New sensors to monitor air quality

Wiltshire Council’s Wiltshire Community Air Network is launching a one-year project to monitor PM2.5 air pollution across the county and is seeking hosts for 100 low-cost air quality sensors.

The air quality sensors will measure PM2.5 air pollution, small particles in the air that can increase the risk of health problems and that can be damaging to the environment. This is part of the council’s Wiltshire Community Air Network project, and the sensors will provide real-time data which members of the public will be able to access online. 

Cllr Paul Sample JP, Cabinet Member for Environment, Climate and Waste, said, "We are seeking assistance from local residents and organisations to better understand PM2.5 air pollution in Wiltshire. We aim to recruit 100 volunteers to host air quality sensors for a year and encourage applications from individuals and groups in Wiltshire who are interested in monitoring PM2.5 pollution in their communities.

“The data collected will enable us to gain a greater understanding of this type of dangerous air pollution and put us in a stronger position to determine requirements for long-term monitoring and identify ways to reduce pollution.”

To ensure a wide range of places and communities are represented in the project, the council will be allocating a number of sensors to each of the 18 community areas of Wiltshire, based on the size of the population. In each area, the council will prioritise placing sensors at or near schools, medical facilities, and supported housing. 

The sensors need to be placed outdoors, plugged into a mains power supply and connected to a stable internet connection. The sensors are easy to use, and volunteers will be supported to set up and maintain them. At the end of the one-year project, hosts can choose to keep the sensor for their own use or return it to the council for recycling.

The approximate location of the sensor will be visible on a publicly available online map. 

The closing date for applications is Monday, 23rd June 2025. 

To host a sensor, people need to:

• Be over 18 years of age 
• Have a suitable outdoor location to place the sensor for one year, without being disturbed. It must be placed outside, between 1.5m and 3m above ground level. The sensor can be secured to a wall, fence, or drainpipe using provided cable ties or screws.
• Confirm that the sensor will be continuously connected to mains power and a reliable Wi-Fi connection (including overnight and during holidays). This is important as the sensor will not work without power and internet connection. 
• Have permission from the bill payer to pay the cost of power and Wi-Fi used by the air quality sensor. The sensors only use a small amount of power and bandwidth, costing under £3 to run for a whole year.

Existing monitoring of key pollutants indicates that the air quality in Wiltshire is predominantly very good.

However, there are a small number of locations where the combination of traffic, road layout and topography results in pollutants being trapped so that concentrations increase to unacceptable levels.

Historically, two pollutants have been of concern in Wiltshire: nitrogen dioxide and particulate matter (PM10).

Recent years have shown significant improvements in the levels of these pollutants, and the council are likely to be able to start revoking some of Wiltshire’s eight air quality management orders, as pollutant levels reach compliance with UK air quality standards.

Recent focus has shifted to very fine particulates (PM2.5), as there is increasing evidence of the harm they can cause.

PM2.5 is not yet incorporated into Local Air Quality Management Regulations, and therefore, there is no statutory requirement for Local Authorities to review and assess PM2.5 for LAQM purposes.

However, since 2016, the government has stated that it expects all local authorities to effectively use their powers to reduce PM2.5 emissions from the sources which are within their control. The WCAN project is Wiltshire Council’s first step in building a baseline understanding of PM2.5 pollution across the county.