In your personal opinion, how bad is the air pollution in Seoul? Sometimes I wonder if the pollution is overblown by expats from Canada or other areas where pollution is minimal. I am from a fairly large metropolitan area (Philly/Baltimore/DC)and just hope that some of these on-line opinions I read are just overblown compared to other areas that are quite polluted.
I like this question because it asks for my personal opinion. Seoul isn't particularly clean, but it is improving. The comments you read online could come from genuine posters or runners, bikers and other outdoor sports enthusiasts, but from experience on my ESL Teacher group over on Facebook, most of the comments are from expats and teachers who like to bash Seoul and Seoulites.
I remember reading about how I would become asthmatic after a few months in Seoul and would be ill most of the time. Not only have I not developed asthma, but I also am ill about a fraction of the amount I was in the US. You should ignore most comments and just look at the facts. Seoul is not on any "Most Polluted" lists that I can find. Seoul does not have factories or any other industry which produces a lot of air pollution. Seoul simply has too many damn drivers. If you're a little more into stats and comparative studies then perhaps a Google search would be best. You'll find all you need to know about the current state of air quality and pollution in Seoul. This picture, however, is something that I have never seen in Seoul.
I know a few cyclists who really had a hard time getting in a solid exercise out of fear of inhaling exhaust and fumes. Seoul has an excellent public transportation system, but still has way too many cars. They're trying to get people to ride bikes more and even have an alternating-day driving program to reduce congestion and pollution, but the smog can get pretty thick on hot summer days.
If you live in a busy city-center, then expect some pollution, but Seoul is not significantly worse than other major world cities. In fact, Seoul has less particulate matter in the air than Busan and Daegu. You mentioned that you're from the DC area and from what I can tell, DC produces more air pollution than Seoul. The time of year also must be considered. Of course, you'll be in Korea for a minimum of a year, but since the winter months experience the greatest increase in pollution, the cold weather usually deters people from spending extended amounts of time on the streets.
I guess the main point is that pollution is a problem of course, but it depends on your lifestyle as to whether or not you let it become an issue for you. If you are a runner, then I suggest you get up early in the morning and beat the cars. If you are a cyclist, then stick to some of the rural trails. If you love the smell of grass and trees, then perhaps Seoul shouldn't be on your list. You are a gym dude, then it won't be a problem. And don't forget that you can always go the mask route...
Anybody developed any illnesses or conditions as a result of the pollution?