Green is not always visible, which is why we liked this sign we spied over the weekend in one of Portland's older neighborhoods. It's a simple question that makes you slow down and think about things that you take for granted, like air... which, in this neighborhood, has been found to contain over 70 known toxic compounds. Yuck! The signs convey a sense of community: after you see four identical signs in a block, it's a clear message that neighbors are looking out for one another. Green, we think, is not about finding one right answer. It's about asking the right questions.