From B92 I learned that it was a bad day for pollution in Pancevo,a town just outside Belgrade:
“Air pollutants in Pančevo reached high levels of concentration yesterday, but have receded since midnight.
Yesterday at 11:30, Pančevo municipal president Srđan Miković turned on the sirens signalling a chemical hazard, after the concentration of benzene in the air reached 117.5 micrograms/m .
Why do people continue to live there? Pancevo was an industrial park created east of Belgrade for heavy industry. Over the years people started moving to the area to be closer to their factories and a town of 100,000 has sprung up. Now its residents regularly protest about the pollution problem and they live with the threat of mass poisoning and chemical sirens!