I always found the frequent sewage scent wafting up from the bowels of the streets in San Francisco very startling. Usually around Embarcadero and SOMA regions.

> Preemptive plea: Please don't shoot the messenger by downvoting me for sharing this demonstrably factual information with you (I know it's coming, I know how this site works now).

Chance of that is higher if you don't talk about downvoting. A number of people will downvote you just for that.

A lot of the PM2.5 (the kind of pollution mentioned in the link offered by parent) in the Bay Area is from houses and apartments burning wood.

Source: http://www.ozy.com/acumen/think-chinas-pollution-is-bad-try-...

FWIW Here is a direct comparison [1] between the Metro Stat Areas (MSA) of 'San Jose-San Francisco-Oakland, CA' and 'Pittsburgh-New Castle-Weirton, PA-OH-WV'

[1] http://www.stateoftheair.org/2015/city-rankings/compare-your...

You're being downvoted for at least two reasons. One, you are off topic, and trying very hard to be inflammatory, and two, because whining about downvotes is, itself, pollution.

I _am_ on topic, we are discussing air pollution, and most people I talk to around here are mistakenly under the impression that SF is this paragon of air quality, so mine is a pretty high entropy post sharing an interesting and not commonly known fact that often surprises people.

Meanwhile, you're attaching unfounded emotion to my post through projection (I've been sitting here the whole time with a perfectly chillaxed and even slightly amused attitude); my post has had a non-negative score its entire lifetime -- only one person downvoted it (you?), so I'm more inclined to believe that somebody else that is not me is the problem here.