Frequently Asked Questions

To find out more about air quality in Sefton, have a look at the FAQs below:

Air pollution means dirty air.  Air pollution is made up of gases, droplets and tiny solid particles known as particulate matter, or PM for short. In terms of our health, the main problem pollutants are nitrogen dioxide (NO2 or NOx for short), particulate matter (PM10 or PM2.5) and a group of chemicals called non-methane volatile organic compounds or NMVOCs. 

You can find out more about these key pollutants here.

Sefton has a good network of monitors. We have five automatic monitors situated at key points within our ‘hotspot’ areas.

Four of these monitors measure Nitrogen Dioxide (N02) and fine particles (PM10) and one measures N02, PM10 and PM2.5. These sophisticated monitors provide hourly, daily and monthly readings. You can see these readings online here.

We also use monitors called passive diffusion tubes; there are around 100 of these monitors in Sefton. A chemical in the test tube reacts with NO2 from the air, forming a new molecule. At the end of the monitoring period each tube is sent off to a specialist laboratory, which measures how much of the new molecule is present to work out how much NO2 was present.

These results are used to calculate the average concentration of N02 in the air at each site for the whole year. You might spot a tube like this sticking out from the side of a building, lamp post or road sign.

In Sefton, traffic is the single biggest cause of air pollution. It is the primary cause of Nitrogen Dioxide and wear and tear from brakes and tyres can create PM2.5s; the smallest and most harmful form of microparticles.

In South Sefton older lorries and buses create a wider problem in addition to the impact of emissions from shipping and other commercial activity.

But it’s not just traffic that causes air pollution; burning from businesses, fires and solid fuel heating systems at home are also to blame.

It’s also important to remember that air pollution does not respect boundaries, and a lot of the pollution in our air comes from agriculture and power stations located further afield.


When it comes to air pollution, cities face the biggest challenges and London is often in the headlines. Generally, the air quality in Sefton is good and the public health impact of air pollution is lower in Sefton compared to other boroughs in the Liverpool City Region and North West.

The law says that council’s must measure levels of NO2, PM10 and PM2.5 using a network of monitors. You can look at this data yourself at

By analysing this data, we have identified four hotspots in Sefton where UK air quality standards aren’t met. These are situated on busy junctions in Bootle, Seaforth and Litherland. 


Last Updated on Sunday, January 3, 2021

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