During a 2018 coastal clean-up by Ocean Conservancy, cigarette butts ranked number one on its list of most littered items. More than two million pieces were collected in over 100 countries. How is this source of pollution affecting China? We find out from CGTN's Jen Kwan.

Many people are aware that smoking has harmful effects to health. But are they aware of how harmful the small yet ubiquitous cigarette butt is to the environment? We went around Beijing to find out.

"I never knew cigarette butts could pollute the environment. I only know smoking does."

"I've never thought of that. I'm just always concerned cigarette butts might burn something. I didn't know they could cause pollution."

"I think I watched something about it when I was a kid, but I haven't heard much about it in recent years."

According to the World Health Organization's representative for China, up to two-thirds of a cigarette stick is often discarded after smoking. Since its filter tip is not biodegradable, cigarette butts easily accumulate and persist in the environment. Almost 200-thousand tons are discarded worldwide, the impact of which is beyond cleanliness.

DR. GAUDEN GALEA WHO REPRESENTATIVE FOR CHINA "More importantly, these chemicals like nicotine, heavy metals are in these discarded wastes, then leach into the environment, and they appear in our soil, appear in our water, so environmental impact of these small seemingly neglectable waste that's left at the end of the cigarette, is accumulated into a significant global impact."

Chen Xiaowei, a sanitation worker in Beijing, says she usually picks up more than a thousand cigarette butts each day.

CHEN XIAOWEI SANITARY WORKER "People dump lots of cigarette butts near the subway entrances or on the streets. I usually sweep them into a dustpan and step on the burning cigarette ends, then throw them into a trash can."

Doctor Galea says the lack of awareness also exists outside of China, and it is a global issue. Aside from raising awareness, he has this advice for smokers.

DR. GAUDEN GALEA WHO REPRESENTATIVE FOR CHINA "That's not something which we outsource to the government, and it's not someone else who has to do the cleaning up for us. The problem is if you continue to smoke, you are still contributing to the overall 175 thousand tons of butts that are adding to the waste problem in the world. But at very least you can mitigate the impact by not exposing others and by being responsible to the discarding."

Though it sounds easy, an environment free of cigarette butts may still be difficult to achieve, difficult yet not impossible. Jen Kwan, CGTN, Beijing.