A pile of cigarette butts collected in Lisbon’s Comercio Square over a week (Photo: Getty)

Photos have shown that an accidentally disposed cigarette butt is no small problem.

In the Portuguese capital Lisbon, climate activists have piled up this mountain of 650,000 butts in one week.

They collected enough dog butts to fill 40 plastic bins to raise awareness of how plastic hidden in cigarette butts contributes to pollution.

German activist Andreas Noe wore a special gas mask to protect himself from toxins while standing at the top of the pile in Comercio Square.

Noe, 34, said: “We asked everyone in Portugal to participate in this community project to raise awareness about plastic pollution, because plastic is in cigarette butts and many people don’t know it.”

The simple cigarette butt is a “good example of how to tackle waste, ocean pollution and ultimately the climate crisis,” he added.

Two years ago, Noe said he collected a million butts in two months.

Fellow protester David Figueira added: “We want to end this problem by asking people to throw their butts in the bin or pocket ashtray – anywhere but on the ground.”

Andreas Noe poses with the pile of cigarette butts in Lisbon (Image: AFP/Getty)

Containers full of cigarette butts collected in a week will be put on display in Comercio Square in Lisbon, Italy, on April 23, 2023.  - Environmentalists collected about 650,000 cigarette butts in one week and piled this kind of pollution today in a square in the center of Lisbon.  (Photo by PATRICIA DE MELO MOREIRA/AFP) (Photo by PATRICIA DE MELO MOREIRA/AFP via Getty Images)

Activists collected enough butts to fill 40 plastic bins in one week (Image: AFP/Getty)

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According to the World Health Organization, about 4.5 trillion butts are thrown away around the world each year.

Cigarette butts contribute to more than 700,000 tons of waste each year, according to The Clean Earth Trust.

Butts make up about 30% of all litter in the UK, with 120,000 tonnes – about the size of a blue whale – of cigarette butts dumped on the streets every day, the environmental group said.