAs consist of towns and cities rather than counties. Source: Federal Highway Administration
Metropolitan Transportation Plan (MTP): The official intermodal transportation plan that is developed and adopted through the metropolitan transportation planning process for the metropolitan planning area, in accordance with 23 U.S.C. 134, 23 USC 135 and 49 U.S.C. 5303. Source: Federal Highway Administration
Mile: A statute mile (5,280 feet). All mileage computations are based on statute miles. Source: Federal Highway Administration
Mixed-income development: A development comprising housing units with differing levels of affordability, typically including a mixture of market-rate and below market-rate housing. Source: Making Healthy Places
Mixed land use: Co-location of diverse land uses, such as residential, commercial, recreational, and retail. Source: Making Healthy Places
Mixed Use Development: A mixed-use development means a relatively large-scale real estate project characterized by: 1) three or more significant revenue-producing uses; 2) significant functional and physical integration of project components; and 3) development in conformance with a coherent plan. Source: Urban Land Institute
Mobile-source Air Pollution: Any nonstationary source of air pollution, such as cars, trucks, buses, airplanes, and locomotives. Source: Making Healthy Places
Mobile Source Air Toxics (MSATS): Identified by the EPA, MSATs are the 21 hazardous air pollutants generated in large part by transportation sources. Source: Federal Highway Administration
Mobility: The ability to move or be moved from place to place. Source: Federal Highway Administration
Modeling: A key component of the social cognitive theory of behavior change, based on the finding that a person is more likely to engage in a behavior when he or she observes other people engaging in the behavior. Source: Making Healthy Places
Mortality: Death. Usually the cause (a specific disease, a condition, or an injury) is stated. Source: Agency for Toxic Substances and Disease Registry
Mortality Rate: A measure of the frequency of occurrence of death among a defined population during a specified time interval. Source: Centers for Disease Control and Prevention
Mortality Rate, Age-Adjusted: A mortality rate that has been statistically modified to eliminate the effect of different age distributions among different populations. Source: Centers for Disease Control and Prevention
Mortality Rate, Age-Specific: A mortality rate limited to a particular age group, calculated as the number of deaths among the age group divided by the number of persons in that age group, usually expressed per 100,000. Source: Centers for Disease Control and Prevention
Mortality Rate, Cause-Specific: The mortality rate from a specified cause, calculated as the number of deaths attributed to a specific cause during a specified time interval among a population divided by the size of the midinterval population. Source: Centers for Disease Control and Prevention
Mortality Rate, Crude: A mortality rate from all causes of death for an entire population, without adjustment. Source: Centers for Disease Control and Prevention
Mortality Rate, Infant: The mortality rate for children aged <1 year, calculated as the number of deaths reported among this age group during a given period divided by the number of live births reported during the same period, and expressed per 1,000 live births. Infant mortality rate is a universally accepted indicator of the health of a nations population and the adequacy of its health-care system. Source: Centers for Disease Control and Prevention
Mortality Rate, Neonatal: The mortality rate for children from age birth up to, but not including, 28 days. In calculating neonatal mortality rates, the numerator is the number of deaths among this age group during a given period, and the denominator is the number of live births reported during the same period. The neonatal mortality rate is usually expressed per 1,000 live births. Source: Centers for Disease Control and Prevention
Mortality Rate, Post-neonatal: The mortality rate for children from age 28 days up to, but not including, 1 year. In calculating post-neonatal mortality rates, the numerator is the number of deaths among this age group during a given period, and the denominator is the number of live births during the same period. The post-neonatal mortality rate is usually expressed per 1,000 live births. Source: Centers for Disease Control and Prevention
Mortality Rate, Race/Ethnic-Specific: A mortality rate limited to a specified racial or ethnic group both numerator and denominator are limited to that group. Source: Centers for Disease Control and Prevention
Mortality Rate, Sex-Specific: A mortality rate among either males or females. Source: Centers for Disease Control and Prevention
Motor Vehicle Emissions Budget: The portion of the total allowable emissions defined in the submitted or approved control strategy implementation plan revision or maintenance plan for a certain date for the purpose of meeting reasonable further progress milestones or demonstrating attainment or maintenance of the NAAQS, for any criteria pollutant or its precursors, allocated to highway and transit vehicle use and emissions. Source: Federal Highway Administration
Motorbus (Transit): A rubber-tired, self-propelled, manually steered bus with a fuel supply on-board the vehicle. Motorbus types include intercity, school, and transit. Source: Federal Highway Administration
Motorcycle: A two- or three-wheeled motor vehicle designed to transport one or two people, including motor scooters, minibikes, and mopeds. Source: Federal Highway Administration
Motorized Vehicle: Includes all vehicles that are licensed for highway driving. Specifically excluded are snow mobiles and minibikes. Source: Federal Highway Administration
Multifamily Dwelling: Any dwelling containing four or more individual dwelling units (this definition may vary by jurisdiction). Source: U.S. Department of Housing and Urban Development
Multilevel analytical framework: The analytical approach by which contextual effects on individual outcomes can be examined by simultaneously considering individual-level and group-level influences on health. Source: Making Healthy Places
Multimodal: The availability of transportation options using different modes within a system or corridor. Source: Federal Highway Administration
Multimodal Level of Service: The level of service for automobile, transit, bicycle, and pedestrian modes on urban streets, especially paying respect to the interaction among the modes. Source: Making Healthy Places
Multimodal Transportation: Often used as a synonym for intermodalism. Congress and others frequently use the term intermodalism in its broadest interpretation as a synonym for multimodal transportation. Most precisely, multimodal transportation covers all modes without necessarily including a holistic or integrated approach. Source: Federal Highway Administration
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. Source: Environmental Protection Agency
Municipal Code: A set or ordinances enacted by local government Source: Making Healthy Places

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National Ambient Air Quality Standards (NAAQS): Federal standards that set allowable concentrations and exposure limits for various pollutants. The EPA developed the standards in response to a requirement of the CAA. Air quality standards have been established for the following six criteria pollutants: ozone (or smog), carbon monoxide, particulate matter, nitrogen dioxide, lead, and sulfur dioxide. Source: Federal Highway Administration
National Cooperative Highway Research Program (NCHRP): The cooperative research, development, and technology transfer (RD&T) program directed toward solving problems of national or regional significance identified by States and the FHWA, and administered by the Transportation Research Board, National Academy of Sciences. (23CFR420) Source: U.S. Department of Transportation Federal Highway Administration
National Cooperative Transit Research and Development Program: A program established under Section 6a) of the Urban Mass Transportation Act of 1964, as amended, to provide a mechanism by which the principal client groups of the Urban Mass Transportation Administration can join cooperatively in an attempt to resolve near-term public transportation problems through applied research, development, testing, and evaluation. NCTRP is administered by the Transportation Research Board. Source: Federal Highway Administration
National Emissions Standards for Hazardous Air Pollutants (NESHAPS): Emissions standards set by EPA for an air pollutant not covered by NAAQS that may cause an increase in fatalities or in serious, irreversible, or incapacitating illness. Primary standards are designed to protect human health, secondary standards to protect public welfare (e.g. building facades, visibility, crops, and domestic animals). Source: Environmental Protection Agency
National Environmental Policy Act of 1969 (NEPA): Established a national environmental policy requiring that any project using federal funding or requiring federal approval, including transportation projects, examine the effects of proposed and alternative choices on the environment before a federal decision is made. Source: Federal Highway Administration
National Highway System (NHS): This system of highways designated and approved in accordance with the provisions of 23 U.S.C. 103b). (23CFR500) Source: Federal Highway Administration
National Highway Traffic Safety Administration (NHTSA): The Administration was established by the Highway Safety Act of 1970 (23 U.S.C. 401 note) to carry out a congressional mandate to reduce the mounting number of deaths, injuries, and economic losses resulting from motor vehicle crashes on the Nation’s highways and to provide motor vehicle damage susceptibility and ease of repair information, motor vehicle inspection demonstrations and protection of purchasers of motor vehicles having altered odometers, and to provide average standards for greater vehicle mileage per gallon of fuel for vehicles under 10,000 pounds (gross vehicle weight). Source: Federal Highway Administration
National Historic Trail (NHT): A historic or prehistoric route of travel of significance to the entire Nation. It must meet three criteria listed in Section 5(b)(11) of the National Trails System Act, and be established by Act of Congress. 16 U.S.C. 1241-51. Source: Federal Highway Administration
National Scenic Byways Program (NSBP): Designates roads that have outstanding scenic, historic, cultural, natural, recreational, and archaeological qualities as All-American Roads or National Scenic Byways, and provides grants for scenic byway projects. 23 U.S.C. 162 Source: Federal Highway Administration
National Scenic Trail (NST): A continuous, primarily non-motorized route of outstanding recreation opportunity, established by Act of Congress. 16 U.S.C. 1241-51. Source: Federal Highway Administration
National Trails System (NTS): The network of scenic, historic, and recreation trails created by the National Trails System Act of 1968. These trails provide for outdoor recreation needs, promote the enjoyment, appreciation, and preservation of open-air, outdoor areas and historic resources, and encourage public access and citizen involvement. 16 U.S.C. 1241-51. Source: Federal Highway Administration
Natural Experiment: An observational study in which events or interventions affect defined subpopulations but are not under the control of the investigator. Source: Making Healthy Places
Natural Surveillance: A component of CPTED that uses design features that facilitate regular observation of areas such as sidewalks and lobbies for safety. Source: Making Healthy Places
Nature Deficit Disorder: A term coined by Richard Louv, referring to physical and psychological consequences associated with insufficient contact with nature. Source: Making Healthy Places
New Source Performance Standards (NSPS): Uniform national EPA air emission and water effluent standards which limit the amount of pollution allowed from new sources or from modified existing sources Source: Environmental Protection Agency
New Urbanism: An urban design movement that promotes walkable neighborhoods, mixed land use, connectivity, and vibrant public spaces and activity centers. Source: Making Healthy Places
NIMBY: “Not in my backyard”—a term used to categorize the attitude that says a project should not be sited near certain residents’ property even though it might be fine to site it elsewhere. Source: Making Healthy Places
Nitrogen Oxide Emissions: Nitrogen oxides (NOx), the term used to describe the sum of nitric oxide (NO), nitrogen dioxide (N02) and other oxides of nitrogen, play a major role in the formation of ozone. The major sources of manmade NOx emissions are high temperature combustion processes, such as those occurring in automobiles and power plants. Source: Federal Highway Administration
Nitrogen Oxides: A product of combustion of fossil fuels whose production increases with the temperature of the process. It can become an air pollutant if concentrations are excessive. Source: Federal Highway Administration
No-Observed-Adverse-Effect Level (NOAEL): The highest tested dose of a substance that has been reported to have no harmful (adverse) health effects on people or animals. Source: Agency for Toxic Substances and Disease Registry
Non-Road Emissions: Pollutants emitted by combustion engines on farm and construction equipment, gasoline-powered lawn and garden equipment, and power boats and outboard motors. Source: Environmental Protection Agency
Nonattainment Area (NAA): Any geographic area that has not met the requirements for clean air as set out in the Clean Air Act of 1990. Source: Federal Highway Administration
Noncompliance: Failure to comply with a standard or regulation issued under 46 U.S.C. Chapter 43, or with a section of the statutes. Source: Federal Highway Administration
Nonmotorized transportation (NMT): Any self-propelled, human-powered mode of transportation, especially walking and bicycling (also called active transportation). Source: Making Healthy Places
Nonoccupant (Automobile): Any person who is not an occupant of a motor vehicle in transport (e.g., bystanders, pedestrians, pedalcyclists, or an occupant of a parked motor vehicle). Source: Federal Highway Administration

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Obesity: 1) For adults, a Body Mass Index (BMI) greater than or equal to 30. 2) An excess amount of subcutaneous body fat in proportion to lean body mass. In this report, obesity in children and youth refers to the age and gender-specific BMI that are equal to or greater than the 95th percentile of the CDC BMI charts. In most children, these values are known to indicate elevated body fat and to reflect the co-morbidities associated with excessive body fatness. Source: Centers for Disease Control and Prevention; Institute of Medicine of the National Academies
Observational Study: A study in which the investigator observes rather than influences exposure and disease among participants. Source: Making Healthy Places
Occupancy: The number of persons, including driver and passenger(s) in a vehicle. Nationwide Personal Transportation Survey (NPTS) occupancy rates are generally calculated as person miles divided by vehicle miles. Source: Federal Highway Administration
Occupancy (Vehicle): The number of persons, including driver and passenger(s) in a vehicle. NPTS occupancy rates are generally calculated as person miles divided by vehicle miles. Source: Federal Highway Administration
Occupant: Any person who is in or upon a motor vehicle in transport. Includes the driver, passengers, and persons riding on the exterior of a motor vehicle (e.g., a skateboard rider who is set in motion by holding onto a vehicle). Source: Federal Highway Administration
On-site wastewater treatment system (OWTS): An alternative to a municipal sewage system, such as a septic tank, that manages wastewater at the point of generation and typically serves individual houses or a small number of households. Source: Making Healthy Places
Other Freeways And Expressways (Highway): All urban principal arterials with limited access but not part of the Interstate system. Source: Federal Highway Administration
Other Principal Arterials (Highway): Major streets or highways, many of multi-lane or freeway design, serving high-volume traffic corridor movements that connect major generators of travel. Source: Federal Highway Administration
Other Revenue Vehicles (Transit): Other revenue-generating modes of transit service, such as cable cars, personal rapid transit systems, monorail vehicles, inclined and railway cars, not covered otherwise. Source: Federal Highway Administration
Overweight: For adults, a Body Mass Index (BMI) of 25 to 29.9. Source: Centers for Disease Control and Prevention
Oxygenated Gasoline: Gasoline enriched with oxygen bearing liquids to reduce CO production by permitting more complete combustion. Source: Federal Highway Administration
Oxygenates: Any substance that when added to motor gasoline increases the amount of oxygen in that gasoline blend. Includes oxygen-bearing compounds such as ethanol, methanol, and methyl-tertiary-butyl-ether. Oxygenated fuel tends to give a more complete combustion of carbon into carbon dioxide (rather than monoxide), thereby reducing air pollution from exhaust emissions. Source: Federal Highway Administration
Ozone 03: 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 VOCs and NOx combine in the presence of sunlight. Ozone is associated with smog or haze conditions. Although the ozone in the upper atmosphere protects us from harmful ultraviolet rays, ground-level ozone produces an unhealthy environment in which to live. Ozone is created by human and natural sources. Source: Federal Highway Administration