Postdoctoral Fellow Maryam Shekarrizfard shares UT-ITE presentation

Head shot of Maryam Shekarrizfard

Maryam Shekarrizfard

Dr. Maryam Shekarrizfard has generously given permission for her March 24 presentation PDF to be shared on the UTTRI website:

Modelling the Spatio-Temporal Distribution of Ambient Nitrogen Dioxide and Investigating the Effects of Public Transit Policies on Population Exposure.

The presentation is the outcome of two published papers:

The research project was carried out in collaboration with the Montreal Department of Public Health with funds granted by the Canadian Institutes of Health Research.


Estimating the future state of air quality associated with transport policies and infrastructure investments is key to the development of meaningful transportation and planning decisions. We designed an integrated transportation and air quality modelling framework capable of simulating traffic emissions and air pollution at a refined spatio-temporal scale. For this purpose, emissions of Nitrogen Oxides (NOx) were estimated in the Greater Montreal Region at the level of individual trips and vehicles. In turn, hourly Nitrogen Dioxide (NO2) concentrations were simulated across different seasons and validated against observations.

Our validation results reveal a reasonable performance of the modelling chain. The modelling system was used to evaluate the impact of an extensive regional transit improvement strategy revealing reductions in NO2 concentrations across the territory by about 3.6% compared to the base case in addition to a decrease in the frequency and severity of NO2 hot spots. This is associated with a reduction in total NOx emissions of 1.9% compared to the base case; some roads experienced reductions by more than half.

Finally, a methodology for assessing individuals’ daily exposure was developed (by tracking activity locations and trajectories) and we observed a reduction of 20.8% in daily exposures compared to the base case. The large difference between reductions in the mean NO2 concentration across the study domain and the mean NO2 exposure across the sample population results from the fact that NO2 concentrations dropped largely in the areas which attract the most individuals.

This exercise illustrates that evaluating the air quality impacts of transportation scenarios by solely quantifying reductions in air pollution concentrations across the study domain would lead to an underestimation of the potential health gains.

Short Biography

Maryam Shekarrizfard is a postdoctoral fellow in Department of Civil Engineering at University of Toronto. She joined Professor Hatzopoulou’s research group at McGill University to start her PhD in 2012. Her research interest is in transportation and traffic analysis focusing on air pollution and exposure. As part of her PhD research, she developed an integrated emission and dispersion model with sensitivity to traffic flows for the assessment of individual exposure under different traffic/transportation scenarios. Her background spans the fields of environmental modelling including air dispersion modelling of traffic sources, linking large-scale land-use and transportation models and uncertainty analysis in environmental problems. Her specific interest is in development of public policy that addresses community-level health.

The Winter Term 2017 Seminar Series is presented by the University of Toronto Institute of Transportation Engineers (ITE) Student Chapter.