TOTAL AND RESPIRABLE DUST IN SWINE CONFINEMENT BUILDINGS - THE BENEFIT OF RESPIRATORY PROTECTIVE MASKS AND EFFECT OF RECIRCULATED AIR

Caretakers and pigs in dusty environments inhale particles and toxic g ases which can cause subclinical illness. We determined the reduction in sampled dust elicited by respiratory masks mounted on glass funnels . Open-faced filters or British cyclones were sampled to measure quant ities of dust which the masks had trapped. Respiratory masks reduced t he sampled total suspended particulates (open-faced filters) by greate r than or equal to 75% with NIOSH/MSHA certified protectant (2-tie) ma sks and greater than or equal to 50% with NIOSH/MSHA non-certified com fort (1-tie) masks, Respirable particulates (British cyclones) were re duced by greater than or equal to 45% with NIOSH/MSHA certified protec tant (2-tie) masks. These data suggest properly worn respiratory prote ctive masks afford significant protection against both total suspended and respirable particulates in swine confinement facilities. Penetrat ion of 3-25% of total aerosol mass through masks allowing only 1% pene tration of a silica aerosol with an aerodynamic diameter of 0.6-1.0 um suggested that measurable portions of the aerosol mass in these confi nement houses behaved as if they were less than 1 um in diameter. Beca use of the small size of the aerosol, NIOSH/MSHA certified respiratory protective masks should be worn when working in those facilities. We also studied concentrations of ammonia, endotoxin and total and respir able dust particles to determine effects of a recirculation fan which increased the nominal air flow capacity of the building by 10%. Recirc ulated air had minimal effects on ammonia, total airborne endotoxin or total particulate mass. Recirculated air limited the mass concentrati on of respirable particles in the breathing zone of swine caretakers a t lower building-air change rates, while having little effect at highe r ventilation air-change rates. These data suggest that adding recircu lated air with fans has merit at Tower air movements, that it could be applied to confinement buildings to reduce airborne dust in occupied regions, and that such application might provide both economic and hea lth advantage to the confinement manager.