Kent and Medway Bonfire Night 2023
Impact of fireworks and bonfires on PM concentrations
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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, blocking sight of the displays.
This report closely examines particulate matter (PM) concentrations at the nineteen Kent and Medway monitoring stations to assess how the country was impacted by Bonfire Night activities.
1.2 Data
In 2023, the KentAir air quality network contained 22 sites. Figure 1 shows a map of these sites. Links to each of their respective KentAir site information pages are included in each marker popup. The sites which measure particulates, are highlighted in green.
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 |
|---|---|---|---|---|---|
| Low | 1 | 0 – 33 |
0 – 67 |
0 – 11 |
0 – 16 |
| 2 | 34 – 66 |
68 – 134 |
12 – 23 |
17 – 33 | |
| 3 | 67 – 100 |
135 – 200 |
24 – 35 |
34 – 50 | |
| Moderate | 4 | 101 – 120 |
201 – 267 |
36 – 41 |
51 – 58 |
| 5 | 121 – 140 |
268 – 334 |
42 – 47 |
59 – 66 | |
| 6 | 141 – 160 |
335 – 400 |
48 – 53 |
67 – 75 | |
| High | 7 | 161 – 187 |
401 – 467 |
54 – 58 |
76 – 83 |
| 8 | 188 – 213 |
468 – 534 |
59 – 64 |
84 – 91 | |
| 9 | 214 – 240 |
535 – 600 |
65 – 70 |
92 – 100 | |
| Very High | 10 | 241+ |
601+ |
71+ |
101+ |
| 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 in Kent and Medway
Figure 2 shows the number of sites at each daily air quality index across November 2023 in Kent and Medway. The DAQI for PM remains in the “low” bound for the entirety of November, which is associated with no adverse public health advice for even the most vulnerable in the population (Table 2).
3 Measured Concentrations
3.1 Air Quality Statistics
Table 3 provides a monthly summary for particulate matter measured throughout Kent and Medway. Sites are ordered by the mean value.
| site | min | median | mean | P95 | P99 | max |
|---|---|---|---|---|---|---|
| PM10 | ||||||
| Swale St Pauls Street | 3.86 | 22.22 | 26.94 | 62.13 | 98.42 | 114.98 |
| Tunbridge Wells A26 Roadside | −5.10 | 16.02 | 17.56 | 35.56 | 47.40 | 62.43 |
| Maidstone Upper Stone Street | −1.67 | 15.00 | 17.46 | 37.50 | 50.55 | 74.16 |
| Swale Newington 4 | 0.97 | 13.53 | 15.62 | 31.88 | 41.66 | 53.14 |
| Stanford-le-Hope Roadside | 0.00 | 12.56 | 14.16 | 30.92 | 40.58 | 120.78 |
| Chatham Roadside | −2.90 | 12.56 | 13.21 | 27.05 | 34.65 | 49.28 |
| London Bexley | 1.40 | 10.40 | 11.48 | 22.50 | 29.86 | 36.80 |
| Rochester Stoke | 1.30 | 10.00 | 11.18 | 23.93 | 26.81 | 61.15 |
| Thurrock | 1.10 | 9.90 | 11.03 | 20.80 | 29.28 | 50.50 |
| Canterbury | 0.72 | 9.07 | 10.57 | 23.03 | 32.80 | 38.92 |
| PM2.5 | ||||||
| Maidstone Upper Stone Street | −2.00 | 11.00 | 12.70 | 29.00 | 38.83 | 170.00 |
| Swale Newington 4 | −1.00 | 10.00 | 10.82 | 19.00 | 27.06 | 39.00 |
| Swale St Pauls Street | 0.00 | 8.00 | 9.58 | 21.00 | 30.00 | 49.00 |
| Chatham Roadside | −3.00 | 8.00 | 8.92 | 20.00 | 24.86 | 39.00 |
| Stanford-le-Hope Roadside | 0.00 | 7.00 | 8.86 | 20.00 | 30.49 | 100.00 |
| Rochester Stoke | 0.61 | 5.98 | 7.28 | 16.80 | 22.07 | 53.87 |
| London Bexley | 0.47 | 5.75 | 7.13 | 16.80 | 24.23 | 29.34 |
| Canterbury | 0.66 | 5.47 | 6.87 | 16.41 | 27.05 | 30.07 |
| Thurrock | 0.38 | 5.47 | 6.54 | 15.20 | 20.50 | 37.83 |
| Tunbridge Wells A26 Roadside | −15.00 | 4.00 | 4.59 | 15.15 | 29.49 | 77.00 |
3.2 Time Plots
Figure 3 shows distributions of the two particulate matter sixes over the November period, including a median value, the 10th, 25th, 75th and 90th percentiles, and the total range of the data. There are no notable peaks, neither around Bonfire Night nor across the rest of November.
3.3 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 4 shows the equivalent to Figure 2 for the last 5 years of Bonfire Nights and clearly illustrates that, in most years, the DAQI does extend into the “moderate” band at least. Considering the period from the 1st to the 10th of November, the following sites have recorded Daily Air Quality Indices greater than 3 for at least one particulate size since 2019; Swale St Pauls Street (zw8, 12 times), Swale Ospringe Roadside 2 (zw3, 5 times), Maidstone Upper Stone Street (mad, 4 times), Dartford Town Centre Roadside (zr2, 3 times), Dartford - St Clements 2 (zr4, 2 times), London Bexley (bex, 2 times), Thurrock (thur, 2 times), Chatham Roadside (zc1, 1 time), Gravesham Industrial Background (zg3, 1 time), Rochester Stoke (roch, 1 time), Stanford-le-Hope Roadside (hope, 1 time), Thanet Ramsgate Roadside (zh4, 1 time), and Tonbridge and Malling, Borough Green Roadside (zt8, 1 time).
Figure 5 shows the median and interquartile range (25th - 75th percentile) of particulate emissions around Bonfire Night from 2019 through to 2023. Comparing these trends reveals that the overall concentrations of PM are much lower in 2023 when compared to previous years, particularly 2021 and 2022. The trend in 2022 is particularly protracted, lasting from the evening of the 4th of November through to the 9th before returning to “baseline” levels.
4 Summary
On Bonfire Night 2023, the daily air quality index (DAQI) across Kent and Medway remained within the “low” (1-3) band (Figure 2), which is associated with no adverse public health advice for even the most vulnerable in the population (Table 2). Time plots show no noticeable peaks in either PM10 or PM2.5 (Figure 3). Low measured particulate concentrations can potentially 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 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.
Past Bonfire Nights have led to increased measured particulate emissions in Kent and Medway, particularly during 2020 when the DAQI reached the “high” (7-9) and “very high” (10) levels multiple times (Figure 4). Measured concentrations during 2020 and 2021 are noticeably higher than in 2023, with 2020’s particulate peak being particularly protracted (Figure 5).
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.