Quality Assured Measurements of Animal Building Emissions: Part 1 - Gas Concentrations

Comprehensive field studies were initiated in 2002, to measure emissions of ammonia (NH3), hydrogen sulfide (H2S), carbon dioxide (CO2), methane (CH4), non-methane hydrocarbons (NMHC), particulate matter less than 10 microns diameter (PM10), and total suspended particulates (TSP) from swine and poultry production buildings in the U.S. This paper focuses on the quasi-continuous gas concentration measurement; at identical locations, in paired barns, in seven states. Documented principles, used in air pollution monitoring at industrial sources, were applied in developing EPA-based quality assurance project plans. Air was sampled from multiple locations with each gas analyzed with one high quality commercial gas analyzer, located in an environmentally-controlled on-site instrument shelter. A nominal 4-L/min gas sampling system was designed and constructed with Teflon wetted surfaces, bypass pumping, and sample line flow and pressure sensors. Three-way solenoids were used to automatically switch between multiple gas sampling lines with 10-min or longer sampling intervals. Inside and outside gas sampling probes were between 10 and 123 m away from the analyzers. Analyzers used chemiluminescence, fluorescence, photoacoustic-infrared, and photoionization detectors for NH3, H2S, CO2, CH4 and NMHC respectively. Data was collected using PC-based data acquisition hardware and software. This paper discusses the methodology of gas concentration measurements, and the unique challenges that livestock barns pose for achieving desired accuracy and precision, data representativeness, comparability, and completeness, and instrument calibration and maintenance.