Air Pollution

Jet engines, having become cleaner since the Environmental Protection Agency (EPA) set hydrocarbon standards in 1982, continue to have a minimal impact on ground-level (defined as 0 to 3,000 feet) air pollution. Supersonic aircraft, however, can now fly in the upper ozone layer that protects all living things from the harmful effects of ultraviolet light. While few supersonic aircraft are in operation today, several hundred could be in service within the next 25 years, and their engine emissions could substantially reduce the ozone layer, making people more susceptible to skin cancer. In addition, preliminary but unproven research suggests that jet aircraft emissions may be adding to greenhouse gas problems. Because of these concerns, EPA must continue to closely monitor global pollution from jet aircraft so that it will be ready to develop a federal response to minimize any environmental consequences that arise.

GAO found that: (1) jet aircraft emissions account for only 0.3 percent of hydrocarbon, nitrogen oxide, and carbon monoxide emissions produced nationwide; (2) jet engines built after 1982 produce 58 percent less of all three types of emissions; (3) officials from four cities with air pollution problems stated that jet aircraft emissions were a small source of pollution and it was more cost-effective to focus on large sources of pollution; (4) jets currently contribute a relatively small amount of carbon dioxide emissions to global pollution; (5) the National Aeronautics and Space Administration (NASA) agrees that supersonic jets flying in the stratosphere are not a threat to the upper ozone layer, but if fleet projections are correct and technology developments cannot reduce emissions to offset the increases it may be a concern in the future; (6) due to concerns regarding the potential impact of jet aircraft emissions at the global level, the Environmental Protection Agency (EPA) plans to add a staff position to monitor NASA research on the effect of jet emissions on upper-level ozone depletion problems; (7) EPA establishes aircraft emission standards and directs the Federal Aviation Administration (FAA) to enforce those standards; (8) EPA established a hydrocarbon standard in 1982 that reduced hydrocarbon and carbon monoxide emissions from jet engines; (9) FAA also represents the U.S. position on jet aircraft emissions in the international forum that sets ground-level emissions standards; and (10) NASA studies the global impact of jet aircraft emissions and is developing engine technology to reduce such emissions.