 Just as you wouldn't drink a glass of dirty water you wouldn't choose to breathe in dirty air So what if you could see the air in such a way that you could know how much pollution you and your family are exposed to? How would it affect your lifestyle? How you travel? How you live or even where you live? Well, that's what I've developed a machine that allows you to see the pollution all around you My name is Mark Richards. I've got a passion for physics and I've found through the machine I've developed a way of applying it to something both meaningful and practical But like most inventions it starts off as a piece of research I'm using this clean water to represent clean air and when I shine a beam of light through the water it goes through fairly uninhibited However, if there are pollutants present then that pollutant will absorb some of the light And this is because when light hits a molecule that molecule will absorb some and transmit the rest as a result the beam gets weaker I can use this principle to measure the amount of pollution in this water If I was to conduct a similar experiment in the air most pollutants are not visible. They absorb very little visible light Luckily, many pollutants absorb light outside of the visible range ultraviolet light Instead of visible light, I can direct an ultraviolet light beam through the air and any chemicals which are present will absorb specific wavelengths Each pollutant has its own signature in the ultraviolet region The resultant beam is measured with something called a spectrometer I've aligned the optics. I've also connected the source and the spectrometer Finally, I've run some air through this chamber and also injected some pollutants So let's look at the results The large peaks here are due to sulfur dioxide an important pollutant It's mainly produced by heavy industry and also diesel engines You can see these Smaller peaks which are due to nitric oxide emitted by petrol engines This setup actually allows me to detect many different gases Simultaneously and not only that we can actually measure how much of each gas is present So now I can see pollution, which is great But this is just an experiment in the lab the challenge is how I can adapt this for use in the real world I helped to set up a company with engineers and business people And the aim was to develop a machine that measures pollution that is portable The optical path of the ultraviolet light beam has to be quite long So I use a series of UV-reflective mirrors to create multiple reflections So that we can make the unit short enough to carry In order to complete the unit It requires a clever computing algorithm and supporting electronics that allows us to take measurements every second Now this makes it ideal for mobile sensing So I'm here at the inside the Quadrat Imperial College and I was just actually checking the pollution levels Seems pretty good so far Sulfur dioxide is near enough zero parts per billion nitrogen dioxide 28 parts per billion The legal limit is about a hundred and five so these numbers are incredibly encouraging But of course, we might see dramatic changes on the road side As you can see multiple lanes of traffic in several directions Let's have a look at the numbers say well both nitric oxide and nitrogen dioxide They're both above a hundred parts per billion But the key thing here is that a traffic lights whilst the cars are idling their engines They're not being overworked But when the lights change the cars will start to rev their engines and as a result The emission levels will start to spike quite dramatically I've managed to couple the unit with GPS Which means I can now map pollution readings to exact locations And when you combine this with the fact that I can measure every second It means that I can now generate a pollution map a bit like a weather map Furthermore you can actually update this map in real time That means as the pollution changes around you you can see the changes straight away So if you're an asthma sufferer, for example, you can actually have a look at this map and decide where to go or when to go Okay, so this is the data great What are we can we go to this this is this the southwest corner that we were at because it would be So this is the quad at Imperial College where we started if we start to include nitrogen dioxide Now we can see a huge spike at the junction Yeah, this spikes interesting actually because this was when we were near three coaches One of them was idling in their engine and just that one coach idling its engine has caused this huge spike here Now I've just put the unit in a weatherproof case. This means I can stick it on top of my car Which means I can cover a much wider area And I can go on to map the whole of London like this Driving around seeing how pollution varies from area to area street by street The implications for this technology are huge in the UK alone over 50,000 deaths are attributed to air pollution each year There's increasing public concern and with this machine we can really find out how bad pollution is for the first time Bottom line is if you knew more about air quality you could build a better environment around you If you knew more about the pollution levels around a school during the school run It might influence parents travel habits with my physics I've managed to develop something real something useful But more importantly something that helps to improve the quality of life for my family by allowing them to see the air they breathe