Planet Earth Podcast

Roland Leigh and Rosie GravesCTSN logo

The Planet Earth podcast - 'Air pollution, dwarf elephants and water footprints'

NERC Planet Earth Online 21 March 2012

The following is a text transcript of the interview, to listen online please visit the NERC Planet Earth website.

Richard Hollingham: I'm Richard Hollingham and welcome to the Planet Earth Podcast. This time I'm in Leicester to discover how air quality is being monitored during the 2012 Olympics. Also how small is a dwarf elephant and how big is your water footprint?

Martin Tillotson: The average for a tee shirt would be in the order of about 1500 litres of water to produce that single garment.

Richard Hollingham: The World Health Organisation estimates that every year almost 2.5 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, for instance, air quality regularly fails to meet European standards.

Well, here at the University of Leicester scientists and engineers have been developing a new scanner system to monitor urban air pollution, which they're getting ready to deploy in time for the Olympic Games.

And with me, outside the laboratory here, with appropriately enough a football match going on in the background, are Roland Leigh and Rosie Graves from the university's Earth Observation Science Group. Now, Roland, just give us a sense of what is in the air around us. We're in, I suppose, a semi-urban location here?RL pdct

Roland Leigh: 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 we then breathe in.

Richard Hollingham: And what's that doing to us?

Roland Leigh: Some of it affects the airways to the lungs, so what we breathe in, and 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 Hollingham: So none of that is good. Where is it all coming from?

Roland Leigh: Much of it – 95 per cent of nitrogen dioxide, for example, in an urban environment, comes from vehicles. It comes from cars, from heavy goods vehicles and from buses.

Richard Hollingham: 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 or, if you're into your television history, one of the original BBC TV cameras from the 1930s mounted on a plinth, so that means it can rotate. It's triangular I suppose, with a hatch at one side.

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Spectrometer<br /> Image credit: Dr Leigh

Roland Leigh: 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 Hollingham: So does that mean you can map where these particular pollutants are, where these chemicals are in the atmosphere, rather than get a snap shot of how much there is?

Roland Leigh: Exactly, yes. With multiple instruments you can get a 3D reconstruction where these gas fields are. So traditional sensors take in a single point measurement, they suck in 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.

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

Roland Leigh: 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. We build the first one of these spectrometers ever to be made in the world. It produces very, very nice data for exactly what we are needing here, which is air-quality information in our scattered sunlight data. So, we have one of those spectrometers sat in the middle of a rotating turret collecting sunlight and mapping out the air quality.

Richard Hollingham: And when you say a spectrometer, what is that actually measuring?

Roland Leigh: So the spectrometer takes in sunlight – in our case we have filters that means it is 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. It is much more sensitive than the human eye would be to those slight subtle changes in colour and 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.

CTSN panorama
Imaged pollution over London at 11:30 am on 9th January 2012. The instrument is situated to the west of London, with North in the centre of this image. A large industrial region to the south west of London can clearly be seen in the data (red = higher pollution, purple = lower pollution). Image credits: CityScan - University of Leicester.

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

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

Richard Hollingham: So is that why you're doing it at the Olympics when you've got this very different traffic flows and a huge number of people as well in the city?

Rosie Graves: Yes, so it's important to know what the conditions are like during the Olympics and see how we cope with this extra traffic and things. We also did a field campaign in January and February this year in London to see how it was before the Olympics and we will be looking at what happens during the Olympics and we can try and compare the two.

Richard Hollingham: 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 Leigh: What this instrument can do is map the emission source and where that emission goes down wind. Much of the information we have at the moment is from these point sources which are then put into a model and that model then produces a good figure that tells you what is happening over an urban environment over a year or over a month or over a week. What this instrument can do is it can say we've imaged this being emitted at point source, we've watched it go down wind, we've watched it mix, we've watched it dynamically evolve, chemically evolve and then we've seen where it ends up and that can happen for every single emission source, even emission sources you didn't realise were there before. So, for example, here several years ago we picked up that the railway station in Leicester with an early prototype of this instrument and watched trains leave the railway station and 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 that pulled out of the station and where that emission went.

Richard Hollingham: Because they are quite smelly old diesel trains that go through Leicester aren't they?

Roland Leigh: They certainly can be.

Richard Hollingham: And do you think things like this will ultimately make a difference and bring down, for instance, those alarming number of deaths from urban air pollution?

Roland Leigh: 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.

Richard Hollingham: Roland Leigh and Rosie Graves, NERC podcast RLthank you both very much. This is the Planet Earth Podcast from the University of Leicester and as you would expect we will be putting some pictures of City Scan on our Facebook page. You can also follow us on Twitter and do visit Planet Earth Online for news and features about the natural world.

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College of Science and Engineering
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University of Leicester 
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