Commuting and polluting – whose health is losing out?

People in London travelling to work on the bus or the tube were exposed to much higher levels of pollution than people travelling by car.

In 2013, outdoor air pollution was identified as a cause of cancer by the International Agency for Research on Cancer (IARC). And although it’s responsible for far fewer cases of cancer than other causes, such as smoking and obesity, air pollution affects everyone.

This is especially true on our journeys to and from work. So researchers have been questioning how much air pollution people might be exposed to on their commutes.

A study published earlier this month found that people in London travelling to work on the bus or the tube were exposed to much higher levels of pollution than people travelling by car. But travelling by car causes more air pollution than using public transport.

Following this study and others, the Mayor of London, Sadiq Khan, announced new plans to tackle pollution levels in the capital.

Too many Londoners have died as a result of air pollution – so we’re doing something about it. My @IndyVoices piece: https://t.co/yrF10uybhl

— Sadiq Khan (@SadiqKhan) February 19, 2017

Commenting on the impact pollution has on health, Professor David Phillips, a Cancer Research UK-funded expert on air pollution at Kings College London, says the evidence that air pollution causes cancer is strong.

“Fine particulates (small particles that can penetrate deep into the lung) are probably the main suspects for cancer,” he says.

And it’s not just London that faces a problem. The European commission has issued the UK with a final warning over breaching air pollution limits in 16 different areas, including Birmingham, Leeds and Glasgow.

So should we be concerned about air pollution as we travel to and from work?

Comparing commutes

In the past, researchers have tried to measure how much air pollution we’re exposed to by putting monitors near to people’s homes, or at other locations like city centres. But as we move about our daily lives, we’re exposed to all sorts of different things in our environment. So monitoring pollution in a single location can only tell scientists so much.

We found that there is definitely an element of environmental injustice among those commuting in London, with those who create the most pollution having the least exposure to it

– Dr Prashant Kumar, University of Surrey

Now researchers at the University of Surrey have been able to compare different routes into London, using pollution monitors attached to a rucksack.

Although they set out to look at whether air pollution exposure on commutes was linked to income, the results, published in the journal Environment International, show that the type of transport people use leaves them exposed to different levels of pollution.

They found that commuting using the tube or bus exposes people to more overall air pollution than driving in a car. The amount of PM2.5 (one of the harmful components of air pollution) also varied by transport type, with concentrations almost twice as high in buses than in cars, and almost five times as high on the tube.

Although the study showed that driving to work in a car reduces exposure for the driver, it’s important to remember that fumes created by cars, particularly diesel cars, contribute in a big way to the air pollution that’s affecting others. The scientists call this “environmental injustice”, where those contributing the least to air pollution on their commutes are exposed to most of it.

Putting things in perspective

Air pollution causes a few different health problems, including lung cancer. But it’s important to keep risks in perspective.

For example, the number of cases of lung cancer caused by air pollution each year is small, compared to other factors like smoking. And air pollution is only known to cause one type of cancer, whereas smoking increases the risk of at least 14 different types.

Equal to the task

Everyone has a right to be healthy.

But it’s difficult for anyone to avoid air pollution completely. And because of how air pollution levels vary across locations, some groups may be exposed more than others through no fault of their own.

Dr Prashant Kumar, one of the researchers involved in the study, is concerned by the finding that those who cause little pollution are being exposed to a large amount.

“We found that there is definitely an element of environmental injustice among those commuting in London, with those who create the most pollution having the least exposure to it,” he says.

This means that the health of those people living and working in cities, those commuting using public transport, and those living in more deprived areas may be more at risk because of the air they breathe.

There’s no straightforward fix for this. But it’s clear that any solutions proposed by local or national government must take these inequalities into account if they are to reduce the impact of air pollution on public health.

And we’ll all need to work together, as individuals but more importantly in local and national governments, to ensure we reduce air pollution for everyone.

Rachel Orritt is a health information officer at Cancer Research UK

• If you’re interested in reducing your risk of cancer, our website has information and tips on the healthy changes that will help to stack the odds in your favour.