Currently, the sulphur dioxide content in the air in the southern city of Stara Zagora is below the alarm threshold, but above the normal content, Stara Zagora district governor Yordan Nikolov stated.

He says the problem is the windless weather. He adds Wednesday`s sulphur dioxide content is between 210 and 400 micrograms per a cubic meter of air. He explains the normal sulphur dioxide content is 210 micrograms per a cubic meter of air and the alarm threshold is 400 micrograms per a cubic meter of air.