• How Might Train Strikes Effect Air Quality?

Air Monitoring

How Might Train Strikes Effect Air Quality?

Dec 13 2022

As the National Union of Rail, Maritime and Transport Workers (otherwise known as the RMT) knuckle down for another series of strikes, public debate has focussed on a broad range of issues, from the ethics of limiting such a vital service to the necessity of fair pay and modern conditions. But from an environmental monitoring perspective, the implications of the strike for air quality have been underexplored, with little thought given to what this might tell us about Britain’s transport systems. 

Of course, exploring this aspect of the strikes is not an argument for or against either party in the current dispute – in the end, the side-effects of the strikes are just that and it’s up to those directly involved to work something out. On the contrary, this brief investigation merely intends to add to our coverage of the relationship between transport infrastructure and air quality.  

As Above, So Below? 

First things first, then: for how much air pollution are trains themselves responsible? 

In 2019, research by Edinburgh University and Kings College London suggested that it took just two weeks for Waverley Station in Edinburgh and King’s Cross in London to breach the European union’s annual indoor limits for nitrogen dioxide (NO2). The report suggested that diesel-powered trains could produce concentrations of NO2 that are at least equivalent to those produced by busy traffic, suggesting that stoppages of any kind might have a positive effect on the air quality of the surrounding area. Research like this has provided further impetus to electrification as well as prompting some reconsideration of idling and the number of stops taken.   

Clearly, then, without effective ventilation, underground train systems must really have poor air quality. Take the London Underground, for example. A recent study by the Committee on the Medical Effects of Air Pollutants took a look into the concentration of particularly dangerous PM2.5, which particulate matter small enough to breach the lung barrier and has been correlated with everything from lung cancer and heart disease. But where are these particulates coming from? Well, the main culprits are the material shed when carriages move along their tracks (quite a common occurrence on the Underground, you’ll find), when brake-blocks rubs against the wheels, and that which is produced by the electrical connections between collector plates and live rails. The researchers located these sources by working backwards from the metallic compound particulates that they found in the atmosphere: iron, steel, copper, barium (from brakes), carbon and molybdenum (found in lubricants on wheels).  

One of the lead researchers for the project, Dr. David Green of the Centre for Environment and Health at Imperial College London, summarises the results of the study when it comes to PM2.5 as follows: “[Travelling on the tube] for one hour every weekday for 48 weeks a year (assuming 4 week’s holiday) on the Victoria would increase your annual exposure to PM2.5 by 6.8μm/m3. This compares to 0.3μm/m3 at a background site in London, 2.6μm/m3 on an average London Underground line or 1.2μm/m3 in a car.” 

All in all, then, though they most certainly will scupper up people’s plans and cause problems for certain businesses, train stoppages will at least give your lungs a break from the trains themselves. But, of course, the real concern are the modes of transport to which people will turn when the trains are stopped. 

Drive to Survive 

When it comes to looking for the detrimental impact that rail strikes might have on air quality in the short term, there’s only one real candidate. Deprived of a reliable service for their commute, some Britons will get in the car to reach their workplaces on time or do their last-minute Christmas shopping – and pollute all the way there. 

If it’s running on petrol or diesel, a car’s exhaust will be spitting out NOx, PM 2.5 and PM 10 as it moves, air pollutants against which the case has been mounting for some time.   At the beginning of the last decade, the World Health Organisation reported that road traffic was producing, on average, 50% of all particulate emissions in those advanced economies that are members of the Organisation for Economic Co-operation and Development (OECD), though this percentage fluctuates wildly from 12%-70% depending on the country you’re looking at. Across the board, though, diesel’s the main offender, as the so-called “Dieselgate” scandal merely confirmed. 

The harm caused by these pollutants is dependent on a lot of factors besides what’s in your fuel tank, though, some of which may mitigate any negative effects. What’s relevant to this discussion, however, are the differences between suburban areas and big cities. The British suburbs were built for cars, they’re the only way to get around, but as a result of their spatial dispersion, it’s unlikely that most suburbanites will be exposed to harmful levels of the pollutants produced by cars. By contrast, a city like London, with its concentrated space and public transport infrastructure, was not really built for cars, but residents are far more exposed to fumes from the traffic that’s right next to their schools, homes, workplaces, restaurants and shops.  

When it comes to rail strikes, then, the picture gets blurry. Will Londoners take advantage of buses or bikes when the trains stop running? Or will they get in the car and start blasting their neighbours with particulates? For a city with the worst air quality in Europe by certain metrics, this choice has fairly serious consequences. 

Re-Cycle 

So, what will happen if people choose the former? Well, quite obviously, this will improve air quality (and give us all a break from the tyranny of motorists). But cities are convenient for cycling, their roads are designed with cyclists in mind and urban concentration makes the slower speeds of a pedal-bike more feasible. It’s just not the same in surrounding areas – or is it? 

As the Russian invasion of Ukraine grinds on, oil prices continue to make their gruelling climb skyward. For many, with a broader economic crisis taking hold, it’s becoming less and less economic to run a car, let alone the two that some 8 million British households have on the driveway. In fact, while we’re on the statistics, it’s been found that more than double this figure (17 million) do not own a car, with the third category, households with one car, being the most populous at 25 million households. In other words, we’re not as car-crazy as we might think. 

Who’s to say how this might play out in the context of the rail strikes? Perhaps, increased traffic and fuel prices will make people sick of the whole thing, selling off their second vehicles and strapping on their helmet. That way, when the dispute is resolved, there’ll be no more parking fees (and fines) or eye-watering fuel costs, just a (hopefully) pleasant cycle to the station. That is, if you’re heading into the office at all. 

Home Economics 

That’s the irony, isn’t it? If your commute requires a train, you’re likely to have a job in an office, doing work which it’s now possible to do at home. If your commute does not require a train, either your workplace is within cycling distance or your job actually requires driving. Of course, I’m speaking in the very broadest of terms. But from this perspective, it’s by no means clear that rail strikes will force people into cars and harm air quality in the process – most likely, it’ll just force people to go downstairs.   

It might be quite reasonable, then, to be fairly up-beat about the effect trains strikes will have on air quality in the short term. With train schedules all jumbled up, it seems that the effect of people turning to cars will be mitigated by other simply working from home, catching the bus or cycling wherever it is that they need to go. And, as we saw earlier, the direct reduction in pollution that will result from running fewer trains is likely to improve air quality for surrounding areas. Of course, this will bring little comfort to those effected by the strikes, whether behind or in front of the picket line, but, at least, we can all take a deep breath to steady ourselves for the difficulties ahead without worrying too much about what we’re inhaling when we do.


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