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Air Sensors Demo - what is air quality sensing and why does it matter?

Oxford Friends of the Earth hosted a demonstration of a small, low-cost air pollution sensor during Oxford Green Week ‘Big Green Day Out’ on Saturday, June 9th. The goal of this demonstration was to start conversations about low-cost, portable air quality sensors and to discuss why we might be interested in monitoring local air quality throughout Oxfordshire.

These small, often portable air quality sensors are now widely available for public purchase online. They vary in cost (approx. £90 - £3000), size, what pollutants they measure, and the methods they use to measure those pollutants. Small air quality sensors can also be DIY (do-it-yourself), and different groups like Public Lab and Smart Citizen walk you through how to put together a sensor.  Many of the flashier, commercially available sensors connect automatically with apps or website that produce visual representations of what pollution concentrations look like in your immediate surroundings. Some of them look like this:

The sensor used for our demo was a prototype developed by OxAir (Oxford air quality mapping project, launching in the next year – more info coming soon!). The prototype used an Alphasense optical particle counter (laser used to count particles) to measure particulate matter or ‘PM’ at 10 and 2.5mm (micrometers). For comparison, a strand of human hair is 50-70mm in diameter, so these particulates are quite small. Pollen can range from 100 to 0.006mm!

It is important to keep informed about air quality because has significant impacts on human health. Decades of research have tied the following pollutants to specific health consequences, particularly among vulnerable groups (children, elderly, those with pre-existing conditions): particulate matter (PM10, PM2.5), ozone (O3), carbon monoxide (CO), sulphur dioxide (SO2) and nitrogen dioxide (NOx). As a result, these pollutants are regulated by county and the national government. DEFRA provides a Daily Air Quality Index and forecast using data from a network of 164 stationary monitors (AURN) across the UK. Smaller, portable sensors allow us to imagine what air quality looks like at more local scales and in real-time. It is important to note however that sensors vary in accuracy - as a result, the data collected using smaller, low-cost air sensors is largely non-admissible in a court of law. Visit www.aqmd.gov/aq-spec/evaluations to see how different low-cost sensors perform.

Exposure to mixtures of these pollutants (multipollutant exposure) can also have serious health consequences. Very generally, larger particulate matter tends to affect the respiratory system, while smaller particles affecting the heart. This can contribute to or exacerbate asthma, heart disease, chronic obstructive pulmonary disorder (COPD) and lung cancer. Ozone affects the respiratory system and can be likened to receiving an internal, low-grade sunburn. Ozone exposures have also recently been linked to the release of stress hormones (Henriquez et al, 2017). In 2014, Public Health England estimated the mortality burden attributed to long term fine (2.5 mm or smaller) particulate matter exposure in Oxfordshire to be equivalent to 276 deaths (Age 25+) and equivalent to 2944 life years lost. On the whole, the estimated cost of air pollution to individuals and society in the UK is more than £20 billion per year.

Local air quality monitoring can illuminate areas across Oxfordshire that suffer from poorer air quality conditions – such as the St. Clements road region. Oxford Friends of the Earth has recently launched the Oxfordshire Clean Air Charter, and we encourage everyone to READ and SIGN on to encourage the city, county and district councils to implement stricter controls on air pollution throughout Oxfordshire.

Click here to download our OxFoE Quick Air Sensors Guide!