National bias adjustment factors

A database of bias adjustment factors determined from Local Authority co-location studies throughout the UK has been collated by the Local Air Quality Management Helpdesk. Using orthogonal regression, combined bias adjustment factors have been calculated for each laboratory, year and preparation method combination for which data are available.

The database, which is in the form of an Excel spreadsheet, is updated regularly and can be downloaded below.

March 2021: The Diffusion Tube Bias Adjustment Factors Spreadsheet for March 2021 is now available to download here (XLSX, 720KB). This provides for the first round of National Diffusion Tube Bias Adjustment Factors for 2021 diffusion tube monitoring data. The next update, which will incorporate diffusion tube monitoring data for 2021, is due June 2021 (Round 2 of 3). Local Authorities can return co-location studies for participating diffusion tubes completed inclusion (pending data quality checks) in the next update using the questionnaire here

For information on how these Bias Adjustment Factors were calculated, please download the Diffusion Tube Co-location Methodology (PDF, 167KB).

It is recommended that all Local Authorities who have carried out a co-location study should add the results to the database of combined bias adjustment factors. To do this, you should fill in the questionnaire provided on the "adding your co-location data" page.

Information on Precision and Accuracy is provided here. You can also download a summary of precision results for the individual laboratories from this page.

back to main Diffusion Tubes pages