A new study led by chemists at the Massachusetts Institute of Technology found that wildfire smoke particles, which can remain in the stratosphere for a year, can cause chemical reactions that deplete the protective ozone layer. The findings occurred during the megafire in Australia in December 2019 to January 2020.

The study, published in the journal Nature, analyzed the atmospheric chemical composition over the Southern Hemisphere at mid-latitudes, including regions over Australia and New Zealand and parts of Africa and South America.

The researchers noted that the wildfire smoke particles created chemical reactions in the stratosphere. They estimated that these reactions caused the megafire to contribute to a 3% to 5% depletion in the ozone in the area studied.

The study model also estimated that the wildfires impacted the ozone layer over Antarctica, widening the hole over the Antarctic by 2.5 million square kilometers by the end of 2020, or widening by 10% of its area in comparison to 2019.

“The Australian fires of 2020 were really a wake-up call for the science community,” Susan Solomon, study author and professor of environmental studies at M.I.T., said in a statement. “The effect of wildfires was not previously accounted for in [projections of] ozone recovery. And I think that effect may depend on whether fires become more frequent and intense as the planet warms.”

The wildfires analyzed in the study were the worst ever recorded in Australia, burning tens of millions of acres and emitting 1 million tons of smoke into the atmosphere, as M.I.T. reported.

Solomon and her colleagues previously identified a chemical reaction between chlorine-containing compounds, typically chlorofluorocarbons (CFCs), and fire aerosols that produced chlorine monoxide, which is known to deplete ozone. So the researchers came back to analyze molecules in the stratosphere following the megafire in Australia.

While the team found that wildfire smoke reactions with hydrochloric acid (HCl) in the stratosphere could deplete ozone, they suspect wildfire smoke could react to other chlorine-containing compounds in the atmosphere, especially when considering how long the smoke particles can remain.

Read the full article about wildfire smoke by Paige Bennett at EcoWatch.