From the Blog

Toxic London


Great news: Living and working in London is now officially toxic to our health.

Picture this: you standing at the bus stop waiting for the bus and as you’re doing this you take a nice deep breath of nitrogen dioxide and fine particle matter also known as PM2.5 as 3 other buses, a large skip truck, 10 lorries/minivans, the garbage truck and the local council street cleaning machine all pass you by. This is the reality of life on the streets of London with its narrow streets, heavily congested roads and traffic jams.

In simple terms, PM2.5 is fine particle matter and a term used to refer to solid particles and liquid droplets with a diameter less than 2.5 micrometres across (that’s one 400th of a millimetre).


Toxic Air pollution is a major contributor to ill health in the UK, but it’s hard to say exactly by how much. Dirty air does not directly kill people, but short and long-term exposure to it contributes to the shortening of people’s lives principally by undermining the health of people with heart or lung problems. Air pollution has also been actively linked to dementia & mental health. Hmmmm.

Concentrations of PM2.5 in London


The World Health Organisation guideline limit is 10 µg m -3

This map of London shows a  first concentration band of light yellow, which is used to colour areas with concentrations of PM2.5 between 10 – 15 µg m-3 , this covers a small area at the very outskirts of the city which is home to only 6.2 percent of the population. 2 3 The other parts of the map (in dark yellow, orange and red) are home to the remaining population of London, meaning the vast majority of Londoners live in an area at least 50 percent higher than the World Health Organisation guideline limit. 7.9 million Londoners – nearly 95 percent of the capital’s population – live in areas of London that exceed the guideline limit by 50 percent or more. This is worrying news.

Where are all these Particles coming from?

A big component of PM2.5 in London comes from regional, and often transboundary (non-UK) sources ( outside the scope of this post).  London’s narrow roads and large numbers of cars makes road transport the biggest LOCAL contributor of London PM2.5, accounting for over half of local contributions.

These emissions are mainly related to non-exhaust emissions (including road wear, resuspension of particles and tyre and brake wear) , the Ultra Low Emission Zone and T charge which started in October 2017 and The Mayor’s commitment to cleaning up the bus and taxi fleets are expected to reduce PM2.5 emissions coming from road transport.

The next biggest local London source of pollution is Non-Road Mobile Machinery and wood burning in urban areas and construction sites which also contribute significantly to local pollution.

The most effective reduction of tyre and brake emissions is to reduce the vehicle kilometres being driven. This will be one of the many co-benefits of the Mayor’s Healthy Streets approach and the huge investments being made in walking, cycling and public transport. The Mayor’s Transport Strategy sets out an objective that by 2041 the proportion of trips undertaken by bike, foot and public transport will have increased to 80 per cent from 64 per cent today.

What can we Londoners do about all this?

We are increasingly being encouraged to use  bikes but face being seriously injured on the roads of London by insensitive and stressed out drivers. The government urges us to walk more but how many of us can walk to work or school from home? Not many.  However we should try to walk more though to improve our general health. Then the best advice seems to be to use Public transportation which is so expensive in London that we might as well term it transport for the richer public not the masses. All these options seem a bit grim when we really scrutinise them more closely  but at least the Mayor of London  seems committed to improving on this issue which is good news.

Understanding air pollution is challenging as it is complex and dynamic, we know it is created by a mix of pollutants, both man-made and natural, which combine together in dangerous ways. The shape of a city basin, the weather and population distribution also have an impact on air quality. This complexity means that it can be hard to point to a single solution as having a particular effect.  Ways to cut air pollution meanwhile can come from all sorts of places –government policy and community action, business and technology innovation.

In the meantime, we urge the Mayor to hand out FREE face masks to all Londoners and visitors as a starting point to addressing our toxic issues.


Find out more about LondonAir  and the  BBC SO I CAN BREATHE SERIES.

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