Virus, Bacteria, Gas and Odour Reductions by an Innovative Air Cleaning System Developed for Animal Housing.

Canada produces more than 25 million pigs per year and is now the third largest exporter of pigs. While economically beneficial for rural communities, animal housings can emit substantial amounts of airborne bacteria and viruses, some of those of concern for public and animal health. A device such as an air treatment unit (ATU) combined with the building ventilation system might be a way to reduce airborne virus dispersion such as influenza virus or porcine circovirus from buildings. The effectiveness of ATUs to reduce airborne virus and bacteria has been evaluated by installing  the device to treat the air exhausted from pig experimental chambers and by injecting non-pathogenic virus surrogates (P008 and PhiX174 phages) with a 24-jet nebuliser upwind of ATUs. Bacteria and artificially-introduced phages have been sampled up- and downwind of ATUs with wet cyclones Coriolis. ATUs were operating at different conditions (three empty bed retention times with the same superficial air velocity, two types of synthetic media and two recirculation times for a nutritive solution). Preliminary results show that 0.8 micrometers aerosolized particles containing P008 and PhiX174 phages are not captured by the studied ATUs. However, we did observe reduced bacteria concentrations as well as lower odour and ammonia levels downwind each evaluated ATUs. Bacteria population diversity will be studied up- and downwind each ATUs by Denaturing Gradient Gel Electrophoresis (DGGE) and pyrosequencing. Furthermore, fluorescent microspheres of different diameters will be injected into ATUs to determine their physical trapping by the studied system. According to our results, ATUs developed by IRDA are effective to reduce airborne bacteria, odour and ammonia emitted from pig housing.