NOTES ON AIR POLLUTION AND GLOBAL WARMING
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Under Massachusetts v. U.S. Environmental Protection Agency (2007), the U.S. Supreme Court
ruled that the Clean Air Act (section 202) authorizes EPA to regulate greenhouse emissions , and
the agency can avoid setting such standards only if it finds that greenhouse gas emissions do not
contribute to climate change, or it can provide some reasonable explanation as to why the
agency cannot or will not exercise its discretion to make such a finding.
A greenhouse gas is any of the atmospheric gases that contribute to the greenhouse effect by
absorbing infrared radiation produced by solar warming of the Earth's surface. They include
carbon dioxide (CO2), methane (CH4), nitrous oxide (NO2), and water vapor. Although
greenhouse gases occur naturally in the atmosphere, the elevated levels especially of carbon
dioxide and methane that have been observed in recent decades are directly related, at least in
part, to human activities such as the burning of fossil fuels and the deforestation of tropical
forests.
In 2003 EPA denied a petition asking EPA to regulate greenhouse gas emissions from new motor
vehicles. It concluded that greenhouse air pollutants (particularly carbon dioxide) are not “air
pollutants,” and therefore EPA has no authority to regulate. EPA tried to justify by arguing that
Bush administration preferred voluntary actions and incentives rather than regulatory
mandates. Also if U.S. established emission standards for greenhouse gases, the President
might not be able to persuade countries like China to reduce their emissions, and U.S. economic
interest would be harmed. Also, EPA claimed that casual link between greenhouse gases and
climate change could not be unequivocally established.
In march 2008 EPA has now officially concluded that greenhouse gases are a health risk
Clean Air Act says EPA may grant a waiver to a state to adopt more stringent vehicle emission
standards. California has proposed cutting exhaust emissions for cars and light trucks by 25%
and for sport utility vehicles by 18%, beginning with 2009 models. Some 13 other states want to
adopt California’s proposed standards. California’s request for a waiver made in 2005 (which
prompted over 50,000 comments); no response from EPA under the Bush administration.
Last year (2008) California became first state to pass a law requiring an across-the-board 20%
reduction in greenhouses gases by 2020.
Industry groups want single national standard since national greenhouse gas emissions
standards for new vehicles now seem inevitable.
Some groups favor “cap and trade” market-based approach; others favor carbon tax.