From the Department of I-Could-Have-Told-You-That: The air is cleaner than it used to be.
From a University of Rochester study in Greenland:
A first-ever study of air trapped in the deep snowpack of Greenland shows that atmospheric levels of carbon monoxide (CO) in the 1950s were actually slightly higher than what we have today. This is a surprise because current computer models predict much higher CO concentrations over Greenland today than in 1950. Now it appears the opposite is in fact true.
Mind you, it's nice to have it scientifically established that atmospheric levels of at least one worrisome pollutant are lower than they were in the 1950's, even though anyone who breathed back in the 60's and 70's could tell you that we've made huge strides in cleaning up the air. I'm not saying that levels of carbon dioxide are not important, but it's nice to have some documentation beyond my own memory that our efforts to control toxic emissions have born significant fruit. And that computer models can be wrong.