Air pollution dropped significantly on Saturday as the World Half Marathon Championships turned Copenhagen into an almost car-free zone.

Independent environmental organisation Miljøpunkt indre By-Christianshavn (MBC) measured the air quality on the busy HC Andersen Boulevard, where the amount of air pollution particles normally exceed the EU safety limit by more than 25 percent.

The test showed that the particle level dropped to a sixth of its normal rate when traffic was blocked off from the street on Saturday.

"This shows that cars really do make a huge difference. The air wasn't completely clean but it was reduced drastically," Anne-Mette Wehmüller, the head of MBC, told Metroxpress newspaper.

Back to car-free Sundays
The findings led Wehmüller to suggest that Copenhagen introduced 'car-free Sundays' to make the city a cleaner place.

The deputy mayor of technical and environmental affairs, Morten Kabel (EL), was open to the suggestion but said that heavy traffic wasn't the biggest problem on weekends.

"I think it's more important to deal with traffic on weekdays, because we know that pollution is hazardous," he told Metroxpress.

Denmark introduced nationwide car-free Sundays between 1973 and 1974 during and following the international oil crisis.