US air quality continues to improve

This trend toward cleaner air has continued since EPA’s formation in 1970, while during the same time, the gross domestic product has increased 158%, miles travelled by cars and trucks have increased by 143%, and energy consumption has increased by 45%. The report, which focuses on national long-term trends in air pollution, not the air quality status of individual cities, shows that all six of the major air pollutants regulated by EPA under the Clean Air Act gradually decreased between 1991-2000. Lead concentrations decreased by 50%, carbon monoxide by 41%, sulphur dioxide by 37%, particulate by 19%, nitrogen dioxide by 11%, and

one hour concentrations of smog decreased 10%.

However, certain types of air pollution continue to present a challenge for some areas of the country, especially smog levels which have actually increased in the southern and north-central regions of the US in the past 10 years. EPA highlighted several steps toward cleaner air that it has taken in the last 12 months, including a rule to reduce emissions from large trucks and buses (see related story), and sulphur levels in fuel (see related story). However, the Agency has also permitted an increase in vehicle emissions of smog-producing volatile organic compounds (VOCs) in order to keep petrol prices down (see related story).

“The Bush Administration is committed to building on the clean-air progress of the last 30 years,” commented EPA Administrator Christie Whitman. “One way we’re going to accomplish this is to work with Congress on a proposal for multi-emissions legislation that will further reduce air pollution from power plants while providing industry the flexibility it needs to produce clean, efficient energy.” She added that she would work with the state’s National Governors Association which has called upon Congress to establish a flexible, market-based programme to significantly reduce and cap emissions of sulphur dioxide, nitrogen oxides and mercury and provide market-based incentives such as emissions trading credits to help achieve the required reductions.

EPA also recently approved smog reduction plans for five major metropolitan areas: Houston, Milwaukee, Chicago, Baltimore and Philadelphia, although it postponed proposed actions in New York City in light of the 11 September attacks. The plans include detailed modelling efforts to show the level of reductions needed to meet the national one-hour ozone standard and the adopted programmes and commitments to achieve the needed emission reductions. They include incentives for diesel equipment operators to install cleaner equipment, new energy efficiency standards, voluntary mobile emissions programmes, and cap and trade programmes allowing industry to trade allowances.