Look out below! Investigating the impact of aviation emissions on the area surrounding the Ottawa International Airport

By Kieran Aston

Researchers are aware that when it comes to outdoor airborne particulate matter, smaller types of particles are more harmful because they can enter the bloodstream when inhaled. Ultrafine particles (UFPs) are a type of air pollution particulate matter of nanoscale size (less than 100 nm in diameter). To put this into perspective, UFPs are about 1/1000 the diameter of a single strand of human hair. There is growing evidence that long term exposure to UFPs increases the risk of serious health outcomes including cancer, respiratory diseases, hypertension, and diabetes. As we learn more about the dangers of long-term UFP exposure, it becomes increasingly important to learn more about the different sources of UFP emissions and their health impacts. We need to look for ways to reduce exposure.

In Canada, the primary source of UFPs is gasoline powered vehicles, but there are many other exposure sources such as diesel emissions and wood burning. That said, one crucial and understudied source of UFPs is aircraft use. Epidemiological studies found that airport related UFP emissions are substantial and may increase the risk of adverse birth outcomes. Since airport-related UFP emissions can spread significantly farther into the surrounding area than roadway-traffic emissions, they pose greater health risks and need to be specifically studied.

By design, airport runways run parallel to the prevailing wind direction to create optimal landing and takeoff conditions. Unfortunately, residential areas downwind of airports are subjected to aviation emissions, particularly in cities with little variation in wind direction.
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During the summer of 2022, I helped collect data for a pilot study of Health Canada’s “Characterization of Aviation-Sourced Air Pollution (CASAP)” project to address UFPs research gaps.  The project is led by Keith Van Ryswyk of Health Canada in collaboration with Dr. Paul Villeneuve of the CHAIM Center at Carleton University. The main component of the CASAP study will take place at Toronto’s Pearson International Airport, focusing on investigating the effect of airport-related emissions on the urban areas downwind of the airport. The project will also examine how new, more fuel-efficient landing technology can affect aviation emissions.

The pilot study at the Ottawa International Airport was intended to provide an opportunity to fine-tune the methodology for data collection and analysis in preparation for the main study. We set up fixed-site monitoring equipment near a runway at the airport by installing a tripod-like contraption fitted with various instruments that continuously collecting data on pollutants, noise and weather. The site we chose is in line with the runway, and lies to the east of the airport, which is ideal for catching air pollution plumes from aircraft with the prevailing western winds in this area.

Monitoring equipment

I was responsible for ensuring that the monitors at the site had everything they needed to collect data on noise, black carbon, and particulate matter at the site. I also contributed to the analysis of the collected data. This meant making weekly visits to the site to replace depleted batteries, clean dirty filters, sync clocks, and offload data, battling mosquitoes and the keep the tech dry during the occasional freakish downpour. I also had to deal with any unexpected errors and mishaps with the devices, of which we had our fair share.

A typical Monday for me started with driving out to Albion Road and heading down a more-than-a-little bumpy gravel road to the monitoring site. Once I made my way up a small hill to the monitoring setup, I connected my laptop to each of the devices, downloaded the data, cleared each device’s memory, and synced their clocks. Then, I replaced the devices that were out of battery with fully charged spares and replaced the dirty parts with clean ones. Finally, before leaving I thoroughly checked each instrument to make sure everything was in working order.

Location of monitoring site

View of a plane taking off, taken at the monitoring site

Since flight data were not yet available at the time of my work on this study, my analysis of the collected data was limited to the effect that wind direction had on UFP concentrations. Some of my preliminary findings showed that UFP concentrations were in general higher during winds that put the monitoring site downwind of the airport (i.e., western winds) than when the monitoring site was upwind of the airport (i.e., during eastern winds), as shown in the graph below. In addition, when comparing UFP concentrations during hours of higher flight traffic (6:00 am – 11:59 pm) and lower flight traffic (12:00 am – 5:59 am), differences seen in both the ​variability and levels of UFP concentrations were much larger when the monitoring site was downwind of the airport than when it was upwind of the airport. For example, during western winds the standard deviation of recorded particle number concentrations (PNC) was 51.0% larger from 6:00 am – 11:59 pm than it was from 12:00 am – 5:59 am. Conversely, the difference in the standard deviation of PNC during eastern winds was more comparable, being 13.2% larger between 6:00 am – 11:59 pm than it was between 12:00 am – 5:59 am.

The project’s next steps include comparing the collected data with flight data to be received from Nav Canada. Flight data allows for a more detailed analysis, and we hope that such an analysis can serve to better inform our methodology for the main portion of the study at Toronto’s Pearson Airport. Our pilot project was the first to collect data on UFPs from aircraft, and in time, we hope to assess whether these exposures impact the health of residents. ​