| Authors | Louisa Kramer, Hannah Walker, Jack Davison |
| Compilation date | 08 January 2026 |
| Customer | Greater Manchester Combined Authority |
| Approved by | David Madle |
| Copyright | Ricardo |
| EULA | http://ee.ricardo.com/cms/eula/ |
| Contract reference | ED10689 | Report reference | 8 |
This is a summary report for Greater Manchester Combined Authority for the period Monday December 01 2025 to Wednesday December 31 2025.
This is a dynamic report containing embedded data from which the report tables, plots and graphs are generated. The embedded data allows the reader a level of interaction with some of the report findings, providing additional insight. This approach enables a more easily navigated and streamlined report providing an engaging and intuitive reader experience.
Maps for example can be panned and zoomed with different layers and markers turned on and off and with popup information by clicking on markers or hovering the mouse over them. Tables may contain much more information than initially displayed and can be set to show different numbers of rows, and can be filtered sorted or searched to display only specific information of interest. Some time series plots can be tracked with the mouse cursor to obtain specific time/date stamps and values and the reader can zoom into a specific time window by dragging with the cursor and double left clicking to return to the full plot extent.
The report is easily navigable using the floating table of contents on the left pane which tracks with the reader’s progress through the report and expands and collapses to a level of detail related to the subheadings used. The layout of the report is also dynamic, with some sections split into specific ‘tabs’ (e.g. per pollutant or per site) for ease of access to those sections.
A summary of site information is presented in the below map and table.
The below map can be zoomed in and out of by using your mouse scroll wheel, or using the widget at the top-left. A satellite view can be toggled on and off using the menu at the top-right. Clicking on individual markers will show the name of the site and the pollutants it measures and, if available, a link to further information.
Clicking on the headers of these tables will sort them. The whole tables can also be searched by using the box at the upper-right. Clicking on the site names will expand to show information about individual pollutants.
Data contained within this report is managed by Ricardo and stored in a dedicated, secure database. This report was generated using the data available at the time of compilation (4 pm on Thursday January 08, 2026). This data is provisional and subject to change, and as such should be treated with caution.
Some of the plots provided in this report use associated meteorological data (typically wind speed and wind direction) in order to show measured pollutant concentrations in a dispersion context. Very few monitoring stations provide quality controlled met data, therefore these reports import data from the Met Office DataPoint.
Gaseous pollutant mass units are at 20 °C and 1013 mb. NOx mass units are NOx as NO2 μg m-3. Particulate matter concentrations are reported at ambient temperature and pressure.
The European Air Quality Directive and Fourth Daughter Directive set out legal limits for different pollutants as Limit Values, Target Values or Long Term Objectives to protect human health. With the UK’s exit from the EU the UK’s Air Quality Strategy (AQS) is no longer tied to that of the EU, however the current objectives are at least as stringent as the EC limit values.
Legal limits for different pollutants in the UK are set out in the Air Quality Standards Regulations 2010. The Limit Values and Target Values for England and Scotland and UK (Except Scotland) and England and Wales and Scotland and Northern Ireland are summarised in the table below. Local authorities don’t typically measure ozone, benzene, B[a]P or metals that are captured within Defra’s national networks. All pollutants measured have been included in this data summary for completeness, irrespective of their significance for local authority policy interests.
The below two tabs contain summary statistics for the reported collection of measurement sites. “Cumulative Statistics” contains all data from the beginning of the year up until and including the reported period, whereas “Monthly Statistics” contains data for only the reported period.
The below tables can be sorted by clicking on the column headers. The ‘search’ box at the top-right can also be used to filter the table.
The following tables present pollutant statistics for the period from the start of the year to the end of the reported month. The Low, Moderate and High indicate the number of days for a particular pollutant when the concentrations are in the corresponding AQI bands from the beginning of the year until the end of the reported month.
The following tables present monthly pollutant statistics for the reported month. For public data, these statistics will match those made available on Air Quality England, and/or UK-air. The Low, Moderate and High indicates the number of days for a particular pollutant when the concentrations are in the corresponding AQI bands during the reported month.
The plots below illustrate the distribution of AQ index values for each site by pollutant. They show the number of days that site concentrations are in each index. More information on the AQ Index is available from GOV.UK.
“Cumulative AQI” visualises all air quality indices from the beginning of the year up until and including the reported period, whereas “Period AQI” visualises the air quality index for only the reported period (December 2025).
Zooming in on specific periods of the plot can be done by dragging a box over the section of the main plot frame. To return to the default (all data) zoom level, double click the plot. Hovering over each bar will show a tooltip displaying the specific number of days at each daily air quality index. Clicking on the legend will toggle the different indices on and off.
The map below shows polar plots for each pollutant at each monitoring station superimposed on the region to help understand the relative strength and direction of sources. The distance from the plot origin shows the wind speed. Different pollutants can be shown using the “layer control” menu at the top-right of the map.
These plots are useful to help identify primary pollutants which are emitted directly into the atmosphere, especially when multiple plots are used in conjunction to “triangulate” a common source. For pollutants with a secondary component (i.e. formed through chemical reactions in the atmosphere, e.g. NO2, PM2.5 and O3) the directional signature seen in the measurements may not be as strong.
The below map can be zoomed in and out of by using your mouse scroll wheel, or using the widget at the top-left. Polar plots for different pollutants can be swapped between using the menu at the top-right.
The plots below are box and whisker plots to show the distribution in concentrations for each monitoring station. The boxes demarcate the lower quartile, median and upper quartile. The whiskers extend to the maximum and minimum values within median ± 1.5 times interquartile range (IQR). Values outside the median ± 1.5 times IQR are generally considered as outliers.
Hovering over each boxplot will show tooltips of the specific summary statistics.
The plots below show the time series of concentrations in 2025 so far. Each pollutant is presented on a different tab and all sites are shown on each plot for comparison. By default the period from 01 December 2025 to 31 December 2025 is shown, but the rest of the time series can be revealled by interacting with the plots.
Holding the mouse over the lines will highlight specific values and time stamp for that record for each station. Clicking on the legend will toggle on and off specific traces, and double clicking on it will isolate single traces. These plots can be zoomed in a similar way to other interactive plots, although the range-slider at the bottom of the plot can also be used to examine a specific time period of interest.
These plots show concentrations over different time intervals such as diurnal, day of week and, if relevant, month of year. The topmost frame shows the concentrations as they vary by hour of the day and day of the week. The hour of the day variation is summarised on its own in the lower left pane and the variation by day of the week is shown in the lower right pane. These plots often help explain variations in concentration according to the emissions activity associated with them. For example, NOx concentrations at roadside sites tend to exhibit peaks according to morning and evening traffic rush hours and tend to decline over weekends when there is generally lower traffic volumes.
Like other interactive figures, the time variation plot can be hovered over to read specific values. Legend items can be clicked to toggle on and off different traces. This may be useful if there are a lot of sites, or if different sites are on drastically different scales.
The plots below show daily variation in concentrations by pollutant (one on each tab) across the period of the report, as laid out in a calendar style. This allows intuitive viewing of day to day headline trends in the wider context of the period. The background colours shown for each day relate to the concentration. An arrow visualises the daily average wind, with the direction indicating wind direction and the size wind speed.
The actual values of pollutant concentrations, wind speed, and wind direction can all be read by hovering over the tiles of the plots.
The back trajectory plots show data from the HYSPLIT model run in analysis mode. This shows the air mass back trajectories for the period covered by the report. Two different kinds of plot are shown. The first statistically groups the trajectories into similar clusters, which is most useful to get an overview of air mass origins during the report period. Plots showing the trajectories associated with the top ten most polluted days provide information on the trajectory direction associated with the top ten measured concentrations for each pollutant during the report period (December 2025).
Air mass back trajectories over these spatial scales do not vary locally so the receptor location used in this report has been selected from a range of national receptor locations maintained by Ricardo. The receptor point is used here is Glazebury which is 11.2 km away from the centre of all monitoring stations analysed in this report.
Hover over each back trajectory to see the proportion of the reporting period that each cluster represents.
The average daily concentration for each pollutant across all the sites is calculated, with the top ten most polluted days identified and linked to its back trajectory data in the plot below.
Click on each point in the back trajectory to see more information relating to it.
| Name | David Madle; Jo Solan |
| Address | Ricardo, Gemini Building, Harwell, Didcot, OX11 0QR, United Kingdom |
| Telephone | 01235 753692 |
| david.madle@ricardo.com; jo.solan@ricardo.com |