The Optimist | The Air We Breathe

London air pollution: How much do we breathe in on our commute?

This is what's in the dirty air we are exposed to as we travel - and what we can do to make it cleaner

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Matt Writtle
Nicola Slawson
19 October 2020

Yolanda Browne normally takes the bus for journeys to and from her home in Stoke Newington, regularly riding the 149 to London Bridge. She has a car, but appreciates the convenience of the bus and since the birth of her daughter August, now four months old, she is also increasingly concerned about air pollution.

“I usually check on my weather app what the air pollution is like for the day,” she says. “When it’s high, I can’t understand why you don’t hear about it on news bulletins."

She is more concerned now she’s a mum: “Air pollution makes me want to stay in because I worry about what I’m exposing my baby to.”

Every day, 5.8 million car journeys are made in London, making the capital one of the most polluted places in the UK. Road vehicles produce some of the most harmful air pollutants: they’re responsible for half of all nitrogen oxides (from burning fuel) and for emitting tiny particles of rubber and metal into the air we breathe, causing and exacerbating heart and lung conditions.

More than 2 million Londoners live in areas that exceed air pollution limits, and exposure to poor air quality is associated with both ill-health and premature death.

Travelling around the city means we are exposed to pollutants — but what impact that air has on us, or how polluted it is, can be difficult to understand. Ms Browne says: “It’s difficult to know what it all means for our health.”

She has seen passengers wearing face masks on her bus route. “That always makes me think: ‘Should I be wearing a mask?’ Or I wonder whether I should stay indoors.”

The Environmental Defense Fund (EDF), a not-for-profit environmental advocacy organisation, worked with partners to create the online Breathe London map to show how polluted the air is in different areas of London.

It collects data through a network of 100 sensors fixed to lamp-posts and buildings which continuously transmit air quality measurements, and Google Street View cars specially equipped with mobile sensors. These measure pollution on a variety of roads, taking readings about every second. Looking at Ms Browne’s journey on the 149 from Stamford Hill Library to London Bridge — a five-mile journey with 27 stops — the EDF team found that pollution readings are high for the majority of the route.

Ms Browne will be exposed to polluted air on her journey to and wait at the bus stop, and when she walks to her destination. How much pollution we are exposed to while travelling on a bus is difficult to ascertain, but bad air circulates when windows are open and when the bus stops to let passengers on or off.

The average nitrogen dioxide (NO2 ) level for a busy A-road is 64µg/m3 (micrograms per cubic metre of air), while the average for Ms Browne’s journey is 58.7µg/m3.

ONE YEAR BREATHING LONDON’S AIR 

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.

The legal limit of NO2 is an annual average of 40µg/m3. But while Ms Browne’s bus journey exposes her to a higher average reading than this, the EDF says that being exposed to this level of NO2 for a couple of hours a day doesn’t mean that your overall daily exposure will exceed the legal average.

Passengers who join the 149 in Dalston, however, are exposed to the highest amount of pollution on the route as they wait outside the Rio Cinema on Kingsland High Street. At 85.3µg/m3, this is 1.3 times the typical London A-road, and almost twice as high as the average local road, based on EDF’s data.

Those waiting for the bus at Hoxton station, meanwhile, might benefit from walking to Falkirk Street, one stop further down the route. Pollution drops by 40 per cent between the two stops.

The city environment, the time of day and the weather can explain why some areas have higher readings than others, and can differ from one hour to the next, explains Elizabeth Fonseca, senior air quality manager for EDF.

Matt Writtle

“Urban canyons” can be created where you have tall buildings on both sides of the road with few gaps in between, she says. “The pollution levels can really build up in those areas, so even if you’re on the pavement you can be exposed to as much if you are in the middle of the road. This is exacerbated by weather conditions, so if there is no wind, it will just hang there.”

Fonseca says that bus users can help minimise their exposure to pollution, by taking back routes to bus stops, walking on the inside of pavements and not waiting for buses right next to the road.

“The problem in London isn’t the bus,” she says. “The bus gets lots of people where they’re going, while only using a small amount of road space. The problem is that we need to get fossil fuels out of our transport system, we need fewer cars on the road and we need the national Government to lead the way as soon as possible."

But the city’s buses are being made greener. More than half of bus journeys in England are taken in London — there were 2.2 billion trips in 2018/19, and more than 9,000 buses operate in London, of which 6,400 are double-deckers.

Electrification of double-decker buses began last year, and the Mayor of London, Sadiq Khan, on Friday pledged to make all buses zero emission by 2030 — seven years earlier than planned.

The Ultra Low Emission Zone, the central London area in which the most polluting vehicles incur a charge, was introduced last April and is thought to have cut emissions by a fifth, with breaches of the legal hourly limit of NO2 falling substantially in pollution hotspots such as Oxford Street.

Transport for London also introduced 12 Low Emission Bus Zones. Among them are Putney High Street, Brixton to Streatham, and Stratford from Mile End Road to Romford Road. An evaluation found they have cut toxic fumes emitted by buses in those areas by 90 per cent.

Jess Salamanca, 25, lives in Elephant and Castle with her boyfriend, and commutes by bus to either Old Street or Aldgate. “I prefer the bus to the Tube as I genuinely feel more comfortable and less stressed in them,” she explains.

“I also love the fact you’re outside on the bus … I love exploring and seeing different parts of London from the bus.”

When Ms Salamanca travels to Aldgate, she travels 12 stops from Hampton Street on the number 343. When EDF analysed her route to work, they found that in just two stops, from Abbots Lane to Tower Bridge/City Hall, pollution more than doubles. The average reading for NO2 for her route is 58.5µg/m3.

Ms Salamanca, founder of Banana Scoops ice-cream, is concerned about air pollution, but hadn’t thought about her commute before. “We recently bought an air pollution monitor. We’re lucky that we live high up in a new build, which means that the air is actually better up here,” she says.

After looking at the results for her commute, she says: “This has definitely opened my eyes to the pollution levels that we bear on a daily basis.”

She will try to make choices that avoid exposure in future, she says. “I’m shocked at how high pollution levels are around Elephant and Castle, London Bridge and Tower Bridge. I wish TfL would take this into account when planning bus routes.”

Gareth Powell, managing director of surface transport at TfL, describes air pollution as a “public health emergency”. He points to the success of the Low Emission Bus Zones, and says ensuring that bus companies operating in London are green is a priority.

“The vast majority of London’s buses have now been brought up to the latest Euro 6 emission standards, with all buses due to meet or exceed these before the end of the year, which will effectively create a city-wide low emission bus zone,” he says.

TfL already has one of the largest electric bus fleets in Europe, but says that making the whole fleet zero-emission will also require depots to be completely revamped and electrified, and there needs to be a way of charging buses en route for longer journeys.

In the meantime, TfL still recommends Londoners take public transport rather than using cars. By 2041 it wants 80 per cent of trips in London to be made on foot, by cycling or by public transport. A recent European study found that across 10 other studies which measured air pollution exposure in active versus passive travel modes, pedestrians were consistently shown to be least exposed.

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