After the US decision to quit the Paris climate agreement, the European Union set its sights on becoming a global leader in curbing fossil fuel emissions.
But some of its eastern neighbours that seek to join the bloc have severe levels of air pollution.
Many people are switching back to coal as a cheaper alternative to imported gas from Russia.
In Bosnia-Herzegovina, the high level of air pollution has become a cause for alarm for the locals.
Produced by Camelia Sadeghzadeh; filmed by Marek Polaszewski