Technology Transfer Network 

2002 National-Scale Air Toxics 

Assessment

Contact Us Search: All EPA This Area 

You are here: EPA Home Air & Radiation TTN Web - Technology Transfer Network Air 

Toxics Web site National-Scale Air Toxics Assessments 2002 National-Scale Air Toxics 

Assessment 

Announcement

August 17, 2009 - EPA has 

updated the 2002 NATA 

results for census tracts near 

Cerritos, CA based on 

corrected emissions and 

location data.

● Updated Table

● Updated Map

Maps

● Summary Risk Maps

● 2002 Google Earth Risk 

Maps

In June 2009, EPA released the 

results of its 2002 national-scale 

assessment of air toxics emissions. 

The purpose of the national-scale 

assessment is to identify and 

prioritize air toxics, emission 

source types and locations which 

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 national-scale assessment modeled 180 of the 187 Clean Air Act air 

toxics (PDF) (3pp, 15k) plus diesel particulate matter (diesel PM). The 

assessment includes four steps that focus on the year 2002: 

1. Compiling a national emissions inventory of air toxics emissions 

from outdoor sources 

2. Estimating ambient 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 2002 assessment, see the Fact Sheet and 

2002 National-Scale Air Toxics Assessment | Technology Transfer Network Air Toxics Web site | US EPA

● Air Toxics Web site

❍ NATA Overview

❍ NATA 1996

❍ NATA 1999

❍ NATA 2002

❍ 2002 Assessment 

Home

❍ About the 2002 

Assessment

❍ Frequent Questions

❍ Assessment Methods

❍ 2002 Results

❍ Risk Characterization

❍ Limitations

❍ Air Toxics Reduction

❍ Glossary

❍ Site Map

http://www.epa.gov/ttn/atw/nata2002/index.html (1 of 2) [12/31/2009 1:11:32 PM]

● Share
2002 National-Scale Air Toxics Assessment | Technology Transfer Network Air Toxics Web site | US EPA

Summary of Results pages. The Summary of Results page also provides 

national maps of cancer and noncancer effects.

The emissions used in the current assessment are from the 2002 emission 

inventory which is the most complete and up-to-date available. Working 

with the states, EPA updates air toxics emission inventories every 3 years. 

The next national-scale assessment will focus on 2005 emissions and will be 

available in late 2009 or early 2010.

As part of EPA's National Air Toxics Assessment activities, EPA conducted its 

first national-scale assessment for the year 1996. That assessment included 

33 air pollutants (a subset of 32 air toxics on the Clean Air Act's list of 187 

air toxics plus diesel particulate matter (diesel PM). 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 

the assessment of 177 hazardous air toxics plus diesel particulate matter. 

Top of page

Frequent Questions

Glossary | Site Map

EPA Home Privacy and Security Notice Contact Us

Last updated on Tuesday, August 18th, 2009.

http://www.epa.gov/ttn/atw/nata2002/index.html

Print As-Is

http://www.epa.gov/ttn/atw/nata2002/index.html (2 of 2) [12/31/2009 1:11:32 PM]