I have lived in Chile for over a year now and if you remember back my biggest fear was the smog.
Here are my words on this topic from May 2009:
As Smog was one of my main concerns about living in Santiago I will be reporting about it throughout the winter
Since I do receive a fair bit of traffic from people searching for Smog combined with Santiago I wanted to give my impression: The smog in Santiago was not a big problem for me!! Yes it is easy to produce pictures that look awful and disgusting (usually from the top of Cerro Saint Cristobal) but if you are down there on the street in Las Condes then it is not that bad or at least it does not feel it for me. I cannot tell you about the center of Santiago because I did not go there this winter.
In May I started a poll. Here is the result of the Poll:
The question was: What about the smog in Santiago
There is one important point to bear in mind:
* I have spent my winter in Las Condes and not in the center of Santiago. The Center is worse as the altitude of the center is lower.
Below you will find a map with the smog levels in each “Comuna” on the 30th of September 2008 The image is from a government site which does not get updated anymore. Here is the link to the site if you want to see more.
I know some people suffer from Smog and I hope Santiago will improve the already very good public transport to cut the smog but since Smog was my number 1 concern I wanted to mention that I had expected the winter to be a nightmare and I was pleasantly surprised it was not and I enjoyed my winter here.