Belgrade's air quality is
just awful. Mind you, it isn't just this one guy who contributes to the lack of clean air, but multiply him by lots more... You can have a look at
this page.
Of course the bigger polluters are vehicles. Like many laws, Serbia has 'enforced'
a prevous law on older vehicles like the one belonging to Yours Truly. These laws are conveniently ignored if palms are greased...