| Authors | Louisa Kramer |
| Compilation date | 04 January 2023 |
| Customer | Greater Manchester Combined Authority |
| Approved by | Andrew Madle |
| Copyright | Ricardo Energy & Environment |
| EULA | http://ee.ricardo.com/cms/eula/ |
| Contract reference | ED10689 | Report reference | December 2022 |
This is a monthly summary report for Greater Manchester Combined Authority for the period 2022 December.
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 interactive map and table below . Full site information can be obtained using the URL hyperlink in the popup for each monitoring station on the map.
Data contained within this report is managed by Ricardo and stored in a dedicated, secure database. The data within this report 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 1.
Gaseous pollutant mass units are at 20 °C and 1013mb. 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.
The UK AQS limits 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 following tables present pollutant statistics for the period from the start of the year to the reported month. The Low, Moderate and High indicates 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 plots below illustrate the distribution of AQ index values for each site by pollutant. It shows the number of days that site concentrations are in each index. More information on the AQ Index is available from UK-Air 2.
Figure 1: Distribution of AQI for NO2.
Figure 2: Distribution of AQI for PM10.
Figure 3: Distribution of AQI for PM2.5.
Figure 4: Distribution of AQI for O3.
Figure 5: Distribution of AQI for SO2.
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 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.