Dust concentration variation in relation to animal activity in a pig barn

The contribution of animal activity to dust concentration in a pig barn, was evaluated through the continuous monitoring of animal activity. PM10 concentrations were measured during a three months observation period, from April to July, in a mechanically ventilated fattening room in Northern Italy. Pigs of 60 kg and with a mean age of 150 days were fed with liquid feed and were lodged on concrete fully slatted floor. PM10 concentration was monitored continuously by a dust sampler. From April 12 at 13:42 until April 13 at 15:09, 33 pigs housed in two of the 16 pens of the barn were monitored using a video camera placed at the height of 5 m above the pen floor. A comparison of data related to dust measurement and to activity index was performed on the hours of recorded images. PM10 concentration reached maximum values at feeding times, during feed release and with lights turned on. An increase in dust concentration took place within an hour after increased animal activity. PM10 concentration decreased until it reached the nocturnal mean concentration (316 μg m-3) after 1 h from feeding time. As expected, correlation analysis showed that particulate matter concentration was associated with ventilation rate (70%, P < 0.001), with relative humidity (-93%, P < 0.001), with inside and outside temperatures which determine ventilation rate a priori, and finally with animal activity (99%, P < 0.001). These results confirmed the strong association that exists between animal activity and particulate matter concentration in animal houses. An increase in PM10 concentration from 316 μg m-3 (the mean value of dust levels was observed at night when the recorded animal activity showed the lowest values) to 624 μg m-3 corresponded to the dust raised by 343 animals (with an increase in animal activity of 0.018 units), in a mechanically ventilated barn with fattening pigs fed with liquid feed, and lodged on a fully slatted concrete floor