The U.S. certainly is ahead of Europe on the regulation of toxic emissions, and European cities are much more likely than American ones to have dangerous levels of pollution:
http://www.nytimes.com/2014/12/31/upshot/pollution-around-th...
Anyway, NOx is not the only gas that the EU is concerned about, C02 figured very large in the whole reduction program as well.
Doesn't that lend further support to the point that U.S. regulations, while also obviously not perfect, are stronger in this area?
> Anyway, NOx is not the only gas that the EU is concerned about, C02 figured very large in the whole reduction program as well.
But you were challenging pwthornton's assertion that "The US is also much more concerned with air pollution that affects human health." While CO2 emissions are undesirable, NOx and particulates are what actually kill people in polluted cities.