As reported by the Agricultural Retailers Association (ARA), Greenhouse gas emissions in the United States decreased by 1.5 percent in 2006 from the year before, largely due to a warm winter and cool summer, rising fuel prices and the use of more energy from renewable sources, the Environmental Protection Agency (EPA) said in a report released March 7. Overall emissions decreased in 2006 by 111.8 million metric tons of carbon dioxide equivalent from the 2005 total of 7,313.7 million metric tons. The 2006 figure still represents a 14.1 percent growth in emissions since 1990. A large percentage of greenhouse gas emissions-6,078.4 out of 7,201.9 million metric tons-were produced by the energy industry, the report found. Carbon dioxide continued to be the most prevalent greenhouse gas, accounting for 83 percent of the United States' greenhouse gas emissions in 2006. The inventory reports U.S. emissions of the six main greenhouse gases: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride.

Carbon dioxide emissions decreased by 1.9 percent since 2005, but the report noted an upward trend of increases of about 1.1 percent per year since 1990. The largest source of CO2, and of overall greenhouse gas emissions, was fossil fuel combustion directly indicating changes for alternate energy sources is necessary. The EPA announced March 12 that it is tightening the primary national ambient air quality standard for ozone. The new standard is 0.075 parts per million, which replaces the existing standard of 0.08 part per million. EPA estimates that the revised ozone standards-both the primary standard to protect public health and a secondary standard aimed at preventing environmental degradation-will yield health benefits valued between $2 billon and $19 billion. "America's air is cleaner today than it was a generation ago. By meeting the requirement of the Clean Air Act and strengthening the national standard for ozone, EPA is keeping our clean air progress moving forward," said EPA Administrator Stephen L. Johnson.