"Last week the U.S. Environmental Protection Agency proposed new legislation that would impose stricter air-quality standards for ground-level ozone concentrations. If implemented, counties and states would have up to 20 years to comply with the new regulations, which would work in tandem with other regulations, such as those on vehicle fuel economy, to reduce health risks and curb greenhouse gas emissions that contribute to global warming trends. Ozone, a key component of smog, is known to cause lung damage, and in 2008 at the request of the EPA, the National Research Council studied the link between ozone and premature death. The resulting report, Estimating Mortality Risk Reduction and Economic Benefits from Controlling Air Pollution, indeed found sufficient evidence that even short-term exposure to ozone can cause increased risk of mortality. Another National Research Council report, Air Quality Management in the United States, recommended that EPA use an approach to target groups of pollutants instead of individual ones and that revised or new regulations also should consider how air pollution travels from state to state and across international borders."