Scientists look to tree bark for clues about the air we breathe

Tree bark is being tested by researchers at the University of Southampton as a new way to trace harmful air pollution in local communities.

Particulate matter – tiny particles of dust too small for the eye to see – is considered to be one of the most harmful types of air pollution for our health.

However, it can be difficult to measure what people are exposed to, and establish where it has come from.

A new approach being trialled at the University and the NIHR Southampton Biomedical Research Centre is seeing if tree bark could hold the answer.

The study is being led by Dr Natasha Easton through an Early Career Colleague Fellowship with the University’s Sustainability and Resilience Institute. She is supported by BRC Air

Pollution lead Prof Matt Loxham and Interstitial Lung Disease lead Prof Mark Jones.

Harmful to health

Particulate matter can be breathed deep into the lungs, and the very smallest particles can even enter the bloodstream.

Long-term exposure to particulate matter has been associated with increased risk of a wide range of health conditions. These include asthma, interstitial lung disease, lung cancer, cardiovascular disease, stroke and dementia.

This dust comes from both man-made and natural sources. Man-made sources include burning fuels, for example in vehicle engines, industrial emissions, as well as tyre and brake wear. 

These sources leave behind a chemical fingerprint. This can be used to work out where the pollution came from.

Dr Easton said: “Air pollution doesn’t affect every area in the same way, so it’s really important that we build a clearer picture of what’s happening in our local environments.

“By looking at what’s captured in tree bark, we hope to uncover these hidden fingerprints to pinpoint sources of pollution and guide strategies to ultimately support healthier communities.”

Analysing tree bark

Particulate matter can become trapped in tree bark. The research team therefore aims to measure the levels of this type of air pollution using the bark from local trees.

The project will collect bark samples from trees across two cities. It is being conducted in partnership with Southampton and Winchester City Councils.

The researchers will then analyse these samples to determine how the composition and sources of particulate matter vary across our region, and by how much. This will allow them to identify who is most likely to be exposed to each of the different sources.

This new approach to monitoring air quality will give a detailed picture of real-world particulate matter distribution. The project will help to identify which sources contribute the most to local air pollution and how our different communities are differentially exposed. This knowledge could steer strategies to improve air quality and inform future studies to relate individual sources to impacts on health.