My father used to comment that cigarette smokers could walk knee deep through cigarette butts without noticing them. They seem oblivious to just tossing the butt on the ground, sidewalk or street, perhaps making a half-hearted gesture of stepping on it and then blithely going about their business. Ironically this article just popped up in the news.
Secondhand Smoke Kills 42,000 Nonsmokers a Year in US - Yahoo! News
That is probably an understatement. How about the smokers who smoke outside the doorways of various buildings or who leave their burning cigs in ashtrays outside buildings so we all get to walk through the poisonous stench?