Air Pollution - The Silent Killer

Air pollution is a silent, invisible killer.

In the UK, air pollution is estimated to account for between 36,000 and 40,000 deaths annually, more than for obesity and alcoholism.


The cost of treating illnesses related to poor air quality, including lost working days, is estimated to be about £20bn a year.

Where does Air Pollution come from?

The biggest contributor to air pollution is road traffic, and particularly diesel vehicles. Diesel vehicles produce significant levels of nitrous oxides and tiny particles of combustion by-products known as Particulate Matter (PM).


These pollutants can cause breathing problems and heart damage, just as breathing in second hand smoke affects your lungs and heart, even if you don't smoke yourself.

What's in the air we breath?

Particulate matter (PM)
Particles less than 10 micrometres (µm) across (called PM10) can penetrate deep into your lungs. 2.5µm (PM2.5) particles are the most damaging and long-term exposure to PM2.5 can impair lung and heart function and increase mortality.

Nitrogen oxides (NOx )
NOx is assumed to be the second most harmful pollutant after PM2.5. Exposure can trigger respiratory problems. 

Ground-level ozone (O3)
Caused by NO reacting with the atmosphere. Ozone can cause wheezing, shortness of breath, inflamed and damaged airways, a range of lung diseases, and exacerbated asthma.

How polluted air affects you

Air pollution aggravates other things that are likely to kill you, such as heart disease, strokes, asthma and dementia. PM2.5, NO2 and ozone interfere with oxidation reactions in the lungs and elsewhere in the body, and this can trigger inflammation and tissue damage.


A 2014 study followed 100,000 people across five European countries over 11 years, and found that a 5µg/m3 increase in average PM2.5 exposure was associated with a 13% increase in angina and heart attacks. Other studies have linked the same 5µg/m3 increase to an 18% increase in lung cancer. Other studies have shown significant links between air pollution and dementia, diabetes, kidney disease, premature births and mental illnesses.

Those most at risk include children who experience reduced lung function, and anyone with a preexisting heart or lung related condition.

How's the air quality in St. Albans?

As part of our commitment to highlight air pollution in St. Albans, Friends of the Earth carried out a nitrogen dioxide measurement exercise at 10 locations across St. Albans between the 7th May 2017 to 21st May 2017. The results are shown on the map opposite.


The numeric values in red are the average nitrous oxide measurement for the two week period. The UK annual average legal limit is 40 µg/m3, and our measurements show that six sites showed levels between 35 to 40 µg/m3, with two sites exceeding the 40 µg/m3 level. The worst site had a level of nitrogen dioxide which was over 70 µg/m3, approaching twice the legal limit.


Note that without testing each site for a full year, it is impossible to know whether a site has exceeded the annual legal limit, but our measurements certainly give an indication that the city centre and major road junctions show high levels of harmful pollutants.

Our Petition to St. Albans District Council

St. Albans Friends of the Earth gathered over 500 signatures of local residents calling for air pollution in St. Albans to be reduced. We presented the petition to the St. Albans District Council on Wednesday 21st February 2018. The council briefly discussed the issue and agreed to examine it in further in the CES Scrutiny sub committee.

To our knowledge, no decisions have yet been made that would lead to a reduction in vehicle air pollution...

How to reduce your exposure

1. Leave the car at home. 

Avoid driving, especially in slow moving traffic.

2. Avoid major roads where air pollution levels are higher. 

Use side roads if possible, especially when walking or cycling.

3. Wear a face mask
Use a face mask with a N95 rating (certified to filter out 95% of particles larger than 0.3
µm in size). These are especially useful if you suffer from symptoms which are aggravated by air pollution. Please make sure the mask fits with no gaps.

4. Avoid using pushchairs
Vehicles emit exhaust fumes closer to the ground, so the closer a child is to the ground, the more pollution they are exposed to. It may also be possible to use a cover to keep out pollution, especially when crossing at busy intersections.

5. Use air purifiers

Use high performance air purifiers when you are in your home or office. A high efficiency filter can dramatically reduce the PM levels you are exposed to.

6. Download our information sheet on how to reduce air pollution:


Here at St.Albans and District Friends of the Earth we’re keen to do what we can to improve our environment here and in the rest of the world. We’re a small, friendly group who meet once a month. 

© 2019 St. Albans Friends of the Earth