lutusp is referring to this study in particular. There are many variables that potentially should be corrected for that aren't mentioned in the article.
I get that, but we're not going to run a double-blind randomized study on whether car exhaust gives kids asthma. So our next best option is to take all of the relevant research, aggregate it as best possible, and make recommendations based on those results. There will be shortcomings, we might never get to a 99.9% significance, but in the mean time -- Kids will stop getting asthma from car exhaust.
> I get that, but we're not going to run a double-blind randomized study on whether car exhaust gives kids asthma.
Yes, but the point I have been trying to make is that, when we don't do science, we need to say we haven't done the science. Too much public information is pseudoscience without anyone saying to.
> ... but in the mean time -- Kids will stop getting asthma from car exhaust.
I understand that you're not getting this, but any number of times people have gone down the wrong path, let astray by pseudoscience, and calling it science all the while. As it happens, asthma is as likely to be caused by an overly clean environment as a polluted one -- observations support either conclusion.
Again, we cannot draw a conclusion without doing some science. My only point in bringing this to your attention is so you realize this issue is by no means settled, and no issue can be settled without science.
Environmental pollution is a serious problem, one I happen to think should be aggressively addressed. But if we offer a bogus reason, opponents in industry will use that bogus reason to fight a needed change.