Tag Archives: Kings College London

October 16th Public Meeting: Part 2 – Dr. Ian Mudway: “Air pollution bad for human health?”

The Q&A session about to start at the No to Silvertown Public Meeting, The Forum, Greenwich, London SE10 - October 16th 2013

On October 16th, 2013 the “No to Silvertown Tunnel” campaign held a public meeting at The Forum in Greenwich to announce the results of our NO2 air pollution monitoring experiment. The following post features transcripts, slides and video from that meeting.

« Part 1 – NO2 Air Pollution in Greenwich Borough

Chris Taylor: Not everyone is going to be familiar with what NO2 means to people and what actual effects it has. So fortunately for us we have with us Dr Ian Mudway, who is a lecturer in Respiratory Toxicology at King’s College. Ian has worked with schools just north of the tunnel in Poplar, and his research has shown some of the impacts of the air pollution on children’s lungs

Dr Ian Mudway, Kings College London

Good evening, everyone.

Dr. Ian Mudway, Kings College London

Sometimes when we get given numbers on maps, it doesn’t mean a great deal and it doesn’t convey to you the sense that air pollution in London is extremely bad.  So I thought I’d start this talk by making it a bit more tangible by showing you an image.  This is a picture taken in March this year. So this is one of those periods where it’s cold and you get higher concentrations of nitrogen dioxide.

And you can see this brown – almost like a cloud hanging over the whole of the city – and this is a cloud of nitrogen dioxide. So forget the number, forget the size of the number though that is important: you can see it from a distance. If you were walking down that street you wouldn’t be able to see it at all, it’s an invisible gas, but from a distance looking across London you can actually see it. And that’s what we all live in. And I’m not immune from this; I’m not from Greenwich although I’m from New Cross so I’m also living under that cloud.

But it’s actually a little bit worse than that: I can show you a picture that was taken earlier in the day. So this was taken in the late afternoon, you can see that the brown is rising above Canary Wharf.  But this was taken in the morning.

Dr. Ian Mudway - Slide 2

So this is now a photograph taken from Woolwich looking out across the city. And you can very clearly here see just how bad the nitrogen dioxide pollution gets in the cold winter months in London.  And this is another thing; sometimes people forget this. There’s this concept that when you emit pollution from vehicles into the air, it just sort of disperses. And there’s a lot of air so we don’t need to worry about it.

If you look at this picture you’ll see that there’s actually quite a sharp line and that’s because in the winter the air’s quite cold, it’s quite stable. So effectively, on a cold day in London, you have an invisible ceiling on the atmosphere at about 300m. And now pause and imagine that all of the fumes from all of the vehicles in London are filling up an area of air that has an effective ceiling. It’s not dissipating out. Later in the day it begins to as the atmosphere warms up, but that’s why in the morning the air pollution gets particularly bad, more so than later in the day. So you can see it.  And if you have a number from an NO2 diffusion tube here, they would be black; it would be in that black sort of range.

And then I pose some questions. And these are the sort of questions which are often raised when people say air pollution’s quite bad and people know it is, but you know, you can derail people’s thought processes.

The first one is: all right, we’ve got air pollution, but it’s not as bad as it used to be. And they’ll always take you back on some historical journey back to the nineteen-fifties, and they’ll show you this picture – a very famous picture – of the 1952 smog. And clearly during the smog, things were pretty bad. The one that occurred in December 1952 killed four and a half thousand people within five days, so clearly something had to be done.

An interesting parallel though – I think this is really important – when they discovered the smog (and this all came from coal burning) was killing people in 1952, they did not jump up in Government and say ‘we must do something to save the public’s health.’  They said ‘we can’t do anything because we’re in a period of economic crisis and it will be destructive to industry and the recovery of the country after the war.’

The reason we have a Clean Air Act and this was dealt with, is not because the Government wanted to do it; it was introduced under the radar by way of a Member’s Bill.  So even back then, when you had an event that was killing four and a half thousand people, the Government always said ‘we can’t do anything because it would affect the economic development of the country.’

Sound familiar? It is a little bit familiar to the situation today.

Dr. Ian Mudway - Slide 3

But there are lessons we can learn.

So if you look back to 1952 you simply ask the question ‘Who died, during that week?’ And what this is looking at is a few areas within Inner London, and it’s looking at the increased ratio of people dying, stratified by age.

And this is really, really important.

Because when you hear about the London smog and how bad it used to be, you’re always told that it was the very old, ill, infirm people who died. And that’s certainly true, if you’re willing to accept that ‘old’ is over the age of 45 – because if you look here you can see a two-fold, three-fold, doubling of death rates within those age groups.  And here’s the thing you’re never told: it’s the other side.  The death rate also doubles in children under one year old. So the sensitive populations, the populations who were suffering the most during this air pollution episode, were the elderly, those entering their retirement age, and the young.

And you know what? That doesn’t change.

So if we’re having an air pollution debate, we should be considering those members of our population who are the most vulnerable. And that does include our children, as I shall point out in the next slide.

Things have changed. So as the smogs of the nineteen-fifties were caused by coal burning – we don’t really have coal burning in London any more. I mean there are some people who burn bio-mass, […] which they shouldn’t really do, but now much of our pollution comes from traffic. And this is again an point where people get a bit confused, because what are we really talking about?

Dr. Ian Mudway - Slide 4

Because there are lots of different types of pollution. We have particles – particulate matter, small particles emitted into the air, which are intangible, you won’t see them. If you talk about something having particulate matter 10 microns, that’s about the size of e. coli. If you’re near a road, particles which come out of an exhaust pipe are about 100 nanometres; that’s the size of the influenza virus.  So you’ve moved from a visible smoke to an invisible killer. It’s still there, it’s just changed its nature.

So then we have all these other things: we have carbon monoxide, nitrogen dioxide – which we’re spending most of our time talking about today – we have black carbon, then we have a whole host of other things that are in this toxic brew.  We have polyaromatic hydrocarbons, we have VOCs, we have metals, in fact diesel exhaust contains one of the most carcinogenic compounds that has ever been identified. So it is quite a complicated mix.

So we have all of these things we have to consider, and then you have to ask: where they come from?  Because the air out there’s a mixture of different sources: you have diesel vehicles, gasoline vehicles. Even if you got rid of all of the exhaust emissions we’d still have pollution come from brake wear, because when you brake, big plumes of copper are released into the atmosphere. You also have resuspension of lying road dust. So it’s a complicated picture, and then there are other things.

So where does it come from? Well in London, you could really take a lot of that information and condense it down and say ‘there are lots of things here’,  but there is a common theme, and it’s largely traffic-derived. In London it’s the traffic-derived pollution we’re concerned about.  And many of these things actually vary together, so that as NO2 goes up, you tend to see an increase in the particles in the air, you see an increase in the black carbon.  It’s traffic, and particularly it’s diesel traffic, diesel vehicles and the preponderance and great density of diesel vehicles on the road.

This is the elephant in the room; it’s called exposure. Just because the air out there is polluted, doesn’t mean you’re all exposed to it to the same extent. How much do you actually breathe? Depends on how much you ventilate – if you’re running you’re going to breathe more than someone who’s walking quietly down the street.

But the reason I’ve highlighted exposure here is, let’s think of a group of individuals who spend more time outdoors than adults? Children. They have a greater exposure because they spend more time outdoors. They have higher ventilation rates – their breathing rate’s faster than an adult’s. So if they’re outside, they breathe more of the air than you do, and they have smaller lungs, which are developing. Which means that the amount of toxins entering their lungs is greater per unit area of lung. So a child outside, if it’s 70 micrograms per metre cubed, is getting a bigger dose of the toxin than an adult in the same environment. It’s one of the reasons why children are a sensitive sub-population.

Dr. Ian Mudway - Slide 5

How serious is it? Well, we’re kind of fortunate in a sense, that this has been reviewed by the government.  This is a report published in 2010, by the Committee on the Medical Effects of Air Pollution.  This is the figure that the Government itself will quote to you about the magnitude of the air pollution problem. In fact this is the figure that they quoted in a very recent House of Lords debate, which was raised by Lord Lawson.

In 2008, the UK population lost 340,000 years of life, so think about everybody in this room losing an amount of their life in relation to the amount of the exposure. But you can think of it another way; if you take that 340,000 and you think about the most sensitive individuals, it means there are 29,000 premature deaths in the United Kingdom per year arising from particulate pollution. That is a huge number. It’s greater than the number of people dying from obesity-related illnesses, it’s greater than the number of people dying from alcohol-related illnesses. It’s only second to cigarette smoking within the United Kingdom as a cause of premature mortality.

So this is a public health disaster, which needs to be dealt with.

And it’s not just a disaster on a personal front; economically if you have a vista which takes in the future, and not just the next immediate four-year period of time, this is a huge burden on the health system. We’re meant to be protecting our investment in the health service by improving the public’s health – this has to be one of our major targets.

Dr. Ian Mudway - Slide 6

I’ve given you information about death because death statistics are very popular, but the problem when you look at death, is that’s just the tip of the iceberg of health effects. So if we have 29,000 premature deaths, that’s going to represent a massive increase in hospital admissions. There’ll be more people visiting doctors: asthmatics, people with Chronic Obstructive Pulmonary Disease, people with cardiac disease, having to see their doctors, having to attend the GPs’ surgeries. We’re going to have increased medication use; so we have cost to the health service all the way down here. And then right at the bottom, in this purple segment, is what’s happening to everyone in the entire country, just from being outside near a road on a polluted day.

Now one of the things I do, is I take happy Scandinavian medical students, from a place called Umea in the far north of Sweden, and I put them inside chambers and I expose them to diesel exhaust at the concentration of diesel exhaust that they would experience if they were in London. I can’t do that study in London, because by the time you’d arrived at my laboratory for me to expose you to diesel, you’d have had more diesel than I’m about to give you as your challenge. If I look at their lungs, their lungs are inflamed. Their lungs react immediately – you can see that it has a physical effect on their airways.

Dr. Ian Mudway - Slide 7

Another thing that I should make a point of  – because we often get completely focussed on roads – and a lot of people in the rest of the world don’t understand that because most people in most cities in the world don’t live slap-bang next to roads. We do, because of the nature of London. I do a lot of work in Tower Hamlets and Hackney, and this just illustrates the number of postcodes within 100m of a major road. And that becomes important in the next slide.

Dr. Ian Mudway - Slide 8

This I think, is the most important figure. If you can take this away with you, this would be the most important thing. I’ve been studying children’s respiratory health in Tower Hamlets and Hackney for the last five years. This year’s going to be the last year we’re doing our study. Each of those dots is an eight to nine year-old child. If you’re looking at this map, and it’s yellow – and this is a map from 2009 – that means that that child is living in an area with an annual level of nitrogen dioxide over 40 micrograms per metre cubed.

That means it’s not a hotspot: it’s not that one tube on that one corner, it’s almost the entirety of Hackney, and over 90% of the area of Tower Hamlets.

In this slide, there’s only one child who lived in an area where the air quality of NO2 was legal, and he was over here. So let’s put a number on that: I did this off the top of my head, and I think I can do it again. Tower Hamlets and Hackney have a combined population of about half a million. If I was to assume, conservatively, that 75% of people in those boroughs lived in a high pollution area, it would mean that about 375,000 people in those two boroughs live in an area of illegal air quality – in that brown cloud. And that is just an unacceptable reality at the present moment in time.

Dr. Ian Mudway - Slide 9

Don’t think about abstract numbers; think about the people. It’s about the people who live in these areas, and people forget that.

Dr. Ian Mudway - Slide 10

I just want to say it’s not a new problem. If you think ‘oh, he’s gone on about diesel exhaust, and we’ve been told diesels are good’. We’ve known diesel is bad since 1956. The first reports were published in the BMJ saying diesel was bad for health a long, long time ago. It’s not a new story, it’s been around for a very long time. And in my area, we are completely surprised that people endlessly say ‘well, we didn’t know’ because we’ve been telling you for years.

And then finally: you don’t have to take my word for it.  This is just one report, but it’s a very important report.

Dr. Ian Mudway - Slide 11

The HEI is a US-funded institution, half funded by the government, half funded by industry. It’s meant to give completely independent, legally sound summaries of air pollution and health advice.  And they published this report, again in 2010, to review the evidence.  And I’ll just give you this final point, because this is something you can wave in front of people, and you can say ‘it’s not just a few scientists who have a vested interest in their next research grant.’ This has been thoroughly reviewed.

Dr. Ian Mudway - Slide 12

There is no doubt that being exposed to high levels of air pollution causes premature mortality.  This is one of the most robust, repeatable pieces of scientific evidence there has been in the last 25 years. There’s no doubt that if children have asthma, it makes their asthma worse. No doubt; and we’re allowing our children to grow up in a city with unacceptably high air pollution. And also, and increasingly, I now believe that there’s no doubt that children who grow up in polluted areas have stunted lung development. Their lungs don’t develop properly. We’re seeing that in our children in Tower Hamlets and Hackney. Their lungs at the age of nine were already smaller than they ought to be. And that’s a burden that they’ll carry with them for the rest of their lives.

Dr. Ian Mudway - Slide 13

« Part 1 – NO2 Air Pollution in Greenwich Borough

“No to Silvertown Tunnel” would like to thank Dr. Ian Mudway for taking the time to come to Greenwich and discuss issues of air quality with us.

Subsequent posts will feature the remainder of the meeting and presentations from Simon Birkett, John Elliot, Sian Berry and Andrew Wood, along with the public Q&A session.