Influence of building maintenance, environmental factors, and seasons on airborne contaminants of swine confinement buildings

Eight swine confinement buildings, selected to cover the widest possible range of cleanliness, were visited twice during winter and once during summer to verify the range, seasonal variations, and correlations between biological and chemical contaminants. Physical aspects were graded for dirtiness (1 = clean, 10 = dirty), ventilation, air temperature, number of animals, building, and room size. Air samples were taken to measure relative humidity, CO,, ammonia, total dust, and microbiological counts and/or identification (bacteria and molds); endotoxin levels also were measured. During winter, average measurements and ranges were: CO2 = 0.304% (0.254 to 0.349%); ammonia = 19.6 ppm (1.9 to 25.9 ppm); dust = 3.54 mg/m(3) (2.15 to 5.60 mg/m(3)). There were 883 cfu/m(3) (547 to 2862 cfu/m(3)) of molds, 4.25 x 10(5) cfu/m(3) (1.67 x 105 to 9.30 x 10(5) cfu/m(3)) of total bacteria, 29 cfu/m(3) (3 to 94 cfu/m(3)) of thermophilic actinomycetes). A significant decrease in bacterial levels (p=0.04), dust (p=0.0008), ammonia (p=0.005), and CO2 (p<0.0001) was observed during summer sampling when compared with winter levels. Mold counts were positively correlated (p=0.03) with dirtiness scores, while bacterial counts were negatively correlated with this parameter (p<0.002), whereas bacteria and endotoxins were correlated with the number of animals (p<0.05). Ambient gases (CO2 and ammonia) correlated with each other (p=0.006), Bacteria were the most important contaminant in swine confinement buildings, and endotoxin levels found were also very high (mean=4.9 x 10(3) EU/m(3)). We conclude that a wide range of air contamination exists in swine confinement buildings of different maintenance. There is a decrease in some of these contaminants during summer. Observed dirtiness of the swine confinement buildings has a poor predictive value concerning air quality.