How do we measure pollution?

People monitor local air quality to understand how safe it is to breathe. You can even try it for yourself!

Diffusion tubes

These cheap little plastic tubes can measure nitrogen dioxide. They’re easy to use – hey, maybe you could give it a go?

1. Remove the cap

Take off the white plastic cap from the bottom of the tube.

2. Set it up

Put the tube in its holder and secure it to an outside wall with the coloured cap at the top. Make a note of the time and day.

3. Leave it be

Diffusion tubes need four or five weeks to collect samples. They contain a steel mesh that’s coated in a special chemical. When gases pass over the mesh, a chemical reaction happens.

4. Send it off

It’s time to get your results! Put the white cap back on. Post the diffusion tube to a laboratory, where a scientist will look at it. They’ll then let you know if the amount of nitrogen dioxide in the air is normal or high.

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Automatic monitoring stations

These clever bits of kit work to provide regular readings, normally about every 15 minutes. They’re super accurate and helpful but really expensive, too. Automatic monitoring measures up to three different pollutants.
Nitrogen Dioxide monitor

Nitrogen dioxide

The nitrogen dioxide in the air sample reacts with the ozone generated inside the monitor to change a light source. The light is then measured to give a nitrogen dioxide reading. Smart!
Ozone monitoring station

Ozone

Ultraviolet light is passed through the sample and compared to another sample that has no ozone in it. The difference between the two lets the machine work out how much ozone is in the local air.
Particulates monitor

Particulates

The machine collects the particulate matter and works out its mass to find out how much there is in the local air. Handy!

more air quality

The History of Air Quality

The world of air quality

What's in the air?