Sulphur Dioxide Comparison*
Sulphur dioxide (SO2) is a colourless gas
with an irritating odour and taste. Major sources are natural gas processing plants, oil sands plants and electric power
generation.
The average SO2 concentrations in Edmonton and Calgary from 1998 to 2003 were 0.002 parts per
million (ppm) and 0.003 ppm, respectively. Both cities experienced a small drop of 0.001 ppm in 2003 when compared to
their five-year averages. These values were lower than most Canadian cities. Montreal, Toronto, Ottawa, Halifax and
Hamilton all had higher SO2 concentrations for the five-year average, as well as in 2003. Halifax had by far
the highest concentration with 0.011 ppm averaged over the five-year period (the same level as New York City). Halifax
did however decrease to 0.009 ppm in 2003, but that was still significantly higher than any other Canadian city. The
American cities used in the comparison had similar values to Canadian cities of similar size, and in some cases had lower
SO2 concentrations. The higher concentrations of SO2 in central Canada are due to the higher
concentration of industry and the transport of pollutants from across the U.S. border.
|
Annual Average SO2 Concentrations in North American Cities (ppm)
|
|
City/County
|
5 Year Average (1998-2003)
|
2003
|
|
Halifax
|
0.011
|
0.009
|
|
Montreal
|
0.004
|
0.004
|
|
Ottawa
|
0.004
|
0.003
|
|
Toronto
|
0.005
|
0.003
|
|
Hamilton
|
0.006
|
0.005
|
|
Regina
|
0.001
|
0.001
|
|
Saskatoon
|
0.000
|
0.001
|
|
Edmonton
|
0.002
|
0.001
|
|
Calgary
|
0.003
|
0.002
|
|
Fort Saskatchewan
|
0.001
|
0.001
|
|
Fort McMurray
|
0.001
|
0.001
|
|
Greater Vancouver
|
0.003
|
0.003
|
|
Victoria
|
0.001
|
0.001
|
|
L.A. County
|
0.004
|
0.003
|
|
New York
|
0.011
|
0.011
|
|
Dallas
|
0.002
|
0.001
|
|
Seattle
|
0.004
|
0.003
|
*The cities were compared by looking at the differences in their annual averages over a five-year period (1998-2003) and their most recent annual averages (2003). The city averages were calculated by finding the average of the annual average values for each station within a city. Each city did not necessarily have the same number of stations and it is important to note that this may affect exactly how representative an average is for a given city. Also, some stations may not have been operational for a majority of the time of the comparison, and therefore only stations that had data for at least four out of the five years were used. These same stations were also used in calculating the 2003 averages. The table below shows the number of stations that satisfied the criteria and were thus used for calculating the city averages.
|
City/County
|
# of Stations Used in Analysis
|
|
Halifax
|
1
|
|
Montreal
|
5
|
|
Ottawa
|
2
|
|
Toronto
|
3
|
|
Hamilton
|
2
|
|
Regina
|
1
|
|
Saskatoon
|
1
|
|
Edmonton
|
1
|
|
Calgary
|
1
|
|
Fort Saskatchewan
|
1
|
|
Fort McMurray
|
1
|
|
Greater Vancouver
|
4
|
|
Victoria
|
1
|
|
L.A. Countyv
|
4
|
|
New York
|
3
|
|
Dallas
|
1
|
|
Seattle
|
1
|
|
