The eastern Croatian town of Slavonski Brod was exposed to high amounts of benzene on Sunday morning, when the local air quality monitoring station recorded 16.4 micrograms of this substance per cubic metre of air, while the upper allowable limit is 5 micrograms per cubic metre.
Later in the morning the concentration of this cancerogenous air pollutant was lowered but it was still above the acceptable levels.
The town authorities recalled in their statement on the town's website that another air pollutant, hydrogen sulfide, had been in excessive amounts a day before.
Air pollution in this Croatian town on the left bank of the River Sava is caused by emissions of gasses in the oil refinery in Bosanski Brod, the Bosnian town across the river.
The local authorities called on residents not to leave homes when the measuring station shows excessive amounts of air pollutants.
They also urge the Croatian environment protection ministry and other state institutions to try solve this problem with Bosnia as soon as possible.