Aviation Impacts

Aviation activities impact the environment pri­marily in two ways: (1) engine-generated emis­sions into the air and (2) noise. Noise legislation has been addressed by the Congress in separate, specific legislation, and we will discuss those statutes later in this chapter. Engine emissions result from both aircraft operations and airport ground operations and are regulated by the EPA under its “mobile source” pollution authority.

The history of EPA regulation of aircraft engine emissions is long-standing:

1974—for engine smoke (revised several times over the years since) and fuel venting; 1984—for hydrocarbon emissions;

1997—for nitrous oxides and carbon monoxide;

2005—for additional nitrous oxides emis­sions standards;

2012—for additional nitrous oxides emis­sions standards.

Emissions Generated from Aviation-Related Combustion Processes

Carbon Monoxide (CO) is produced due to the incomplete combustion of the carbon in fuel;

Particulate Matter (PM) consists of small solid or liquid particles that form as a result of incomplete combustion, and are small enough to be inhaled;

Sulfur Oxides (SOx) are produced when small quantities of sulfur, present in essen­tially all hydrocarbon fuels, combine with oxygen from the air during combustion;

Hydrocarbons (HC) are emitted due to incomplete fuel combustion. They are also

referred to as volatile organic compounds (VOCs);

Nitrogen Oxides (NOx) are produced when air passes through high temperature/high pressure combustion and nitrogen and oxy­gen present in the air combine to form NOx;

Carbon Dioxide (C02) is the product of incomplete combustion of hydrocarbon fuels like gasoline, jet fuel, and diesel. Carbon in fuel combines with oxygen in the air to pro­duce C02;

Water Vapor (H20) is the other product of incomplete combustion as hydrogen in the fuel combines with oxygen in the air to pro­duce H20.

Ozone (03) is not emitted directly into the air but is formed by the reaction of VOCs and NOx in the presence of heat and sunlight. Ozone forms readily in the atmosphere and is the pri­mary constituent of smog.

Since 1985, aggregate emissions of the air pol­lutants the EPA regulates (nitrogen dioxide, ozone, sulfur dioxide, particulate matter, carbon monoxide, and lead) have declined by 25 percent nationally.

Success in reducing particulate matter (PM) in the exhaust of jet engines was realized fairly early. This was due in part to the fact that this
type of emission was the most noticeable and a solution was, therefore, quickly sought. In addi­tion, jet-engine-produced black smoke consists of fine carbon particles, partially burned fuel, and raw fuel. These PMs contain carcinogen content and descend to earth, creating health hazards. The reduction of exhaust smoke was accom­plished by developing a more complete combus­tion process whereby the hydrocarbons in jet fuel are converted to carbon dioxide and water. Figure 34-1 shows the decline in air-quality pollutants since 1980. Aircraft emissions have also declined over time but increases in pollution from air traf­fic are likely to occur as aviation itself increases.

Take off and landing operations produce the highest rates of PMs and NOx. Nitrogen oxides are a primary contributor to the formation of ozone, which is the most significant air pollutant in urban areas and which is a greenhouse gas in the upper atmosphere. Paradoxically, as inno­vative jet engine designs have produced more power while using less fuel and with lower car­bon monoxide emissions, NOx emissions have increased due to their higher operating tempera­tures. This also accounts for the comparatively high regulatory concern at the EPA over NOx in recent years, as shown above. See Figure 34-3 for comparatively high measures of NOx. Since essentially all NOx comes from combustion

Lung function impairment, effects on exercise performance, increased airway responsiveness, increased susceptibility to respiratory infection, increased hospital admissions and emergency room visits, and pulmonary inflammation, lung structure damage

Cardiovascular effects, especially in those persons with heart conditions (e. g., decreased time to onset of exercise-induced angina)

Lung irritation and lower resistance to respiratory infections Premature mortality, aggravation of respiratory and cardiovascular disease, changes in lung function and increased respiratory symptoms, changes to lung tissues and structure, and altered respiratory defense mechanisms

Eye and respiratory tract irritation, headaches, dizziness, visual disorders, and memory impairment

TABLE 34-1 Representative health effects of air pollutants.

Pollutant Representative Environmental Effects

Ozone Crop damage, damage to trees and decreased resistance to disease for both

crops and other plants

Carbon Monoxide Similar health effects on animals as on humans

Acid rain, visibility degradation, particle formation, contribution toward ozone formation

Visibility degradation and monument and building soiling, safety effects for aircraft from reduced visibility

Contribution toward ozone formation, odors and some direct effect on buildings and plants

TABLE 34-2 Representative environmental effects of air pollutants.

processes, electric utilities, manufacturing plants and factories, and transportation companies make up the largest share of such emissions. Still, the aviation sector contributes only 0.4 percent of total emissions, which is a miniscule part of the whole. See Figure 34-4 for a graphic comparison of different transportation sources of NOx.

Aircraft idle and taxi operations produce the highest rates of VOCs and carbon monoxide. Ground-operated support equipment is mostly powered by gasoline or diesel engines, which pro­duce VOCs, carbon monoxide, NOx, and PMs.

Carbon dioxide, while not considered a pol­lutant in the lower atmosphere, can form ozone. Greenhouse gases as a separate measured cat­egory are contributed by the transportation sector to the total at 27 percent, but with aviation con­tributing only 2.7 percent.

Airport operators have no direct control over aircraft emissions, although two foreign countries have imposed landing fees based on the amount of aircraft emissions. Airports are theoretically sub­ject to nationally supervised state control of emis­sions through State Implementation Plans (SIPs). These plans must be submitted by the states to the EPA for reducing emissions in areas that fail to meet the National Ambient Air Quality Stan­dards set by the EPA under the Clean Air Act. The power of states in controlling pollution at airports is limited, however, since the EPA retains control of regulating mobile sources of emissions and because states are preempted from regulating air­craft operations generally. This is a federal respon­sibility (in order to maintain a consistent national policy) and the FAA is responsible for enforcing emission standards. For these reasons only three states have even attempted to target airports for emission reductions.3 Operators of some of the busiest airports in the country have initiated vol­untary programs to reduce emissions from sources over which they have control under the Voluntary Airport Low Emission Program (VALE).

VALE is an FAA program established in 2003 under the Vision 100 Century of Aviation Reau­thorization Act. It provides funding to be used to reduce ground emissions from static and mobile equipment at airports. It promotes the use of elec­tric-powered ground support equipment, such as baggage tugs, belt loaders, and pushback tractors. It also promotes capital construction projects such as the installation of underground fuel distribution sys­tems to eliminate the need for aircraft fuel trucks.