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.

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