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Air Quality

Study Method

The purpose of the environmental studies are to:  

  • Establish existing (baseline) conditions;  
  • Identify and characterize existing features;  
  • Complete impact assessments; and  
  • Develop measures to avoid, minimize or mitigate potential negative effects.  

Methods undertaken to complete these studies include the following: 

  • Examine vehicle exhaust and greenhouse gas emissions (GHGs). The assessment was based on publicly available historical data from ambient air quality monitoring stations close to the study area.  
  • Five-years of data was averaged to capture existing air quality data from monitoring stations. Emissions captured included:  
    • Vehicular emissions;  
    • Diesel rail emissions; and  
    • Industrial emissions.  
  • Identify potential adverse impacts, determine the need for mitigation and provide a strategy or list of potential mitigation measures based on construction and operation plans.  

Existing Environmental Conditions

Toronto 

  • Background air quality levels are predominately below respective provincial and federal ambient air quality criteria and standards; however, some levels show significant exceedances, including: 
    • Benzo(a)pyrene;  
    • Benzene; and  
    • Nitrogen dioxide.  
  • Contaminants showing higher levels of background concentration above 80% of the federal standards include nitrogen dioxide and fine particulate matter (PM2.5).  
  • Meteorological data from the Toronto Pearson Airport over a five-year period (2016 – 2020) shows predominant wind direction blowing from northwest, west and southwest, and low-speed wind predominance from the southeast. 

Mississauga East

  • Background air quality levels are predominately below respective provincial and federal ambient air quality criteria and standards; however, some levels show existing exceedances, including:  
    • Benzo(a)pyrene;  
    • Benzene; and  
    • Nitrogen dioxide.  
  • Contaminants showing higher levels of background concentration above 80% of the federal standards include nitrogen dioxide and fine particulate matter (PM2.5).  
  • Meteorological data from the Toronto Pearson Airport over a five-year period (2016 – 2020) shows predominant wind direction blowing from northwest, west and southwest, and low-speed wind predominance from the southeast. 

Mississauga West

  • Background air quality levels are predominantly below respective provincial and federal ambient air quality criteria and standards; however, some contaminants show exceedances, including:  
    • Benzo(a)pyrene;  
    • Benzene; and  
    • Nitrogen dioxide.  
  • Contaminants showing higher levels of background concentration above 80% of the federal standards includes particulate matter (PM2.5).  
  • Meteorological data from the Toronto Pearson Airport over a five year period (2016 – 2020) shows predominant wind direction blowing from northwest, west and southwest, and low-speed wind predominance from the southeast. 

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