Relative and qualitative aspects of aerial bacteria and dust in swine houses.

Aerial levels of bacterial-colony-forming particles (BCFP) in lung-depositable size ranges were determined using an eight-stage Andersen viable sampler with t ryptose agar. Aerial levels of BCFP~< 4.7/am and ~<3.3/am in aerodynamic diameter were significantly and positively correlated with total-aerial-BCFP level in swinehouse air. On average, 31% of aerial BCFP were ~<4.7 /am and 15% were ~<3.3 /am in four University enclosed swine houses (n = 192); 30% and 22%, respectively, in a University modified-open-front house (n = 44) and 28% and 11%, respectively, in 12 houses at five commercial operations (n = 24). Aerial-dust level was determined using a Staplex highvolume sampler. Aerial-BCFP a n d d u s t levels were significantly and positively correlated. There tended to be fewer aerial BCFP per unit of aerial dust in the modified-open-front house than in the enclosed houses at the University. Ten swine houses at commercial operations and four at the University were studied a total of 16 times to determine concentrations and sizes of aerial bacterial particles which formed colonies on t ryptose (general medium), Chapman-Stone (special medium for staphylococci) , KF Streptococcus (fecal streptococci) and MacConkey (coliforms) agars, respectively. Ratio of bacterial-colony-forming-particle (BCFP) count on Chapman-Stone agar to that on t ryptose