ABSTRACT

Agriculture is currently facing more restrictive emission limits as a consequence of air quality regulations. A number of State Air Pollution Regulatory Agencies (SAPRAs) are focusing their efforts on particulate matter (PM) emissions from field operations. In particular, PM emissions from concentrated animal feeding operations (CAFO) are of concern. The problem with regulating air emissions from ground-level area sources (GLAS) is the lack of accurate emission flux data. This is partially due to the difficulties of directly measuring the emission rate of dust from a given source. In order to quantify the emissions from agricultural operations, net downwind concentrations are measured and the resulting concentrations are used to back into an emission flux using dispersion modeling. Emission fluxes can subsequently be reported as emission factors. One use of emission factors is for permitting new and existing sources. According to the EPA, "Modeling is the preferred method for determining emissions limitations for both new and existing sources," (EPA, 1999). It should be expected that emission factors will be used to estimate downwind concentrations using dispersion modeling and that the resulting estimated concentrations will be used in the air pollution regulatory process. The box model has been used in the past to estimate fluxes with the resulting fluxes being used in Industrial Source Complex-Short Term, Version 3 (ISC) to estimate downwind concentrations for regulatory purposes. This paper presents a proposed process for estimating fluxes using the box model with the criterion that the subsequent concentrations with ISC will be conservative.