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How Low Emission Bus Zones and electric fleets are helping to reduce pollution

An evaluation of the zones found emissions of NO2 and NO were down by an average of 90 per cent

Paul Fiedler via Unsplash
25 February 2020

In 2018, the Mayor of London, Sadiq Khan introduced 12 Low Emission Bus Zones, air pollution hotspots where only buses that meet the cleanest emission standards are allowed.

An evaluation of the zones found that emissions of nitrogen dioxide (NO2) and nitric oxide (NO), together known as NOx, have reduced by an average of 90 per cent. This equates to reduced NOx emissions of 881 tonnes, or a 29 per cent reduction in London-wide bus fleet emissions.

At Putney High Street, annual mean NO2 concentrations have reduced by 39 per cent, and the number of times the hourly mean limit is exceeded has been reduced by 99.7 per cent since 2016. The Brixton Road zone has seen annual mean NO2 concentrations fall by 49 per cent and exceedances of the hourly mean limit have reduced by 100 per cent since 2016.

London now has one of Europe’s largest electric bus fleets. Electrification of London’s double decker buses began in 2019. All buses on route 43 between Friern Barnet and London Bridge became electric in late 2019, and in mid-February, all buses — around 29 vehicles — followed suit on the 94 route between Acton and Piccadilly Circus.

Electric buses are also being introduced on route 134 between North Finchley and Warren Street, and once conversion is complete, there will be around 97 double-deck electric buses in the fleet.

A further 12 routes in London will be electrified between 2020 and 2021, and Khan pledged last week that all London’s buses will be zero emission by 2030.

But the bus fleet won’t just be electric. London’s first hydrogen double-decker buses are being built in the UK, and they will only emit water as exhaust. Jim Gregory, European business development manager for alternative fuels at Luxfer Gas Cylinders, is developing low emission alternative fuel solutions for transportation and is involved in developing hydrogen buses for London.

He says: “Hydrogen is one of the most abundant gases in the universe and if used with a fuel cell can run efficiently and cleanly as the only emission from the running of the bus is water vapour.” As an individual you can minimise your exposure to road pollution by spending time away from main routes when possible.

Walking along back roads to get to your bus stop, and even walking along the inside of the pavement closer to the buildings along busy roads, can help to lower your exposure to air pollution.

Audrey de Nazelle, senior lecturer in air pollution management at Imperial College London, says: “In general we find that buses are less polluted inside than cars. Cars tend to be the worst. Buses and bikes are about the same and pedestrians are the least exposed.”

This is because pollution is worse in the middle of the road and at a low level because of the position of exhaust pipes.

Elizabeth Fonseca, senior air quality manager for the Environmental Defense Fund, suggests Londoners use, a website that enables you to choose routes with lower levels of pollution.

Fonseca points out that a Cambridge study found that the physical activity benefits of active travel outweighed the harm caused by air pollution, so people shouldn’t avoid going for a run or a walk.

The study found that in London the health benefits of active travel always outweigh the risk from pollution.


The Air We Breathe is a year-long project that considers the impact of London’s air on our health and asks how we can take action to limit it.

This project is supported financially by the Children’s Investment Fund Foundation, Guy’s & St Thomas’ Charity, and the Clean Air Fund, who share the project’s aims, but our journalism remains editorially independent.

This project is part of our Future London initiative, which looks for solutions to some of the biggest issues facing the capital.