The years 2003, 2004 and 2005 showed the first truly split picture for the nation’s air quality since the American Lung Association started these annual report cards. Both of the nation’s most widespread and dangerous pollutants tracked in decidedly different directions in the eastern U.S.—ozone went down, but particle pollution went up. In the west, the direction is clearly toward lower pollution levels for both pollutants.

Good news—less ozone everywhere.
Ozone grades improved significantly in many parts of the U.S., especially in the eastern half. Grades of F—common among many states in the past—improved to passing grades, even among some of the counties that had historically been among the most ozone-polluted. Many states saw a dozen or more counties improve into passing grades, including Kentucky, Michigan, North Carolina, New York and Ohio.

These improvements appeared even in the cities that face the most ozone pollution. Los Angeles metropolitan area returned to the top of the most polluted list, but reduced the number of days that its residents suffered from the nation’s worst ozone levels. In eastern cities, a combination of favorable weather and reduced emissions dropped some cities off the most polluted list for the first time. For example, ten cities in the eastern U.S. dropped off the list of the 25 most polluted for ozone, including Knoxville, TN, which had been a fixture on the list from the first report.

What made the difference? Favorable weather and lower emissions, primarily. Cooler summers in 2003 and 2004 combined with a widespread cut in nitrogen oxide emissions—one of the raw ingredients in ozone pollution—to make measurable differences in the ozone levels in much of the east. Cuts in the nitrogen oxide emissions in power plants that began in 2002 meant that the ozone levels stayed lower even though 2005 was a hot summer in much of the east.

In the west—particularly in California—continued aggressive measures to slice emissions from wide range of air pollution sources contributed to fewer ozone days. Even with the improvements, California returns nine cities to the list of the most polluted by ozone. Fourteen of the most ozone-polluted counties are also in California.

Changes in the Ozone Rankings
Los Angeles returned to the top of the list of cities most polluted by ozone despite having fewer days with unhealthy ozone levels. The same cities remain in the top eight although the rankings shifted slightly. Bakersfield, Visalia-Porterville, Fresno-Madera, Merced, Sacramento, Hanford-Corcoran, Modesto and El Centro are California cities on the most ozone-polluted list. Texas has three cities on the list: Houston, Dallas-Ft. Worth and Beaumont-Port Arthur.

Widespread ozone reductions meant that it took fewer total days to be among the nation’s most ozone polluted in this report. The nation’s improvements in ozone appear also in the list of cities dropped off the worst for ozone list, some for the first time: Knoxville, TN; Pittsburgh, PA; Columbus, Youngstown and Cincinnati, OH; Raleigh, NC; San Antonio, TX; South Bend, IN; Huntingdon, WV; Buffalo, NY. Returning to the list are Atlanta, GA, and Chicago, IL, although they had fewer high ozone days than in previous reports. Their return to the list comes from the overall improvement of other cities. Moving onto the most ozone polluted list are metropolitan newcomers: Phoenix-Mesa-Scottsdale, AZ; Las Vegas, NV; Milwaukee, WI; St. Louis, MO-IL; El Centro, CA; Kansas City, MO-KS; Beaumont-Port Arthur, TX; and Grand Rapids, MI.

Bad news—more particle pollution in the east.
Unfortunately, levels of particle pollution rose in the eastern United States, likely because coal-fired power plants increased their production of electricity by seven percent.¹ Across the nation, 334 counties had higher real levels of year-round particle pollution in 2003-2005 compared to 2002-2004, while only 108 monitored cleaner air. Roughly two-thirds of the counties showing increases were in the eastern U.S. In the eastern states levels rose in 2003-2005, in stark contrast to the consistent decline in levels seen in the period from 2002-2004, as shown by both the analysis that the Lung Association completed for this report and data prepared by the U.S. Environmental Protection Agency.

In this report, looking simply at the number of Fs masks the growth of this problem. Many counties maintained a failing grade, but their air quality worsened. Alabama, Florida, Georgia, Illinois, Indiana, Kentucky, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee and Virginia all had over a dozen counties with increases in year-round particle pollution during this period.

This trend is especially troubling in light of U.S. EPA’s failure to tighten the annual particle pollution standard in 2006. For this report, the Lung Association continued to use U.S. EPA’s definition of unhealthy levels—officially the National Ambient Air Quality Standard—as the basis for the annual particle pollution grades. However, the Lung Association and many other public health groups, environmental groups and medical societies had urged EPA to use a much tighter standard. Under EPA’s official standard for unhealthy particle pollution, only 73 counties were given failing grades for year-round exposure. Under the level recommended by the American Lung Association and much of the medical community, 299 counties have dangerous air pollution year-round.

Fortunately, outside of the eastern U.S., particle levels continue to drop, even in areas which rank historically high in particle pollution. California showed the most improvement with 32 counties reducing their year-round particle pollution levels, including some improving by over 10 percent.

Changes in the particle pollution rankings
Los Angeles remained atop both lists of cities most polluted by particle pollution, though its level of year-round particle pollution actually improved from the last report. Pittsburgh, PA, moved up to the number two slot in both lists, triggered by increases in pollution levels in that metropolitan area. Other eastern metropolitan areas worsened significantly in particle levels, including: Birmingham, AL; Detroit, MI; Cleveland, OH; Cincinnati, OH; Indianapolis, IN; Atlanta, GA; Lancaster, PA; Harrisburg, PA; and Chicago, IL. By contrast, many California cities reduced their particle pollution and improved their place on the list of most polluted year-round including Visalia-Porterville; Fresno-Madera; Hanford-Corcoran, CA. Dropping off both particle lists for the first time was Merced, CA.

The list for most polluted by short-term particles includes several cities where the smoke from burning firewood in the winter puts their population at risk: Logan, UT-ID; Salt Lake City-Ogden-Clearfield, UT; Eugene-Springfield, OR; and Provo-Orem, UT. An unusually widespread wildfire in 2004 put Fairbanks, AK, on the list for most polluted by short-term pollution with the report’s only maroon days, signaling very hazardous air pollution levels.²

The Most Polluted Counties
California and Texas lead for ozone pollution.
Among the most polluted counties, Riverside County, CA remains the most burdened by particle pollution, while San Bernardino County, CA has the worst ozone levels. Three California counties appear on all three lists of worst polluted in addition to these two: Los Angeles County, Fresno County and Kern County. California and Texas counties occupy the top 17 places in the list of counties most polluted by ozone. Fourteen of the 25 most ozone polluted counties are in California, five are in Texas, and New Jersey and Louisiana have two counties each on that list.

The Midwest and the Mid-Atlantic lead for particle pollution.
Particle pollution is more widespread. Many states in the Midwest and Mid-Atlantic have among the highest levels of annual particle pollution. Nine Midwestern counties (in Ohio, Michigan, Illinois and Indiana) and seven Mid-Atlantic counties (in Pennsylvania, Maryland, and West Virginia) are on this list. For worst exposure to short-term levels, California has the most counties on the list, with nine. Five counties on the list for worst short-term exposure are in the Midwest, in Ohio,  Illinois, Indiana and Michigan. Five others are in the Mid-Atlantic, in Pennsylvania, New Jersey and Maryland. Utah has the three counties on the worst for short-term particles list.

Several counties improved enough in ozone levels to drop off the most polluted list, including Anne Arundel County, MD; Fairfax County, VA; New Haven County, CT; Blount County and Sevier County, TN. Falling off the annual particle pollution list were Orange County and Merced County, CA. Falling off the short-term particle pollution list were Klamath County, OR; Tulare County, Kings County and Stanislaus County, CA; and Jefferson County, KY.

The Cleanest Cities
Only three cities made all three lists of cleanest cities in the nation: Fargo-Wahpeton, ND-MN; Rapid City, SD; and Salinas, CA. Miami-Fort Lauderdale-Miami-Beach, FL is the largest city listed among the cleanest for particle pollution, followed by Tucson, AZ and Colorado Springs, CO. Phoenix-Mesa-Scottsdale, AZ is also on the list of cleanest cities for long-term particle pollution, despite its presence on the list of the cities most polluted by ozone.

Forty-five cities had no days of ozone in unhealthful ranges. The largest of these metropolitan areas are Portland-Vancouver-Beaverton, OR; Honolulu, HI; and Omaha-Council Bluffs-Freemont, NE-IA. Twenty-five cities had no days with unhealthful particle pollution levels. Cheyenne, WY, topped the list as the cleanest city for year-round particle pollution with the lowest average concentration.