Air pollution in Harwell

So you think Harwell’s air is unpolluted? Think again!

Summary: Air pollution is invisible but pernicious. At high levels its effect on our health may be significant. We often assume that it is solely an urban/industrial problem. It is not. A website is now available which enables us to obtain an estimate of pollution levels for our immediate neighbourhood, based on postcode. Read on.

“This most excellent canopy, the air, look you, this brave o’erhanging firmament, this majestic roof fretted with golden fire – why, it appears no other thing to me but a foul and pestilent congregation of vapours!”
William Shakespeare, Hamlet, Act ii, scene ii.

Air pollution comprises both gaseous and particulate elements, many, but not all, of which are derived from the burning of fossil fuels. General levels of pollution over long periods and over large areas are comparatively easy to determine. However, air pollution may vary considerably over a very short distance and at the shorter time scales. Higher levels are associated inevitably where there are high concentrations of people and industry – within urban areas.

Outside industrial areas, most air pollution derives from road vehicle sources:

• NO_x (nitrogen oxides: NO, nitric oxide; NO₂, nitrogen dioxide),
• CO (carbon monoxide),
• SO₂ (sulphur dioxide),
• O₃ (ozone),
• NVOCs (Non-methane Volatile Organic Compounds), and
• particulate matter (PM).

For the last, PM_2.5 – particulates of less than 2.5 microns (µ) in diameter – and PM₁₀ (<10µ diameter) are the most common sizes monitored.

The World Health Organisation (WHO) has recently updated its critical Air Quality Guidelines (AQGs)* which should be tolerated. The table at the end shows 2005 and 2021 guidelines for a selection of these.

Air pollution peaks at certain times of day when high traffic flow occurs, in rush hours, and closest to the main transportation arteries, particularly major roads. So, it is easy to conclude that air pollution to levels which should be of concern for health, only occur in the largest urban areas. Think again!

So, how may we obtain some estimate of air pollution in and around our homes in Harwell? An important, and user-friendly, source has recently come to our aid in the form of this website, addresspollution.org. This website has been constructed based on an attempt to model the spatial variation in the major air pollutants over the UK, combining hard data with theory. The project is the result of co-operation between the Central Office of Public Interest (COPI) and Imperial College London. The resulting ‘map’ provides estimates of pollution at a resolution of 20 x 20 m², and shows only the estimated vales for PM_2.5, PM₁₀ and NO₂, the most common and potentially the most harmful. All you do is input your postcode, and its long-term pollution levels are indicated, crucially, compared to WHO AQGs.

The actual results?

• Generally, about 75% of UK addresses experience levels of these three main pollutants which exceed current WHO safe limits.
• Locally? Try using the postcode for Harwell High Street (OX11 0EX). Input one for the Reading Road, or near to the A34, and the result may well shock! Elsewhere in the village … you may well be horrified!

Graham Sumner, June 2022.

Reference:
*World Health Organisation (2021), What are the WHO Air quality guidelines?

The 2005 and 2021 WHO guidelines for selected air pollutants