Although the use of catalytic converters has reduced smog-producing compounds in motor vehicle exhaust emissions, recent studies have shown that in so doing the converters produce nitrous oxide, which contributes substantially to global warming . The massive combustion produces tons of ash, soot, and other particulates responsible for the gray smog of cities like New York and Chicago, along with enormous quantities of sulfur oxides. These oxides rust iron, damage building stone, decompose nylon, tarnish silver, and kill plants. Air pollution from cities also affects rural areas for many miles downwind. Every industrial process exhibits its own pattern of air pollution.
Petroleum refineries are responsible for extensive hydrocarbon and particulate pollution.
Uninsulated high-voltage power lines ionize the adjacent air, forming ozone and other hazardous pollutants. Airborne pollutants from other sources include insecticides , herbicides , radioactive fallout , and dust from fertilizers, mining operations, and livestock feedlots. Licensed from Columbia University Press. All rights reserved.