. Pollution

ollution is the process of making the environment dirty, dangerous, or in other ways unpleasant or unhealthy for people, animals, and plants. Flying contributes to pollution through the emissions from airplane engines and through noise and environ­mental damage around airports.

Transportation is a major source of air pollution in the United States and other industrial nations. Jet engines, like automobile engines, burn carbon-based fuel. During the burning process or com­bustion, airplane engines give off car­bon monoxide, carbon dioxide, hydro­
carbons (compounds of carbon and hydrogen), and nitrogen oxides (com­pounds of nitrogen and oxygen). These substances are all pollutants, and too many of them in the atmosphere can have damaging effects on people, on animals, on plants, and even on build­ings. Polluted air is unhealthy to breathe. Heavy concentration of pollu­tants around cities can form smog, reducing visibility and air quality and endangering the health of people.

Scientists believe that carbon-based pollutants are causing damage to Earth’s atmosphere. A buildup of carbon diox­ide gas in the atmosphere from burning fossil fuels-such as gasoline and avia­tion fuel-is thought by many experts to contribute to the greenhouse effect. The gases trap heat from sunlight, therefore contributing to global warming and climate change.

High-flying jet aircraft emit those gases close to Earth’s surface and at higher altitudes. The primary gas in jet engine emissions is carbon dioxide, which can linger in the atmosphere for up to a hundred years. Aviation emis­sions account for up to 4 percent of all global carbon dioxide emissions from the burning of fossil fuels. Carbon diox­ide combined with other airplane exhaust gases could be having a much greater impact on the air than carbon dioxide alone.

Most legislation passed in recent decades to cut air pollution has been directed at industry and automobiles. With aviation growth at around 5 per­cent a year, however, the development of cleaner aircraft engines is vital.

Airports also are a source of pollu – tion-not simply because of the number of airplanes using them, but because a busy airport draws in thousands of cars and trucks every day. Airport buildings and handling facilities consume a lot of energy and produce a lot of waste. Even the chemicals used to de-ice airplanes in winter pose a pollution risk to the soil and the water cycle.

NOISE POLLUTION

As air traffic increases, there are concerns about noise pollution. Anyone who has stood on a runway close to a jet plane taking off knows that it is very noisy. The loudness is measured in decibels. A jet plane taking off can reach 130 decibels. Supersonic planes also make a sonic boom. Protests about the boom ended airline plans to fly the Concorde on transcontinental super­sonic flights in the 1970s. Modern turbofan engines are more efficient and less noisy than the engines of fifty years ago, but many airports suspend flights at night so that local residents can sleep undisturbed.

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Some campaigners argue for cuts in flights or at least increased airport and airline taxes-and thus higher fares – to reflect the true environmental cost of flying. Aircraft manufacturers respond that new airplane engines are becoming increasingly efficient and clean. They also say the introduction of larger air­planes means fewer flights, less fuel burned, and therefore less pollution.

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SEE ALSO:

• Aircraft Design • Airport • Engine

• Fuel • Future of Aviation

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