Local air quality management: policy guidance

Updated guidance for local authorities to take account of changes to industrial emissions legislation and requirements.

3: Review and Assessment

3.1 Report templates are available on the Report Submission Website. Examples of completed reports are available on the Review and Assessment helpdesk web site at http://laqm.defra.gov.uk/review-and-assessment/good-practice/examples.html

New monitoring data

3.2 The progress report should provide a summary of all available monitoring data in a format suitable for comparison with the air quality objectives. For example nitrogen dioxide data should be reported as annual mean concentrations, and where possible as the number of exceedences of the 1-hour objective value of 200 µg/m 3. Reporting full hourly data, or full monthly data for diffusion tubes, is not necessary.

3.3 To maximise the value of air quality monitoring, careful attention should be paid to the type of equipment used and the locations where the monitors are placed, as well as the QA/ QC and data verification procedures. Detailed guidance on these issues is provided in LAQM. TG (16), and reference should be made to this when setting up and operating monitoring equipment. Particular matters to take account of when preparing and assessing monitoring results are set out in Box 3.1.

Other information to include in the progress report

3.4 When reporting the monitoring data the following should be included where possible:

  • a map showing the monitoring locations. It may be possible to refer to a map in a previously published document, as long as it is readily available e.g. published on the web; and
  • plots showing trends in concentrations e.g. plots of annual mean nitrogen dioxide concentrations for the last ten years.

Box 3.1: Matters to take into account when reporting monitoring data


When presenting automatic monitoring data, it should be made clear whether the results have been ratified. It may be necessary to report a combination of ratified and unratified data. The fully ratified data can then be updated in the next report. Information on data capture should also be provided.


Where data are available for fewer than nine months, then they should be adjusted to provide an estimate of the annual mean using the procedure set out in LAQM. TG (16).


To help understand the results, the type of monitoring site should be specified. For roadside sites the distance from the kerb should be provided. For industrial sites the distance to the source(s) should be specified. This information could be provided as an Appendix to the report.


Where nitrogen dioxide diffusion tube data are provided, it should be made clear whether the results have been adjusted for laboratory bias. Where they have been adjusted, brief details should be provided of the adjustment factor used and its source. Details should also be provided of the laboratory being used, the tube preparation method and the exposure period.


Summary information should be provided on QA/ QC. This can be by way of a reference to a previously published document, so long as the document is still readily available.


Where results are presented for new monitoring sites, a description of the sites should be provided. This should include the reason they were set up e.g. do they represent worst-case relevant exposure locations?


When describing sites, it should be made clear whether they represent relevant exposure. For instance, if the site is kerbside, it would be appropriate to say that "the nearest relevant exposure is residential properties set back 5 m from the kerb."


For short-term objectives, e.g. 1-hour for nitrogen dioxide, the results should be presented as number of hours (or 15-mins for sulphur dioxide, or days for PM 10) above the objective value. This should only be done where data capture is >90% of a full year. If data capture is <90% or monitoring is for less than a full year, then it is only appropriate to present the results as percentiles. The following percentiles roughly equate to the objectives: 99.8 th percentiles for 1‑hour nitrogen dioxide; 99.9 th percentiles for 15-min sulphur dioxide; 99.7 th percentiles for 1‑hour sulphur dioxide; 99.2 nd percentile for 24-hour sulphur dioxide; and 90 th percentile for PM 10. Guidance on calculating percentiles is available in LAQM. TG (16).


When reporting results a note should be made of any local circumstances that may have affected the results e.g. construction activities close to a PM 10 monitor, or temporary changes in traffic flows during road works.

3.5 The progress report should also draw attention to:

  • results for new monitoring sites and whether they reveal any new information about air quality; and
  • evidence of any trends over recent years. Care should be exercised in discussing trends, as changes in concentrations occur from year to year due to weather conditions. It is normal practice to only consider a trend as being significant when five years' worth of data are available, although a longer timescale may be appropriate for some pollutants e.g. PM 10.

Progress on implementation of action plans

3.6 Although local authorities can submit separate action plan progress reports, they are strongly advised to submit a single combined report.

Assessment of monitoring data

3.7 The minimum requirement is to report monitoring data and trends over recent years. It will also prove helpful to project the measured concentrations forward, using the guidance in LAQM. TG (16). This will provide early warning of likely exceedences that may not have been previously identified and also help to gauge progress on when the objectives are likely to be complied with.

Box 3.2: Progress Report Checklist


Minimum Requirement

Recommended Additional Elements

New Monitoring Results




Present a map showing monitoring locations

Present summary tables of concentrations of regulated pollutants in a format to allow comparison with the objectives

Provide plots of summary data to show annual trends

Project forward results using LAQM. TG (16) guidance



Highlight results for new sites

Discuss trends. Take account of number of years of available data


New Local Developments

Identify and list new developments that may affect air quality


Action Plans


List measures in action plan and implementation timescales

Provide update on progress implementing measures

Local Air Quality Strategy


Summarise Strategy or progress on preparing a Strategy or reviews of the Strategy

Describe consultation/publicity for Strategy

Report on progress on implementing measures within strategy

Planning and Policies


Log planning applications for new developments for which air quality assessment is being provided

List local policies that relate to air quality and any changes that may have been introduced

Regional Transport Strategies and Local Transport Plans


Summarise measures in the Strategies that have a direct bearing on air quality

Report on progress with implementing these measures


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