In several other cities and towns -- in Budapest, Debrecen, Dorog, Miskolc, Nyíregyháza, Sopron, Székesfehérvár, Szolnok and Szombathely, among others -- concentrations of particulate matter (PM10) in the air exceed what is considered to be a safe level, OKI said.

The effects of the air pollution level in these cities can be dangerous for vulnerable groups such as children, people suffering from a chronic illness and the elderly, OKI added.