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  1. Title: Passenger Rail Lines: United States, 2014

    Contributors:

    Summary: The Rail Network is a comprehensive database of United States railway system at 1:24,000 to 1:100,000 scale. This polyline shapefile depicts Amtrak rail lines within all 50 states plus the District of Columbia. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. This passenger rail line dataset is a topological network that provides location and attributes information for use in network analysis applications. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Passenger Rail Lines: United States, 2014. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/pg378hd7973.

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  2. Title: Amtrak Stations: United States and Canada, 2010

    Contributors:

    Summary: This point shapefile depicts Amtrak inter-city railroad passenger terminals in the United States and Canada. Attribute data include services and passenger amenities provided at the station. This data is collected and maintained by the Federal Railroad Administration (FRA) and was last updated in 2010. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. This data provides an updated version of the location and attribute information for all Amtrak stations in the United States and Canada. This data is used for national and network analysis applications. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Amtrak Stations: United States and Canada, 2010. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/jd927rr8778.

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  3. Title: Administrative Boundaries of National Park System Units, 2011

    Contributors:

    Summary: This polygon shapefile depicts service wide boundary set for display and general analysis purposes. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. This coverage displays National Park Service unit boundaries United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Administrative Boundaries of National Park System Units, 2011. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/mg196xb7926.

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  4. Title: Nonattainment Areas for Ozone Pollution: United States and Territories, 1979

    Contributors:

    Summary: This polygon shapefile depicts nonattainment and maintenance areas for the United States and its Territories for the enforcement of the ozone (O3) 1 hour NAAQS, which is 0.12ppm. Ozone (O3) is a photochemical oxidant and the major component of smog. While O3 in the upper atmosphere is beneficial to life by shielding the earth from harmful ultraviolet radiation from the sun, high concentrations of O3 at ground level are a major health and environmental concern. O3 is not emitted directly into the air but is formed through complex chemical reactions between precursor emissions of volatile organic compounds (VOC) and oxides of nitrogen (NOx) in the presence of sunlight. These reactions are stimulated by sunlight and temperature so that peak O3 levels occur typically during the warmer times of the year. Both VOCs and NOx are emitted by transportation and industrial sources. VOCs are emitted from sources as diverse as autos, chemical manufacturing, dry cleaners, paint shops and other sources using solvents. The reactivity of O3 causes health problems because it damages lung tissue, reduces lung function and sensitizes the lungs to other irritants. Scientific evidence indicates that ambient levels of O3 not only affect people with impaired respiratory systems, such as asthmatics, but healthy adults and children as well. Exposure to O3 for several hours at relatively low concentrations has been found to significantly reduce lung function and induce respiratory inflammation in normal, healthy people during exercise. This decrease in lung function generally is accompanied by symptoms including chest pain, coughing, sneezing and pulmonary congestion. Title 40, Part 50 of the Code of the Federal Regulations lists the ambient air quality standards for ozone. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. In United States environmental law, a nonattainment area is an area considered to have air quality worse than the National Ambient Air Quality Standards (NAAQS) as defined in the Clean Air Act Amendments of 1970 (P.L. 91-604, Sec. 109). Nonattainment areas must have and implement a plan to meet the standard or risk losing some forms of federal financial assistance or other consequences, such as industrial facilities being required to install pollution control equipment, enforce limits on their production and otherwise offset their emissions. An area may be a nonattainment area for one pollutant and an attainment area for others. This dataset establishes the spatial boundaries of each nonattainment and maintenance area. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Nonattainment Areas for Ozone Pollution: United States and Territories, 1979. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/yq764cj7216. The 1 hour standard is incorporated within the Ozone dataset.

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  5. Title: Ports: United States and Territories, 2012

    Contributors:

    Summary: This point shapefile depicts physical information on commercial facilities at the principal United States coastal, Great Lakes and inland ports. The data consists of listings of port area waterfront facilities, including information on berthing, cranes, transit sheds, grain elevators, marine repair plants, fleeting areas, and docking and storage facilities. Collection of data is performed on a rotational basis to ensure on-site accuracy at each facility. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. The Navigation Data Center (NDC) had several objectives in developing the United States Waterway Data. These objectives support the concept of a National Spatial Data Infrastructure to: provide public access to national waterway data; foster inter-agency and intra-agency cooperation through data sharing; provide a mechanism to integrate waterway data (U.S. Army Corps of Engineers Port/Facility and U.S. Coast Guard Accident Data, for example); provide a basis for intermodal analysis; assist standardization of waterway entity definitions (Ports/Facilities, Locks, etc.); provide public access to the National Waterway Network which can be used as a basemap to support graphical overlays and analysis with other spatial data such as waterway and modal network/facility databases; and provide reliable data to support future waterway and intermodal applications. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Ports: United States and Territories, 2012. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/gz919pm1319.

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  6. Title: Nonattainment Areas for Carbon Monoxide Pollution: United States and Territories, 1990

    Contributors:

    Summary: This polygon shapefile depicts nonattainment and maintenance areas for the United States and its Territories for the enforcement of the carbon monoxide (CO) 8 hour NAAQS, which is 9 ppm. Carbon monoxide (CO) is a colorless, odorless and poisonous gas produced by incomplete burning of carbon in fuels. When CO enters the bloodstream, it reduces the delivery of oxygen to the body's organs and tissues. Health threats are most serious for those who suffer from cardiovascular disease, particularly those with angina or peripheral vascular disease. Exposure to elevated CO levels can cause impairment of visual perception, manual dexterity, learning ability and performance of complex tasks. 77% of the nationwide CO emissions are from transportation sources. The largest emissions contribution comes from highway motor vehicles. Thus, the focus of CO monitoring has been on traffic oriented sites in urban areas where the main source of CO is motor vehicle exhaust. Other major CO sources are wood-burning stoves, incinerators and industrial sources. The National Ambient Air Quality Standard for carbon monoxide is 9 ppm 8-hour nonoverlapping average not to be exceeded more than once per year. The rounding convention in the standard specifies that values of 9.5 ppm, or greater, are counted as exceeding the level of the standard. An area meets the carbon monoxide NAAQS if no more than one 8-hour value per year exceeds the threshold. (High values that occur within 8 hours of the first one are exempted. This is known as using "nonoverlapping averages.") To be in attainment, an area must meet the NAAQS for two consecutive years and carry out air quality monitoring during the entire time. Air quality carbon monoxide value is estimated using EPA guidance for calculating design values (Laxton Memorandum, June 18, 1990). Title 40, Part 50 of the Code of the Federal Regulations lists the ambient air quality standard for carbon monoxide. Sections 107(d)(4)(A) and 186 of the Clean Air Act lists the requirements for designations and classifications of carbon monoxide areas. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. In United States environmental law, a nonattainment area is an area considered to have air quality worse than the National Ambient Air Quality Standards (NAAQS) as defined in the Clean Air Act Amendments of 1970 (P.L. 91-604, Sec. 109). Nonattainment areas must have and implement a plan to meet the standard or risk losing some forms of federal financial assistance or other consequences, such as industrial facilities being required to install pollution control equipment, enforce limits on their production and otherwise offset their emissions. An area may be a nonattainment area for one pollutant and an attainment area for others. This dataset establishes the spatial boundaries of each nonattainment and maintenance area. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Nonattainment Areas for Carbon Monoxide Pollution: United States and Territories, 1990. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/cg949bx5174. Carbon monoxide (CO) is a colorless, odorless and poisonous gas produced by incomplete burning of carbon in fuels. When CO enters the bloodstream, it reduces the delivery of oxygen to the body's organs and tissues. Health threats are most serious for those who suffer from cardiovascular disease, particularly those with angina or peripheral vascular disease. Exposure to elevated CO levels can cause impairment of visual perception, manual dexterity, learning ability and performance of complex tasks. 77% of the nationwide CO emissions are from transportation sources. The largest emissions contribution comes from highway motor vehicles. Thus, the focus of CO monitoring has been on traffic oriented sites in urban areas where the main source of CO is motor vehicle exhaust. Other major CO sources are wood-burning stoves, incinerators and industrial sources. The National Ambient Air Quality Standard for carbon monoxide is 9 ppm 8-hour nonoverlapping average not to be exceeded more than once per year. The rounding convention in the standard specifies that values of 9.5 ppm, or greater, are counted as exceeding the level of the standard. An area meets the carbon monoxide NAAQS if no more than one 8-hour value per year exceeds the threshold. (High values that occur within 8 hours of the first one are exempted. This is known as using "nonoverlapping averages.") To be in attainment, an area must meet the NAAQS for two consecutive years and carry out air quality monitoring during the entire time. Air quality carbon monoxide value is estimated using EPA guidance for calculating design values (Laxton Memorandum, June 18, 1990). Title 40, Part 50 of the Code of the Federal Regulations lists the ambient air quality standard for carbon monoxide. Sections 107(d)(4)(A) and 186 of the Clean Air Act lists the requirements for designations and classifications of carbon monoxide areas.

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  7. Title: Nonattainment Areas for Patriculate Matter Pollution: United States and Territories, 1987

    Contributors:

    Summary: This polygon shapefile depicts nonattainment and maintenance areas for the United States and its Territories for the enforcement of the particulate matter 10 (PM10) 24 hour NAAQS, which is 150 micrograms per cubed meter. Air pollutants called particulate matter include dust, dirt, soot, smoke and liquid droplets directly emitted into the air by sources such as factories, power plants, cars, construction activity, fires and natural windblown dust. Particles formed in the atmosphere by condensation or the transformation of emitted gases such as SO2 and VOCs are also considered particulate matter. Based on studies of human populations exposed to high concentrations of particles (sometimes in the presence of SO2) and laboratory studies of animals and humans, there are major effects of concern for human health. These include effects on breathing and respiratory symptoms, aggravation of existing respiratory and cardiovascular disease, alterations in the body's defense systems against foreign materials, damage to lung tissue, carcinogenesis and premature death. The major subgroups of the population that appear to be most sensitive to the effects of particulate matter include individuals with chronic obstructive pulmonary or cardiovascular disease or influenza, asthmatics, the elderly and children. Particulate matter also soils and damages materials, and is a major cause of visibility impairment in the United States. Annual and 24-hour National Ambient Air Quality Standards (NAAQS) for particulate matter were first set in 1971. Total suspended particulate (TSP) was the first indicator used to represent suspended particles in the ambient air. Since July 1, 1987, however, EPA has used the indicator PM-10, which includes only those particles with aerodynamic diameter smaller than 10 micrometers. These smaller particles are likely responsible for most of the adverse health effects of particulate matter because of their ability to reach the thoracic or lower regions of the respiratory tract. Title 40, Part 50 of the Code of the Federal Regulations lists the ambient air quality standard for particulate matter. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. In United States environmental law, a nonattainment area is an area considered to have air quality worse than the National Ambient Air Quality Standards (NAAQS) as defined in the Clean Air Act Amendments of 1970 (P.L. 91-604, Sec. 109). Nonattainment areas must have and implement a plan to meet the standard or risk losing some forms of federal financial assistance or other consequences, such as industrial facilities being required to install pollution control equipment, enforce limits on their production and otherwise offset their emissions. An area may be a nonattainment area for one pollutant and an attainment area for others. This dataset establishes the spatial boundaries of each nonattainment and maintenance area. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Nonattainment Areas for Patriculate Matter Pollution: United States and Territories, 1987. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/xq566tb2444.

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  8. Title: United States National Transportation Atlas Interstate Highways, 2008

    Contributors:

    Summary: This line shapefile represents rural and urban interstate highways. U.S. National Transportation Atlas Interstate Highways is part of the National Highway Planning Network, published by the Federal Highway Administration as part of the National Transportation Atlas Databases for the United States. This layer is part of the 2014 ESRI Data and Maps collection for ArcGIS 10.2. U.S. National Transportation Atlas Interstate Highways provides a comprehensive database of interstate highways from the nation's principal arterial highway system and the National Highway System. The data is generalized to improve draw performance and be used effectively at a national level. ESRI and U.S. Bureau of Transportation Statistics. (2014). United States National Transportation Atlas Interstate Highways, 2008. ESRI. Available at: http://purl.stanford.edu/qn309jc5979

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  9. Title: Freight Analysis Framework Network: United States, 2010

    Contributors:

    Summary: This polyline shapefile depicts the spatial component of the FAF network derived from National Highway System Version 2009.11 and contains state primary and secondary roads, National Highway System (NHS), National Network (NN) and several intermodal connectors as appropriate for the freight network modeling. The network consists of over 447,808 miles of equivalent road mileage. The data set covers the 48 contiguous States plus the District of Columbia, Alaska and Hawaii. The nominal scale of the data set is 1:100,000 with a maximal positional error of ±80 meters. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. The Freight Analysis Framework (FAF) integrates data from a variety of sources to create a comprehensive picture of freight movement among states and major metropolitan areas by all modes of transportation. The FAF region boundaries are a geographic database of state and metropolitan boundaries. The database includes boundaries for all 123 regions, including Washington D.C. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Freight Analysis Framework Network: United States, 2010. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/np510vw8315.

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  10. Title: Nonattainment Areas for Sulfur Dioxide Pollution, United States and Territories, 1978

    Contributors:

    Summary: This polygon shapefile depicts nonattainment and maintenance areas for the United States and its Territories for the enforcement of the sulfur dioxide (SO2). There are 3 NAAQS for SO2: an annual arithmetic mean of 0.03 ppm (80 ug/m3); a 24 hour level of 0.14 ppm (365 ug/m3); and a 3 hour level of 0.50 ppm (1300 ug/m3). High concentrations of sulfur dioxide (SO2) affect breathing and may aggravate existing respiratory and cardiovascular disease. Sensitive populations include asthmatics, individuals with bronchitis or emphysema, children and the elderly. SO2 is also a primary contributor to acid deposition, or acid rain, which causes acidification of lakes and streams and can damage trees, crops, historic buildings and statues. In addition, sulfur compounds in the air contribute to visibility impairment in large parts of the country. This is especially noticeable in national parks. Ambient SO2 results largely from stationary sources such as coal and oil combustion, steel mills, refineries, pulp and paper mills and from nonferrous smelters. There are three NAAQS for SO2: . an annual arithmetic mean of 0.03 ppm (80 ug/m3); . a 24-hour level of 0.14 ppm (365 ug/m3); and . a 3-hour level of 0.50 ppm (1300 ug/m3). The first two standards are primary (health-related) standards, while the 3-hour NAAQS is a secondary (welfare-related) standard. The annual mean standard is not to be exceeded, while the short-term standards are not to be exceeded more than once per year. Title 40, Part 50 of the Code of the Federal Regulations lists the ambient air quality standard for sulfur dioxide. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. In United States environmental law, a nonattainment area is an area considered to have air quality worse than the National Ambient Air Quality Standards (NAAQS) as defined in the Clean Air Act Amendments of 1970 (P.L. 91-604, Sec. 109). Nonattainment areas must have and implement a plan to meet the standard or risk losing some forms of federal financial assistance or other consequences, such as industrial facilities being required to install pollution control equipment, enforce limits on their production and otherwise offset their emissions. An area may be a nonattainment area for one pollutant and an attainment area for others. This dataset establishes the spatial boundaries of each nonattainment and maintenance area. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Nonattainment Areas for Sulfur Dioxide Pollution, United States and Territories, 1978. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/hb122jb8130.

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  11. Title: Nonattainment Areas for Ozone Pollution: United States and Territories, 1997

    Contributors:

    Summary: This polygon shapefile depicts nonattainment and maintenance areas for the United States and its Territories for the enforcement of the ozone (O3) 8 hour NAAQS, which is 0.075ppm. Ozone (O3) is a photochemical oxidant and the major component of smog. While O3 in the upper atmosphere is beneficial to life by shielding the earth from harmful ultraviolet radiation from the sun, high concentrations of O3 at ground level are a major health and environmental concern. O3 is not emitted directly into the air but is formed through complex chemical reactions between precursor emissions of volatile organic compounds (VOC) and oxides of nitrogen (NOx) in the presence of sunlight. These reactions are stimulated by sunlight and temperature so that peak O3 levels occur typically during the warmer times of the year. Both VOCs and NOx are emitted by transportation and industrial sources. VOCs are emitted from sources as diverse as autos, chemical manufacturing, dry cleaners, paint shops and other sources using solvents. The reactivity of O3 causes health problems because it damages lung tissue, reduces lung function and sensitizes the lungs to other irritants. Scientific evidence indicates that ambient levels of O3 not only affect people with impaired respiratory systems, such as asthmatics, but healthy adults and children as well. Exposure to O3 for several hours at relatively low concentrations has been found to significantly reduce lung function and induce respiratory inflammation in normal, healthy people during exercise. This decrease in lung function generally is accompanied by symptoms including chest pain, coughing, sneezing and pulmonary congestion. Title 40, Part 50 of the Code of the Federal Regulations lists the ambient air quality standards for ozone. The 8 hour standard is incorporated within the Ozone dataset. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. In United States environmental law, a nonattainment area is an area considered to have air quality worse than the National Ambient Air Quality Standards (NAAQS) as defined in the Clean Air Act Amendments of 1970 (P.L. 91-604, Sec. 109). Nonattainment areas must have and implement a plan to meet the standard or risk losing some forms of federal financial assistance or other consequences, such as industrial facilities being required to install pollution control equipment, enforce limits on their production and otherwise offset their emissions. An area may be a nonattainment area for one pollutant and an attainment area for others. This dataset establishes the spatial boundaries of each nonattainment and maintenance area. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Nonattainment Areas for Ozone Pollution: United States and Territories, 1997. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/dh456sh0677. The 8 hour standard is incorporated within the Ozone dataset.

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  12. Title: Railway Nodes: United States, 2014

    Contributors:

    Summary: The Rail Network is a comprehensive database of the nation's railway system at 1:24,000 to 1:100,000 scale. This point shapefile covers all 50 States plus the District of Columbia providing location based on partial attribute information for use in national and regional network analysis. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. This data is used for national and network analysis applications. This rail nodes dataset supports the topological network that provides location and attributes information for use in network analysis applications. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Railway Nodes: United States, 2014. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/bx620js8977.

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  13. Title: Nonattainment Areas for Sulfur Dioxide Pollution, United States and Territories, 2010

    Contributors:

    Summary: This polygon shapefile depicts nonattainment and maintenance areas for the United States and its Territories for the enforcement of the sulfur dioxide (SO2). There are 3 NAAQS for SO2: an annual arithmetic mean of 0.03 ppm (80 ug/m3); a 24 hour level of 0.14 ppm (365 ug/m3); and a 3 hour level of 0.50 ppm (1300 ug/m3). High concentrations of sulfur dioxide (SO2) affect breathing and may aggravate existing respiratory and cardiovascular disease. Sensitive populations include asthmatics, individuals with bronchitis or emphysema, children and the elderly. SO2 is also a primary contributor to acid deposition, or acid rain, which causes acidification of lakes and streams and can damage trees, crops, historic buildings and statues. In addition, sulfur compounds in the air contribute to visibility impairment in large parts of the country. This is especially noticeable in national parks. Ambient SO2 results largely from stationary sources such as coal and oil combustion, steel mills, refineries, pulp and paper mills and from nonferrous smelters. There are three NAAQS for SO2: . an annual arithmetic mean of 0.03 ppm (80 ug/m3); . a 24-hour level of 0.14 ppm (365 ug/m3); and . a 3-hour level of 0.50 ppm (1300 ug/m3). The first two standards are primary (health-related) standards, while the 3-hour NAAQS is a secondary (welfare-related) standard. The annual mean standard is not to be exceeded, while the short-term standards are not to be exceeded more than once per year. Title 40, Part 50 of the Code of the Federal Regulations lists the ambient air quality standard for sulfur dioxide. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. In United States environmental law, a nonattainment area is an area considered to have air quality worse than the National Ambient Air Quality Standards (NAAQS) as defined in the Clean Air Act Amendments of 1970 (P.L. 91-604, Sec. 109). Nonattainment areas must have and implement a plan to meet the standard or risk losing some forms of federal financial assistance or other consequences, such as industrial facilities being required to install pollution control equipment, enforce limits on their production and otherwise offset their emissions. An area may be a nonattainment area for one pollutant and an attainment area for others. This dataset establishes the spatial boundaries of each nonattainment and maintenance area. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Nonattainment Areas for Sulfur Dioxide Pollution, United States and Territories, 2010. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/tb136th4875.

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  14. Title: Nonattainment Areas for Lead Pollution: United States and Territories, 2008

    Contributors:

    Summary: This polygon shapefile depicts nonattainment and maintenance areas for the United States and its Territories for the enforcement of the lead (Pb) 3 month average NAAQS, which is 0.15 micrograms per cubed meter. Exposure to lead (Pb) can occur through multiple pathways, including inhalation of air and ingestion of Pb in food, water, soil or dust. Excessive Pb exposure can cause seizures, mental retardation and/or behavioral disorders. A recent National Health and Nutrition Examination Survey reported a 78% decrease in blood lead levels from 12.8 to 2.8 ug/dL between 1976 and 1980 and from 1988 to 1991. This dramatic decline can be attributed to the reduction of leaded gasoline and to the removal of lead from soldered cans. Although this study shows great progress, infants and young children are especially susceptible to low doses of Pb, and this age group still shows the highest levels. Low doses of Pb can lead to central nervous system damage. Recent studies have also shown that Pb may be a factor in high blood pressure and in subsequent heart disease in middle-aged males. Lead gasoline additives, non-ferrous smelters, and battery plants are the most significant contributors to atmospheric Pb emissions. In 1993 transportation sources contributed 33% of the annual emissions, down substantially from 81% in 1985. Total Pb emissions from all sources dropped from 20,100 tons in 1985 to 4,900 tons in 1993. The decrease in Pb emissions from highway vehicles accounts for essentially all of this decline. The reasons for the decrease are noted below. Two air pollution control programs implemented by EPA before promulgation of the Pb standard in October 1978 have resulted in lower ambient Pb levels. First, regulations issued in the early 1970's required gradual reduction of the Pb content of all gasoline over a period of many years. The Pb content of the leaded gasoline pool was reduced from an average of 12.0 gram/gallon, to 0.5 gram/gallon on July 1, 1985, and still further to 0.1 gram/gallon on January 1, 1986. Second, as part of the EPA's overall automotive emission control program, unleaded gasoline was introduced in 1975 for automobiles equipped with catalytic control devices. These devices reduce emissions of CO, VOCs and NOx. In 1993, unleaded gasoline sales accounted for 99% of the total gasoline market. In contrast, the unleaded share of the gasoline market in 1984 was approximately 60%. These programs have essentially eliminated violations of the Pb standard in urban areas except those areas with Pb point sources. Programs are also in place to control Pb emissions from stationary point sources. Lead emissions from stationary sources have been substantially reduced by control programs oriented toward attainment of the PM-10 and Pb ambient standards. However, significant and ambient problems still remain around some Pb point sources, which are now the focus of new monitoring initiatives. Pb emissions in 1993 from industrial sources, e.g., primary and secondary Pb smelters, dropped by about 91% from levels reported in 1970. Emissions of Pb from solid waste disposal are down about 76% since 1970. In 1993, emissions from solid waste disposal, industrial processes and transportation were: 500, 2,300 and 1,600 short tons, respectively. The overall effect of the control programs for these three categories has been a major reduction in the amount of Pb in the ambient air. Additional reduction in Pb are anticipated as a result of the Agency's Multimedia Lead Strategy issued in February 1991. The goal of the Lead Strategy is to reduce Pb exposures to the fullest extent practicable. Title 40, Part 50 of the Code of the Federal Regulations lists the ambient air quality standard for lead. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. In United States environmental law, a nonattainment area is an area considered to have air quality worse than the National Ambient Air Quality Standards (NAAQS) as defined in the Clean Air Act Amendments of 1970 (P.L. 91-604, Sec. 109). Nonattainment areas must have and implement a plan to meet the standard or risk losing some forms of federal financial assistance or other consequences, such as industrial facilities being required to install pollution control equipment, enforce limits on their production and otherwise offset their emissions. An area may be a nonattainment area for one pollutant and an attainment area for others. This dataset establishes the spatial boundaries of each nonattainment and maintenance area. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Nonattainment Areas for Lead Pollution: United States and Territories, 2008. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/fd969wz6137.

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  15. Title: Nonattainment Areas for Ozone Pollution: United States and Territories, 2008

    Contributors:

    Summary: This polygon shapefile depicts nonattainment and maintenance areas for the United States and its Territories for the enforcement of the ozone (O3) 8 hour NAAQS, which is 0.075ppm. Ozone (O3) is a photochemical oxidant and the major component of smog. While O3 in the upper atmosphere is beneficial to life by shielding the earth from harmful ultraviolet radiation from the sun, high concentrations of O3 at ground level are a major health and environmental concern. O3 is not emitted directly into the air but is formed through complex chemical reactions between precursor emissions of volatile organic compounds (VOC) and oxides of nitrogen (NOx) in the presence of sunlight. These reactions are stimulated by sunlight and temperature so that peak O3 levels occur typically during the warmer times of the year. Both VOCs and NOx are emitted by transportation and industrial sources. VOCs are emitted from sources as diverse as autos, chemical manufacturing, dry cleaners, paint shops and other sources using solvents. The reactivity of O3 causes health problems because it damages lung tissue, reduces lung function and sensitizes the lungs to other irritants. Scientific evidence indicates that ambient levels of O3 not only affect people with impaired respiratory systems, such as asthmatics, but healthy adults and children as well. Exposure to O3 for several hours at relatively low concentrations has been found to significantly reduce lung function and induce respiratory inflammation in normal, healthy people during exercise. This decrease in lung function generally is accompanied by symptoms including chest pain, coughing, sneezing and pulmonary congestion. Title 40, Part 50 of the Code of the Federal Regulations lists the ambient air quality standards for ozone. The 8 hour standard is incorporated within the Ozone dataset. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. In United States environmental law, a nonattainment area is an area considered to have air quality worse than the National Ambient Air Quality Standards (NAAQS) as defined in the Clean Air Act Amendments of 1970 (P.L. 91-604, Sec. 109). Nonattainment areas must have and implement a plan to meet the standard or risk losing some forms of federal financial assistance or other consequences, such as industrial facilities being required to install pollution control equipment, enforce limits on their production and otherwise offset their emissions. An area may be a nonattainment area for one pollutant and an attainment area for others. This dataset establishes the spatial boundaries of each nonattainment and maintenance area. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Nonattainment Areas for Ozone Pollution: United States and Territories, 2008. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/vn426gx0851. The 8 hour standard is incorporated within the Ozone dataset.

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  16. Title: Nonattainment Areas for Sulfur Dioxide Pollution, United States and Territories, 1971

    Contributors:

    Summary: This polygon shapefile depicts nonattainment and maintenance areas for the United States and its Territories for the enforcement of the sulfur dioxide (SO2). There are 3 NAAQS for SO2: an annual arithmetic mean of 0.03 ppm (80 ug/m3); a 24 hour level of 0.14 ppm (365 ug/m3); and a 3 hour level of 0.50 ppm (1300 ug/m3). High concentrations of sulfur dioxide (SO2) affect breathing and may aggravate existing respiratory and cardiovascular disease. Sensitive populations include asthmatics, individuals with bronchitis or emphysema, children and the elderly. SO2 is also a primary contributor to acid deposition, or acid rain, which causes acidification of lakes and streams and can damage trees, crops, historic buildings and statues. In addition, sulfur compounds in the air contribute to visibility impairment in large parts of the country. This is especially noticeable in national parks. Ambient SO2 results largely from stationary sources such as coal and oil combustion, steel mills, refineries, pulp and paper mills and from nonferrous smelters. There are three NAAQS for SO2: . an annual arithmetic mean of 0.03 ppm (80 ug/m3); . a 24-hour level of 0.14 ppm (365 ug/m3); and . a 3-hour level of 0.50 ppm (1300 ug/m3). The first two standards are primary (health-related) standards, while the 3-hour NAAQS is a secondary (welfare-related) standard. The annual mean standard is not to be exceeded, while the short-term standards are not to be exceeded more than once per year. Title 40, Part 50 of the Code of the Federal Regulations lists the ambient air quality standard for sulfur dioxide. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. In United States environmental law, a nonattainment area is an area considered to have air quality worse than the National Ambient Air Quality Standards (NAAQS) as defined in the Clean Air Act Amendments of 1970 (P.L. 91-604, Sec. 109). Nonattainment areas must have and implement a plan to meet the standard or risk losing some forms of federal financial assistance or other consequences, such as industrial facilities being required to install pollution control equipment, enforce limits on their production and otherwise offset their emissions. An area may be a nonattainment area for one pollutant and an attainment area for others. This dataset establishes the spatial boundaries of each nonattainment and maintenance area. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Nonattainment Areas for Sulfur Dioxide Pollution, United States and Territories, 1971. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/ym219gb2804.

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  17. Title: Nonattainment Areas for Ozone Pollution: United States and Territories, 1990

    Contributors:

    Summary: This polygon shapefile depicts nonattainment and maintenance areas for the United States and its Territories for the enforcement of the ozone (O3)1 hourNAAQS, which is 0.12ppm. Ozone (O3) is a photochemical oxidant and the major component of smog. While O3 in the upper atmosphere is beneficial to life by shielding the earth from harmful ultraviolet radiation from the sun, high concentrations of O3 at ground level are a major health and environmental concern. O3 is not emitted directly into the air but is formed through complex chemical reactions between precursor emissions of volatile organic compounds (VOC) and oxides of nitrogen (NOx) in the presence of sunlight. These reactions are stimulated by sunlight and temperature so that peak O3 levels occur typically during the warmer times of the year. Both VOCs and NOx are emitted by transportation and industrial sources. VOCs are emitted from sources as diverse as autos, chemical manufacturing, dry cleaners, paint shops and other sources using solvents. The reactivity of O3 causes health problems because it damages lung tissue, reduces lung function and sensitizes the lungs to other irritants. Scientific evidence indicates that ambient levels of O3 not only affect people with impaired respiratory systems, such as asthmatics, but healthy adults and children as well. Exposure to O3 for several hours at relatively low concentrations has been found to significantly reduce lung function and induce respiratory inflammation in normal, healthy people during exercise. This decrease in lung function generally is accompanied by symptoms including chest pain, coughing, sneezing and pulmonary congestion. Title 40, Part 50 of the Code of the Federal Regulations lists the ambient air quality standards for ozone. The 1 hour standard is incorporated within the Ozone dataset. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. In United States environmental law, a nonattainment area is an area considered to have air quality worse than the National Ambient Air Quality Standards (NAAQS) as defined in the Clean Air Act Amendments of 1970 (P.L. 91-604, Sec. 109). Nonattainment areas must have and implement a plan to meet the standard or risk losing some forms of federal financial assistance or other consequences, such as industrial facilities being required to install pollution control equipment, enforce limits on their production and otherwise offset their emissions. An area may be a nonattainment area for one pollutant and an attainment area for others. This dataset establishes the spatial boundaries of each nonattainment and maintenance area. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Nonattainment Areas for Ozone Pollution: United States and Territories, 1990. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/fh042hq5479. The 1 hour standard is incorporated within the Ozone dataset.

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  18. Title: Freight Analysis Framework Regions: United States and Territories, 2013

    Contributors:

    Summary: This polygon shapefile contains United States freight analysis framework (FAF) regions. FAF domestic region level datasets and products provide information for states, state portions of large metropolitan areas and remainders of states. Metropolitan areas consist of Metropolitan Statistical Areas or Consolidated Statistical Areas as defined by the Office of Management and Budget. When a metropolitan area is entirely within a state or when a state's portion of a multi-state metropolitan area is large enough to support the sampling procedures in the Commodity Flow Survey, the area becomes a separate FAF region. Small single-state metropolitan areas and small portions of a multi-state metropolitan area are part of the State or Remainder of State. FAF has two metropolitan areas that are each divided into three FAF regions, four that are each divided into two FAF regions, and several that have small pieces combined with States or Remainders of States. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. The Freight Analysis Framework (FAF) integrates data from a variety of sources to create a comprehensive picture of freight movement among states and major metropolitan areas by all modes of transportation. The FAF region boundaries are a geographic database of state and metropolitan boundaries. The database includes boundaries for all 123 regions including Washington D.C. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Freight Analysis Framework Regions: United States and Territories, 2013. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/fq627kg2594.

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  19. Title: County Boundaries with Politicial Limit: United States and Territories, 2014

    Contributors:

    Summary: This polygon shapefile contains United States county boundaries with political limits extracted from the U.S. Census Bureau's MAF/TIGER Database (MTDB). The MTDB represents a seamless national file with no overlaps or gaps between parts, however, each TIGER/Line shapefile is designed to stand alone as an independent data set, or they can be combined to cover the entire nation. The primary legal divisions of most states are termed counties. In Louisiana, these divisions are known as parishes. In Alaska, which has no counties, the equivalent entities are the organized boroughs, city and boroughs, and municipalities, and for the unorganized area, census areas. The latter are delineated cooperatively for statistical purposes by the State of Alaska and the Census Bureau. In four States (Maryland, Missouri, Nevada, and Virginia), there are one or more incorporated places that are independent of any county organization and thus constitute primary divisions of their States. These incorporated places are known as independent cities and are treated as equivalent entities for purposes of data presentation. The District of Columbia and Guam have no primary divisions, and each area is considered an equivalent entity for purposes of data presentation. The Census Bureau treats the following entities as equivalents of counties for purposes of data presentation: Municipios in Puerto Rico, Districts and Islands in American Samoa, Municipalities in the Commonwealth of the Northern Mariana Islands, and Islands in the United States Virgin Islands. The entire area of the United States, Puerto Rico and the Island Areas is covered by counties or equivalent entities. The 2010 Census boundaries for counties and equivalent entities are as of January 1, 2010, primarily as reported through the Census Bureau's Boundary and Annexation Survey (BAS). This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. This data was sourced from the information contained in the Census Master Address File/Topologically Integrated Geographic Encoding and Referencing (MAF/TIGER) database. The content of the MAF/TIGER database is undergoing continuous census data updates and is made available to the public through a variety of TIGER/Line® shapefiles. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). County Boundaries with Politicial Limit: United States and Territories, 2014. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/zp894xx0678.

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  20. Title: Nonattainment Areas for Patriculate Matter Pollution: United States and Territories, 1990

    Contributors:

    Summary: This polygon shapefile depicts nonattainment and maintenance areas for the United States and its Territories for the enforcement of the particulate matter 10 (PM10) 24 hour NAAQS, which is 150 micrograms per cubed meter. For more detailed information on this dataset, see the Overview Description in the Resource Fields section of this metadata document. Air pollutants called particulate matter include dust, dirt, soot, smoke and liquid droplets directly emitted into the air by sources such as factories, power plants, cars, construction activity, fires and natural windblown dust. Particles formed in the atmosphere by condensation or the transformation of emitted gases such as SO2 and VOCs are also considered particulate matter. Based on studies of human populations exposed to high concentrations of particles (sometimes in the presence of SO2) and laboratory studies of animals and humans, there are major effects of concern for human health. These include effects on breathing and respiratory symptoms, aggravation of existing respiratory and cardiovascular disease, alterations in the body's defense systems against foreign materials, damage to lung tissue, carcinogenesis and premature death. The major subgroups of the population that appear to be most sensitive to the effects of particulate matter include individuals with chronic obstructive pulmonary or cardiovascular disease or influenza, asthmatics, the elderly and children. Particulate matter also soils and damages materials, and is a major cause of visibility impairment in the United States. Annual and 24-hour National Ambient Air Quality Standards (NAAQS) for particulate matter were first set in 1971. Total suspended particulate (TSP) was the first indicator used to represent suspended particles in the ambient air. Since July 1, 1987, however, EPA has used the indicator PM-10, which includes only those particles with aerodynamic diameter smaller than 10 micrometers. These smaller particles are likely responsible for most of the adverse health effects of particulate matter because of their ability to reach the thoracic or lower regions of the respiratory tract. Title 40, Part 50 of the Code of the Federal Regulations lists the ambient air quality standard for particulate matter. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. In United States environmental law, a nonattainment area is an area considered to have air quality worse than the National Ambient Air Quality Standards (NAAQS) as defined in the Clean Air Act Amendments of 1970 (P.L. 91-604, Sec. 109). Nonattainment areas must have and implement a plan to meet the standard or risk losing some forms of federal financial assistance or other consequences, such as industrial facilities being required to install pollution control equipment, enforce limits on their production and otherwise offset their emissions. An area may be a nonattainment area for one pollutant and an attainment area for others. This dataset establishes the spatial boundaries of each nonattainment and maintenance area. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Nonattainment Areas for Patriculate Matter Pollution: United States and Territories, 1990. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/kd518dq2303.

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