The colours, bangs and excitement of fireworks thrill many of us but what looks pretty comes with a pollution penalty, harming air and rivers.
A network of three UK university research observatories have revealed the complexity of the unique air pollution that fireworks create.
Guy Fawkes fireworks and bonfires are rarely confined to the marking of the gunpowder plot on 5 November, as often people celebrate early. This year peaks in particle pollution were seen on the preceding Saturday evening, especially across the West Midlands and London, perhaps due to the combination of Diwali and Guy Fawkes fireworks events.
In most places the worst air pollution was measured on the night of 5 November, reaching level seven on the government’s 10-point scale across Yorkshire. Notable peaks in particle pollution were also seen across Merseyside, as well as north-east England, Worthing, Norwich, Bristol and Cardiff.
The three university observatories work together to understand air pollution sources in Manchester, Birmingham and London.
We all remember school science lessons when we placed metal samples in a Bunsen flame to reveal distinct colours. The same process makes firework colours too; blue from copper, red from strontium, and bright green from barium compounds. Other metals, including potassium, aluminium and bismuth, are used in firework propellants and to create the crackles and bangs. Many of these metals are carefully controlled for the chimneys of industrial plants, including waste incinerators, but fill our air during firework celebrations.
Dr Michael Flynn of the University of Manchester explained the measurements taken in that city on 5 November: “The dominant metal by far was potassium, with aluminium, barium, copper, bismuth, zinc, strontium and lead. We also got strong signals for chlorine and sulphur that are used in propellants.”
Potassium also dominated the metal pollution measured in Birmingham along with zinc, copper, barium, bismuth and strontium. Here the peak in firework pollution was followed by smoke from bonfires.
Dr Anja Tremper, from Imperial College London, said: “After measuring firework chemicals in the early evening we saw a buildup in arsenic and lead particles. These lingered in London’s air until the following morning. These are often associated with burning of lead-painted scrap wood and wood that had been treated with arsenic-based preservatives.”
What goes up does come down. A small number of studies have found firework chemicals in lakes and rivers. The most recent study focused on New York’s East River after the Independence Day fireworks in 2023. In the Austrian alps, snow has been contaminated by firework metals, especially barium, after new year firework displays.
Efforts to reduce air pollution from fireworks have included using compressed air to launch fireworks, rather than chemical propellants, the use of less harmful chemicals and using drones instead to create coloured light displays.
