A health warning was issued on Wednesday in Zagreb after the level of air pollution exceeded safe levels, with authorities recommending residents to stay indoors as much as possible.

The warning was triggered by the concentration of PM10 particles in the air which was about double from the maximum safe level of 50 microgrammes per cubic metre (μg/m3) as measured by one of the air quality monitoring stations in the city’s southern neighourhood of Dugave.

According to Vecernji List daily, at 3 am on the night between Wednesday and Thursday, the level rose to nearly 271 μg/m3, only to drop on Thursday to the still unsafe level of 106 μg/m3.

The latest spike in air paticles saw Zagreb join the club of major cities in the region which regularly struggle with unsafe and sometimes hazardous air pollution levels as temperatures drop, the problem compounded by a combination of outdated coal-fuelled heating systems and the popularity of diesel-powered vehicles.

Over the past few weeks the poor air quality in Sarajevo and Belgrade put those cities among the most polluted in the world, with authorities repeatedly warning residents to stay indoors, or adopting other measures like temporarily banning some types of road traffic and encouraging locals to wear face masks or use public transport.

On Thursday, Croatia’s Environment Minister, Tomislav Coric, was asked to comment on the spike in pollution.

“Am I concerned? Yes, I am, but this is something that keeps happening year after year. We have a combination of unfavourable weather, the fact that we are in the middle of the heating season, there are the biomass heating systems, transport… all these result in the air quality being less than ideal… We simply have periods like these every year when the concentration of PM10 particles is above safe levels,” Coric told reporters.

When asked what could he do as environment minister about this, Coric responded by calling on the public to think about long-term solutions and how they can help fix the problem.

“There is nothing I can do about this, as minister, in the short term… How can we all do something about this in the long term? We could switch to electric vehicles, and also to heating systems which use non-polluting fuels,” Coric said, and added that only 30 percent of the electric energy Croatians use comes from renewable sources.

“That’s way below the European average,” Coric said.