Dear Mark,
Many, many years ago I was an avid smoker; at least 2 packs a day. I was always diligent in NOT throwing the butts on the ground. Walking around my neighborhood I see the ground littered with cigarette butts. Where do they go? Washed down the street drains, eventually ending in the waterways/ocean. They are not biodegradable but are harmful to the Ecosystem. Please, please dispose of the butts or carry a personal ashtray; a zippered pouch that can eventually be emptied into an appropriate receptical.