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2005 National-Scale Air Toxics Assessment


NATA video modules provide an overview, demonstration of how to navigate 2005 results, and examples of how NATA is used.

The NATA 2005 assessment includes a Technical Methods Document (TMD). This document presents more details on the sources of data, methods, models, and assumptions used than is available on this website.

In 2011, EPA released the results of its 2005 national-scale assessment (NATA) of air toxic emissions. The purpose of NATA is to identify and prioritize air toxics, emission source type, and locations that are of greatest potential concern in terms of contributing to population risk. EPA uses the results of these assessments in many ways, including:

  • To work with communities in designing their own local-scale assessments,
  • To set priorities for improving data in emissions inventories, and
  • To help direct priorities for expanding and improving the network of air toxics monitoring.

The 2005 NATA provides information on 177 of the 187 Clean Air Act air toxics (PDF) (3pp, 15k) plus diesel particulate matter (diesel PM was assessed for noncancer only). The assessment includes four steps that focus on the 2005 emissions year:

  1. Compiling a national emissions inventory of air toxics emissions from outdoor sources
  2. Estimating ambient and exposure concentrations of air toxics across the United States
  3. Estimating population exposures across the United States
  4. Characterizing potential public health risk due to inhalation of air toxics including both cancer and noncancer effects

For information summarizing the 2005 assessment, see the Fact Sheet and Summary of Results (PDF format,0.48 MB). The Summary of Results document also provides national maps of cancer and noncancer effects such as in the text box to the right.

As part of EPA's National Air Toxics Assessment activities, EPA conducted its first national-scale assessment (NATA) for 1996. That assessment included 32 air toxics on the Clean Air Act's list of 187 air toxics plus diesel PM (noncancer results only). In February of 2006, EPA released the second of its NATA assessments. This assessment was based on emissions from the 1999 National Emission Inventory and included results for 177 air toxics plus diesel PM (noncancer results only). In June of 2009, EPA released its third NATA, which was based on emissions estimated for 2002. This assessment included results for 180 air toxics plus diesel PM (noncancer results only).

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