OBSERVED AIR POLLUTION SPECIFICS OF THE VALLEY-BASED TOWNS

Observed air pollution specifics of the valley-based towns. There are 21 valley-based towns in the 100 most populated ones of Hungary. This topographical feature may be advantageous due to mezoscale circulation between the valley or basin, containing these settlements and the surrounding hills. On the other hand, the hills form a mechanical obstacle that may limit the vertical mixing of pollution. Final result of these counteracting features are analysed by comparing air pollution characteristics of these settlements with those in two control groups, also counting 21-21 non-valley towns of the country. Each group represents slightly over 1 million inhabitants. Nitrogen dioxide (NO2), sulphur-dioxide (SO2) concentrations and the total particulate matter below 10 μm (PM10) are considered. Annual mean, maxima and median values are analysed in 2007. For NO2 the valley-based towns are slightly cleaner, whereas for SO2 the situation is the opposite. The PM10 values do not indicate much difference between valley based and fully plain settlements. For explanation of these results, selected settlement and communal statistics are also compared. The paper is terminated by a sub-collection of similar valley-based towns in Central Europe.