The British government faces huge fines from the European Court of Justice for failing to curb air pollution linked to thousands of early deaths in Britain every year.
The European Commission announced it was referring the UK to the EU's top court on Thursday in Brussels but the lawsuit was first reported in March by The Telegraph.
The decision fires the starting gun on a race to bring Britain back in line with air pollution limits before EU judges in Luxembourg impose hefty fines in the form of a daily penalty or lump sum.
That ruling is expected within two years but could come sooner if proceedings are fast-tracked. If a Brexit deal is agreed, Britain will be in the transition period and...