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Dison, nestled in the province of Wallonia, Belgium, occupies a geographically significant position within the broader Ardennes region. Its coordinates (50.6098, 5.8543) place it within a gently undulating landscape, characterized by rolling hills and valleys carved by ancient glacial activity. The town sits at an elevation of approximately 230 meters above sea level, contributing to localized microclimates and influencing air circulation patterns. Dison is situated near the Hoëgne valley, a tributary of the River Venn, providing a degree of moisture and influencing local humidity levels. The surrounding landscape is a mosaic of agricultural fields – primarily pastureland and arable crops – interspersed with patches of deciduous forest, typical of the Ardennes foothills. This agricultural activity, while vital to the regional economy, can contribute to seasonal particulate matter emissions. The urban–rural gradient around Dison is relatively gradual; the town blends seamlessly into the surrounding countryside, with smaller villages and hamlets dotting the landscape. Historically, the area has seen limited heavy industry, though proximity to industrial belts in Liège (approximately 40km to the east) means that pollutants can be transported via prevailing winds. The terrain, with its valleys and hills, can trap pollutants, particularly during periods of low wind speed and stable atmospheric conditions. The Ardennes' geology, dominated by sandstone and shale, also influences the dispersion of airborne particles. The valley setting, while aesthetically pleasing, can exacerbate localized air quality issues due to reduced ventilation.

Dison’s air quality experiences a distinct seasonal cycle heavily influenced by meteorological conditions. Spring (March-May) often brings a gradual improvement as temperatures rise and winds increase, dispersing accumulated winter pollutants. However, agricultural activities, such as fertilizer application and tilling, can contribute to ammonia emissions and particulate matter, particularly during drier periods. Summer (June-August) generally sees the best air quality, with consistent winds and higher temperatures promoting good ventilation. However, heatwaves can lead to stagnant air and ozone formation, potentially impacting sensitive individuals. Autumn (September-November) marks a shift, with cooler temperatures and decreasing sunlight leading to more frequent temperature inversions, trapping pollutants close to the ground. Agricultural burning, though regulated, can also contribute to particulate matter. Winter (December-February) typically presents the most challenging air quality conditions. Cold temperatures, frequent fog, and stable atmospheric conditions create ideal circumstances for pollutant accumulation. Residential heating, particularly the use of older, less efficient systems, significantly increases particulate matter and nitrogen dioxide levels. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should limit prolonged outdoor exposure during these periods, especially on days with low wind and dense fog. The valley location can exacerbate these issues, as the surrounding hills impede air movement. Increased vigilance and awareness of local air quality reports are crucial during the colder months to protect public health. Periods of rain can help to cleanse the air, but the benefits are often temporary.