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Air pollution levels and monitoring them

The main sources of air pollution in Cambridge are vehicle exhausts and local combustion.

Local air quality management is a statutory process by which we monitor, assess and take action to improve local air quality. We monitor nitrogen dioxide and particulate matter (PM10 and PM2.5). We are working to meet the following annual health based national air quality objectives:

  • Nitrogen dioxide: The annual mean concentration should not exceed 40µg/m3. The 1-hour mean objective should not exceed 200µg/m3 more than 18 times per year.
  • Particulate matter (PM10): The annual mean concentration should not exceed 40µg/m3. The 24-hour mean objective should not exceed 50µg/m3 more than 35 times per year.

We compile an annual report of the local levels of nitrogen dioxide and particulate matter. When levels are exceeded, we must create an air quality management area and develop an action plan to reduce them.

We designated the area inside the ring road as an air quality management area in 2004. This was primarily because of high levels of nitrogen dioxide caused by traffic. The area extends along some radial roads outside of the ring road.

We have recently updated our air quality action plan – find out more about how we are improving air quality.

Follow the link for more information about air pollutants, their effects on health and levels in Cambridge today.

Monitor locations

We manage five ‘continuous monitoring’ stations, which calculate hourly average pollution levels. A sixth continuous monitor, which is managed externally, is located at Station Road.

The nitrogen dioxide, PM10 and PM2.5 data from the continuous monitors has been ratified by Ricardo AEAT. An appropriate correction factor has been applied to the PM10 data to convert to a gravimetric equivalent, where required. Diffusion Tube data has been bias-adjusted. Follow the links to see the latest data from each monitor:

There are also around 70 ‘passive diffusion’ tubes around the city, which record nitrogen dioxide levels.

Diffusion tubes do not show day-to-day fluctuations related to changing traffic levels or weather conditions. But they do provide us with a good indication of levels in the area and allow us to monitor and pick up on any changing trends.

Defra says an annual average from diffusion tubes below 60µg/m3 is a good indication that short-term nitrogen dioxide targets are being met. Levels in Cambridge are below 60µg/m3.

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