environment

Canada’s air quality is much improved—no need for more costly regulation

Over the last four decades, Canada’s carbon monoxide levels have dropped by 90 per cent.
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Canada's Air Quality Since 1970: An Environmental Success Story

Canadians have long been concerned about the state of our air quality and the belief that air pollution is a major problem seems to be widespread. This publication examines the evolution of air quality in Canada from the 1970s onward and looks at how the current state of air quality compares to the stringent standards established by Canadian government policy. The conclusion is that air quality in Canada has improved substantially and that this significant change over the past four decades occurred at the same time there was considerable growth in Canada’s population, economic activity, energy use, and consumption of motor fuel.

Using data from Environment Canada on emissions and ambient concentrations, the study provides accurate and up-to-date information on the status of five major air pollutants in Canada: ground level ozone, fine particulate matter, sulphur dioxide, nitrogen dioxide, and carbon monoxide. Comparing trends for the five air pollutants on three levels—national, city, and monitoring station—against existing national and international air-quality standards shows that air quality is improving for the most part and is now at levels generally deemed safe.

Ground-level ozone
Concentrations of ground-level ozone, a key component of smog, have generally decreased in Canada since 2000. In 2015, the national concentration of ground-level ozone was 27% lower than in 1979 and ozone concentrations have been consistently below the new stringent air-quality standard since 2005. Major Canadian cities have lower ozone concentrations than they had during the late 1970s. In the same period, over 70% of monitoring stations throughout Canada reported ozone concentrations that were above the air-quality standard; that number has fallen to 16% during the most recent interval.

Fine particulate matter
Concentrations of fine particulate matter in Canada have only been measured since 2000 and national ambient levels have consistently remained below the new air-quality standards.

Sulphur dioxide
In the last four decades, concentrations of sulphur dioxide have fallen dramatically across Canada and have met the strictest annual air-quality standard since 1999. In 2015, ambient levels of sulphur dioxide in Canada were 92.3% lower than in 1974. Major Canadian cities also significantly reduced their ambient levels of sulphur dioxide during the same period. In the mid-to-late 1970s, over 60% of monitoring stations across Canada recorded concentrations out of compliance with the annual air-quality standard, but today only 3% of stations record non-conforming levels.

Nitrogen dioxide
Concentrations of nitrogen dioxide have also been decreasing for decades in Canada. Ambient concentrations of nitrogen dioxide in Canada decreased 74.4% from 1974 to 2015 and ambient levels have been consistently below the strictest air-quality standard since 1985. The decrease in ambient levels was also apparent in all major Canadian cities. Whereas in the mid 1970s, 54% of stations across Canada reported readings out of compliance with the annual air-quality standard for nitrogen dioxide, in 2015 the percentage was zero. All monitoring stations throughout Canada have met the strictest annual air-quality standard for nitrogen dioxide since 2011.

Carbon monoxide
There has also been a substantial reduction in concentrations of carbon monoxide in Canada during the last four decades. Ambient levels fell 90.4% in Canada from 1974 to 2015 and have conformed to the strictest air-quality standard since 1985. Levels of carbon monoxide in major cities have also fallen dramatically over the past four decades. In mid-1970s, 84% of stations had readings for carbon monoxide exceeding the air-quality standards but, since 1999, all stations across Canada—with the exception of one in New Brunswick in 2011—recorded values conforming to the air-quality standard.

Socioeconomic trends
Between 1970 and 2015, real gross domestic product increased by 242% and the Canadian population grew by 68%. From 1980 to 2015, consumption of motor fuel rose by 26% and from 1995 to 2015 energy use increased 21%. At the same time emissions and ambient levels of major air pollutants dropped significantly, indicating the extent to which air pollution has been decoupled from energy use and economic growth in Canada. For this reason, discussions about the need for new policies to tighten emission policies even further should begin with the recognition that air pollution has already substantially declined in Canada and is largely in compliance with some of the strictest standards in the world.

William Watson: Among the ecofiscalists

No one really knows the true cost to humanity of an extra tonne of, say, carbon dioxide put into the air.

It’s official—Ontario’s coal phase-out was all for nothing

The coal phase-out had no apparent effect on nitrogen oxide levels.
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Did the Coal Phase-out Reduce Ontario Air Pollution?

In 2005, the province of Ontario began a process that would eventually lead to the phasing out of its coal-fired power plants, the largest of which were the Lambton and Nanticoke facilities in southern Ontario. The rationale for shuttering these plants was a 2005 cost-benefit analysis that assumed that about $3 billion in annual savings to the health care system would come from the reduction of smog-related air contaminants. However, that analysis, and another one done for the province the same year on the effects of cross-border air pollution, reported that the phase-out of coal would have only very modest effects on Ontario air quality, which is consistent with emissions inventory data showing that electric power generation was a minor contributor to particulate and ozone pollution at the time. The cost savings estimate came from assuming very large health effects associated with very small changes in air pollution.

In the aftermath of the coal phase-out, and the extremely costly changes to the electricity system this transition required, we examine whether the removal of coal from the grid explains changes in air pollution levels since 2002. We develop statistical models of air pollution concentrations in Hamilton, Toronto, and Ottawa, looking at monthly average levels of fine particulates (PM2.5, or particulate matter smaller than 2.5 microns), nitrogen oxides (NOx) and ground-level ozone (O3). Our explanatory variables include electricity generation from coal-fired and natural gas-fired power plants, NOx and PM2.5 emissions from other sources in Canada and the US, weather conditions, and seasonal indicator variables.

We find the elimination of coal was associated with a reduction in average urban PM2.5 levels by about 1 to 2 mg/m3 (about 6–12 percent from the peak levels), but the effect was not statistically significant in Toronto or Hamilton. We find no evidence that the coal phase-out reduced NOx levels, which were instead strongly affected by reduction in US NOx emissions. We find a statistically significant reduction in peak O3 levels from the coal phase-out, offset by a significant increase associated with natural gas plant emissions.

Overall, we conclude that the coal phase-out yielded small improvements in air quality in some locations, consistent with projections done prior to the plant closures, which were comparable in size to projected air quality improvements that could have been achieved through installation of new pollution control systems rather than closing the plants. This has implications for understanding the costs and benefits of a coal phase-out, such as the one being contemplated in Alberta.

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