Auditing and Assessing Air Quality in Concentrated Feeding Operations1,2,3

Professional Animal Scientist, Feb 2008 by Cole, N A, Todd, R, Auvermann, B, Parker, D

ABSTRACT

The potential adverse effects of concentrated animal feeding operations (CAFO) on the environment are a growing concern. The air quality issues of most concern to CAFO vary but generally include ammonia, hydrogen sulfide, particulate matter, volatile organic compounds, greenhouse gases, and odors. Air pollutants may be regulated by federal and state laws or by nuisance complaints. The United States Environmental Protection Agency, and poultry, swine, and dairy industries recently agreed to the National Air Emissions Monitoring System to fund research on atmospheric emissions from production farms in the United States. Air quality regulations may be based on actual emissions, atmospheric concentrations, or human perception, or via limiting the size or location of CAFO. Measuring the concentrations or emissions of most air pollutants is expensive and complex. Because of spatial and temporal variability, concentrations and emissions must be measured continuously over an extended period of time. Because different methods or models can give different results with the same data set, a multitude of methods should be used simultaneously to assure emissions are reasonable. The "best" method to measure concentrations and emissions will depend upon atmospheric concentrations, cost, facility characteristics, objectives, and other factors. In the future, requirements for monitoring of air emissions from CAFO will probably increase. Reliable process-based models need to be developed so that emissions of air pollutants can be estimated from readily obtained diet, animal, facility, and environmental variables. Auditors will need to be trained in a variety of disciplines including animal sciences, chemistry, engineering, micrometeorology, instrumentation, modeling, and logic.

Key words: air quality, concentrated animal feeding operations, dispersion, modeling, regulation

INTRODUCTION

The potential adverse effects of animal feeding operations (AFO) on the environment are a growing concern. The effects of concentrated animal feeding operations (CAFO) on water quality have been regulated under the Clean Water Act for many years. However, the effects of intensive and extensive livestock operations on air quality have received less attention at least until recently. Even in rural communities, the general public has become less tolerant of the odors and dust emitted from agriculture because of concerns about health, quality of life, property values, and the environment.

In general, the air pollutants of most concern to livestock operations include ammonia, hydrogen sulfide, particulate matter (PM), volatile organic compounds (VOC), greenhouse gases (methane, nitrous oxide, and carbon dioxide), and odors or odorants. However, the predominant air quality concerns of livestock and poultry feeding operations will vary with the location of the operation, the species reared, type of operation (enclosed or open-lot), and other factors.

To successfully audit and assess air quality at AFO, it may be necessary to quantify gaseous and PM emissions. Measuring atmospheric emissions is difficult and entails 2 major challenges: 1) measuring the atmospheric concentration, and 2) estimating the flux to the atmosphere based on direct measurement or on a flux model that describes or simulates the turbulent dispersion of gases and particulates. Thus development of process-based models will be needed to adequately monitor atmospheric emissions from CAFO.

CURRENT RULES AND REGULATIONS

The ultimate responsibility for air quality regulations resides with the federal government. However, state and local governments can also regulate pollutants in some cases. In addition, based on real, perceived, or potential quality-of-life issues, many air pollutants are "regulated" through the court system via injunctions and law suits. The permitting process is, in itself, a potential regulatory mechanism for CAFO. Some pollutants (odor, PM) have short travel distances and affect relatively small geographic areas. Therefore, local or regional, rather than federal, regulations may be most appropriate. In other cases, for example ammonia, the ultimate negative effects may be both local (dry deposition on sensitive ecosystems) and longer range (formation of respirable particulates near urban areas; wet deposition); thus Federal regulations may be more appropriate.

A small group of "criteria" pollutants {PM [both larger (PM^sub 10^) and smaller particulates (PM^sub 2.5^)], ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, and lead} are regulated under The Clean Air Act of 1970 and its amendments (EPA, 1987). [The PM^sub 10^ and PM^sub 2.5^ are particles having an aerodynamic equivalent diameter (AED) of less than 10 and 2.5 �, respectively.] The Environmental Protection Agency (EPA) established a set of primary and secondary National Ambient Air Quality Standards (NAAQS) designed to protect the public against adverse health effects and to protect the environment. Recent court cases have established that ambient air quality standards apply not only to large, heterogeneous air sheds but also at the property line of an individual source (EPA, 2007a). As monitoring methods improve and as the weight of scientific evidence increases, ambient air quality criteria are to be modified to accommodate the latest science.