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The University of Southampton

Low cost pollution sensors could help improve air quality in Southampton

Published: 18 June 2019
Car Air Pollution
Residents are encouraged to engage in discussions about air pollution

Over the past year, scientists at the University of Southampton have deployed low-cost air pollution sensors in Southampton, laying the foundations for the longer term aim of improving our understanding of local air pollution levels with the help of volunteers across the city.

Currently, scientists’ ability to monitor air pollution is limited by the high cost of the advanced equipment used to measure particulate matter - microscopic airborne dust particles which come from many sources including car exhausts, wood burners, and ship funnels.

In this latest study, published in Nature’s Scientific Reports, the University of Southampton researchers carried out a trial with much cheaper sensors that anyone can buy online to assess whether they could provide a cost effective way to monitor the particles in the air on a wider scale.

Exposure to particulate matter is association with almost 9 million premature deaths per year worldwide, and increased risk lung cancer, asthma, and diseases of the cardiovascular system.


Air box
A monitoring box containing low-cost air quality sensors at St John's

Six monitoring boxes, each containing multiple sensor devices, were positioned at St John's Primary School and at Sholing Junior School in Southampton. The results indicated that multiple sensors give readings which generally agree well with each other, albeit with some model-specific differences.  It was even noted that, because these sensors report readings every minute, they are able to monitor short-lived pollution events which may not be detected by a more expensive “reference” grade instrument normally used to monitor urban particulate matter levels, which reports values averaged over a longer period. 

Ahead of Clean Air Day on 20th June, Southampton PhD Student Florentin Bulot who led the study said: “This is the first step towards deploying a wider network of low-cost sensors around the city. Low-cost sensors for air pollution are commercially available and are used by the public but the extent to which we can trust the data they produced is not yet well understood. Our results highlight some of the limitations of these sensors but also provide hope that, with appropriate further understanding, such sensors may be of use in providing more information about air quality in our cities, when used appropriately alongside current, more expensive, equipment.”

His work is now being taken further through the installation of multiple sensors in residential properties across in Southampton in partnership with local community project Breathing Spaces. This next stage will further engage local residents by getting them involved in discussions about air pollution, and to stimulate innovative and inclusive solutions.

Dr Matt Loxham of the Faculty of Medicine at the University of Southampton, who co-supervised Florentin's work, said “because of their high cost, particulate matter monitoring stations are few and far between in our cities.  As a result, it’s hard to get a good idea of how PM concentrations vary across cities, making it much harder to determine someone’s exposure and how certain sources of PM may affect this.”

Overall the authors concluded that, with appropriate consideration on their limitations, which include susceptibility to temperature and humidity, as well as a reduced sensitivity to lower levels of pollution, low cost fine particles sensors may be a cost-effective means to improve the scale of air quality monitoring in urban areas.  Further research is now being conducted to better quantify the limitations and how data should be interpreted.

Dr Steven Johnston and Prof Simon Cox of the Faculty of Engineering and Physical Sciences at the University of Southampton added “Low cost PM sensors may offer an opportunity to improve our knowledge of how PM levels vary between areas within a city, but only when their shortcomings are understood and taken into account.”


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