Climate activists in Portugal are collecting some 650,000 cigarette butts and piling them up in the heart of Portugal's capital Lisbon in an effort to raise awareness about this often-overlooked form of pollution. "The main problem with cigarette butts is that they are not biodegradable - they contain a form of plastic and, even worse, a lot of toxins, heavy metals and chemicals," explains climate activist Andreas Noe. IMAGES AND SOUNDBITES