Ross McKitrick, the Canadian economist who helped expose the “hockey stick” diagram for overstating the modern warming trend, has just published a paper questioning another article of faith among environmental extremists: the notion that government regulations to combat smog would result in significant health benefits. McKitrick looked carefully at the available data and can’t find the claimed effect:

For his study, he looked at breathing-related hospital admissions and pollution levels in 11 Canadian cities between 1974 and 1994. The period covered a time when pollution was worse and there were more dramatic changes in air quality, which he said would produce more robust results.
He also factored in smoking rates, with their obvious effects on respiratory health, and income levels, which he said can also alter hospitalization statistics.
Prof. McKitrick and two colleagues at the University of Strathclyde in Glasgow used the Bayesian method of averaging, which he argued would, in essence, provide a more all-encompassing picture of the situation.
The results were clear: lower smoking rates meant fewer respiratory-health hospital admissions, higher income levels were sometimes linked to slightly more admissions and air-pollution had no effect, he said.

Some years ago, one of my John Locke Foundation colleagues found a similar lack of evidence for claims that reducing smog from already-low levels would affect hospitalizations for asthma. Advocates of increased regulation have always counted on the fact that, because asserted links between pollution reduction and health benefit appear plausible, no one will check them out.

With the likes of McKitrick on the case, don’t count on it.