This Saturday is Earth Day, a worldwide celebration of environmental protection. Canadians care about the environment, especially the quality of the air we breathe. According to a survey conducted in 2016 by researchers at the University of Montreal, 73 per cent of Canadians want the government to increase efforts to improve air quality and public health. And many commentators continue to suggest that air quality is poor and getting worse. But is this true?

Simply put—no, it’s not. Although it may surprise many people to learn that Canada’s air quality has substantially improved over the past few decades. Our recent study published by the Fraser Institute explains this success story.

We used a massive archive of data from Environment Canada to examine the evolution of air quality from the 1970s onward, spotlighting emissions and ambient concentrations (basically the amount of pollutants in the air) of five major air pollutants—ground level ozone, fine particulate matter, sulphur dioxide, nitrogen dioxide and carbon monoxide. The study findings, again, contradict common misperceptions of Canada’s environment.

For example, ambient levels of ground-level ozone, an air pollutant caused by emissions, decreased 27 per cent from 1979 to 2015. In fact, in the late 1970s, more than 70 per cent of air quality monitoring stations across Canada reported ozone concentrations above the air quality standard, but by 2015 this number had fallen to 16 per cent. Regarding fine particulate matter (smoke, fumes, etc.), the data on ambient concentrations only go back to 2000. But more good news—from 2000 to 2015, fine particulate matter consistently remained below the most stringent air quality standard.

Canada’s ambient levels of sulphur dioxide, a pollutant largely associated with the combustion of oil and coal, plummeted by 92 per cent from 1974 to 2015. During the 1970s more than 60 per cent of monitoring stations recorded concentrations exceeding the annual air quality standard, but this number fell to only 3 per cent in 2015. Emissions of sulphur oxides also dropped 66 per cent from 1990 to 2014.

Likewise in the last four decades Canada experienced substantial reductions in nitrogen dioxide and carbon monoxide—two pollutants largely associated with automobiles—with national levels decreasing by 74 per cent and 90 per cent, respectively, from 1974 to 2015. In the mid-1970s, 54 per cent of stations in Canada recorded nitrogen dioxide levels exceeding air quality standards—there were zero such readings in 2015. For carbon monoxide, all stations since 1999—with the exception of one in New Brunswick in 2011—have recorded levels conforming to air quality standards.

Interestingly, all of these noteworthy developments have occurred despite considerable growth in population, energy use, motor fuel consumption and the Canadian economy.

Our findings have important policy implications particularly as the United States, our biggest trading partner, has begun relaxing air pollution and climate policies. This lifts a cost burden from American industry and puts Canada at a competitive disadvantage. In reality, while Canadian policymakers want to make our pollution standards ever-tighter, the numbers indicate that we are well within the target zone of air quality and should instead consider regulatory relief. Imposing tighter regulations and tougher emission policies will increase economic costs without generating appreciable environmental benefits.

Canada has effectively decoupled air pollution from energy use and economic growth over the past few decades. Contrary to common misperception, our air quality conforms to the strictest standards in the world. This is an achievement we should celebrate on Earth Day and beyond.