AT-RISK AREAS AT-RISK AREAS In 2002, 2.2 million Americans lived in neighborhoods where air pollution caused an excess cancer risk greater than 100 in 1 million, a level EPA considers unacceptable. A look at the states and U.S. territory with the largest number of people living in such neighborhoods: State Pop. at highest risk N.Y. 862,012 Calif. 445,781 Ore. 140,169 Wash. 105,454 Ala. 76,452 Pa. 73,046 Ind. 57,498 Puerto Rico 54,161 Ill. 44,785 Texas 37,399 Source: EPA (UPDATE, July 26: California officials have challenged a U.S. Environmental Protection Agency air pollution assessment that identified a neighborhood in Cerritos as facing the nation's highest cancer risk from air emissions. After the EPA released its assessment, which USA TODAY reported on June 24, California's South Coast Air Quality Management District reviewed the data and found "gross overestimation" in Cerritos and several other places because the EPA relied on outdated or incorrect emission data. The AQMD also tested emissions from a facility the EPA report blamed for much of the risk in Cerritos and found its current pollution levels were far lower than those the EPA cited. The EPA sent a letter July 16 to Cerritos Mayor Bruce Barrows saying emissions from the facility "are now known to be at a safe level." The letter said the EPA would investigate further and promised "to continue to improve the accuracy" of the information it releases.) The government's latest snapshot of air pollution across the nation shows residents of New York, Oregon and California faced the highest risk of developing cancer from breathing toxic chemicals. The results, compiled by the Environmental Protection Agency, represent the most sweeping analysis to date of the state of the nation's air. The analysis is based on emissions from 2002, the latest year for which the EPA had detailed estimates of pollution from across the nation. CLOSER LOOK: A county-by-county cancer risk map YOUR NEIGHBORHOOD: See data for your area MORE INFORMATION: Toxic air pollutants CANCER FORUM: Share your story FULL COVERAGE: Toxic air and America's Schools Called the National-Scale Air Toxics Assessment, or NATA, the study is used by the EPA to identify parts of the country where residents could face the greatest health threats from air pollution. The assessment found air pollution generally presented high health risks around major cities such as New York and Los Angeles — although some of the counties where the air was even worse were in rural areas of Mississippi and Kentucky. Almost 2.2 million people lived in neighborhoods where pollution raised the risk of developing cancer to levels the government generally considers to be unacceptable. There, toxic chemicals were significant enough that people who breathed the air throughout their lives faced an extra 100-in-1 million risk of getting cancer. Many of those people — about 847,000 — lived in New York City. The worst single neighborhood lay between two freeways in Cerritos, Calif., outside Los Angeles. There, the EPA estimated an excess cancer risk of more than 1,200 in 1 million, 34 times the national average. Pollution threats are still less pronounced than risks such as smoking, says John Walke, clean air director for the Natural Resources Defense Council. Even so, the assessment "shows we have a problem we should expect government to solve by reducing toxic air pollution, because it makes a lot of people sick." Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more