The U.S. EPA Air Consent Agreement (ACA) with major livestock and poultry groups required the industry groups to fund the National Air Emissions Monitoring Study (NAEMS). The NAEMS was a two-year (2007-09) quality-assured field measurement of ammonia (NH₃), hydrogen sulfide (H₂S), particulate matter (PM) and volatile organic compounds (VOC) emissions from 10 poultry houses, 16 swine barns, and 9 dairy freestall barns and NH₃ and H₂S from a dairy corral, 4 dairy manure storages, 5 swine manure lagoons and a swine manure basin, all selected to be representative of the industries. The NAEMS monitoring portion consisted of a comprehensive array of air quality measurements that accounted for temporal and spatial variations across species (swine, dairy, egg laying, and meat chicken operations), facility types, and manure handling methods.

This presentation will focus on NH₃ which was measured with photoacoustic analyzers and tunable diode lasers at barn and open sources, respectively. The average NH₃ concentrations measured at the mechanically-ventilated poultry, pork and dairy buildings were 29.1, 9.7 and 2.9 ppm at the fan exhausts, and 1.04, 0.33 and 0.22 ppm at the inlets, respectively.

The whole farm NH₃ emission rates were calculated based on barns and lagoons for swine and dairy operations. At swine sites, the overall average emission rates were 37.2 g/d per sow and 9.78 g/d per finishing hog. The lowest sow farm emission was observed at deep pit buildings in Iowa and the highest was observed at a sow site in Oklahoma with pull-plug barns and an anaerobic treatment lagoon. The lowest swine finisher farm emissions were observed at a deep pit operation in Indiana. Generally, NH₃ emissions increased with the number, weight and activity of pigs in swine finishing barns; sow activity and air temperature in gestation barns; and piglet age in farrowing rooms. The lagoon emissions from a North Carolina finisher site were estimated to be only 27% of the farm whereas they averaged 83% of the total emissions at the two sow sites. Ambient temperature caused greater lagoon emissions during the day as compared with night and during the summer as compared with winter.

The overall average whole farm NH₃ emission from dairy sites was 40.0 g/d-cow. In general, NH3 emissions from dairy waste lagoons and basins were influenced by air temperature and wind speed, however, crusting was observed to remove these influences.   

The NH₃ emission from egg laying operations averaged 0.88 g/d-hen for high rise houses and 0.29 g/d-hen for manure belt houses. The average daily mean NH₃ emission from two 21,000-head broiler houses in California was 0.50 g/d-bird.

The U.S. EPA is currently using the hourly and daily means of the 60-s records of emission to develop livestock emission estimating methods, which they will publish when completed, and use thereafter in determining compliance with the CAA and EPCRA. The livestock and poultry industries can use the data in considering the potential of abatement methods for complying with regulations. Finally, the data has been and is currently being used to validate mechanistic source emissions models developed by academic researchers. Publication of NAEMS data is ongoing.