Harmful traffic pollution levels on Oxford Street and Putney High Street have already breached annual limits just a few days into January.
Concentrations of nitrogen dioxide - a gas linked to asthma and other serious respiratory problems - are not supposed to go above 200 ug/m3 on more than 18 occasions a year under Government clean air targets.
However, the Standard has learned this total was exceeded on 5 January on Oxford Street and yesterday on Putney High Street.
The biggest source of nitrogen dioxide is diesel fumes from buses. Both routes are notorious for the huge volumes of buses passing down them every day.
London politicians called on Mayor Boris Johnson, who has already ordered filters to be fitted to hundreds of buses, to take far tougher action to clean up the capital’s air.
Murad Qureshi, Labour’s environment spokesman on the London Assembly, said: “It is appalling that just five days into the New Year the hourly legal limit for nitrogen dioxide on one of our busiest roads has already been exceeded. Air pollution is a known killer causing over 4,000 premature deaths every year.
Green party assembly member Jenny Jones said: “Oxford Street is a disgraceful example of the Government and Mayor’s failure to take responsibility for air pollution. As a result even more people will die prematurely, suffer worse asthma and other respiratory conditions”
A spokesman for the Mayor said: "Significant progress has been made in reducing emissions of Nitrogen Dioxide thanks to the measures the Mayor has implemented, including tighter low emission zone standards, the introduction of 500 new hybrid buses and retiring more than 3,000 of the oldest most polluting taxis.
"However, the Mayor recognises that more needs to be done and has proposed a central London Ultra Low Emission Zone from 2020 and a number of other measures to help ensure continued improvements in London’s air quality."
