New research shows that the unreliability of fossil fuel supply chains and consequential price surges can lead to deterioration in air quality as people change their consumption behaviour.

The conflict in Ukraine has had well-documented impacts on the immediate environment. Fires from destroyed buildings and industry, movement of military vehicles and extensive wildfires have added to air pollution. The war also disrupted energy supplies and increased fossil gas prices in Europe, spreading the impacts far beyond the conflict zone.

Dr Giancarlo Ciarelli, of the University of Helsinki, said the research team asked: “Did householders respond by replacing part of their gas consumption with wood burning and, if so, what were consequences for air quality and public health?”

Ciarelli and the team focused on northern Italy, where wood combustion is a major source of particulate pollution. “Even a small shift in heating behaviour could have measurable environmental impacts,” he said.

Researchers looked for changes in the amount of benzo[a]pyrene, a chemical found in wood smoke, in the air.

Prof Federico Bianchi, also of the University of Helsinki, said: “In areas of northern Italy, residential wood combustion is one of the main sources of benzo[a]pyrene. It is typically attached to tiny particles suspended in the air that we can breathe into our lungs. It is highly toxic and carcinogenic.”

Fossil gas consumption in northern Italy decreased by about 18% in December 2022 as people responded to requests to use less energy after Russia’s invasion of Ukraine. Warmer weather helped by reducing heating demand, but this explained only about a third of the decreased gas use.

Changes in benzo[a]pyrene varied from place to place, the researchers found. Not everywhere experienced an increase but concentrations increased by more than 10% at 17 of the 63 measurement locations across the Po Valley, with significant increases at five locations, pointing to more local wood burning.

Ciarelli said: “What happened in 2022 was a warning. During periods of high energy prices, households may consider switching to fuels that are cheaper or more readily available, including wood. While this can help reduce heating costs, it can also increase air pollution if it occurs on a large scale.”

The researchers also carried out a computer simulation to predict what could have happened if wood burning had increased by 30% across the region. For December 2022, an extra 2 million people would have been exposed to particle pollution above the annual legal limit. Deaths attributable to air pollution would have increased from 280 to 314 for the month.

This effect has been seen before. In winter 2012-13, at the height of the Greek financial crisis, residents of Thessaloniki turned to wood heating as the cost of heating oil soared. The increased air pollution led to an estimated 200 extra deaths along with new cases of bronchitis and heart and breathing problems, costing the Greek economy more than €230m.

Bianchi concluded: “Even though we focused our analysis on Italy, similar air quality impacts could emerge elsewhere during periods of energy stress. The key takeaway is not the specific Italian context but the broader vulnerability of air quality to energy market volatility.”