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Anantha Valsalan, Greg Evans, Cheol-Heon Jeong Southern Ontario Centre For Atmospheric Aerosol Research, University Of Toronto
Fine particulate matter (PM2.5) refers to small particles of solids or liquids suspended in the air which have a diameter < 2.5 µm.
PM2.5 is responsible for many harmful health effects such as asthma and cardiopulmonary disease.1The WHO claims safe PM2.5
levels to be below a daily average of 25 µg/m3.2
Figure 1: Diesel and gasoline vehicles are known sources of PM2.5
• To quantify the contribution of vehicles to the PM2.5 concentration on College Street
• To identify diurnal and seasonal trends in the vehicular PM2.5 on College Street
• Two OPS were used for sampling: one at rooftop elevation (~30 m), one at road level from January to June 2013
• Rooftop OPS sampled for ‘Background’ concentration while the road level OPS sampled ‘Vehicular + Background’ concentration. (Both OPS were corrected with each other)
• Difference between ground and rooftop concentrations gives vehicular PM2.5 only
Figure 4: The variation in diurnal trend of emissions due to vehicles on weekends and weekdays. The average daily concentration from vehicles on weekdays is 0.81 µg/m3 and on weekends it is 0.73 µg/m3. Combined, this is ~10% of total PM2.5 emissions for the 6 month period.
Figure 3: A comparison between total road level and rooftop level PM2.5 concentrations. It can be seen that road level concentrations are consistently higher than roof level – this consistent difference is assumed to be the vehicular contribution to PM2.5. The large spikes at road level are due to high-emitting vehicles.
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Diurnal Trend Of Weekend and Weekday Emissions Of Vehicular Fine Particulate Matter
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Weekends
Figure 5: The PM2.5 contribution from vehicles varies seasonally. It can be seen that summer contributions are lower than winter and spring.
11% (0.85 µg/cm3)
11% (0.72 µg/cm3)
7.6% (0.76 µg/cm3)
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Bar Chart Showing Variation In Seasonal Contribution Of PM2.5 From Vehicles
• Vehicles contribute approximately 10% of the total PM2.5 emissions on College Street.
• PM2.5 from vehicles is highest in the winter with little significant difference between spring and summer
• Measures taken to reduce emissions from cars are working
• PM2.5 concentration due to vehicles is well within the levels considered safe by the WHO
• Funding was generously provided by the Centre For Global Change Science
• Technical guidance and data provided by Cheol-Heon Jeong and many other members of SOCAAR.
1National PEP Weighing Laboratory US-EPA, Region 4, “PM2.5 Objectives and History” [Online] Accessed August 19 2013. Available: http://www.epa.gov/region4/sesd/pm25/p2.html#2
2World Health Organization (2006), “WHO Air quality guidelines for particulate matter, ozone, nitrogen dioxide and sulfur dioxide” [Online] Accessed August 19 2013. Available: http://whqlibdoc.who.int/hq/2006/WHO_SDE_PHE_OEH_06.02_eng.pdf
Figure 2: Optical Particle Sizer (OPS, TSI Inc.) used to obtain particle concentrations at 1 minute time resolution
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Graph Showing Variation of Rooftop And Road Level PM2.5 On A Time Scale
Road Level PM2.5
Roof Level PM2.5
• Vehicles contribute approximately 10% of the total PM2.5 emissions on College Street.
• PM2.5 from vehicles is significantly lower in the summer than in winter and spring
• Measures taken to reduce emissions from cars are working
• Vehicles are not a significant contributor to the PM2.5 levels in the atmosphere.