Salgótarján, nestled in the undulating hills of the Mátra range in northern Hungary, occupies a geographically significant position within the Nógrád county. Located at approximately 48.0853° N, 19.7867° E, the city sits at an elevation of around 330 meters (1,083 feet) above sea level, contributing to its often-cool climate and influencing local air circulation patterns. The surrounding landscape is dominated by the Mátra Mountains, a heavily forested region that acts as a partial barrier to prevailing winds, sometimes trapping pollutants within the valley. To the south and west, the terrain gradually descends into agricultural plains, a mix of arable land and pastures, which can contribute to particulate matter through agricultural practices, particularly during harvest seasons. The city’s urban fabric is a blend of historical architecture and post-industrial development, reflecting its past as a coal mining and industrial hub. While the coal mines have largely ceased operation, legacy industrial sites and ongoing manufacturing activities still contribute to localized pollution sources. The urban–rural gradient is relatively sharp; the city transitions quickly into the forested hills and agricultural areas, impacting air quality as pollutants disperse or are diluted by cleaner air from the surrounding natural environment. The lack of significant nearby bodies of water further limits natural air purification processes, making the city’s topography a key factor in its air quality profile. The regional position, far from major industrial belts, means that Salgótarján’s air quality is primarily influenced by local sources and meteorological conditions.

Salgótarján’s air quality experiences a distinct seasonal cycle heavily influenced by its continental climate. Winter months (November to March) typically see the poorest air quality, characterized by frequent temperature inversions. Cold, stable air becomes trapped near the ground, preventing the vertical dispersion of pollutants emitted from residential heating (primarily wood and coal) and remaining industrial activities. Fog, common during these months, further exacerbates the problem by trapping particulate matter close to the ground. Spring (April to May) brings a gradual improvement as temperatures rise, and wind speeds increase, facilitating pollutant dispersal. However, agricultural burning, a traditional practice in the surrounding areas, can occasionally lead to spikes in particulate matter. Summer (June to August) generally offers the best air quality, with warm temperatures and frequent convective mixing promoting efficient pollutant dispersion. However, heatwaves can lead to stagnant air conditions and ozone formation. Autumn (September to October) presents a transitional period. While wind speeds remain relatively high, cooler temperatures and increased humidity can lead to the formation of ground-level fog, particularly in the mornings, temporarily reducing visibility and trapping pollutants. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during winter months, limiting outdoor activity on days with persistent fog or temperature inversions. Spring agricultural burning requires awareness and potential avoidance of outdoor exercise during those periods. Overall, the shoulder seasons (spring and autumn) require vigilance, as conditions can shift rapidly, impacting air quality.