An Olympic Effort to Monitor Air Pollution

17 April 2012

Interview with 

Roland Leigh and Rosie Graves, Earth Observation Science Group, University of Leicester


Ben - The World Health Organisation estimates that every year almost two and a half million people worldwide die as a direct result of air pollution.  Many more suffer respiratory problems and lung disease, which can cut life expectancy by years.

In London, air quality regularly fails to meet European standards - which is of particular concern this year when the city hosts the Olympics.

At the University of Leicester scientists and engineers have been developing a new scanning system to monitor urban air pollution, which they're getting ready to deploy in time for the games.

Planet Earth Podcast presenter Richard Hollingham went there to meet Roland Leigh and Rosie Graves from the University's Earth Observation Science Group.

Standing outside his lab, Roland explained what was in the air...

Roland -   Urban environments are cleaner than they used to be, but still, we have a lot of emissions that come from the traffic network.   In particular, we have nitrogen dioxide, we have particulate matter, and we have ozone coming out of the exhaust of cars that then we breathe in.

Diesel smoke from a big truckRichard -   And what's that doing to us?

Roland -   Some of it affects the airways to the lungs, so what we breathe in in our respiratory tract and the way that our body responds to that, and some of it gets into our bloodstream and actually affects the cardiovascular system and how our heart responds.

Richard -   So none of that is good.  Where is it all coming from?

Roland -   Much of it, 95% of the nitrogen dioxide for example in an urban environment comes from the vehicles - from cars, from heavy goods vehicles, and from buses.

Richard -   Now pollution is already monitored.  There are monitoring stations around the country, particularly in big cities, but you've developed a new type of scanner which is here in front of us.  Now I guess, it looks a bit like an oversized speed camera, mounted on a plinth, so that means it can rotate.  It's triangular, I suppose, with a hatch at one side.

Roland -   We realised several years ago that we could monitor air quality using scattered sunlight, so there is a possibility to create an instrument that just receives scattered sunlight and tells you how much nitrogen dioxide there is in the air.  So this instrument is designed to sit on top of a tall building and produce an image of the nitrogen dioxide over a complete urban environment, really letting you see the individual emission sources and where those pollutants end up downwind.

Richard -   So does that mean you could map where these particular pollutants are, where these chemicals are in the atmosphere, rather than get a snapshot of how much there is?

Roland -   Exactly, yes.  With multiple instruments, you can get a 3D reconstruction of where these gas fields are.  So traditional sensors take in a single point measurement.  They suck in air down a tube and they give you a very accurate point measurement that might be by a roadside.  We, between two or three instruments can map out a complete urban area, and tell you where the nitrogen dioxide is in that space.  So for example here, several years ago, we picked up the railway station in Leicester with an early prototype of this instrument and watched trains leave the railway station.  That was quite a new bit of information for the local authority that didn't really realise how much was coming out of an individual train as it pulled out of the station and where that emission went.

Richard -   It is a curious looking machine.  Imagine around the size of a microwave oven, but a triangular microwave oven.  You look inside, it's full of circuit boards and wires, and there's a box in the middle which is covered in a silver bubble wrap.  I guess that the heart of it.

Roland -   Exactly, that's the heart of the instrument.  That's a spectrometer that was originally designed to be a satellite instrument for air quality mapping by Surrey Satellite Technologies.  So the spectrometer takes in sunlight.  In our case, we have filters that means it's just above UV to what is about yellow to red, and we then pull out bits of information in the blue to green bits of that light, to the point where it's much more sensitive than the human eye would be to those slight subtle changes in colour.  But this spectrometer can really tell us how much of one shade of green there is and that one shade of green is a shade that is absorbed by nitrogen dioxide.  So with that real high sensitivity to these colours, you can pull out that information on the gases.

Richard -   Now Rosie, you're looking to use this during the Olympics, as a way of testing it out.

Rosie -   As part of a UK-wide project called ClearfLo, we'll be going to the Olympics in July and August this year.  We'll be deploying three of the instruments on three different buildings around the city centre, to the west of the city generally, and try to map out the pollution over the city in this quite unusual time for us.  Obviously, the roads will be different, there'll be a lot more people in London than normal so it would be quite interesting to see what happens.

Richard -   So Roland, how is information from this going to be used, or from other sensors going to be used?  Because you can look right now on a website and see London or a lot of other cities around the country and around the world, that pollution levels are being exceeded.  This will again tell you that pollution levels are being exceeded.

Roland -   We are in fact developing systems which take in data from this and enable the local authorities to make decisions on traffic management and air quality management at the same time, and that's where we're really trying to make a difference, where people can be informed when there's going to be poor air quality days in the future so the local authority knows where to direct traffic, which roads to avoid, which areas have sensitised individuals - that's really where you start making a difference to people's lives and having that societal impact that we all try and achieve.


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