Skip to main content

How we monitor air quality

We continually monitor levels air pollution in Waverley. We do this through automatic monitoring and diffusion tubes.

Automatic monitoring

We have two monitoring stations in our Air Quality Management Areas (AQMA) in Farnham and Godalming town centres.  These automatic analysers offer very reliable data and can track increases in pollution levels depending on traffic flows.  They run continuously to measure:

  • Nitrogen Dioxide (NO2)
  • Particulate Matter (PM10)


The automatic monitor is located in the town centre on South Street next to Sainsbury’s and the South Street car park.


Located on Ockford Road near the junction with the High Street, this monitors NO2.


You can view the monitoring results from 2018 onwards on the Air Quality England website. Results are ratified once a quarter.

Categories of air pollution levels

Air pollution levels are categorised using Defra’s UK Air air quality index from Low (1) to Very High (10).  

Diffusion tubes

We have 52 diffusion tubes throughout Waverley. These measure levels of NO2 and give us a general indicator of air pollution in the borough.

Map showing diffusion tube locations

The green markers show the diffusion tube locations in 2022 and 2023

The red markers show the diffusion tube locations in 2020 and 2021.

The purple markers show the diffusion tube locations in 2019.

The yellow markers show the diffusion tube locations in 2018.

You can turn these layers on and off.

You can download diffusion tube results for:

The results show raw data - they are provisional results that have not yet been annualised, bias adjusted or distance corrected. Please don't use this raw data for interpretation - view the annual air quality reports.

More information

See the UK Air website for general information on air pollution, current air quality and pollution forecasts.