Today’s poll of 1,132 adults, by YouGov for the environmental law charity ClientEarth, found 68 per cent believed higher-polluting vehicles should pay more to drive through London, with 18 per cent opposed.
Three-quarters of respondents said it was the “moral responsibility” of the mayor to provide good air quality for future generations, with 11 per cent disagreeing.
Two-thirds of respondents – 68 per cent – said they were worried about children breathing dirty air, with 23 per cent not concerned.
Asked if air quality had become more of a problem, 44 per cent said yes, while 27 per cent said there had been no change.
Mr Bailey believes the best way to tackle air pollution is to replace the capital’s 9,000 diesel buses with electric buses, even though TfL buses are responsible for less than 15 per cent of NOx emissions.
Diesel cars are responsible for a third of transport NOx emissions and diesel vans a sixth. Overall, transport accounts for almost half of NOx emissions in the capital.
Roadside nitrogen dioxide emissions in central London have fallen by 44 per cent since the Ulez was introduced in the congestion charge zone two years ago.
The Ulez will be expanded to the boundaries of the A406 North Circular Road and A205 South Circular Road on October 25 if Mr Khan is re-elected.
This will bring about a million vehicles a day within the expanded area, of which 90 per cent already comply with the exhaust emissions rules, meaning they will not have to pay the £12.50 levy.
Petrol vehicles will have to have Euro 4 engines or newer, and diesel vehicles will have to have Euro 6 engines. This means that petrol cars more than 15 years old and diesel cars more than five years old are likely to have to pay.
Mr Khan believes it is a “matter of social justice” to extend protection against toxic air to more Londoners. But Ms Berry says it is wrong to stop the Ulez at the North and South Circulars and wants it to cover all of Greater London.
Simon Alcock, ClientEarth’s head of public affairs, said: “Toxic air is not going to disappear on its own. This poll clearly shows Londoners want their mayor to do something about it.
“We know the Ulez works. That’s why we should make it as wide as possible so it benefits people’s health in all corners of the capital.”
Last week the coroner who said air pollution made a “material contribution” to the death of Ella Adoo-Kissi-Debrah called for national air pollution limits to be tightened. The nine-year-old, who lived near the South Circular, died in 2013.
Ella Fern, mother of two in Barnet, said: “I worry every day that by living where we do, I am exposing my children to high levels of air pollution that will harm their long-term health.”
About two-thirds of households in outer London have a car, compared with 40 per cent in inner London.
Ms Berry has pledged to increase the frequency of suburban bus services and deliver a “fully connected” cycle network.
On a visit to a transformed road junction at Blackhorse Road Tube station today, she said: “Londoners in the outer boroughs are burdened by higher fares, less frequent services, hostile streets and fewer options to leave their cars at home.
“It is no good talking about bringing down air pollution and cutting congestion if we don’t give better options than the car. This means lower fares, better services and safe routes to walk or cycle.”