Air quality survey

Meadow detectives investigating lichens

On the 1st May we carried out our first Meadow air quality (lichen) survey, developed by the Natural History Museum as a country-wide OPAL initiative.

We were looking for the nine most common types of lichen: three types which were indicators of very clear air; three types which were nitrogen loving and were indicators of the polluted air, and three types which can grow anywhere.

What did we find?

Whitchurch air pollution score

Unfortunately, the air on the Meadow is not so clean. No surprises here: A34! The good news is that it might be improving: there were clean air lichens on very young branches. Maybe trees are getting bigger and screen the Meadow better from the A34. Maybe cars are getting cleaner. Maybe recession is kicking in and reduces traffic along the A34. We are not sure.

The pollution scale used by OPAL ranges from +54 (very clean air) to -54 (very polluted air).

The Meadow’s pollution score was calculated to be: -15! This was calculated using an average of all the trees we analysed on the Meadow. You can see our results on the national map.

What would we like to do next?

First of all, we would like to keep repeating the survey twice a year and record our results. This way we will be able to tell if the air is changing. Who knows, maybe in 20-30 years when we run out of oil, our grandchildren will be hunting that precious sample of bright yellow pollution-loving lichen which is so abundant on the Meadow now!

How can you help?

We have another idea you can help us with! Help us to plot the Whitchurch map of air pollution!

We would like to know: How far away from the A34 do you need to go to find clean air lichens?

Lichen pocket guide (Adobe Acrobat pdf)

Are you a keen walker? Print out the OPAL pocket guide to lichens (or contact us and we will get one to you) and then let us know where in Whitchurch (or surroundings) you can spot any of the three clean air lichens: Usnea, Evernia and Hypogymnia. The first two are easy to identify: they are sticking out of the branches. The last one is closely attached to the tree but should be easily recognisable by its puffed hollow lobes.