Mary Poppins was spotted floating through Oxford as part of a campaign urging the government to protect children against pollution.

The famous nanny appeared last week with a little help from Greenpeace, which is urging the Government to end the sale of new diesel cars.

Donning a pollution mask, she appeared on the road last Friday, after the UK broke 2017’s annual air pollution limits just five days into the year – three days earlier than last year.

Greenpeace activist Julia Spragg said: “It’s shocking that it’s taken only five days to break the UK’s annual limit of air pollution.

“Despite growing concerns about the health impacts of diesel fumes, the government has done almost nothing to tackle car companies since they were caught cheating emissions tests.

“Unbelievably, the government is still incentivising consumers to buy brand new diesel cars that are pumping out illegal levels of pollution. If cars coming off the production line had dodgy brakes, you know the government would step in to sort it out.

“We urgently need to stop the sale of new diesel models until emission testing is truly fit for purpose. Better still, we need car companies to phase out diesel completely and concentrate on hybrid and electric alternatives.”

Recent measurements for Oxford show the amount of harmful nitrogen dioxide (NO2) in the most polluted part of the city - St Clements - rose three per cent between 2014 and 2015, from 65 micrograms per cubic metre to 67.

Levels are also rising in other parts of the city centre including George Street, High Street and Magdalen Street.

But overall in Oxford roadside levels of nitrogen dioxide have dropped by an average of 35 per cent across the city in the last 10 years. 

In the past few months, doctors, health professionals and campaigners have spoken out about the devastating impact of air pollution on human health, especially children’s.

Air pollution can cause asthma in otherwise healthy children, stunts children’s lung growth permanently by up to 10 per cent, and is linked to strokes, heart disease and diabetes in older people.

In November 2016, the High Court ruled for the second time in 18 months that the government is not doing enough to combat the air pollution crisis.