· The number of days exceeding the eight-hour ozone standard in Los Angeles during the last 30 years has dropped significantly, from 201 in 1975 to 75 in 2005.
· In the Washington, D.C., area, not a single Code Red day for poor air quality was declared over the summer of 2005, despite the hot temperatures. Ozone levels are falling in 19 eastern states where smog has been a recurring problem in the summer.
· Automobile tailpipe emissions from carbon monoxide have been reduced by 96 percent since the 1950s. These emissions rates are per mile -- not an average for the whole auto fleet.
In other areas:
· In 2005, the Center for Disease Control reported declining amounts of chemicals in human blood and urine almost across the board.
· Grizzly bears may be coming off the endangered species list. The largest population in the continental United States outside of Alaska lives in and near Yellowstone National Park, where the grizzly population has grown from about 200 in the early 1980s to about 600 today.
· The Environmental Protection Agency (EPA) found significant declines in acid rain in every region except New England, where there was no change from 1990 levels.
Source: "2006 Index of Leading Environmental Indicators; 11th Edition," Pacific Research Institute and American Enterprise Institute, April 12, 2006.