Air pollution from diesel vehicles is attracting legal attention in the UK, after a recent ruling in the European Court of Justice required ministers to take immediate steps toward cleaner air.

Nitrogen dioxide, the pollutant of most concern, is extremely high in UK cities and comes primarily from diesel vehicles. Although the government had promised to clean up nitrogen dioxide pollution by 2015, they have since extended the deadline to 2030.

The ruling has widespread support from environmentalists who believe it will force the government to take action toward cleaner air and create healthier living conditions for UK residents.

“This ruling is a big victory for the millions of people who want to live healthy lives in the UK’s towns and cities. This will force the government to finally take this issue seriously and come up with an urgent plan to rid our towns and cities of cancer-causing diesel fumes,” ClientEarth lawyer Alan Andrews told BBC News.

Early morning emissions in London. © Simon Birkett 2014.

Decades of government diesel endorsement have contributed to the UK’s current dilemma. While diesel has long been viewed as a “green” alternative in the fight to slow climate change, the UK has adopted lax diesel regulations and allowed itself to be overrun by so-called “dirty diesel.”

Although still controversial, “clean diesel” is considered safer and has attracted interest in the U.S. because of diesel’s notoriously high mpg and low CO2. In order for diesel to be considered “clean” it must have “ultra low” sulfur levels (15 parts per million as opposed to the 500 ppm in regular diesel), and be treated with exhaust-scrubbing components—supposedly resulting in less harmful emissions.

SEE ALSO: Will America Avoid Europe’s ‘Clean’ Diesel Problems?

While it’s easy for the U.S. to learn from the UK’s mistakes, the UK is still faced with the daunting task of undoing over 20 years of poorly regulated diesel emissions. According to the organization that brought the case, ClientEarth, this can be accomplished through a ban on diesel cars in cities, pollution control devices on public transportation vehicles, and technology that guarantees compliance with manufacturer emissions data.

Although it is still uncertain which of these actions the government will take, the courts and public are relieved that the ruling mandates immediate action on this long-standing issue.

“It is not acceptable for ministers who live in leafy suburbs to tell people living next to busy roads in towns and cities that they have to wait until 2030 to breathe clean air. Today’s ruling will force the government to prioritize the issue of air quality in all decisions on transport policy and infrastructure,” the chair of the Environmental Audit Committee (EAC) Joan Walley told BBC News.