Around 30 million people in Europe live in mountain valleys. A large part of this population is more affected by air pollution than previously assumed. This is the conclusion of a Slovenian-German research team from measurements in the Northern Dinaric Alps. Due to temperature inversions in winter, pollutants are trapped in the valleys to such an extent that soot and fine dust could reach alarming levels even in small villages, as they otherwise occur mainly in the centers of congested metropolises, write researchers from the Universities of Ljubljana, Molise and Nova Gorica and the Leibniz Institute for Tropospheric Research (TROPOS) in Atmospheric Chemistry and Physics (ACP). With mobile measurements using an instrumented backpack by TROPOS, it had become possible to examine the pollutant distribution in more detail.