Particulate matter dynamics in naturally ventilated freestall dairy barns H.S. Joo a , P.M. Ndegwa a, * , A.J. Heber b , J.-Q. Ni b , B.W. Bogan b , J.C. Ramirez-Dorronsoro c , E.L. Cortus d a Biological Systems Engineering, Washington State University, PO Box 646120, Pullman, WA 99164, USA b Agricultural & Biological Engineering, Purdue University, 225 South University Street, West Lafayette, IN 47907, USA c Natural Resources and Environmental Management, Ball State University, 2000 W. University Avenue, Muncie, IN 47306, USA d Agricultural & Biosystems Engineering, South Dakota State University, Brookings, SD 57007, USA highlights < Particulate matter concentrations and ventilation rates in dairy barns were monitored for two years. < Concentrations of PM 2.5 , PM 10 , and TSP, exhibited non-normal positively skewed distributions. < The respective emission rates of PM 2.5 , PM 10 , and TSP ranged between 1.6e4.0, 11.9e15.0, and 48.7e52.5 g d 1 cow 1 . < Concentrations of PM 2.5 and PM 10 increased with ambient air temperature (R 2 ¼ 0.60e0.82). < Concentrations of TSP (but not of PM 2.5 and PM 10 ) tended to increase with cattle activity. article info Article history: Received 2 October 2012 Received in revised form 2 December 2012 Accepted 5 December 2012 Keywords: Air quality Air pollution Animal agriculture Dairy operations Emission rates abstract Particulate matter (PM) concentrations and ventilation rates, in two naturally ventilated freestall dairy barns, were continuously monitored for two years. The first barn (B1) housed 400 fresh lactating cows, while the second barn (B2) housed 835 non-fresh lactating cows and 15 bulls. The relationships between PM concentrations and accepted governing parameters (environmental conditions and cattle activity) were examined. In comparison with other seasons, PM concentrations were lowest in winter. Total suspended particulate (TSP) concentrations in spring and autumn were relatively higher than those in summer. Overall: the concentrations in the barns and ambient air, for all the PM categories (PM 2.5 , PM 10 , and TSP), exhibited non-normal positively skewed distributions, which tended to over- estimate mean or average concentrations. Only concentrations of PM 2.5 and PM 10 increased with ambient air temperature (R 2 ¼ 0.60e0.82), whereas only concentrations of TSP increased with cattle activity. The mean respective emission rates of PM 2.5 , PM 10 , and TSP for the two barns ranged between 1.6e4.0, 11.9e15.0, and 48.7e52.5 g d 1 cow 1 , indicating similar emissions from the two barns. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction In general, the size of particulate matter (PM) suspended in air is dependent upon the level of energy input into the producing process. Relatively higher energy processes, such as combustion, produce finer particles, while lower energy processes, for instance crushing or grinding, produce coarser particles (Auvermann et al., 2006). Particulate matter from animal feeding operations (AFOs) therefore includes both fine particles, from engine exhaust of farm vehicles, and coarse particles, from hoof action on dry manure and soil or feed grinding. In contrast to PM in urban areas, however, coarse PM dominate AFO emissions because most are generated by lower energy mechanical processes (Auvermann et al., 2006). Particulate matter from AFOs may also contain harmful substances (heavy metals, VOCs, nitrates, sulfates, etc) and bioac- tive components (pathogens, endotoxins, antibiotics, allergens, dust mites, etc) that could exacerbate respiratory diseases and mortality in the herd, in addition to adversely affecting the health of farm workers, farm residents, and neighbors in the vicinity of these facilities (Cambra-Lopez et al., 2010; Matkovic et al., 2009; Hamscher et al., 2003). Epidemiological studies, for instance, have reported strong associations between adverse cardiopulmonary and respiratory conditions and human exposure to air-suspended PM 10 (Schartz, 2001; Anderson et al., 1995; Pope et al., 1995; * Corresponding author. Tel./fax: þ1 509 335 8167. E-mail address: ndegwa@wsu.edu (P.M. Ndegwa). Contents lists available at SciVerse ScienceDirect Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv 1352-2310/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.atmosenv.2012.12.006 Atmospheric Environment 69 (2013) 182e190