Ammonia Emissions from Animal Agricultural Operations: 2002 and Beyond

William Schrock and Gail Lacy
U.S. EPA, Office of Air Quality Planning and Standards


The increased size and consolidation of agricultural operations B including poultry, swine and dairy operations B have been the focus of an increasing number of citizen complaints and concern about possible health and environmental impacts. However, data on air emissions, including ammonia, from animal feeding operations (AFOs) are scarce. A 2002 report by the National Academy of Sciences called on EPA to improve its method for estimating emissions from AFOs – a key step in mitigating any air pollution from those operations.

In updating the National Emissions Inventory for ammonia for the year 2002, EPA laid the groundwork for estimating emissions using a process-based framework. This framework characterizes a wide variety of manure management trains, and includes emission factors to estimate the emissions from each of the processes within the manure management train. Estimates of the animal population subject to each of these management trains are input to develop national emission estimates. Nationally, poultry and beef production are the highest emitters, followed by dairy cattle and swine, although there are strong regional variations in the prevalence of each of these animal sectors.

Many data gaps in the emissions for each of the processes areas exist, including temporal (seasonal and diurnal) characterization. A multi-year research effort is underway with the ultimate goal a process-based emissions model. The study is funded through an air quality compliance agreement between EPA and the industry. Monitoring began in spring 2007 on 25 sites at 21 farms in 10 states. The farms monitored represent typical operations for different animals (swine, dairy cows and poultry) and different regions of the country. The selected farms had to meet several criteria related to practices commonly used by the industry, meteorological conditions and waste management methods. The states in which the farms are located are: California, Indiana, Iowa, Kentucky, New York, North Carolina, Oklahoma, Texas, Washington and Wisconsin. Particulate matter, hydrogen sulfide and volatile organic compounds are being monitored in addition to ammonia. Selected sites will be monitored for two years to ensure that the data account for seasonal variability as well as the impact of any operational changes. The two-year period also will help EPA determine whether the data are similar from one year to the next, and to account for any data anomalies. Monitoring will take place at barns, lagoons, and waste or manure storage piles. Land application sites are not included. A website is being developed to provide information related to the study, including monitoring protocols. Interim data will be made available on the website periodically.