Uros Macerl was awarded the Goldman Prize for taking on a polluting industry and forcing it to mothball its operations

When he saw swallows nesting in the barn for the first time in almost two decades, Slovenian farmer Uros Macerl felt vindicated. His exhausting battle against a polluting industrial giant had been worthwhile.

A role model to some, an “eco-terrorist” to others, Mr. Macerl recently picked up one of the world’s most prestigious environmental awards for shutting down a cement plant owned by French corporation Lafarge in Trbovlje region in 2015.

The 48-year-old flew to New York in April to receive the U.S. Goldman Prize, which honours “environmental heroes” for their efforts to protect nature, often at great personal expense.

In Mr. Macerl’s case, the 13-year fight cost him his marriage. “I’ve paid a high toll with my family... but it also taught my children the struggle was worth it,” the father of three said.

Black snow

For as long as Mr. Macerl could remember, heavy industry had not only been providing jobs to Trbovlje’s 16,000 or so inhabitants, but also polluting its air. Emissions from a glass factory and coal-fired power plant would slowly rise from the Central Sava valley, enveloping the farms on the surrounding hills in a toxic fog. In winter, “the snow was always black” because dust and ashes would turn the white blanket into dark slush within 24 hours, Mr. Macerl recalled.

Things got worse in 2002 when Lafarge took over a 130-year old cement factory. The company intensified exploitation using petroleum coke—a dirty byproduct of oil refining that burns extremely hot—and industrial waste instead of coal.

‘Unbearable situation’

Lafarge’s actions had a devastating effect on the environment and people’s health. Within a year, the level of benzene in the air jumped by more than 250%. Cancer rates in the region were above the national average, 2012 data from the Organisation for Economic Co-operation and Development (OECD) showed. The high concentration of acid and other toxic substances also began to destroy the vegetation.

When Mr. Macerl took over his parents farm at the age of 23, he decided to raise sheep because the fruit trees died. But the “sheep often had miscarriages,” he said.

A meeting with Lafarge representatives failed to produce results. “I described the unbearable situation on top of the hills but they just made fun of me. ‘If you don’t like it sue us,’ they told me,” Mr. Macerl said.

Frustrated, he and other locals took matters into their own hands, gathering data on toxic emissions. Their research revealed that the Lafarge factory was exceeding permitted emission levels. But the local authorities ignored the findings, according to Mr. Macerl. “They turned a blind eye because Lafarge provided jobs, sponsored local sports clubs, donated to hospitals and heavily invested in infrastructure,” he said.

The tide turned in 2009 when Lafarge applied for a new licence to incinerate car tyres and plastic. Looking at the plans, Mr. Macerl realised that a tiny part of his farmland fell inside the so-called “pollution zone”, entitling him to challenge the company’s permit.

When the government failed to act upon Mr. Macerl’s complaints, he filed a petition with the European Commission in 2010. After a five-year legal battle, Lafarge was eventually forced to mothball its operations in March 2015 after Brussels ruled that Slovenia had run foul of E.U. rules regarding the plant’s permits.