Clearing the Air: Recent Media Coverage Overstates Cattle’s Contribution to L.A. Smog

Recent headlines read, “California dairy herds contribute heavily to smog” and “LA smog: More cows than cars?” Attention grabbing? Yes. True? No.

The stories, which appeared in numerous blogs and even the Washington Post, were based on recently published research results by a team from the University of Colorado and the National Oceanic and Atmospheric Administration’s (NOAA’s) Earth System Research Laboratory. Using aircraft to gather atmospheric samples, the researchers studied the impact of ammonia on air quality in the Los Angeles Basin. Extrapolating from just three samples gathered on two spring days in 2010, the researchers and subsequent media reports incorrectly concluded that emissions from dairies play a large role in the formation of LA smog.

Unfortunately, this conclusion simply wasn’t correct. The mistake can largely be chalked up to assuming emissions from a few minutes of sampling represented conditions year-round, day and night. More importantly, the conclusions of the recent articles are contradicted by overwhelming evidence from air quality regulators who have studied these emissions for nearly two decades. Consider the following:

  • The South Coast Air Quality Management District (AQMD) attributes more than half of the basin’s ammonia emissions to motor vehicles (30 percent, or 35 tons/day) and domestic sources (23 percent). Dairies and composting facilities are the next largest sources, each responsible for about 15 percent of emissions.
  • Dairy cattle populations have dropped by more than half in recent years, from about 253,000 milking cows in 2001 to less than 100,000 currently.
  • Southern California dairies are strictly regulated by the South Coast AQMD and are required to implement management measures to reduce emissions of dust, ammonia and odors.

The Geophysical Research Letters article implies that reducing dairy ammonia emissions would have the greatest impact on reducing aerosol particulates. However, South Coast AQMD has done extensive monitoring and modeling studies that show further control of dairy emissions would not be effective or necessary to attain federal health standards. Instead, the South Coast AQMD’s main focus has been on reducing oxides of nitrogen from mobile sources – in other words, further reductions of smog from automobiles. Hardly a shock, but certainly a less interesting headline.

Setting the record straight
The real story of California dairy families’ efforts to improve air quality across our state is one of continued success. Dairies in Southern California, the San Joaquin Valley and elsewhere in California currently operate under the nation’s strictest air quality regulations for dairies. In fact, California is the only place in the nation where dairies are regulated for natural emissions of volatile organic compounds, or VOCs, from feed and manure. As a result of efforts by dairy families to adopt improved management practices, the emissions have dropped more than 25 percent in the San Joaquin Valley and even more in Southern California, according to air regulators.

Meanwhile, dairy farmers continue to support research aimed at further improvements, including further reductions of dust from corrals and emissions from silage. Dairy families are also implementing new technologies that promote energy efficiency and cleaner air such as the use of Global Positioning Satellite (GPS) technology on their tractors to increase precision and reduce fuel use, and the switching of diesel fuel pumps to electric pumps for irrigation. Dairy farmers also continue to support efforts to develop and promote new technologies for converting manure into clean-burning renewable fuel or biomethane. With roughly 1,600 family dairies in the state, California has the potential to lead the nation in the development of this green, renewable fuel, reducing dependence on fossil fuel, cleaning the air, and cutting greenhouse gas emissions.

While these efforts aren’t always in the headlines, consumers can continue to rely on California dairy families as they continue to lead the nation in air quality protection and other sustainability efforts, even as they provide affordable, nutritious and safe food for millions of American families to enjoy.

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Dairy Cares is a statewide coalition supporting economic and environmental sustainability and responsible animal care. Our members include the Alliance of Western Milk Producers, Bank of the West, Bar 20 Dairy Farms, California Dairies Inc., California Dairy Campaign, California Farm Bureau Federation, Conestoga – Rovers and Associates, Dairy Farmers of America-Western Area Council, Dairy Institute of California, Hilmar Cheese Co., HP Hood, Joseph Gallo Farms, Land O’Lakes, Milk Producers Council, Ruan Transport Corp., Western United Dairymen, and others. For information, visit our web site or call 916-441-3318.