When the 2012 study came out saying cows were as guilty as cars for LA’s smog, I contacted Ying Wang, director of Life Cycle Assessment research for the Innovation Center for U.S. Dairy. She told me that the EPA had done a study that found the average ammonia emissions per cow per day are approximately 60.9 grams. When you take 60.9 grams and multiply them by the 298,000 cows in the eastern LA basin (as cited by the Boulder researchers), you get 18.15 million grams per day, which is about 18 metric tons. Yet, the Boulder study blamed cows for 33 to 176 metric tons per day. Look even further and there aren’t that many cows. Dairy cows are most obvious presence in the area, and at the time the study was released in the spring of 2012 the Milk Producers Council of California estimated there were about 100,000 mature dairy cows ― milking and dry ― in the area. That would put ammonia emissions closer to 6 metric tons than the 33 to 176 estimated by the Boulder group.
Cows as guilty as cars? I would rather be caught in a closed garage with a group of cows than one running automobile.