Common air emissions from animal agriculture and their impacts

Some air emissions have local human health and nuisance impacts while other emissions pose problems at a regional scale

Odors from all sizes and types of animal feeding operations can cause concerns with nearby neighbors. While odor may be what causes a neighbor to have concerns it isn’t the only thing emitted from farms. Air emissions have both local and regional impacts.

Odors from livestock farms can be comprised of hundreds of different compounds (odorants). How these odorants interact with each other contributes to the specific character of an odor. That character depends on which odorants are present, which reflects not only the type of farm but also the management of that farm. Even stored feeds and complete feeds can impact the odor a farm emits. Odorous compounds tend to be carried on dust particles. It has been reported that as much as 50% of the odor emitted is attached to dust particles. Therefore, strategies to reduce odors from animal agriculture often include strategies to reduce dust.

Volatile Organic Compounds (VOCs) are carbon-containing compounds that participate in atmospheric photochemical reactions. Some of these reactions may lead to detrimental conditions, such as destruction of the ozone layer. In addition, VOCs are often odorous so they are part of the suite of odorants that make up a farm’s odor.

Particulate matter, or dust (particulates), can be a nuisance as well as have health impacts. Large particles (PM10) in arid regions of the country can cause ‘dust outs’ near feedlots. Small particulates (PM2.5) contribute to localized regional haze events as well. Small particles can also be inhaled and become respiratory irritants, even exerting a carcinogenic effect.

Emissions of different pollutants differ in the potential severity and the spatial scales of their effects. For example, the effects of odor are of interest mainly at a very local level (nearby neighbors). Conversely, ammonia (NH3) has relevant impacts on a regional-scale perspective mainly because, once in the atmosphere, it may travel for hundreds of miles before being deposited in waterways or combining with other gases to form a fine particulate. Unlike NH3,hydrogen sulfide (H2S) does not travel far; its impact are more at the farm level than even the neighborhood scale.

Potential Importance of AFO Emissions at Different Spatial Scales (adapted from NRC (2003)

Emissions Global, Regional Local, Property Line Primary Effects of Concern
Odor Insignificant Major Nuisance, quality of life
VOC Significant Minor Odorous, ozone formation
H2S Insignificant Significant Odorous, health
NH3 Major Minor Atmospheric deposition
Dust (particulates) Insignificant Significant Health, haze
GHG Significant Insignificant Global climate change
Rank order from high to low importance is major, significant, minor, and insignificant.VOC = volatile organic compounds, H2S = hydrogen sulfide, NH3 = ammonia, GHG = greenhouse gases

Regardless of where the impact of an emission might occur, farms should make a concerted effort to reduce air emissions to the extent possible. Controlling air emissions, whether it be from farms or non-agricultural industries makes good local, national and global sense.

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