A long time ago, someone in the automobile industry supposedly said that environmentalists were wack because cows caused more pollution than cars did (Reagan also allegedly said something like trees are the greatest polluters).
Well it turns out that they may be right, at least in my great state's San Joaquin Valley, where ruminating dairy cows are exploding--in number. One of every five cows in the United States lives in the San Joaquin Valley, which means lots and lots of methane. They have surpassed cars (probably about the only time cows will ever pass cars) as the biggest single source of smog-forming gases.
According to the Los Angeles Times, every year the average dairy cow produces 19.3 pounds of gases, called volatile organic compounds, which react with other pollutants to form ground-level ozone, or smog.
The San Joaquin Valley (that's the really big, really flat valley shaped like a giant amoeba in the middle of California) is one of the three worst areas for pollution (along with Houston and Los Angeles). Over the last six years, however, the San Joaquin Valley has violated the federal limit on ozone smog over an eight-hour period more than any other region.
This means the dairy industry will be forced to invest millions of dollars in expensive pollution-control technology in feedlots and waste lagoons, and may even have to consider altering animals' diets to meet the region's planned air-quality regulations.