Author
|
Submitted to: Air and Waste Management Annual Conference Proceedings
Publication Type: Proceedings Publication Acceptance Date: 4/16/2016 Publication Date: 8/24/2016 Citation: Silva, P.J., Lovanh, N.C. 2016. Particle size distributions in and around a poultry house before, during, and after flock cleanout. Air and Waste Management Annual Conference Proceedings. 1-5. Interpretive Summary: Atmospheric emissions from animal housing include both gas-phase compounds such as ammonia as well as particulate matter. Recent changes to the regulation of fine particulate matter put an emphasis on secondary particle formation (chemical reactions producing particulates from the gas phase) rather than just primary particles (directly generated dust). This change requires new and specific data on particle concentrations in different size ranges because chemical reactions occur at smaller particle sizes than direct dust emissions. Here we describe a study looking at the size range of particles in a poultry house during growth of a flock. Particle size distributions in the house were obtained using several methods from 0.01 – 20 micrometers in diameter. Data was obtained for six weeks at three minute intervals to determine size distribution changes during the growth time. Results indicate that particle size concentrations changed significantly during the sampling period. As expected due to flock growth, particle size distributions skewed larger as the study proceeded. Spikes of dust were observed due to animal activity. Some evidence of secondary particle formation was also observed at the house although on a mass basis, these particles were a small fraction of the overall concentration compared to direct emissions. These data are important for scientists and modelers to assess the contribution of near-source new particle formation from chemical reactions versus traditional dust. Technical Abstract: Recent proposals to adjust the regulation of fine particulate matter (PM2.5) put an emphasis on precursor chemistry to secondary particle formation. Ammonia is a contributor to secondary particle formation as may some volatile organic compounds (VOCs). Secondary particulate formation can contribute to particle nucleation (formation of new particles) or added mass loading to the accumulation mode. The traditional analysis of particulate size distributions from agricultural sources focuses on coarse mode particulates. Here we describe a study looking at the full particulate size range of particles in a poultry house during a flock to assess if and when new particle formation is observed or if only particle accumulation is seen as a flock grows and emissions increase. Particle size distributions were obtained using a scanning mobility particle sizer (SMPS) for the small size range (0.01 – 0.5 micrometer in mobility diameter) and an aerodynamic particle sizer (APS) for the larger size range (0.3 – 20 micrometer in aerodynamic diameter). In addition, optical particle counters (OPCs) were place inside and outside the house at an exhaust fan to assess the concentrations and changes in particle size distribution in the house compared to emitted particles. Data was obtained at three minute intervals over six weeks of a flock run. Results indicate that particle size distributions and number concentrations both changed significantly over the time period. As expected due to flock growth, particle size distributions in the accumulation mode skewed larger as time went on. Large spikes in particle concentration could also be observed at times correlated to bird activity, but the spikes were typically in the larger sized particles rather than smaller. |
