Coarse Particulate Matter Emissions from Cattle Feedlots in Australia

Open cattle feedlots are a source of air pollutants that include particular matter (PM). Over 24 h, exposure to ambient concentrations of 50 μg m −3 of the coarse‐sized fraction PM (aerodynamic diameter <10 μm [PM 10 ]) is recognized as a health concern for humans. The objective of our study was to document PM 10 concentration and emissions at two cattle feedlots in Australia over several days in summer. Two automated samplers were used to monitor the background and in‐feedlot PM 10 concentrations. At the in‐feedlot location, the PM 10 emission was calculated using a dispersion model. Our measurements revealed that the 24‐h PM 10 concentrations on some of the days approached or exceeded the health criteria threshold of 50 μg m −3 used in Australia. A key factor responsible for the generation of PM 10 was the increased activity of cattle in the evening that coincided with peak concentrations of PM 10 (maximum, 792 μg m −3 ) between 1930 and 2000 h. Rain coincided with a severe decline in PM 10 concentration and emission. A dispersion model used in our study estimated the emission of PM 10 between 31 and 60 g animal −1 d −1 These data contribute to needed information on PM 10 associated with livestock to develop results‐based environmental policy.