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Bonfire night celebrations contaminate our air with extremely high amounts of soot, scientists have found.
Researchers from the University of Leeds tested the air quality during the Guy Fawkes Night events in the city and found that soot in the atmosphere was around 100 times its normal level.
Soot, or black coal, is produced by incomplete combustion. The black carbon particles are so small that they can penetrate deep into the lungs and cause irritation. Long-term exposure can cause damaging effects on the heart and lungs and contributes to millions of deaths worldwide each year.
“Our measurements have shown that the high concentrations of soot and other pollutants in the atmosphere should be a warning to those with pre-existing health conditions …”
The team took hourly air quality samples on the university campus during bonfire night celebrations in 2016 and 2017.
On the balcony of the School of Earth and Environment, 15 m above ground level and more than 0.5 km from any bonfires or fireworks displays, equipment was installed to provide a representative view of air quality throughout the city.
Researchers did not expect to see such high levels of pollutant matter in the atmosphere.
Lead author Michael Adams, Research Fellow in Atmospheric Ice Nucleation and PhD student at School of Earth and Environment, said, “Our measurements have shown that the high concentrations of soot and other pollutants in the atmosphere should be a warning to those who have health conditions, as the aerosol particles are in the range of sizes that they can enter the lungs and cause problems. “
An air filter before and after the experiment, showing the amount of pollutants collected during bonfire night 2017. Credit: Michael Adams
Research Supervisor Benjamin Murray, Professor of Atmospheric Sciences at the School of Earth and Environment in Leeds, said: ‘Bonfire night is a huge pollution event across the UK. People with existing health problems, such as heart and lung disease, are at greater risk.
“I was surprised to see such persistently high black carbon levels for so long over several nights. The poor air quality during the bonfire night was surprising. “
Weather conditions can affect how long the particles stay in the air. The team found that pollution was swept away from the city within hours during the 2016 experiment, due to a strong north wind.
But in 2017 the air was relatively calm, and the pollution continued until the next day.
While providing information on the levels of black carbon emitted during bonfire night, the team’s findings also contributed to the understanding of several sources of nuclear ice particles, a key research area in climate science.
Ice occurs naturally in clouds, but tiny particles of desert dust, soil dust, fungi and bacteria carried high up in the air can cause supercooled water droplets in clouds to freeze. High concentrations of these nuclear ice particles can cause clouds to freeze, potentially impacting Earth’s climate.
“Clouds containing super-cooled water and ice are of prime importance for the climate.”
Black carbon is known to cause climate warming, but its impact on clouds was unclear.
The researchers found that the black coal produced on bonfire night did not act like nuclear ice particles.
Professor Murray said: “Clouds containing super-cooled water and ice are of prime importance for the climate. Vast cloud systems consisting of a mixture of ice and water over the world’s oceans dampen the warming effect of CO2.
“But the buffer capacity depends on the amount of ice they contain, which in turn depends on the concentration and distribution of the nuclear ice particles.
“We found that the aerosol particles emitted during the celebration are not as effective in nuclear ice as the aerosol particles already present in the atmosphere.
“We conclude that aerosol particles emitted from combustion processes such as those observed on bonfire night are not a major source of nuclear ice particles.”
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