Zagreb was the third city in the world with the highest air pollution on Monday, according to the Swiss IQAir website, which publishes global data on air quality.

Lahore, Pakistan was the city with the most polluted air, with the air quality index of 264, followed by Delhi, India with the air quality index of 198, and Zagreb was third with the air quality index of 183.

Traffic, industry, the heating season and fog contribute to air pollution.

“Yes, traffic and industry affect the increase of pollution. But the heating season does too. And the weather conditions also contribute,” Zvjezdana Bencetic, a professor at the Zagreb Faculty of Science, said recently when asked to comment on the fact that Zagreb is often ranked among cities with high air pollution.

As in recent days, the worst pollutant in Zagreb were the PM2.5 particles, which today were 11.7 times above the World Health Organization guideline value.

These particles are generated by the burning of fossil fuels such as vehicular emissions or the use of wood or coal for heating.

Slavonski Brod is another Croatian city with air pollution problems.