She frowned and hugged the clipboard to her chest. "It's the carbon monoxide in the cigarette smoke! Trace amounts of it that when combined with all that the automobiles in the city are putting out, build up to a really big problem. It's all part of global warming. Plus, the cigarette filters don't decompose. They sit in landfills and take up space. The less of those that get put into the environment the better it is for everyone."