[craigdalton]

There are well established hierarchies of evidence in health studies and this study would rank as low quality evidence due to inability to control for other factors. See https://gdt.gradepro.org/app/handbook/handbook.html#h.3183vu... for background.

In studies of pollution and impacts on health, the confounding factors often have a larger impact on the health outcome than the pollutant, such as particulate level, and therefore significant control of confounders is required to estimate any impact on the health outcome. The strong effect in this study is highly suggestive of a confounder rather than a real effect from particles or other pollutants and therefore would require a much better study design to support tacking action at a policy level with an expectation of a huge impact.

Fine to put filters into improve overall air quality but just not with the benefit rationale suggested in this study.