Tunisia has announced plans to stop its supermarkets and pharmacies from using single-use plastic bags from next month before phasing them out completely in 2021.

Plastic pollution has been a growing problem in the north African country in recent years, along with the challenges presented by its ancient industrial plants and barely managed household waste.

Under government plans, major supermarkets and pharmacies will stop issuing the bags from 1 March, with all bags banned by January 2021. Reusable bags – defined by the government as having a thickness of 40 micrometres and a capacity of more than 30 litres – will remain in circulation.

Discarded plastic bags have become a common blight on the Tunisian landscape, blown across the countryside, enmeshed in trees and impacting the country’s land and marine ecosystems. Often used to transport household waste to local collection areas, they are commonly piled by the side of the road, where they lie awaiting collection by the local municipality.

An attempt to introduce a ban in 2016 failed following vocal resistance from industry. However, it was enough to stop many of the country’s leading supermarkets issuing free bags. Instead, the stores started charging for a smaller number of more durable bags, resulting in a dramatic reduction in the overall number of bags in circulation.

“We have become addicted to single-use or disposable plastic — with severe environmental consequences,” said Wassim Chaabane, founder of the Association Tuniso-Méditerranéenne de l’Environnement, an environmental group.

“In Tunisia, more than 4.2bn single-use plastic bags are consumed, where 1.2bn bags are imported informally.”

Profile Plastic - what's the problem? Show Why the sudden focus on plastics? Mankind produces roughly its entire body weight in plastics every year. But the vast majority of it is either not recycled, unrecyclable, or doesn't get reused once it's been recycled. Volumes ending up in the natural environment are surging. Plastic can take as much as 500 years to decompose.

What are the implications? Plastic is ubiquitous – and often deadly. It kills sea creatures that eat it but cannot digest it. It gets into the human food chain by contaminating the fish that we eat. It is even in our tap water. There is no science about the long-term impact of humans ingesting plastic.

What is to be done? Taxing plastic bags – or even banning them outright as Kenya has done – has changed consumer and producer behaviour. But what next? Deposit return schemes for plastic bottles work well in several countries. Charging for one-time coffee cups also seems to be on the agenda. But the real solutions may not be top down but ...

... bottom up? Yes. Grassroots movements led the way on plastic bags, and have spawned others such as Refill, which emphasises reusing bottles, and A Plastic Planet, which urges plastic-free aisles in supermarkets. Popular culture remains hugely important: it's just possible that the British series The Blue Planet has changed attitudes overnight.

Photograph: Zakir Chowdhury/Barcroft Images/Barcroft Media

Plastic bags can take anywhere between 400 and 1,000 years to break down through exposure to light. Once reduced to tiny particles, they continue to contaminate the soil and waterways, endangering local habitats and polluting seas and rivers.

Chebli Hedi, the general director of environment and quality of life at the ministry of local affairs and the environment in Tunis, explained: “Since the revolution we have had serious difficulty in different areas and different cities with plastic bags, which are small and have been thrown away and disturb the environment.”

Unlike the earlier attempt to ban their use, Hedi stressed, this latest initiative came following extensive consultation with the public and the commercial Utica union, and also involved voluntary participation by most supermarkets and pharmacies. Negotiations over the wider ban, to be introduced next year, are ongoing.

The move was welcomed by campaigners in Tunis and the environmental pressure group Break free from Plastic. All cautioned against its introduction without adequate monitoring and support. Most vulnerable will be small shopkeepers who rely on regularly issuing bags to their customers.

Even here, however, the government’s proposals found support, albeit cautious. “This news definitely makes me happy,” said Mohammad El Weti, a shopkeeper in Tunis’s ancient medina. “We’re used to politicians giving vague promises, but I’m happy they managed to pass an actual law this time. I hope they will manage to apply it.”

Tunisia faces other significant environmental challenges. Single-use plastics, such as drinking straws and plastic used in commercial packaging, remains commonplace. Elsewhere, Tunisia’s reliance on often antiquated heavy industry, not least phosphate production, has left entire swathes of the country and coastline unusable.

While the government is making some headway on limiting pollution, in a country where unemployment sits at 15% nationally any measure that could be perceived as damaging to industry, and therefor a danger to jobs, is likely to prove controversial.

Hedi nonetheless remains optimistic. “With the environment, you cannot say: ‘This is very big, so we need to start with it,’ or: ‘This is very small, so I can ignore it.’ With the environment, everything counts.”