Air Emissions and Animal Agriculture


Ammonia (NH3) is a gas that results from the incomplete conversion of feed nitrogen into animal product (meat and/or milk). While livestock raised in commercial farms are more efficient in using feed nutrients than most humans, not all of the nutrients in feed are converted into product (growth, meat, milk, eggs, offspring). According to ASABE manure characteristic standards reported in 2005, N excretion for animals can range from 0.99 lb/day-animal (lactating dairy cows) to 0.0035 lb/day-animal (layers). Thus, a considerable amount of nitrogen in animal feed is excreted in urine and feces with the potential to be to be converted to NH3 gas. Atmospheric NH3 is an important pollutant due to its impact on ecosystems. Too much NH3 in the air can lead to deposition into surface waters via rainfall and cause over-enrichment, or eutrophication, of surface waters (algal blooms). Deposition often occurs far away from where the NH3 gas was produced. Red tide outbreaks in the Chesapeake Bay are attributed, in part, to over-enrichment with nitrogen.

Ammonia gas can react in the atmosphere with other gaseous compounds (acids such as those arising from natural processes in land or from coal production) to form fine particulates (ammonium (NH4+) aerosols), which are of a health concern. These fine particulates (called PM2.5 particulates) are respiratory irritants. Because both ammonia and ammonium (NH3 and NH4+) linger in the atmosphere for days and can be transported hundreds of miles. A regional-scale perspective is necessary when considering the environmental effects of NH3.

While the focus here is on farm sources of emissions, NH3 concentrations inside our own homes may be as high as that in farm areas, particularly when concentrated cleaning agents, litter boxes and even smokers are present.


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Last Updated 10/31/2011