Alun Davies looks across to the plumes of steam that rise from Port Talbot’s last blast furnace, soon to be extinguished.

The mood in the rainswept south Wales steel town is “heartbreaking”, says Davies, the national officer for the steelworkers’ union Community and a former steelworker of nine years.

“It’s smashed to pieces,” he says. “You could be watching people and families fall apart. It’s just shocking, I can’t put it into words. I’ve been in steel all my life and it’s heartbreaking.”

He pulls out his phone to show a photo of workers lined up to finish their last shift at blast furnace 4. “I’ve just been sent this. That’s my old shift. It’s personal for me.”

It is hard to overstate the impact of the closure of the blast furnace on the town’s largest private employer. After years of heavy losses its Indian owner Tata shut blast furnace 5 in July, and eventually announced the last furnace would close at the end of September. An estimated 1,900 jobs will be lost in the coming months.

But unions say that for every job that goes in the steel plant, about three or four jobs are supported in the wider community, which will be hard hit by the heavy losses.

In this part of south Wales iron has been melted for more than 800 years, since Cistercian monks first forged tools in the grounds of Margam Abbey. In the 1960s, Port Talbot was the biggest steel complex in Europe, employing more than 18,000 people.

The closure brings an end to the ability to make “virgin” steel from coal and iron ore in south Wales, leaving just the British Steel plant in Scunthorpe as the home of Britain’s last blast furnaces.

The decision is part of Tata’s transition towards a greener form of steelmaking. The company, which also owns Jaguar Land Rover and Tetley Tea, will build a £1.25bn electric arc furnace on the Port Talbot site by 2027.

As she serves customers at Portablo Coffi in the town’s Aberafan shopping centre, Vichuda Walker-Hunt says her husband, Cassius, a fourth-generation steelworker, is not serving in their coffee shop on Monday as he is working at the plant. “He’ll be in tomorrow,” she says. “We have been open for six months and a lot of customers have come in to support him but the job losses are worrying.”

Her sentiment is reflected by Suzanne Hopkins, the owner of Cash & Carry Carpets. “There will be an impact on all the businesses and for cafes and local companies who rely on steelworkers and they lose that income.”

Breaking off from cutting a customer’s hair, Mustafa Bilen, who owns a barber’s shop in the town, says he is “very upset” about the job losses and has noticed that customers are already being more cautious. “People used to come in for a haircut every three weeks and now it’s every four weeks or every two months,” he says.

Jack Harper, 28, a former apprentice at Tata who was laid off this month, is now a project worker for Community at a newly opened support centre for steelworkers in the Aberafan shopping centre. Originally from Swansea, he joined Tata on a contract as an apprentice after eight years in the army. His cousin works at the plant.

“I left the army and I didn’t know what I wanted to do,” he says. “I thought the steelworks are a big employer and it isn’t going anywhere and so I took a big wage cut and joined as an apprentice.

“It’s a sad moment – a lot of these guys have been on the furnaces for 30 or 40 years. Some have worked there their entire working lives. Some have never written a CV.”

The steelworks’ links run deep in Port Talbot’s wider community . Jeremy Hurley, 60, a councillor who is a cabinet member for climate change and economic growth at Neath Port Talbot council, volunteers at Tonmawr rugby club where a coach and seven players work for Tata. He himself worked as a contractor for Tata and has two sons and a niece employed by the company.

“At council meetings when we have to show who has an interest in Port Talbot at least half put their hands up,” he says. “It’s going to be a sad day as the closure will have a huge local impact but I know in the background that there is a pipeline of projects to make the transition better.” What is “critical” is that the Welsh and UK governments give extra support “to mitigate the huge impact” on the town, he says.

Jo Stevens, the Welsh secretary, who chairs the Tata/Port Talbot transition board, said £13.5m had already been released to help suppliers affected by the closures.

The blast furnace shutdown is “poignant” and “very worrying”, she says. As a teenager growing up in north Wales, Stevens well remembers the closure of the blast furnaces at Shotton in 1980, which led to the loss of 6,500 jobs in a single day.

“We cannot see in Port Talbot what I saw in Shotton in the 1980s which took decades to recover,” she says. “It is hard to explain, but it was literally pulling the rug from everyone’s feet overnight. I was at the local high school and everyone had family or friends in the steel work or supply chain. It happened overnight and it was devastating.”

Many fear Port Talbot’s fate will be echoed at British Steel’s site at Scunthorpe, Lincolnshire, where the plant’s Chinese owner, Jingye, could shut the UK’s remaining blast furnaces before the end of the year, putting another 2,500 jobs at risk.

If those closures go ahead, Britain would become the only major economy in the G20 with no ability to produce steel from iron ore and coal. Unions and politicians have warned of the threat to the UK’s economy and security from its lack of ability to make primary steel.

The new Labour government agreed a taxpayer-backed deal earlier this month for the Port Talbot plant in which it will provide £500m towards the construction of the new greener electric arc furnace at the site, with Tata paying £750m.

The electric arc furnace is far less labour intensive and greener, with about 500 jobs being created during its construction. It is expected to be operational in late 2027.

Rajesh Nair, the chief executive of Tata Steel, said in a statement that he was “deeply conscious” of how difficult the closure of the last blast furnace in Port Talbot is. “Throughout this transition we are doing everything possible to minimise the impact on all those who are affected by the changes we are making,” he said.

Union leaders are still angry that a better deal could not have been struck earlier this year, with Tata’s management rejecting their alternative plan to keep one blast furnace at Port Talbot open until 2032 to reduce the scale of the job losses. Sharon Graham, the Unite general secretary, called the job losses “industrial vandalism”.

Stephen Kinnock, the Labour MP for Aberafan Maesteg, criticised the previous Tory administration for securing “a bad deal for steel that offered Tata £500m with no strings attached on jobs”. He said Labour had secured important concessions from Tata on areas such as redundancy pay and retraining.

“Of course we have to recognise this is a sad day,” he says, standing outside the plant’s gates. “My heart goes out to every single steelworker and their families who are going to be facing such an uncertain time now but we also know there is inevitability in this because of the way the market is moving.”

At Port Talbot more than 2,000 workers have already expressed an interest in taking voluntary redundancy and will receive an enhanced deal. As he looks over at the sprawling site, Alan Coombs, a Community union representative and chair of the multi-union at Port Talbot, says it brings a lump to his throat when he reflects on the plant where he worked for more than 35 years, starting as a 16-year-old.

“As far as I’m concerned it’s the worst-case scenario, being a blast furnace man,” he says.