The burning issue of bonfire night pollution

Bonfire Night celebrations contaminate our air with extremely high amounts of soot, scientists have found.

Researchers at the University of Leeds were monitoring air quality to determine if soot created by fires and fireworks, known as black carbon, could help create ice in clouds.

They found that the soot in the atmosphere around the Guy Fawkes Night events was about 100 times its normal level.

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.

The team conducted experiments on November 5, 2016 in the early hours of the next day and in 2017 from November 4 and 5, filtering the air with samples taken every hour. On the balcony of the School of Earth and Environment building, 15 m above ground level and more than 0.5 km from any single bonfire or fireworks display, equipment was installed to provide a representative view of the air quality throughout. the city.

The filters were washed and the liquid subjected to different temperatures to replicate atmospheric conditions.

The researchers found that the black coal produced on the bonfire night did not act like nuclear ice particles, but they did not expect to see such high levels of pollutant matter in the atmosphere.

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.

The article, A major combustion aerosol event had negligible impact on atmospheric ice nuclear particle population, was published in Journal of Geophysical Research: Atmospheres today.

Lead author Michael Adams, Research Fellow in Atmospheric Ice Nucleation, said, “Our measurements have shown that while the pollution emitted during bonfire night should have no effect on whether clouds are liquid or frozen, the high concentrations of soot and other pollutants in the atmosphere should be a warning to those with pre-existing health conditions, as the aerosol particles are in the range of sizes that they can enter the lungs and cause problems. “

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 diseases cardiac and pulmonary are more at risk. “

“The impact on clouds and climate was unclear. The good news is that bonfire night does not affect ice formation in super-cooled cloud droplets. But we know that BC causes climate warming in other ways.

“I was surprised to see such persistently high black carbon levels for so long over multiple nights. It was surprising how poor the air quality was during the bonfire night.”

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 insight into the levels of black carbon emitted during bonfire night, the team’s findings also contributed to understanding the different sources of nuclear ice particles, a key research area in climate science.

Professor Murray said: ‘Clouds containing super-cooled water and ice are of primary importance for the climate. Vast cloud systems made up of a mixture of ice and water on the world’s oceans mitigate the warming effect of CO₂.

“But the buffering capacity depends on the amount of ice contained, which in turn depends on the concentration and distribution of the nuclear particles in the ice.

“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.”