As nearly 200 countries discuss how to cut plastic pollution at UN talks in Paris this week, environmental campaigners are pushing for a global ban on plastic filters in cigarettes - one of the biggest sources of plastic waste worldwide.
On the short walk to Wednesday's session of the negotiations on a global plastics treaty, Shannon Mead picked up a full bag's worth of cigarette butts.
"It's not surprising to me, unfortunately, but of course it's disgusting nonetheless," says Mead, the founder and "chief butt officer" of No More Butts, an Australian charity that campaigns against cigarette litter.
He's in Paris to remind delegates that there's a source of single-use, non-biodegradable, highly polluting plastic that often goes unnoticed: discarded cigarettes.
"There are millions of cigarette butts littered every day," says Mead, whose group organises volunteer clean-ups.
"So no matter where you look, whether it's a beach, whether it's a suburban city, it's likely you're going to find a bunch of cigarette butts."
Part of the problem is that smokers don't necessarily realise that cigarettes contain plastic.
But most filters in cigarettes are made of cellulose acetate, the same polymer that's commonly used to make glasses frames and children's toys.
It takes years to break down and when it does, ends up as tiny fragments of microplastic that can find their way into the sea, food and living creatures.
What's more, by the time they make it onto our streets, into drains and onto beaches, cigarette filters have absorbed nicotine, chemicals and heavy metals that then leach into water and soil.
That makes them an environmental hazard in several respects, explains Mead.
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"It can be mistaken for food - there are photos of birds feeding it to their young," he says, adding that strands of plastic are also ingested by fish, which can ultimately result in them ending up in humans and other animals.
"And then there's the water pollution as well: every cigarette butt will pollute anywhere from 40 litres up to 400 litres."
Filters that don't filter
No More Butts and several other environmental and public health groups that form part of the global Stop Tobacco Pollution Alliance are attending this week's negotiations in a bid to get cigarette filters added to the list of problematic single-use products in the world's first international treaty on plastic pollution.
But even before that treaty is finalised - in 2024 at the earliest - the campaigners urge national governments to consider banning filters alongside plastic bags, straws and cutlery.
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What would that mean for smokers? Not much, according to Mead, who points to extensive research that shows plastic filters do little or nothing to stop users inhaling harmful substances.
According to a recent report by Belgium's Superior Health Council, "cigarette filters have no proven benefits in preventing adverse health effects of smoking".
Worse, they may even encourage smokers to smoke more cigarettes or inhale more deeply by offering "a false sense of security".
The World Health Organisation been calling for countries to consider banning cigarette filters since 2022, so far without any takers.
However, Belgium's health council, which advises the government, recently recommended a ban nationwide and across the European Union.
Lawmakers in the Netherlands have also proposed a national ban.
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While cigarette filters hadn't yet come up halfway through the Paris talks, Mead was optimistic that the world would eventually see butts for what they are: plastic waste.
In the meantime, there's only so much picking up you can do.
"One person can collect, you know, a thousand butts in an hour," he says. "That's fine, but what we need is a systemic change - and that's why things like this treaty are important."