Air Quality on Bonfire Night 2023
Automatic Urban and Rural Network Report
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1 Introduction
1.1 Purpose
Every year on the 5th of November, Britons celebrate Guy Fawkes Night, or “Bonfire Night”, by lighting bonfires and setting off fireworks. While these activities are entertaining ways to spend a winter evening, they are known to emit both gaseous pollutants (NOx) and particulate matter (PM10, PM2.5). The composition of these particulates includes the toxic metals used to give fireworks their colour, the inhalation of which have harmful impacts on human health.
In 2023, Bonfire Night fell on a Sunday. The UK had only recently experienced the effects of Storm Ciarán, which brought yellow weather mornings to much of the South of England. Many regions across the UK experienced wet and stormy weather, leading to firework displays being postponed or cancelled. In other instances, atmospheric conditions prohibited smoke from dissipating, with the display at Birmingham’s Edgbaston Stadium in particular making national news (Flash and Reide 2023).
Flash, Oprah, and Kevin Reide. 2023. “Refund Calls as Smoke ‘Blocks’ Edgbaston Fireworks Display.” BBC News. BBC. https://www.bbc.co.uk/news/uk-england-birmingham-67326273.
This report examines the impacts of the 2023 Bonfire Night on air quality in the UK through analysis of the Automatic Urban and Rural Monitoring network (AURN). Both the daily air quality index (DAQI) and hourly measured concentrations are considered in this analysis.
Photo by Elisha Terada on Unsplash.
1.2 Data
This report considers data from 172 sites in the AURN. Of these sites, 71 are Urban Traffic, 68 are Urban Background, 21 are Rural Background, and 13 are other site types (e.g., suburban, industrial, etc.).
Figure 2 shows a map of all the AURN sites in 2023 which measure at least one of nitrogen dioxide (NO2), ozone (O3), or particulate matter (PM10 / PM2.5). Links to each of their respective UK-AIR site information pages are included in each marker popup. Markers are coloured by site type; green for Rural Background, blue for Urban Background, red for Urban Traffic, and gray for any other site types.
2 Daily Air Quality Index (DAQI)
2.1 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, low (1) to very high (10), and divided into four bands to provide detail about air pollution levels in a simple way, similar to the sun index or pollen index (“What Is the Daily Air Quality Index?” 2023).
“What Is the Daily Air Quality Index?” 2023. Defra. https://uk-air.defra.gov.uk/air-pollution/daqi.
| Band | DAQI | O3 | NO2 | PM2.5 | PM10 | SO2 |
|---|---|---|---|---|---|---|
| Low | 1 | 0 – 33 |
0 – 67 |
0 – 11 |
0 – 16 |
0 – 88 |
| 2 | 34 – 66 |
68 – 134 |
12 – 23 |
17 – 33 |
89 – 177 | |
| 3 | 67 – 100 |
135 – 200 |
24 – 35 |
34 – 50 |
178 – 266 | |
| Moderate | 4 | 101 – 120 |
201 – 267 |
36 – 41 |
51 – 58 |
267 – 354 |
| 5 | 121 – 140 |
268 – 334 |
42 – 47 |
59 – 66 |
355 – 443 | |
| 6 | 141 – 160 |
335 – 400 |
48 – 53 |
67 – 75 |
444 – 532 | |
| High | 7 | 161 – 187 |
401 – 467 |
54 – 58 |
76 – 83 |
533 – 710 |
| 8 | 188 – 213 |
468 – 534 |
59 – 64 |
84 – 91 |
711 – 887 | |
| 9 | 214 – 240 |
535 – 600 |
65 – 70 |
92 – 100 |
888 – 1064 | |
| Very High | 10 | 241+ |
601+ |
71+ |
101+ |
1065+ |
| AP Band | Accompanying Health Messages | |
|---|---|---|
| at-risk individuals | 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. |
2.2 DAQI Statistics
During the period of 2023-10-30 to 2023-11-06, each site in the AURN reached different maximum Daily Air Quality Indices. Table 3 summarises the number of sites which peaked at each index for each DAQI pollutant. It is clear that, despite the fact that bonfires and fireworks are known sources of NOx and PM, the daily air quality index does not increase over Bonfire Night; the DAQI remains in the “low” (1-3) band throughout.
| DAQI | NO2 | O3 | PM10 | PM2.5 | SO2 |
|---|---|---|---|---|---|
| 1 | 120 | — | 64 | 72 | 27 |
| 2 | 34 | 38 | 47 | 27 | 1 |
| 3 | — | 51 | 1 | 3 | — |
| 4 | — | — | — | — | — |
| 5 | — | — | — | — | — |
| 6 | — | — | — | — | — |
| 7 | — | — | — | — | — |
| 8 | — | — | — | — | — |
| 9 | — | — | — | — | — |
| 10 | — | — | — | — | — |
This lack of response by the DAQI may reflect that it is too coarse a tool to examine Bonfire Night this year. Measured concentrations will be explored more in Section 3 to determine the likely cause of this. It should be noted, however, that the DAQI has responded to Bonfire Night historically; Figure 3 shows the DAQI reaching the “high” (6-9) and even “very high” (10) bands for PM in 2018 and 2020.
3 Measured Conditions
3.1 Time Plots
Figure 4 through Figure 8 show some key distributions of the five pollutants included in the daily air quality index. There are clear peaks on the evenings of the 4th and 5th for both sizes of particulate matter. The other pollutants do not show interesting features around Bonfire Night.
3.2 Historical Comparisons
The reason behind the low daily air quality index this Bonfire Night can best be illustrated by comparing it to previous Bonfire Nights which did see an elevated DAQI. Figure 9 shows the median and interquartile range (25th - 75th percentile) of particulate emissions around Bonfire Night in 2023, 2020 and 2018.
Comparing these trends shows some clear differences:
The overall concentrations of PM are lower in 2023. For example, the median line peaks during the Bonfire Night spike at just under 16 μg m3 in 2023 and just over 62 μg m3 in 2018.
The Bonfire Night peaks in previous years have been more protracted. Most clearly, in 2018 the peak in the evening of the 4th seems to merge with that of the 5th, creating a singular extended period of elevated PM emissions.
This Bonfire Night can also be compared to the previous year’s, which was analysed in Davison (2022). 2022’s Bonfire Night experienced similarly wet conditions, with the peak in particulates being similarly short and sharp. However, a small number of sites did reach the “moderate” (4-6) DAQI band, unlike in 2023.
Davison, Jack. 2022. “Automatic Urban and Rural Network Report: Bonfire Night 2022.” Ricardo. https://www.ricardo.com/media/1wabi14m/aurn-bonfire-night-2022.html.
4 Summary
On Bonfire Night 2023, the daily air quality index (DAQI) across the AURN remained within the “low” (1-3) band, which is associated with no adverse public health advice for even the most vulnerable in the population (Table 2). Despite this, time plots of measured particulate concentrations do indicate peaks in particulate matter on the evening of Bonfire Night (Figure 4, Figure 5), albeit smaller in size and duration compared to previous years (Figure 9). This can likely be attributed to wet weather and relatively low winds.
These observations should not be used to dismiss the air quality impacts of fireworks on public health. The particulate concentrations measured by air quality monitoring networks like the AURN are influenced by the distance between the fixed measurement sites and the locations of bonfire events. The DAQI as a statistic may be useful for pollutant events which last throughout a given day, but may underestimate the health impacts of a particularly short-lived but significant increases in pollutants. Despite the DAQI remaining “low”, Bonfire Night attendees may have experienced immediate, short-term effects of breathing air contaminated with particulates.
Historic Bonfire Nights did appear to cause more protracted periods of elevated particulates across the UK (Figure 3, Figure 9). Future Bonfire Nights should continue to be analysed as varying meteorology, evolving legislation, and even the day of the week on which Bonfire Night falls will continue to influence particulate emissions as time goes on.