"People who smoke use it as a stress reliever. It is satisfying to just toss it down when you are done."
~~ Annalynn LaChica, San Francisco
With this explanation, Ms. LaChica wins points for honesty, but not good citizenship. Having done a few beach cleanups, I can confirm that cigarette butts do not break down and they do float -- often to otherwise pristine beaches.
I am glad to see NYT covering this persistent problem of environmental behavior. More of my thoughts on the subject are at http://webhost.bridgew.edu/jhayesboh/nosmoke/.