Dan Syrek is mentioned as a litter expert (detailed quotes on this Ireland blog). One of my pet peeves is cigarette butts. It occured to me the other day while walking down the street that cracks in sidewalks trap them very effectively. Other depressions in large flat surfaces also trap butts. Since they blow across open spaces and into depressions, it seems to me that we might take this into account when puoring new sidewalks, etc. It could help reduce litter to design litter traps which would need to be vacuumed or otherwise cleaned on a regular basis.
Made to Stick