Since 1988, the toxic emissions of American industry have declined more than 35 percent, even as production of petrochemicals has increased.

While emissions have declined in three out of the last four years, 2009 was exceptional.

Total emissions had declined by 48 percent since 1970, Bush administration officials said, adding that the new source review had been incidental to that trend.

Lead emissions from gasoline have declined by 95% since the EPA began regulating clean air standards more than three decades ago.

Similarly, in areas where local emissions have declined but the acidity of rainfall has increased, this points to long-distance transport of pollutants into the area.

Toxic emissions declined by half; days of dangerous smog levels declined by two-thirds.

When industrial production declined, emissions of air pollutants from those sources also declined, although the amount of motor vehicles on the roads skyrocketed.

National average air quality continues to improve as emissions decline through 2008.

The urea-formaldehyde emissions decline over time and significant levels should no longer be present in the homes today.

Indeed, emissions of the major pollutants addressed by the act have declined substantially.