In an article from triplepundit, the California Academy of Science is advertising its opening by putting green roofs on a number of bus shelters in the San Francisco area.
This is same museum that I wrote about in July, in a post titled, "California Academy of Science's 2.5 Acre Green Roof,"which discusses the museum and the enormous green roof.
What the triplepundit article doesn't mention is that this marketing scheme is actually a very good thing, for several reasons. First and foremost, air pollution from large diesel vehicles is greatest during acceleration. When the buses pull away from the shelter, those giant black clouds of soot and sulfur dioxide can be mitigated (at least a little) by the shelter green roof. Secondly, the green roof will help keep the shelter about 10% cooler. Finally, the green roof will help reduce runoff, while also capturing the fine particulate matter in the rain as it falls.
Perhaps green roofs on bus shelters is a idea who's time has come. If placed on every shelter in a major metropolitan area, the clean air benefits would likely exceed the cost of acquisition and installation, as well as providing a little bit of green in the urban jungle.