The rising concern of non-tailpipe emissions

Cheol and Cuilian
L-R: Cheol Jeong and Cuilian Fang

Tailpipe emissions are often the focus of air quality studies, as they contribute to climate change and a myriad of heath problems, but are non-tailpipe emissions just as concerning? Researchers from the Southern Ontario Centre for Atmospheric Aerosol Research (SOCAAR) are proving that they are.

For over 15 years, scientists, graduate and undergraduate students from SOCAAR have been monitoring air quality and crunching enormous amounts of data in partnership with the Ontario Ministry of the Environment Conservation and Parks, as well as Environment and Climate Change Canada.

Dr. Cheol Jeong, a senior research associate from SOCAAR, has been part of this effort – developing methodology, performing experiments, data collection, managing research activity, and preparing and presenting the group’s findings.

His papers – Long-term analysis of PM2.5 from 2004 to 2017 in Toronto: Composition, sources, and oxidative potential and Impact of the COVID-19 lockdown on the chemical composition and sources of urban PM2.5 – published in Environment Pollution in August 2020 and January 2022, investigate the long-term trend of chemical composition of particulate matter (PM) and identifies their sources by time and location. The COVID-19 lockdown provided a unique opportunity to directly measure air quality under a reduced traffic-emission scenario.

“Based on comprehensive measurements and analyses, we found that the contribution of non-tailpipe emissions related to brake/tire wear is increasing even though the total PM mass has dropped over the last decade,” says Cheol. “Non-tailpipe emissions substantially dropped during the lockdown period mainly due to the reduced number of trucks,” he added.

Furthermore, his study pinpoints that non-tailpipe emissions can be much higher near major roadways compared to urban background areas. This finding implies that exposure to non-tailpipe emissions is disproportionally affecting people living and spending time near major streets across Toronto (such as low-income housing) and supports the development of targeted strategies and regulations to effectively improve local air quality.

Without the reliable long-term data collected through SOCAAR, Cheol would not have been able to achieve his findings. “Long-term measurements and data analysis for physical and chemical properties of air pollutants are rare because it takes a lot of work to maintain the required instruments and process the humongous data,” explains Cheol. “PM is a complex mixture of solid and liquid particles influenced by numerous emission sources, many which are unregulated. Non-tailpipe emissions may potentially cause significant health effects due to their metal-rich chemical properties.”

Cuilian Fang, a SOCAAR MASc student, is looking to characterize these metals by investigating their composition and testing the samples in a simulated lung environment. “By comparing samples of different origins (road vs. tire vs. brake), we can potentially find out which metals are more often emitted from which source and understand its associated health implications. Through this, we can possibly impact regulations. For example, make positive changes to the manufacturing of tires or brakes to reduce the toxicity of dust found on the roadside,” elaborates Cuilian.

SOCAAR’s research helps us understand the air we breathe and hopefully influence people to make better choices for the benefit of everyone and the environment that we all depend on.