Climate activists in Portugal have collected some 650,000 cigarette butts and piled 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 Andreas Noe, the activist behind the initiative.
According to the World Health Organization, 4.5 trillion cigarette ends are thrown away each year worldwide.
