Blog: The Legal and Regulatory Implications of IARC Classifying Outdoor Air Pollution and Particulate Matter as Carcinogenic to Humans


On October 17, 2013, the International Agency for Research on Cancer (IARC), a specialized agency of the World Health Organization, announced that it has classified outdoor air pollution and particulate matter as carcinogenic to humans (Group 1), following a thorough review of the available scientific literature (over 1000 scientific papers from studies on five continents). IARC noted that the most recent data indicate that in 2010, lung cancer deaths worldwide attributable to outdoor air pollution totalled 223,000. Though the IARC program has in the past evaluated individual chemicals and mixtures that occur in outdoor air pollution, such as solvents, metals, and diesel engine exhaust, this is the first time that experts have classified outdoor air pollution itself as a cause of cancer. The IARC evaluation was driven by findings from large epidemiologic studies that included millions of people in Europe, North and South America, and Asia. IARC identified the predominant sources of outdoor air pollution as being transportation, stationary power generation, industrial and agricultural emissions, and residential heating and cooking.

Implications for Canada

Air pollution is a classic tragedy of the commons story writ large. However, the IARC announcement could serve to change the story ending to produce a better result. Certainly, in Canada the announcement could have a number of legal and regulatory implications for governments, the regulated community, the public, and the courts.


For federal and provincial levels of government in Canada, i.e. those levels with considerable constitutional and jurisdictional authority for regulating air pollution, there are a number of implications arising from the IARC announcement.

It should cause them to accelerate development and implementation of air emissions standards in a number of ways to reduce levels of cancer-causing chemicals in the emissions of the industries subject to the standards:

  • At the federal level this could mean expansion of the categories of industrial sectors that would be subject to release regulations under the Canadian Environmental Protection Act (e.g. air emissions of mercury from chlor-alkali plants are subject to emission standards but mercury air emissions from industrial power generation sources are not);
  • In Ontario, under the Environmental Protection Act this could mean addressing background concentrations, cumulative, synergistic, persistent, and bioaccumulative effects of substances as well as focusing on total annual loadings of pollutants in air instead of simply concentrations in air measured over minutes or hours (i.e. moving from the long-criticized point of impingement approach to an emissions standard approach);
  • It should also serve to make more robust government efforts, already underway in Ontario under the Toxics Reduction Act, to foster reductions in the use and creation of toxic substances in industrial processes that could otherwise end up as industrial air emissions, and cause other provinces to enact similar laws; and
  • It should further spur federal, provincial, and municipal government efforts to improve and expand mass transit and reduce reliance on the car in urban and suburban areas of the nation.

Perhaps the most interesting governmental issue going forward is whether the IARC announcement will fuel the interest of municipal governments in wanting to become direct regulators of air emissions within their geographic territory. Despite more limited jurisdiction and resources to address air pollution than senior government levels, it is possible the IARC announcement may prompt more municipalities to do what the Town of Oakville did in 2010. The Town’s Health Protection Air Quality By-law, 2010-035, requires facilities emitting into the air more than 300 kilograms per year of fine particulate matter (smaller than 2.5 microns) within the municipality to obtain an approval for their proposed air emissions, regardless of any provincial approvals they may have. Although Oakville’s by-law has not been tested judicially, it is an example of what we may see more of in future if local governments perceive senior government levels not moving quickly enough to address sources of air pollution in their area. The IARC announcement can only serve to further whet municipal interest in such an approach.

Regulated Community

For industry, the announcement and the eventual government response to it:

  • may prompt industries to get as many chemicals and particulates out of industrial air emissions as possible in order to reduce potential liability from government regulation as well as liability to third parties (i.e. victims who might sue individually or in class action proceedings); and
  • may spur those industries who want to get well ahead of the regulatory and third party liability curve, to recognize the economic benefit and reduced costs of making do with less chemicals – in jurisdictions that have laws requiring planning for reductions in the use and creation of toxic chemicals, industries have seen improvements to their economic bottom line – so the IARC announcement may encourage these companies to accelerate the trend to toxics use reduction.

On the other hand, industries may largely do nothing except what they are pushed to do by government. So don’t hold your breath. Actually, do hold your breath.

Members of the Public

For members of the public suffering health effects caused, or contributed to, by air pollution or fearing such effects in future, the announcement may provide a new evidentiary base:

  • to support individual or class action lawsuits against companies who are the primary sources of air emissions (the Supreme Court of Canada has already shown a willingness to venture on to this ground in St. Lawrence Cement Inc. v. Barrette, [2008] 3 S.C.R. 392);
  • to support challenges to regulatory issuance of new or amended air pollution approvals that are not sufficiently protective of environmental health (Ontario tribunals and courts have shown a willingness to venture on to this ground in Lafarge Canada Inc. v. Ontario (Environmental Review Tribunal), (2008), 36 C.E.L.R. (3d) 191 (Ont. Div. Ct.); and
  • to argue for an expansion in the application of international law principles, such as the precautionary principle, in the interpretation of domestic environmental laws so as to err on the side of caution in the face of scientific uncertainty about the environmental health impacts of air pollutants (the Supreme Court of Canada has twice applied the precautionary principle to domestic law, once in Quebec in Spraytech v. Hudson (Town), [2001] 2 S.C.R. 241, and just last week in Ontario in Castonguay Blasting Ltd. v. Ontario (Environment), 2013 SCC 52).


The IARC announcement classifying outdoor air pollution and particulate matter as carcinogenic to humans has the potential to influence the conduct or decision-making of governments, industry, the public, and the courts. It remains to be seen how they will each respond.