Air Pollution

8 February 2018

by EH for the NH&SGP

 Car fumes with baby

What is air pollution and why should we be concerned about it?

Air pollution can come from a wide range of sources; the three types of pollution that are of particular concern are highlighted on the Friends of the Earth website:

Particulate Matter (PMs): These are tiny particles of material which come from a variety of sources, both natural and human-made. In the UK, one of the biggest human-made sources of PMs is road transport, which produces particles from engine emissions, tyre and break wear and other non-exhaust emissions. This particulate matter can find its way into our lungs and some of it into our bloodstream, and hence can worsen both heart and lung diseases.

Oxides of nitrogen (NOx): Nitrogen dioxide (NO2) and nitric oxide (NO) are oxides of nitrogen which are produced by combustion processes in the air. Again, road transport is the main source of NOx, followed by the electricity supply industry and other industrial sectors. High levels of NO2 can also cause problems with breathing, and may provoke asthma attacks in some individuals.

Ground level Ozone (O3): Ozone comes from chemical reactions between various air pollutants, including NOx. The formation of ozone can take place over several hours or days, and may have arisen from emissions many hundreds or even thousands of kilometres away. Being exposed to high concentrations of ozone can cause irritations to the eyes and nose.

Friends of the Earth point out that there are 40,000 premature deaths a year in the UK which are linked to air pollution – more than the number of deaths due to obesity or alcohol. Of these premature deaths, 23,500 are specifically linked to NO2 emissions from diesel traffic. As well as asthma symptoms, lung and heart disease, air pollution has even been associated with changes in the brain linked to dementia and can lead to children growing up with smaller lungs.

In April 2017, a joint investigation by Greenpeace and the Guardian newspaper found that over 2,000 schools, nurseries, further education centres and after school clubs across the UK were within 150 metres of a road emitting illegal levels of nitrogen dioxide. The legal limit is 40µg/m3 (micrograms per cubic metre of air). This investigation highlighted that dangerous levels of NO2 were not limited to large cities like London, but could also be found near some schools and nurseries in smaller towns and cities such as Oxford and Plymouth.

Is there a problem with air pollution in Hitchin, and what is the local council doing about it?

As might be expected, levels of air pollution are at their greatest in major urban areas such as London. In most areas in North Hertfordshire, the levels of NOx are below the limit set by government of 40µg/m3, but there are two areas where these limits are exceeded. These two areas are in Hitchin, in Paynes Park and Stevenage Road, near the Three Moorhens roundabout. The levels of NO2 in these areas come from more than 6 years’ of data, and from more than one monitoring tube within the location which have been averaged out:

Stevenage Road: 47.2µg/m3

Paynes Park: 51.9µg/m3

The main source of this pollution is exhaust emissions from petrol and diesel vehicles moving through these areas. Heavy goods vehicles (HGVs) produce a disproportionate amount of this pollution, as they make up less than 4% of this traffic, but produce between a quarter and a third of NOx emissions.

These two areas have been designated as Air Quality Management Areas (AQMAs) where the local council carries out monitoring of air quality and has to produce an Air Quality Action Plan to set out the steps it is going to take to improve air quality in these areas.

The recent Air Quality Action Plan for these two areas does acknowledge that while NOx levels have been declining slightly in recent years, the demand for housing and associated growth in the area has the potential to delay or reverse this trend in the coming years.

What has the local Green Party been doing to take action on this problem?

North Hertfordshire and Stevenage Green Party has recently commented on the Air Quality Action Plan for these two areas. We feel that the plan does not go far enough in the proposals it puts forward for tackling air pollution.

We would like to see much more being done to tackle pollution from HGVs. The plan recommends encouraging firms to sign up to the voluntary ECO stars scheme, which reviews the fuel management of companies and recognises best practice. However, we feel that this is unlikely to make any real difference. We would like to see the council taking action to try to reduce daily peak pollution levels to the government limit. This could be by restricting access through the two AQMAs or levying a hefty charge on polluters. Particularly polluting vehicles should be regulated in terms of how often they can pass through or be banned outright.

We would also like to see more done to encourage the use of electric vehicles (EVs) locally. The council is planning some schemes to encourage EV use including free parking, free electricity and replacing council vehicles with EVs. There are plans to provide two EV charging points in central Hitchin car parks with free electricity - but each will take an average of 4 hours to charge a car from empty, and so each charging point will only enable a maximum of 5-6 cars parked sequentially over 24 hours. Another idea might be to attach chargers to lamp-posts.

To see our detailed response to the local Air Quality Action Plan, please go to:

We have also recently used an air monitoring tube provided by Friends of the Earth to monitor NO2 levels under the Cambridge Road railway bridge in Hitchin, near the train station. We are concerned that the levels of air pollution that pedestrians are exposed to under the bridge are relatively high and have written to the local Environmental Protection officer about this. He provided a very helpful response. While we accept that people are only exposed to these levels of pollution for a relatively short time while walking under the bridge, we feel that people should be aware of this issue, as it may be of particular concern to those with respiratory problems such as asthma or those with young children.


Friends of the Earth web pages about air pollution:

NHDC Air Quality Action Plan for Stevenage Road and Payne’s Park Air Quality Management Areas:

ECO Stars project:

Lamp-post chargers:







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