Since last weekend, towns in Bosnia-Herzegovina topped global rankings for air pollution with the capital Sarajevo issuing an air quality warning, and experts attributing the rise to transportation and the burning of solid fuel in homes.

Despite Sarajevo authorities' pledge to make the city carbon-free by 2035, a cost of living crisis has forced people to choose more affordable solid fuels for home heating and to drive older cars with higher emissions of pollutants, experts say.

The use of gas in the capital has fallen 18% so far this year from the last due to higher prices, the data show.

Most people would rather use more ecological fuels but they use what they can afford, said Enis Krecinic, an environmental expert at the Hydro-Meteorological Institute of Bosnia-Herzegovina's autonomous Bosniak-Croat federation.

"The social aspect influences what people will use to heat their homes, what cars they will drive, what fuel they will choose," Krecinic told Reuters.

Bosnia-Herzegovina has among the highest levels of fine particulate matter (PM2.5) pollution in Europe, to which the burning of solid fuel for home heating and the transport sector contributes about 50% and 20% respectively, according to the World Bank.

The country, and especially Sarajevo, which is nested in a valley among mountains, has suffered from poor air quality for decades.

Despite the closure of its mining and heavy industry, Bosnia-Herzegovina remains one of the most polluted countries in Europe.

Krecinic said Sarajevo was at risk during winter months due to temperature variations but that other cities, such as Zenica located in the central Bosnian "coal valley," have had more days of excessive pollution during the calendar year.

Physicians say that exposure to fine particulate matter poses serious health risks, leading to respiratory infections, cancer, cardiovascular diseases and premature deaths.

"Absolutely the air pollution ... in Sarajevo brings about changes and health difficulties, such as pneumonia, for both young and old," said Teufik Hadziosmanovic, a lung specialist.