Authors Jack Davison
Compilation date 09 November 2022
Customer Scottish Government
Approved by David Hector
Copyright Ricardo Energy & Environment
EULA http://ee.ricardo.com/cms/eula/

1 Introduction

1.1 Purpose

This is the Scottish Air Quality Network (SAQN) air quality episode report for bonfire night 2022. Commonly, the UK experiences particulate matter episodes at this time of year, which are effected by weather conditions, the arrival of air masses, and local bonfire and firework displays. This report summarises PM concentrations (both PM2.5 and PM10) over the bonfire night period.

1.2 Using this Document

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.

2 Monitoring Stations

A summary of site information is presented in the interactive map and table below. Select the relevant tab to learn more about the sites used in this analysis.

Map

Click on each marker to learn more about the specific site. The “base map” can be swapped between a vector illustration and satellite image using the menu to the top-right of the map.

Map 1: A map of SAQN sites measuring particulate matter.

Table

The below table can be reordered by clicking on the blue headers. The search box in the top right can be used to search the whole table, or the search boxes below each header can filter specific columns.

3 Hourly Particulates

Figure 1 and Figure 2 show hourly concentrations of PM across early November. Each grey line represents a different SAQN site, with the average trend of all sites overlaid in dark blue. The dates surrounding bonfire night (November 5th and 6th) are highlighted using a light blue band.

The average hourly concentrations of PM2.5 and PM10 over November 5th and 6th were 8.67 and 13 μg m-3, compared to 4.62 and 8.96 μg m-3 for the rest of the visualised period. The maximum hourly concentrations of PM2.5 and PM10 over November 5th and 6th were 216 and 249 μg m-3, compared to 49.9 and 83.7 μg m-3 for the rest of the visualised period.

PM2.5

Figure  1: A timeseries showing hourly PM<sub>2.5</sub> concentrations for all SAQN sites. The weekend of bonfire night (Nov 05 & 06) is highlighted in blue.

Figure 1: A timeseries showing hourly PM2.5 concentrations for all SAQN sites. The weekend of bonfire night (Nov 05 & 06) is highlighted in blue.

PM10

Figure  2: A timeseries showing hourly PM<sub>10</sub> concentrations for all SAQN sites. The weekend of bonfire night (Nov 05 & 06) is highlighted in blue.

Figure 2: A timeseries showing hourly PM10 concentrations for all SAQN sites. The weekend of bonfire night (Nov 05 & 06) is highlighted in blue.

4 Daily Air Quality Index (DAQI)

4.1 What is the DAQI?

The Daily Air Quality Index (DAQI) tells you about levels of air pollution and provides recommended actions and health advice. The index is numbered 1-10 and divided into four bands, low (1) to very high (10), to provide detail about air pollution levels in a simple way, similar to the sun index or pollen index.

Click on the tabs below to learn more about the air quality index. Further information on air pollution banding can be found on UK AIR.

Boundaries

Table 2: Defra DAQI boundaries for particulate matter. Boundaries are based on daily mean concentrations.
Band DAQI PM2.5 PM10
Low 1 0-11 0-16
2 12-23 17-33
3 24-35 34-50
Moderate 4 36-41 51-58
5 42-47 59-66
6 48-53 67-75
High 7 54-58 76-83
8 59-64 84-91
9 65-70 92-100
Very High 10 71 or more 101 or more

Health Advice

Table 3: Suggested actions and health advice at different DAQI boundaries.
AP Band Accompanying health messages for at-risk individuals Accompanying health messages for the general population
Low (1-3) Enjoy your usual outdoor activities. Enjoy your usual outdoor activities.
Moderate (4-6) Adults and children with lung problems, and adults with heart problems, who experience symptoms, should consider reducing strenuous physical activity, particularly outdoors. Enjoy your usual outdoor activities.
High (7-9) Adults and children with lung problems, and adults with heart problems, should reduce strenuous physical exertion, particularly outdoors, and particularly if they experience symptoms. People with asthma may find they need to use their reliever inhaler more often. Older people should also reduce physical exertion. Anyone experiencing discomfort such as sore eyes, cough or sore throat should consider reducing activity, particularly outdoors.
Very High (10) Adults and children with lung problems, adults with heart problems, and older people, should avoid strenuous physical activity. People with asthma may find they need to use their reliever inhaler more often. Reduce physical exertion, particularly outdoors, especially if you experience symptoms such as cough or sore throat.

4.2 Bonfire Night

Figure 3 shows the number of sites at different air quality indices. Each dot represents a unique combination of date and DAQI boundary, with its size being the number of sites at that index, n. The black dots show the mean DAQI on that day. On bonfire night, the maximum DAQI was 3 for PM10 and 4 for PM2.5, compared to 3 and 4 on the other visualised nights, respectively. On bonfire night, the average DAQI banding was Low (1) for PM10 and Low (1) for PM2.5.

Figure  3: The DAQI for PM in early November.

Figure 3: The DAQI for PM in early November.

Map 2 and Map 3 both illustrate the geographic distribution of the changing DAQI over early November. Readers can change dates using the radial menu (top-right) and click on each marker to learn more about the DAQI that day.

The five highest daily PM2.5 concentrations were measured at N Lanarkshire Kirkshaws, East Dunbartonshire Kirkintilloch, Falkirk Main St Bainsford, and Falkirk Haggs, and the five highest daily PM10 concentrations were measured at N Lanarkshire Kirkshaws, East Dunbartonshire Kirkintilloch, N Lanarkshire Coatbridge Whifflet A725, and Falkirk Main St Bainsford.

PM2.5

Map 2: The DAQI for PM2.5 in early November. Each dot represents a unique combination of date and DAQI boundary, with its size being the number of sites at that index.

PM10

Map 3: The DAQI for PM10 in early November. Each dot represents a unique combination of date and DAQI boundary, with its size being the number of sites at that index.

5 Historical Comparisons

Figure 4 and Figure 5 are interactive timeseries graphs comparing mean PM concentrations in 2022 with 5 previous bonfire nights. Readers can highlight over the traces and read the mean hourly concentrations in the popup to the top-right of the plot. The bonfire night period (05 and 06 Nov) is highlighted using black dashed vertical lines.

It should be noted that, in general, there were no organised bonfire night events during 2020 and 2021 due to the COVID-19 pandemic restrictions.

PM2.5

Figure 5: A timeseries showing PM2.5 concentrations on historical bonfire nights.

PM10

Figure 5: A timeseries showing PM2.5 concentrations on historical bonfire nights.

6 Air Mass Trajectories

Fireworks and bonfires is the obvious source to which elevated PM levels can be attributed during this period. However, it is important to consider the significant affect meteorology and long-range transportation of particulate matter can have on local pollution levels.

Map 4 shows data from the HYSPLIT forecast model (NOAA HYSPLIT). The plot illustrates where the air masses that affected Scotland have travelled from over the 96-hour period up to 05 and 06 November. Readers can switch between the two days using the drop-down menu at the top-right of the map, where they can also toggle on site markers. Clicking on the trajectory nodes will provide more information on the air masses, and clicking on site markers will identify the receptors associated with each trajectory path.

Air mass trajectories are an important factor on air pollution levels as they provide a useful indicator of the likelihood of transboundary air pollutants (pollutants such as PM2.5 and PM10 that can travel large distances in the air masses) affecting Scotland. Air coming from the west is likely to be mainly clean and good pollution dispersion conditions (wind and precipitation), whilst air masses from the south and east can bring more settled conditions and also pick up background emissions from mainland Europe causing background pollution levels to become elevated.

Map 4 shows that the air masses during the 5th and 6th were from the North Atlantic and brought relatively good pollution dispersion conditions. This in turn resulted in, though elevated, relative low pollution levels when compared to other non-covid years.

Map 4: Air mass origins for the UK and Western Europe on 05/11 and 06/11.



For further information, please contact:

Name Jack Davison
Address Ricardo Energy & Environment, Gemini Building, Harwell, Didcot, OX11 0QR, United Kingdom
Telephone N/A
Email