I remember something that one of my friends said when I was living in Taipei. It was during his interview for the school newspaper having been awarded the school's male athlete of the year. In response to the question to tell what were the most healthy and most unhealthy things that he did, his response was (something like), "The most healthy thing that I do is to exercise for several hours every day. The most unhealthy thing that I do is to exercise for several hours every day in Taipei."
This was wa~ay back in 1993 or 1994, and I haven't been back to Taipei since I left it in June of 1994, so I don't know if air pollution levels have improved significantly over the intervening 16 years. However, I do remember it having quite a lot of air pollution during that time, partly due to an already-crowded road network made even more so during the simultaneous construction of a subway system and an elevated train system (meaning that some major avenues were being torn up to install the subway, while others would have many lane closures because of overhead work). Since the only real way to travel to and from school was to take the bus, I was stuck in the middle of all that car exhaust.
I was reminded of all this when I read a summary of a new scientific finding from Mexico City that showed that the air pollution of Mexico City had deleterious effects on the hearts of young people. Caveat time: I understand that there are many variables that differ between Mexico City and Taipei, but both have car- and people-clogged streets, so I would imagine that the general principle holds true. I wonder, then how sadly true my friend's statement was, and how much damage his long-distance running did to his heart (and lungs). I also wonder what effect it had on my own heart and lungs, since I was quite active in competitive swimming at that time. (Traveling to swim-meets in other Southeast Asian capitol cities likely didn't ameliorate the situation much, either.)
In contrast, currently as I cycle in Ann Arbor, I am reminded of something that another friend of mine commented on when he came to visit: "Wow! You can actually breathe here, and it feels refreshing!" (And it wasn't a particularly bracing or fresh day, but one from mid-late summer.) Compared to living in Chicago, I suppose this is true; it's definitely true in comparison with Taipei. However, this statement rings true for me since I am rarely bothered by the exhaust of the car next to me as they pass me by or as I wait with them at a stoplight.
"The solution to pollution is dilution," is a phrase that, in addition to its mnemonic quality, seems somewhat apt here, for (although one cannot dilute what we breathe by adding more air) the dilution factor is controlled by the amount of pollutants in the atmosphere, and the fewer pollutants, the better the breathing.
To compare (non-rigorously) air quality measurements: