Ammonia Sources In The California South Coast Air Basin And Their Impact On Ammonium Nitrate Formation
This study found that dairy farms are as (or more) likely to be responsible for smog in the Los Angeles basin in California. The study measured nitrate emissions in the air in May 2010 and found that cars generate 62 metric tons of ammonia each day while ammonia emissions from dairy farms in the area range from between 33 and 176 metric tons per day. The authors conclude that addressing emissions from dairy farms would have the larger impact on smog in the basin.
This study measured levels of ammonium nitrate, a major component of smog that is typically associated with vehicle emissions. While most studies of pollution have focused on vehicles, this study also measured emissions from dairy farms, which also have high nitrate emissions resulting from a bacteria that consumes cattle waste.
The 9.9 million cars in the area generate about 62 metric tons of nitrate each day. The 298,000 cows, located on the dairy farms in the area, generate a range each day between 33 and 176 metric tons. The emissions from dairy are more concentrated than those from cars, leading the authors to conclude that more benefit will result from reducing emissions from the dairy farms than from cars.