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National Air Toxics Assessment

2005 NATA: Assessment Results

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2005 State-specific NATA Emissions

The National Emissions Inventory (NEI) is EPA’s comprehensive, facility-specific emissions inventory database. It is used to support air quality modeling and other activities within the Air Toxics Program. For the 2005 NATA, the point source inventory used was developed by starting with the 2005 NEI.

The following PDF files may also be useful for understanding the 2005 NEI:

The 2005 NEI data have undergone reviews by regional, state, local, and tribal agencies. Those comments and additional changes are summarized in the files below:

The final 2005 NATA inventory files accessed below provide the pollutant-specific tons/year emissions and modeling data for the year 2005 for every state (including Puerto Rico, the Virgin Islands, and the District of Columbia) and for every county in each state. These tables also provide a breakdown of the emissions by source sector, i.e., stationary point and nonpoint, and mobile sources. These files provide the emissions for all air toxics assessed, with the exception of diesel PM. The diesel PM emissions are summarized for each state and accessed by clicking on the Summary of DPM Emissions (ZIP) (215 K, MS Access 2007)

The document, 2005 NATA Air Toxics Pie Charts (PPT) (29 pp, 3 MB) , provides the percent contribution of each emission source to the total emissions of each air toxic in the inventory. Note that while forest and wildfires are included in the emission inventory, these emissions were NOT modeled and thus, not included in the risk estimates in the 2005 NATA.

NOTE: Emission inventories submitted by State, Local, and Tribal agencies may vary in the level of detail and completeness. For this reason, NATA risk estimates should not be compared across these agencies in different geographic regions without considering differences in their respective inventories.

After you select a state, press download to open or save the associated MS Access ZIP file. Please note that file sizes range from 390K to 15MB

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2005 County-Level Modeled Ambient Concentrations, Exposures, and Risks

The following tables present the EPA's 2005 national-scale assessment estimates for ambient concentrations, exposures, and risks across the United States plus Puerto Rico, the Virgin Islands, and the District of Columbia using 2005 national air toxics emission inventory as input to the models ASPEN, AERMOD, CMAQ, and an inhalation exposure model (HAPEM5). Exposure modeling takes into account that people move from one location to another (e.g., from outside environments to inside environments).

Risk Results:

The Nationwide, County-level Results, present each endpoint risk or hazard quotient estimate by state and county. Additionally, the data are presented by source sector (i.e., stationary, mobile, background, and secondary pollutant). The County-level Pollutants files present individual pollutant results for each state and county in the assessment. Conversely, the State Summaries present the results by state and county for all pollutants.

While the files, 2005 NATA US Neurological Risk County and 2005 NATA US Respiratory Risk County, present the noncancer results specifically for those endpoints, the County-level Pollutants files provide the noncancer information for other endpoints (e.g., reproductive system), when a dose-response value was available for that air toxic. Information on these additional endpoints, (e.g., the endpoint and critical concentration used for each), can be found in the file,  Health Effects Information (PDF). For a more complete discussion and list of RfC concentrations used in this NATA, see section 5.0 and Appendix-H in the Technical Methods Document
 
The NATA results are identified as “point” and “nonpoint” stationary sources rather than “major” and “area” sources. The point and nonpoint designations reflect the way each source of emissions was modeled. For example, larger sources as well as some smaller sources, i.e., area sources in the inventory, are included in the point source summaries if the location of their emissions was identified with latitude and longitude coordinates. Smaller, area source emissions where a specific location for the emission source was not known, were presented as nonpoint sources. Emissions from these nonpoint sources, which are generally inventoried on a county-wide basis, are allocated to a census tract for modeling using appropriate surrogates. This nonpoint source approach was used for mobile source emissions as well. For the airports modeled in NATA, the locations of these emissions were actually known and thus, were modeled at their actual locations. However, the risk results for airports are summarized under the nonroad, mobile source category.

Nationwide, County-level Results
County-level Pollutants
After you select a pollutant, press download to open or save the associated MS Access ZIP file. Please note that file sizes range from .2MB to 1.5MB.
 
After you select a state, press download to open or save the associated MS Access ZIP file. Please note that file sizes range from 390K to 15MB.

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2005 Tract-Level Modeled Ambient Concentrations, Exposures, and Risks

The census tract was the smallest spatial resolution for the 2005 NATA. The files below provide ambient concentrations, exposures and risks for each of the endpoints listed. These results also provide the contribution of each source sector to the total risk or hazard quotient. The tract-level results are also presented by pollutant and by state.

Nationwide, Tract-level Results (zipped MS ACCESS format)

Note: Cancer risks presented in the above Onroad and Nonroad Mobile Risk files identify cancer risks that are not due to the diesel PM component of diesel engine emissions. These cancer risks are due to the other air toxics, such as benzene, which are found in the gaseous component.

Tract-level Pollutants
After you select a pollutant, press download to open or save the associated MS Access ZIP file. Please note that file sizes range from 1.4 MB to 28 MB.
 
State Summaries
After you select a state, press download to open or save the associated MS Access ZIP file. Please note that file sizes range from 1.5 MB to 400 MB. this is right
 

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