Hamilton can do more to improve local air quality, but the CBC Hamilton article claiming we are "lagging behind" is misleading.
By Nicholas Kevlahan
Published April 17, 2015
Ontario's Ministry of the Environment and Climate Change has just released its Air Quality in Ontario 2013 Report [PDF].
The report presents a picture of air quality improving province-wide by a variety of measures: nitrogen dioxide (NO2), sulphur dioxide (SO2), carbon monoxide (CO), fine particulate matter (PM2.5), and greenhouse gases (GHGs). Ozone (O3) is the one pollutant that is increasing at almost all locations.
But an article in CBC Hamilton yesterday suggests that Hamilton is not sharing in the improvement:
[W]ithin that trend, Hamilton's picture is a less positive one for some key pollutants.
Ozone levels in the city have risen sharply in the last 20 years, the report shows. The annual mean for ozone levels downtown rose 62 percent in the last two decades, and jumped 43 percent on the Mountain and 41 percent in the west end, respectively.
I was shocked and surprised by this headline, because past studies have shown that Hamilton is, on most measures, quite similar to other cities in the Greater Toronto and Hamilton Area with regards to air pollution.
Because I found the results surprising, I downloaded the report and read it myself. It turns out that the results in the report don't back up the article's claim that Hamilton is doing much worse than other cities.
Figure 3 in the report compares the number of hours in 2013 when each city was above the one-hour Ozone Ambient Air Quality Criterion (AAQC):
Comparison of 1-Hour Ozone AAQC across Ontario, 2013
Hamilton is comparable to the other southern Ontario municipalities.
Likewise, Figure 6 in the Report compares the number of hours in 2013 when each city was above the 24-hour PM25 Reference Level:
Comparison of 24-Hour PM25 Reference Level across Ontario, 2013
Again, Hamilton is comparable to the other southern Ontario municipalities, matching Newmarket and Brampton.
Table 5.2 compares Hamilton with other cities for ozone and PM2.5 CAAQS (particulates), finding Hamilton is around average:
|City/Town||8h Ozone (ppb)||24h PM2.5 (μg/m3)||Annual PM2.5 (μg/m3)|
The annual mean levels for ozone in Hamilton did indeed show the highest jump in the province at 23 percent, but many locations showed large increases: Windsor at 23 percent, Mississauga at 19 percent, Burlington at 21 percent, Toronto East at 16 percent.
The report also notes:
[W]hile ambient concentrations have improved, the province continues to experience high levels of ozone due to transboundary air pollution which can result in exceedances of the ozone standard.
This suggests that Hamilton's issue may be primarily atmospheric rather than due to local industry. (A higher level in West Hamilton is not surprising since previous mobile measurements by Brian McCarry showed that the climb up Hwy 403 makes West Hamilton and Ancaster one of the most polluted areas in the city, especially in the summer.)
It is indeed noteworthy and concerning that sulphur dioxide has declined by only 3 percent in Hamilton in ten years while every other location measured has declined by much more, from 34 percent in Sudbury to 85 percent in Ottawa.
Nevertheless, sulphur dioxide has declined by 38 percent over 20 years in Hamilton downtown and by 50 percent at Hamilton Mountain, and NOX is down 48 percent in Hamilton Downtown over 10 years (slightly more than Downtown Toronto).
The fact that Hamilton Downtown recorded the highest annual mean level of particulates in 2013 (10.1 μg/m3, slightly higher than Windsor West's level of 10.0 μg/m3 and significantly higher than Toronto West's 8.8 μg/m3) is worrying, although the long term trend actually shows slightly decreasing levels, similar to other cities.
The CBC claim, "those levels have risen since 2004" is not true: using the old measurement technique the 2013 level was 7.8 μg/m3, which is lower than every year except 2010 (at 7.7 μg/m3) since 2004.
Table A13 includes the caveat:
Ontario’s move to new measurement technology in 2013 has resulted in increased PM2.5 annual means; the increases are not an indication that the air quality has changed, but that the measurements are more accurate.
Most importantly, contrary to the 'belching smokestacks" photo and text accompanying the article, the Provincial report suggests that the high particulates levels in Hamilton in 2013 (especially the peak values) could be due in part to forest fires.
Many of these days recorded above the 28 μg/m3 reference level can be attributed to forest fire smoke that originated in northwestern Quebec, east of James Bay; these include July 1, 2 and 3, 2013 for Hamilton.
The CBC article plays into the stereotype of Hamilton as an extremely polluted city, makes a number of misleading claims and interpretations, and avoids any attempt to actually try to understand why two pollutants, sulphur dioxide and particulates, were relatively high in Hamilton (although still declining).
Hamilton can and should do more to improve local air quality, but the Provincial report does not back up the claim that "Hamilton's air quality lagging behind as province's improves".
With the exception of sulphur dioxide in the past ten years, Hamilton shows similar trends to everywhere else.
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