Hand in hand with Active Travel is the need for clean air. In Salisbury, the two major air pollutants are nitrogen dioxide and PM2.5 (small particulate matter at or below 2.5 micrometres in diameter; See link to understand these sizes).

As levels are high across the country, nitrogen dioxide has been the pollutant that councils focus on the most, but now PM2.5 is thought to be the most dangerous to health, as it can penetrate further into the lungs and affect health in a number of ways, including increasing the risk of cancer.

The major emitter of nitrogen dioxide is road traffic that still uses fossil fuels. However, for PM2.5 other emitters are possible, including non fossil fuel methods of transport, wood burners and some industrial and agricultural practices.

By law Wiltshire Council has to monitor the levels of these pollutants across the city and declare areas that exceed the national thresholds for each pollutant monitored.

In order to understand the levels of pollutants in the city, Salisbury has a DEFRA approved monitoring system in Exeter Street.

However, this has not been operational for a good part of 2025. In the past it monitored levels of nitrogen dioxide and PM10 (particles at or below 10 micrometres in diameter) in hourly intervals but did not directly measure PM2.5. It is anticipated that Wiltshire Council will install a new system in the latter half of 2025.  This will include a reference system that can directly measure PM2.5.

In 2007 Wiltshire Council declared three areas, known as Air Quality Management Areas (AQMAs),  in Salisbury where nitrogen dioxide levels exceeded the national threshold. This is the highest number of local AQMAs in Wiltshire and they are:

  • Salisbury City Centre within the Ring Road
  • Salisbury London Road (A30) between St Marks Roundabout and the Rail Tunnel Allotments
  • Salisbury Wilton Road (A36T) between St Paul’s Roundabout and Skew Bridge

Although things have significantly improved since 2007, to date, none of these AQMAs have been revoked for nitrogen dioxide. It is likely that some of the AQMAs for nitrogen dioxide will be revoked within the next two years as the levels will be below the national threshold. However, it should be noted that the English threshold is 4x higher than that recommended by the World Health Organisation (WHO).

In addition, new legislation associated with reduced thresholds for PM2.5 will come into effect in 2028. Therefore, it is reasonable to assume that even if AQMAs are revoked for nitrogen dioxide, it is possible they will be replaced by new ones for PM2.5.

Case Studies

To address the issue of the AQMAs as part of the remit of the Environmental Action Group, Wiltshire Council along with Salisbury City Council and Salisbury citizens has developed an Air Quality Management Plan. Citizens are welcomed into the group for their input. However, it is most likely that the biggest impact on the levels of nitrogen dioxide pollution has been the National Government’s initiative to increase the number of electric vehicles on the roads. Therefore, any new Air Quality Management Plans need to be more effective at local government levels.

In the city, Salisbury Transition City has been running a pilot Citizen Scientist Air Quality Monitoring Project. This is supported by the City Council and reports PM2.5 values in real time here. In 2025 Wiltshire Council has continued this theme with their own low cost PM2.5 monitoring systems.

Wiltshire Council have distributed over 100 PM2.5 monitors across the county with Salisbury currently having at least 10 (see link and enter your post code to see the results for the sensors in and around the city). It is hoped that these systems will allow greater understanding of PM2.5 levels across Salisbury and the county and will educate Wiltshire citizens of the harm of this pollutant and the need to reduce it. It should also identify any local hot spots for further investigation and potential remediation strategies.

Advantages

All citizens have the right to clean air. Clean air gives the individual, including vulnerable citizens, longer life expectancy and improved living conditions. Improved traffic management that will lead to improved air quality in the city centre will benefit residents and visitors to the city. There will be more locations where it is safer to walk, wheel and cycle. In the longer term there will be improved public health outcomes where there will be reduced hospital admissions. Advantages of improved traffic management will mean that there is less congestion and therefore public transport including the local buses and park are ride will be more efficient, particularly at peak periods.

Disadvantages

Traffic management controls implemented in the city centre to improve air quality / public health may have an impact on the routes drivers currently use in the city. 

The frequency of bus services (local buses and park and ride) is only every 30 minutes and traffic congestion results in bus delays and impacts on services in the city centre.

Traffic congestion has a major impact on the number of residents cycling as many do not feel safe in the traffic densities currently observed in Salisbury (up to 11,000 vehicles a day on Fisherton St)

Recommendations

  1. Ensure all citizens are aware of the local sources of information on air quality.
  2. Ensure that citizens are aware of the harm of air pollution and educate them in ways to reduce it.
  3. Introduce local efficient and effective means to improve areas of high pollution including traffic management systems and improved efficiencies in public transport.

Ongoing Activities

  1. Citizens will continue to provide advice and work with Salisbury City Council and Wiltshire Council to deliver information on concentrations of air pollutants.
  2. Understanding what can be done to monitor the statistical information on improvements in citizens’ health in order to monitor success.
  3. The Environmental Action Group will investigate other local action groups.
  4. Citizens will continue to work alongside Salisbury City Council and Wiltshire Council to develop improved strategies to reduce pollution.

This text was written and supplied by Elaine Reid in September 2025 as part of the Salisbury Air Quality Strategy and edited by the Salisbury Active Travel Group.