Dispersion Modelling of Bioaerosols Emitted from Livestock Operations: Fate of Microbes and Antibiotic-Resistance Genes

JOANIE LEMIEUX, Patrick O'Shaughnessy, Araceli Dalila Larios Martínez, Marc Veillette, Valérie Létourneau, Nathalie Turgeon, Cindy Dumais, Stéphane Godbout, Caroline Duchaine, Université Laval

     Abstract Number: 152
     Working Group: Bioaerosols in Agriculture: Sources, Risks and Mitigation

Abstract
Introduction. Confined animal feeding operations (CAFOs) are important producers of bioaerosols. CAFOs can have mechanical ventilation systems from which a proportion of indoor bioaerosols is emitted through the fans. CAFOs bioaerosols can contain microorganisms and antibiotic-resistance genes (ARGs). These contaminants have the potential to disseminate and travel unknown distances from the barns with unknown impacts on surrounding communities and environment.

Objective. Evaluate microbial and ARGs emissions from two conventional pig finishing buildings (PFB) and broiler chicken barns (BCB) to model their dispersion in the environment using AERMOD.

Methods. Indoor bioaerosols were collected on filters using the SASS^® 3100 Dry Air Sampler. DNA was extracted from filters and used for quantification by PCR of ARGs and bacterial biomass (16S rRNA genes). PFB and BCB were visited three times in the warm season for bioaerosols sampling. Ventilation rates were measured (m³/h) directly at the fan exhaust. Emissions (gene copies/h) were then calculated and used in AERMOD software to model the dispersion of bioaerosols components from CAFOs according to meteorological data and topography.

Preliminary results. Mean emissions of total bacterial biomass (16S rRNA geneS) ranged from 10¹¹ to 10¹² gene copies/h for the four CAFOs. Some ARGs detected indoor such as aac(3) (aminoglycoside), blaTEM (beta-lactams), sul1 (sulfonamide), tetM (tetracycline) and vanA (vancomycin) were emitted at 10⁹ gene copies/h. Those emission rates data were used to feed the AERMOD model and evaluate the dispersion of bioaerosols up to 10 km away from the barns. Analyses are underway.

Implication. The use of dispersion models will help to understand how bioaerosols components behave once emitted outdoors and up to what distance their concentrations are significant. Those incoming results will help understand at which extent people living nearby CAFOs are exposed to bioaerosols containing potentially harmful pathogenic agents.