It seems that SIDS is less likely if the baby is in moving air , such as from a fan. Quick observation on my part: I have emphysema, which is exacerbated by smoke or increased humidity. When I was too broke to afford an air conditioning unit for the last two years, my condition tended to exacerbate for longer periods, and was much worse. However, I also found that just running a fan seemed to ease my condition a lot, it just seemed that with a bit of air flowing past me, it made breathing easier. Still not as easy as in A/C environment but none the less, the years I used a fan were much easier on me than the year I didn't, all things considered.
So. Perhaps, there's a need to keep windows open and air flowing. For whatever reasons, it seems to be of benefit.