The Cyprus Institute: Wood Burning Can Cause Intense Air Pollution

Air-pollution can become more severe during wintertime due to residential wood burning, finds a new study recently published in collaboration with researchers from the Climate and Atmosphere Research Center (CARE-C) of The Cyprus Institute.

This tends to be more prevalent in urban centres, where the topography does not allow for air movement, causing air-pollution to be trapped in specific areas for longer periods. An example of such location is the city of Ioannina in Greece, where the study was conducted and where air pollution during wintertime was shown to reach levels as high as those observed in large, global megacities, such as Paris or Beijing.

The study, conducted by CyI researchers in collaboration with the National Observatory of Athens and the University of Ioannina, Greece, has highlighted the occurrence of intense air pollution events during winter in Ioannina, primarily from wood burning. The city of Ioannina is surrounded by mountains prohibiting atmosphere to be well mixed. During winter, a common method for home heating is wood burning particularly as the city is not connected to the national gas grid. Wood burning is also commonly used for social and cultural occasions, for instance at Christmas and New Year celebration gatherings.

Wood burning is an extremely important source of numerous atmospheric pollutants such as carbon dioxides, carbon monoxide, nitrogen oxides, particulate matter and volatile organic compounds. Researchers focused on understanding the origin, and levels of those volatile organic molecules by deploying a state-of-the-art Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS), capable of detecting several toxic organic molecules in the atmosphere by their precise mass, with a very high temporal resolution of one second. The study found that the levels of those volatile organic species during winter nights in Ioannina, were comparable to those experienced in large global megacities, such as Paris or Beijing.

The researchers also used advanced computational statistical algorithms (Positive Matrix Factorization) to separate groups of molecules being emitted together. That information allowed the identification of the pollution sources contributing to the deterioration of air quality. Specifically, 55% of the organic mixture was attributed to residential wood burning, while 28% was found to be emitted by fossil fuel combustion (traffic and heating). The remaining 17% was the product of daytime photochemical production. The study also utilises the source apportioned volatile organic data to provide updated emission factors for residential wood burning, as current emission inventories have not updated those numbers for over a decade.

The study highlights the important implications of heavy reliance on wood burning as a primary heat source for poorly ventilated urban centres around the world, and underscores the need for taking measures to tackle this issue as a critical step towards bettering air quality and human health.