An Analysis of Primary Contributing Sources to the PM2.5 Composition in a Port City in Canada Influenced by Traffic, Marine, and Wildfire Emissions

Abstract

Ambient air quality, specifically fine particulate matter (PM2.5) pollution, poses a global health concern due to its associations with adverse health effects and persistent presence in urban settings. This study investigates PM2.5 exposure in a traffic-influenced residential area in Vancouver, employing chemical speciation data sampled in the vicinity of a major road throughout 2018. Using receptor-oriented models, Positive Matrix Factorization (PMF), and Principal Component Analysis (PCA), major emission sources contributing to the total PM2.5 mass were identified. The Organic and Elemental carbon concentration time series analysis reveals impacts from traffic and episodic influences from wildfires and residential heating. Applying PMF, we attribute identified factors to specific sources: traffic (33%), secondary aerosols (27%), dust (14%), Marine Heavy Fuel Combustion (HFC) (12%), Local (9%), and rare metallic elements (5%), respectively. This apportioning is subsequently verified by PCA, which introduces a sea salt factor to the analysis. Applying the conditional probability function analysis on the integrated wind speed and direction, and the PM concentration data further confirms the partial PM mass apportionment to marine HFC, rare metallic elements, and local factors. Lastly, comparing the results with the 2015 emission inventory of Vancouver shows similarities in apportioning the share of primary sources while overlooking secondary emissions in the latter, emphasizing the importance of field sampling for accurate source characterization. This study highlights the necessity of receptor modeling coupled with field sampling in quantifying the contribution and chemical characteristics of secondary emission sources, particularly near residential neighborhoods. Precise characterization aids health exposure studies that contribute to informed air quality management and policy regulations.