Pilot project identifies wood smoke as local source of air pollution
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Introduction
Members of the Hovese environmental council went out in the first months of 2024 with fine dust sensors to map local sources of air pollution. Much more than traffic, wood smoke in particular stood out as a local source. The pilot project was supervised by environmental council member Jordy Vercauteren. He works at the Air Quality department of the Flemish Environment Agency (VMM). He and seven other members of the environmental council together covered approximately 500 kilometers with mobile sensors. These small devices measure fine dust in the air and automatically send the data to the internet.
With the sensors, the 'citizen scientists' cycled, walked or ran through the streets of Hove to measure PM 2.5 particulate matter. These are floating particles smaller than 2.5 micrometers (= 1/400th of a millimeter) that are not visible to the naked eye, but can penetrate deep into our lungs. They are responsible for numerous diseases, including cardiovascular diseases and lung cancer. It is estimated that in Flanders we lose an average of 15 months of healthy life years due to particulate matter and that approximately 3,500 premature deaths can be attributed to this form of air pollution each year.
The concentration of fine dust can vary greatly over time due to the weather. Wind, rain and the supply of polluted continental air or clean sea air affect the air quality. This causes the concentrations to fluctuate throughout Flanders. That is why the researchers always subtracted the regional background values, this is the pollution that comes from outside Hove. In this way they were able to calculate the local contribution to air pollution. By looking at how often peaks occurred in certain places, a better picture emerged of the local sources of fine dust.
Sample
Although the participants were on the road for many hours, measurements were of course not always and everywhere. Some streets were covered much more than others, for example because they were centrally located or because they were on commuter routes. For example, there were more than 80 measurements in the Kapelstraat, while there were remote corners of the municipality where only one or two measurements were taken. The measurements should therefore mainly be seen as a sample that gives an idea of the variation in local air pollution. Despite the sample nature, there were still a few places with relatively many peaks in air pollution. This was the case, for example, for the neighbourhood of the Donderbrug and the Lintsesteenweg near the chapel. At these places, the dust peaks were always caused by wood smoke. It is certainly not impossible that there are more of these 'hotspots' in Hove in places where there were now relatively few passages.
95% due to wood smoke
That wood smoke was by far the most common local source was clear from the diaries that a number of participants kept. In these, they indicated whether the source of a local peak of particulate matter was known. They were able to identify more than a hundred peaks and it turned out that approximately 95 percent were due to wood smoke. Surprisingly enough, traffic turned out to be a less important source of particulate matter than most expected. This shows that vehicles have become considerably less polluting in recent years in terms of particulate matter. For wood stoves, this 'cleaning' is hardly there and the emission still amounts to several grams per hour. VMM calculated a few years ago that an average stove emits as much particulate matter in four hours as an average car that drives more than 2,000 kilometers. New stoves are somewhat cleaner on paper, but still emit enormous amounts of particulate matter. In addition, many people still burn older stoves. Burning wet or treated wood or smothering stoves also causes extra pollution and nuisance.
The results of the project not only highlight the impact of wood smoke on local air quality, but also serve as a call to action. The environmental council hopes that citizens will become more aware of the impact of wood burning on their environment and on their own health. It is also not permitted to burn insufficiently dry or treated wood. Temporarily not burning during unfavourable weather conditions, such as foggy or windless weather, can already limit the nuisance, but simply burning less or not at all remains the best solution for local air quality.