Who would imagine a bright, sunny winter day could have higher concentrations of some air pollutants than a hazy summer day?
Not only is it uncommon for people to consider air quality during the coldest months of the year, but scientists rarely conduct winter air quality testing, says chemistry PhD student Daniel Persaud of York University's Faculty of Science. This is likely especially true during a polar vortex like Toronto, and the rest of Canada, is currently experiencing.
Even more unusual, though, is the possibility that Toronto's cold winter air could be worse than in summertime, adds York's Lassonde School of Engineering master's degree student Samir Singh.
Daniel Persaud tending to High Park instruments
Researchers won't know for sure which pollutants are worse until all measurements and analysis are done for the Study of Winter Air Pollution in Toronto (SWAPIT), led by Environment and Climate Change Canada (ECCC). That data analysis is currently underway for last year's campaign and SWAPIT scientists plan to meet next week to share initial results with each other to generate new insights and plan the release of the findings publicly.
"The unique thing about this study is that it's occurring during the winter months when there are different sources of pollutants from indoor heating to the de-icing of highways, which could have impacts. It is now evident that the levels of some pollutants are elevated in the winter months," says Persaud. "Most of the other studies focused on smog, which normally occurs during the summer months."
Persaud and Singh are two of several York grad students taking part in the SWAPIT study to better understand the mix of pollutants in Toronto's urban winter air and why known pollutants haven't declined as expected over the years. Persaud is under the supervision of Professor Cora Young with Associate Professor Trevor VandenBoer, both atmospheric chemists in the Faculty of Science, while Singh is supervised by Associate Professor Mark Gordon, director of the Graduate Program in Earth and Space Science at Lassonde and the Air Pollution Lab.
Elisabeth Galarneau
Elisabeth Galarneau, air quality research scientist at ECCC, is leading the study, with York as one of the collaborators. "Studies like this can lead to improved tools for testing air quality and provide better information about our urban cities across the country," she says.
ECCC calls it the largest urban study of its kind in Canada with more than 90 scientific and technical experts with some 44 sub-projects. The winter phase of the study took place over an intensive six-week field measurement campaign last winter.
"There is a need to understand what pollutants are most prevalent in the air in the winter as different sources of contaminants become more prevalent during that time compared to the summer, things like high particulate matter from forest fires which is unlikely during winter," says Young.
It's not the first time York has been a partner in large atmospheric projects. A couple of summers ago, Young and VandenBoer led THE CIX (Toronto Halogens, Emissions, Contaminants and Inorganics Experiment) in collaboration with the Atmospheric Emissions and Reactions Observed from Megacities to Marine Areas (AEROMMA) project organized by NASA and the National Oceanic and Atmospheric Administration.
SWAPIT, like THE CIX, uses York's rooftop Air Quality Research Station to monitor air quality, but this time it also included another York research station perched on the east edge of the Keele Campus, plus several other non-York stations spread out across the GTA.
"In both of these studies, we are looking at the mix of pollutants and their source. It's one thing to know there is a particular level of a toxic gas in the atmosphere, but how that might combine with another pollutant to create a whole new contaminant is one of the things we're working on," says VandenBoer.
As part of the instrumentation used to gather air quality data for this study, Singh and Gordon installed a spectrometer on the roof of one of York's administrative buildings to measure the distribution of particle sizes, along with a particulate matter sensor, an anemometer to measure wind speed and direction, and two cameras to measure the amount of traffic. In addition to particulate matter, some of the pollutants measured are per- and polyfluorinated substances (PFAS), ozone and volatile organic compounds, such as benzene, as well as trace contaminants like flame retardants and plasticizers. Given the sheer number of pollutants to be measured, it is considered the largest study of its kind globally.
"It will be interesting to see the variation over time, spatially, as well as how the pollutants vary throughout the city, from one testing site to another," says Singh, who routinely checks on the York sites and collects initial raw data along the way to gauge how things are progressing or if there is anything significant.
"Until we investigate what kind of pollutants and in what amounts are circulating at various times throughout the year and where they are coming from, whether that's vehicle emissions in the country's major cities or emissions from the oil sands facilities in the west, we don't know what effect they may be having," says Gordon. "This type of information has not been readily available, which makes combating air quality issues difficult."
The York students involved in the study also worked with ECCC scientists at additional locations, including Pearson International Airport, High Park, and the Evergreen Brickworks. Both Singh and Persaud say they appreciate the opportunity to be involved in this study and to collaborate with external partners.
"It's a unique opportunity to use our skills, resources and data with various groups, not only here at York, but with Environmental Canada, and hopefully we get some good data out and it can lead to changes that would benefit human health and air quality," says Persaud, who adds it gives him the opportunity to gain hands on experience in environmental monitoring and data analysis.
The goal, he adds, is to hopefully influence policy in the end, but for now they need to identify what's responsible for pushing up the air quality index whether that's in the winter or summer months. In addition to human health, it's also important for the health of the environment, including the Great Lakes.
As Singh points out, the data they collect can help understand what pollutants are in the air and the direction they're coming from, which the wind sensor they installed will help to do. The results will hopefully illuminate some of the impacts these pollutants might have on people's health during the winter. They can be also be an indicator of the influence of a changing climate and be compared to similar research to give them a bigger picture of the issues.
Persaud not only helped deploy custom built wet deposition samplers for this study, but also went on to co-author a paper, Cost-effective off-grid automatic precipitation samplers for pollutant and biogeochemical atmospheric deposition, with VandenBoer, Young and others, about the instrument in the peer-reviewed journal Atmospheric Measurement Techniques. (See the video abstract.)
Wet deposition includes rain, sleet and snow, which can all carry contaminants. He will collect and analyze those samples for things like PFAS, which don't break down in the environment and can travel thousands of kilometres away from their source and accumulate in soil, water and snow. Traces can even be found in wildlife, including fish, and even people.
Equipment to measure air pollutants on top of York's chemistry building
"We hope to understand, to get an idea of the concentration and spatial distribution of these compounds," says Persaud, who has been studying atmospheric deposition for the past six years. "We look for trends, we correlate them with atmospheric tracers, and we hope that we can compare our measurements to measurements that other groups are making in the study so we can truly understand the big picture with atmospheric transport and deposition."
A different project Persaud participated in with Young was investigating the presence of these compounds in ice cores, which were collected and analyzed from Ellesmere Island, Nunavut in Canada's High Arctic - A 50 year record for perfluoroalkyl acids in high arctic: implication for global and local transport - published in the peer-reviewed journal Environmental Science: Processes and Implications. They were able to date perfluoroalkyl acids going back to about 1967.
"We could see a gradual increase as more industrial revolution happened," says Persaud, who has always been interested in chemistry and interactions with the environment.
Persaud realized during his undergrad that he wanted to pursue a career investigating contaminants in the environment. That passion led him to York where he is now part of the Analytical Environmental Chemistry group run by Young, one of the few research groups that use and develop analytical techniques to understand environmental issues, he says. "I'm fortunate to be a part of Dr. Young's group. We use and develop analytical techniques to solve environmental issues. PFAS is a hot topic in environmental chemistry."
For Singh, he saw York as having the best professors and programs in atmospheric science, which made the decision to move to this University for his graduate work easy. As part of Gordon's Air Pollution Lab, students like Singh can study emissions and the mixing of pollutants caused by city and highway traffic, emissions from oil sands production facilities, and how pollutants interact with forest environments and mix within the forest canopy.
It's the kind of academic work both students are excited about and eager to apply their new knowledge to the real world, such as participating in the SWAPIT project, toward making a difference in the health of people and the environment.
"This can generate meaningful insights and develop evidence-based solutions for improving air quality," says Persaud.
