BEIJING (REUTERS) - Beijing removed 180,000 old and polluting vehicles from its roads in the first four months of 2017, the Chinese capital's environmental bureau has said, as part of its efforts to tackle congestion and cut smog.

An action plan published in 2015 committed Beijing to removing a total of 1 million ageing vehicles over the 2013-2017 period. Beijing needs to take 300,000 off the road this year to meet the target.

The Beijing Municipal Environmental Protection Bureau said late on Thursday (May 5) the capital has a total of 5.7 million vehicles, responsible for half of the city's nitrogen oxide emissions, a major source of smog.

Traffic is responsible for 31 per cent of Beijing's total particulate matter, environment minister Chen Jining said earlier this year.

The city has promised extraordinary measures this year to meet its 2013-2017 air pollution targets following a spike in smog in the region in January and February.

Average readings of small breathable particles known as PM2.5 reached 95 micrograms per cubic metre in Beijing in the first two months of 2017, up 69.6 per cent from the same period of last year.

The World Health Organization recommends concentrations of just 10 micrograms.

The city aims to bring the average down to around 60 micrograms this year, a cut of more than 25 per cent from 2012 levels.

Dust storms sweeping across northern China sent PM2.5 readings to 630 micrograms in parts of Beijing on Thursday.