Nitrogen dioxide results - diffusion tube sampling

Diffusion tubes are used to monitor nitrogen dioxide within the Borough. Diffusion tubes are a simple way of monitoring air pollution and allow a greater number of sites to be monitored. We currently have 57 sites within the borough, these are located at both roadside and background locations. The tubes are exposed for a month and then sent off to a laboratory for analysis.

The location of the diffusion tubes between 1991 and present day are shown here(pdf, 33KB).

Nitrogen dioxide diffusion tube results (not bias adjusted)

The following 1991 to 2011 results are the raw data from the laboratory analysis of diffusion tubes.

View the 1991 to 2011 results here(pdf, 168KB).

The following charts show the annual nitrogen dioxide concentration at each location. Each year has two charts due to the number of monitoring locations.






Chart 1(pdf, 23KB) Chart 1(pdf, 23KB) Chart 1(pdf, 19KB) Chart 1(pdf, 25KB) Chart 1(pdf, 25KB)
Chart 2(pdf, 23KB) Chart 2(pdf, 16KB) Chart 2(pdf, 17KB) Chart 2(pdf, 24KB) Chart 2(pdf, 24KB)






Chart 1(pdf, 22KB) Chart 1(pdf, 26KB) Chart 1(pdf, 28KB) Chart 1(pdf, 24KB) Chart 1(pdf, 27KB)
Chart 2(pdf, 24KB) Chart 2(pdf, 23KB) Chart 2(pdf, 24KB) Chart 2(pdf, 26KB) Chart 2(pdf, 22KB)

London Wide Environmental Programme Annual Reports (not bias adjusted)

The primary aim of the Diffusion Tube Surveys is to identify locations where people may be exposed to high nitrogen dioxide concentrations, to identify long term trends in London and to update the nitrogen dioxide Diffusion Tube Survey Database. The results provide valuable information in the continuing assessment of compliance with European Union (EU) air quality standards for nitrogen dioxide and in the assessment of the effectiveness of pollution control measures.

The reports contain sources of nitrogen dioxides, health effects, air quality standards and sampling results. The reports also include the results for participating London Boroughs.

The historical reports consist of results within the Richmond Borough whilst the current reports include results from other participating London Boroughs. The results in the following report are quoted in ug/m3.

Historical reports

Current reports

Bias adjusted results

It is widely recognised that diffusion tubes have a tendency to under or over read, as much as 30% is not uncommon, and that a 'bias adjustment' of the raw data is often required, based on corrections from the more accurate continuous monitors. Hence the following results give the monthly bias adjusted data.

Nitrogen dioxide annual concentration results

The following results have been bias adjusted using the appropriate calculation. The calculation for each year can be seen on the bias adjustment page opposite.

View the 2002 to 2011 results here(pdf, 76KB).(pdf, 64KB)

Nitrogen dioxide annual average graphs

The following graph show the above results of nitrogen dioxide monitoring. The graphs indicate that most of the sites do not comply with the air quality objective of 40ug/m3. The results have been ranked against the 2004 results:


The following map shows the locations of the NO2 diffusion tubes and includes bias adjusted data for 2011.

The graph below shows the results of long term monitoring at four sites in the Richmond Borough. The graph shows that there is a general increase in NO2 levels since 2001. The location of the tube at RUT02 was changed from the rear of Paradise Road, Richmond to the curbside of George Street, Richmond. This accounts for the dramatic increase in NO2 levels.

View the 1993 to 2011 results(pdf, 20KB) (pdf, 20KB)h(pdf, 20KB)e(pdf, 20KB)r(pdf, 20KB)e(pdf, 20KB).

Updated: 19 August 2015