06/01/2017 09:59 GMT | Updated 07/01/2018 05:12 GMT

What Can Be Done To Tackle London's Toxic Air Problem?

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London's toxic air has breached legal limits for the whole year just five days into 2017. This is another shameful reminder of the severity of London's air pollution.

Brixton Road in Lambeth won the dubious honour this year of being the first to breach the legal limit - where levels of nitrogen dioxide (NO2) should not exceed 200 micrograms per cubic metre (μg/m3) for more than 18 hours over the entire year.

In fact, NO2 levels on Brixton Road were above 200μg/m3 for 17 consecutive hours on Thursday 5th January - this is almost the entire year's limit in just one day. With high levels in the preceding days, it broke the annual legal limit at 10pm on Thursday.

At these levels, the government guidelines say that "at-risk individuals", such as "adults and children with lung problems, and adults with heart problems, who experience symptoms, should consider reducing strenuous physical activity, particularly outdoors." Little warning, however, was given to people living near Brixton Road yesterday.

NO2 in towns and cities comes mostly from road traffic. Much of the pollution is produced by diesel cars, which on the road emit about six times more than the legal emission limit. A report published today by The International Council on Clean Transportation found that new diesel cars produce twice the amount of toxic air pollution than heavy lorries and buses.

The Mayor has rightly made tackling London's toxic air a top priority. Today he has announced a dozen green bus zones which will help clean up some of the hotspots by ensuring only the cleanest buses service London's most polluted streets.

The Mayor's key policy proposal is to introduce a bigger Ultra-Low Emission Zone (ULEZ) in 2019. This shows clear ambition to clean up London's dirty air but he should look at extending the ULEZ to Greater London for all vehicles to tackle pollution hotspots outside central London. This would protect the health of everyone who lives and works in the capital.

We also need immediate action to protect Londoners' health during these pollution spikes. The Mayor is rightly bringing in the T-Charge this year (this is an extra charge on the most polluting vehicles entering central London) but this should be extended to apply to more diesel vehicles, and there are other immediate measures he needs to consider.

This should include a proactive, mass public information campaign so people can reduce their exposure to pollution and avoid contributing to it by changing how they travel during high pollution episodes. A similar campaign was successful in reducing congestion during the Olympics The Mayor has brought in a new air pollution alert system but we need better localised warnings of high pollution episodes. There were no warnings yesterday when Brixton breached the legal limits.

Other cities that struggle with harmful levels of air pollution implement emergency measures during similar high pollution events. Paris makes public transport free and Madrid bans cars from the most polluted parts of the city.

It is essential that the Mayor delivers on his promise to clean up London's air and that the national Government backs him. While London has the worst air pollution, this is a national problem which requires a national solution. The government's draft plans to tackle air pollution, as ordered by the High Court following ClientEarth's court case, are due in April. They must include a national network of clean air zones, which stop the dirtiest diesel vehicles entering pollution hotspots. They also have to stop the perverse fiscal incentives which encourage people to use diesel vehicles and instead help them to buy cleaner ones.

Finally, the government needs to bring in a new Clean Air Act that tackles the sources of modern air pollution, promotes clean technologies and allows us to hold governments to account where they fail to clean up the air we breathe.