Enclosure design for flock-level, chronic exposure of birds to air contaminant mixtures

Abstract

The objective of this study was to design an enclosure suitable for studying the ecotoxicological effects of vehicle emissions on groups of wild birds without compromising welfare. Two, adjacent enclosures sheltered from sunlight, wind and rain, were bird-proofed and wrapped with thick polyethylene sheeting. Emissions were directed into the treatment enclosure from the exhaust of a light-duty gasoline truck, using flexible, heat-proof pipe, with joins sealed to prevent leakage. During active exposure, the engine was idled for 5 h/day, 6 days/week for 4 weeks. Fans maintained positive pressure (controls) and negative pressure (treatment), preventing cross-contamination of enclosures and protecting investigators. Four sets of passive, badge-type samplers were distributed across each enclosure, measuring nitrogen dioxide, sulfur dioxide and volatile organic compounds (NO₂, SO₂ and VOCs, respectively), and were complemented by active monitors measuring VOCs and particulate matter (2.5 µm diameter, PM_2.5). We found that the concentrations of NO₂, SO₂ and PM_2.5 were not different between treatment and control enclosures. Volatile organic compounds (e.g. benzene, toluene, ethylbenzene and xylenes) were approximately six times higher in the treatment enclosure than control (13.23 and 2.13 µg m⁻¹, respectively). In conclusion, this represents a successful, practical design for studying the effects of sub-chronic to chronic exposure to realistic mixtures of vehicle exhaust contaminants, in groups of birds. Recommended modifications for future research include a chassis dynamometer (vehicle treadmill), to better replicate driving conditions including acceleration and deceleration.

Keywords:

• Air pollution
• vehicle emissions
• inhalation toxicology
• experimental avian exposure
• VOCs

Acknowledgements

We thank the Alberta Centre for Toxicology for their generous supply of passive samplers, with particular thanks going to Lorinda Butlin and Elham Jahromi for their analytical support and diagnostic expertise. We thank Markey Johnson and Ryan Kulka of Health Canada for the loan and instruction in the use of their monitoring equipment. We also appreciate the assistance of Alan Glassman and Greg Boorman with the experimental set-up and execution.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Discovery Grant from Natural Sciences & Engineering Research Council, Canada (NSERC300) [grant number: RGPIN/04557-2016] to J.E.G.S., and in part by a scholarship from the Air & Waste Management Association (A&WMA) for air quality research and study, with summer assistants supported by the Department of Ecosystem & Public Health of Faculty of Veterinary Medicine, University of Calgary.