Henry
F. Tyrrell
USDA/CSREES
Although
ammonia is not identified as a pollutant under the EPA’s Clean Air Act, it
reacts with sulfur dioxide and nitrous oxides in the atmosphere to form
particulate matter with a mass median diameter of 2.5 microns (PM-2.5).
In 1997, the EPA implemented new standards restricting the atmospheric
concentration of PM-2.5. Based on
current monitoring of PM-2.5, the EPA is expected to designate areas of
non-attainment by 2005 after which regulations will be implemented requiring
states to set mandates for compliance. The
states will have until 2017 to meet the PM-2.5 standards, although two one-year
extensions are possible.
Ninety percent of ammonia emissions to the atmosphere are associated with agriculture. Based on the EPA’s inventory of ammonia emission factors, cattle produce the highest amount followed by poultry, hogs then inorganic fertilizers. Calculations by animal scientists indicate that the EPA’s factors may be up to 40% too low. Although manure management has focused on the release of nitrogen and phosphorus to water resources, it is clear that ammonia releases to the atmosphere will also have to be managed. At this time, there is no technology that that can eliminate ammonia and more research is needed to reduce emissions, better understand the flow of nutrients in a system and identify tradeoffs of alternative systems.