Air pollution and cycling: do I need to worry?

Medical Director for Development at Bupa UK
10 July 2017

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This article is more than three years old. It reflects the best available evidence at the time of publication.

With this year’s Tour de France in full swing, and the British summer warming up, you may be inspired to embrace pedal power.

But while the likes of Chris Froome and Alberto Contador cruise through the crisp, clear air of the French Alps, sometimes the conditions back home can feel a little less inviting. Especially in the UK’s cities, pollution may be an issue, and you could be concerned about the possible impact on your health.

Steven Luttrell is Bupa UK’s Medical Director for Development. Here, he explains why he’s also a keen cyclist, and looks at whether air pollution in the UK is something you need to worry about if you’re looking to get on your bike.

A cycling nation?

The UK is slowly falling in love with cycling. Bike traffic on our roads has risen steadily for the last decade, with 3.5 billion miles cycled in 2016. It’s taken off as a sport as well: over 75,000 people have joined British Cycling since Team GB dominated the velodrome at the 2012 Olympics. Considerable government investment in cycling schemes and infrastructure should help this trend continue, as we become a nation more comfortable on two wheels.

Why I cycle

My main reason for cycling is to commute. In fact, this is the single most common reason for cycle trips in the UK.

One of the most obvious advantages of cycling is the health benefits it brings. Most of the time it counts as moderate-intensity exercise, helping you towards the 150 minutes you’re supposed to do each week. If you’re clocking some good speeds or going uphill, it could even count as vigorous exercise.

I also choose to cycle for the environmental benefits. Unlike taking the car or public transport, your journey won’t produce any emissions, and also reduces congestion on the roads.

Cycling is flexible as well. You don’t need to commit to doing it all the time, and I like to pick and choose my days to suit my working patterns. To be honest I’m also something of a fair-weather cyclist. (Cycling for work means it’s not ideal to get absolutely soaked on your journey!)

But most of all I just enjoy it. It’s really satisfying being able to get down busy roads nice and quickly, and there’s a feeling of freedom you don’t get with other forms of transport.

Air pollution and cycling

One of the concerns people have about cycling in the UK is being exposed to air pollution. This is understandable; the gases, fumes, particles and chemicals can have a damaging impact on our health. My colleague Steve Iley has outlined some of these in his blog on air pollution in our cities. But the picture isn’t as bad as you might think ...

Air pollution across the UK

The Department for Environment, Food & Rural Affairs (DEFRA) gathers lots of data relating to air quality in the UK. Their ‘Daily Air Quality Index’ gives a daily pollution score for different areas, depending on the concentration of five different pollutants:

  • nitrogen dioxide
  • sulphur dioxide
  • trioxygen (also known as ozone)
  • particles smaller than 2.5 micrometres (PM2.5)
  • particles smaller than 10 micrometers (PM10)

When you look at the average pollution scores over the course of a year, there’s actually hardly any difference between all areas in the UK. In fact, everywhere has an average score comfortably within the ‘low’ index band. So if you cycle regularly, your overall exposure to air pollution over the course of the year won’t be really that different between different areas.

However, there are differences in the highest pollution levels recorded in certain areas. Some regions can – for short periods – have pollution levels in the ‘high’ or ‘very high’ bands, while other areas don’t get this at all.

In the year up to 2 July 2017, the area with the most days of ‘very high’ air pollution was Northern Ireland. It hit this maximum level on four days (though three of these were back to back). During the same period, the area with the most days of ‘high’ or ‘very high’ air pollution was London, which saw eight days in these bands.

On the other hand, some areas hardly had any days of bad air pollution during the same period. In North East Scotland and Edinburgh Urban Area, there were only three days when the air pollution levels rose above ‘low’.

To find out more about pollution levels in the UK, and how DEFRA gather their data, visit their Daily Air Quality Index webpage.

Checking pollution levels

Because the pollution levels can vary so much, and high pollution levels come in short bursts, you may want to know when high-pollution days are going to occur. Fortunately, DEFRA and the Met Office produce an air pollution forecast, which shows what the conditions in your area are likely to be over the coming days.

DEFRA also provides specific advice on adjusting your usual activities, depending on the expected pollution levels and whether you’re at particular risk from the effects of the pollution. For example, if the forecast is ‘very high’, everyone should reduce the amount of physical activity they do outdoors, which would include cycling. If the forecast is ‘high’ or ‘moderate’, certain people – for example those with lung or heart problems – should reduce their activity. For the full advice, as well as information on who is at particular risk from air pollution, see the Daily Air Quality Index webpages.

Choosing your route

Even when the pollution in a general area is low, you have to take into account that conditions on certain roads may be different. In particular, on busy urban roads the pollution may be two or three times worse than at ‘background locations’, where general pollution levels are measured. This is because of the number of fume-emitting vehicles on these roads, but also the fact that tall buildings can trap pollution and increase its concentration. Between 2012 and 2016, 14 per cent of cycle traffic was on busy urban roads.

If your regular bike journey takes you down these sorts of roads, see if you can plan a different route using some quieter back streets. They’re likely to be safer as well. Another option, if it’s possible, is to make your journey at times when the roads are less busy, so outside of typical rush hours.

Is it worth it?

You may be wondering whether the health risks from pollution would ever cancel out the benefits of cycling. There has actually been research into this: one study conducted at the University of Cambridge concluded that the benefits of cycling and walking outweighed risks associated with air pollution. You can find out more about the study here. This is just one investigation so we can’t say it’s conclusive, but the general consensus of public health advice is that cycling is good for us, on balance.

For me, all the positive aspects of cycling – in terms of fitness, satisfaction and enjoyment – are more significant than any of the risks involved. This includes not only air pollution exposure, but also things like the risk of accidents, or my bike getting stolen – both of which play on my mind more. My tips for making your cycle journey safer are:

  • Use cycle lanes wherever they’re available: they’re safer and easier to use.
  • Make sure you wear a helmet.
  • Get yourself some high-vis gear (I recently invested in a jacket) – be seen, be safe.
  • If a tricky junction looks too dangerous to take on, avoid it, or get off your bike and use the pedestrian crossings.

On top of these, if you stay aware of the pollution forecast, and take steps to avoid the worst roads, you can really minimise any potential damage from air pollution and experience all the joys of cycling ... even if you won’t be donning the yellow jersey any time soon!

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Dr Steven Luttrell
Medical Director for Development at Bupa UK

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