Project Description

What We Do

Air Quality Monitor

Many people are concerned about air quality not least because it is an invisible hazard. Wiltshire has relatively good air quality in national terms, but parts of Westbury are amongst a small number of locations in Wiltshire where quality is below national targets. Because of this, Wiltshire Council has declared an AQMA (Air Quality Management Area) along the A350 in the town centre as nitrogen dioxide has exceeded targets for many years.

Link or picture

Triggers for an AQMA
Pollutant Air Quality Objective
Concentration Measured as
Nitrogen dioxide 200 µg/m3 not to be exceeded more than 18 times a year 1 hour mean
40 µg/m3 Annual mean
Particulate Matter (PM10) (gravimetric) 50 µg/m3, not to be exceeded more than 35 times a year 24 hour mean

You can find out about other targets here:

The effects of some of these pollutants are discussed here:

Wiltshire Council only monitor oxides of nitrogen in Westbury by simple “diffusion tubes” which measure amounts absorbed over several months.

Westbury Town Council aware of residents’ air quality concerns, acquired a multi-function “Zephyr” air quality monitor.

This can give continuous readings (recording and reporting wirelessly) of nitrogen dioxide , nitrogen monoxide, ozone and also small particles (called “particulates”) which are referred to as PM10 (10 microns or smaller), PM2.5 (under 2.5 microns) or PM1 (the smallest – under 1 micron). Note: that although research is suggesting that the smallest of these particles, PM1, may have significant health issues, there are currently no targets for these or PM2.5.

The device is very accurate, but is not a government calibrated “reference standard monitor” so cannot be used for “enforcement”; but Wiltshire Council is following our data and any hotspots identified would be prospects for the siting of one of their few AURN reference monitors.

We plan to use the town’s device to monitor at the roadside and in communal areas such as play areas – so that we can either assure people of good air quality or notify Wiltshire Council of problems. As the device is very portable (self-configuring using GPS and GSM), we have a number of other imaginative ways we hope to use it e.g. by schools for science projects or to help in the design of school travel policies and perhaps even to monitor air quality on walking routes. You can find out more in the council’s policy document (when it is published).

Westbury Town Council would like hear from schools or community groups interested in measurement projects and from anyone with suggestions for possible roadside monitoring locations (there are some restrictions as Wiltshire Council have told us that many of Westbury’s lamp posts are in too poor condition to support the solar panel from which the Zephyr is powered). Email:

** A new link to view the data below will be made available soon. We apologise for any inconvenience **

Our unit has been replaced (now Z00441). Unfortunately, the new unit has not been linked to our sign in, so to see our data on the above, either enlarge the map, select Westbury and close the map if you opened a zoomed one (Unit 441 should be showing) or scroll in the list of Zephyrs across the country to the very end and choose Z-00441. Note Z00314 is our old unit and will still show historical data. It is unclear whether this will be “fixed” as this version of the website is going to be retired.