As reported in the Edmonton Journal on 13 February 2013, Edmonton was under a week long air quality advisory due to elevated levels of particulate matter (PM), a constituant of smog. The smog was detected at two of the three AESRD stations in Edmonton - Edmonton East and Edmonton Central. From Alberta Health Services, here:
Precautionary air quality advisory lifted for city of Edmonton
February 13, 2013
EDMONTON– Alberta Health Services has lifted the precautionary air quality advisory issued February 6, 2013 for the city of Edmonton.
Monitoring indicates air quality in the city of Edmonton is no longer being impacted by the temporary air-inversion event.....
Information about the air quality in some areas of the Edmonton Zone is updated regularly on the Alberta Environment Air Quality Website:http://environment.alberta.ca/0977.html. Air quality information is also available by phone, toll-free, at 1-877-247-7333.
The reporting of this air quality event was thin in many respects. What causes smog in general, and what caused the smog in this specific event? How do we know the extent of the problem, and is there any way to identify the pollution sources that are contributing to the problem? I will attempt to answer these questions.
The USEPA defines smog as...
...a condition that develops when primary pollutants (oxides of nitrogen and volatile organic compounds created from fossil fuel combustion) interact under the influence of sunlight to produce a mixture of hundreds of different and hazardous chemicals known as secondary pollutants. Smog is the brownish haze that pollutes our air, particularly over cities in the summertime.
As indicated by the USEPA, smog is more commonly found in the summertime. In Edmonton, for the week of 06 - 13 February, a health advisory was called as a result of vehicle and other emissions being trapped under a temperature inversion, where the temperatures aloft are warmer than those on the ground. In this instance, the temperature inversion acted as a cap, not allowing the pollution to dissipate by wind. The Edmonton Journal article also indicated that the smog was a result of vehicle emissions. How widespread is the 'problem' of vehicle emissions, and how to we track them?
The following map of Edmonton does NOT depict air pollution. Rather, it indicates where some of the sources of air pollution are, and where the monitoring takes place that tracks these pollutants.
The Map: The black diamonds indicate industrial emissions sources from the NPRI database found within Edmonton. The white circles are the Alberta Environment run air monitoring stations, and the colour layer indicates density of traffic from the City of Edmonton open data catalogue where I ran an IDW analysis to define a 'topography' of traffic flow - the blue is no or low traffic density, yellow moderate and red high (the highest volumes of traffic are over 100 000 vehicles per day, and the lowest less than 50). Rail lines are dashed. I do not indicate other emissions sources such as light or moderate industrial activity that would not report under the NPRI.
It is apparent from the map that there are many 'hotspots' of high vehicle flow, most notably on the Yellowhead, Whitemud and Henday. There are also some smaller pockets of high traffic flow in the downtown core, along 57th Street / Wayne Gretzky Drive, and Gateway BLVD. Environment's monitoring is located in the downtown, east Edmonton, and SW Edmonton. It is worth noting that the downtown monitoring station is on the top of a small building.
These regional monitors are great at pickup large are trends over time and are vital to the AQHI network, which is national in scope. There are three main issues with this AQ network: (1) it is limited in geographic area; (2) it is not at street level, and; (3) it is expensive to install and maintain.
So, we don't know the relative contributions of vehicle emissions vs other sources such as industrial or rail. We don't monitor or even really model in a public way vehicle emissions (The Clean Air Strategic Alliance, in 2007, released a ROVER report documenting vehicle emissions on Alberta roadways - the CASA link to the ROVER 2 report is broken, but I have a copy if you're interested), and so we cannot even speculate on the extent of smog pollution in Edmonton. This is a problem as the City of Edmonton becomes more urban, denser and bigger. How many cars can we add to the roadways, and how do we balance this with an appropriate amount of 'alternative' transportation options?