Is Azerbaijan polluted?

It depends on the location. During the times that Azerbaijan was part of the Soviet Union (USSR) there were many chemical factories in Azerbaijan. The areas around some of these factories are polluted. but these days the government is cleaning up pretty fast.
However, overall Azerbaijan has very clean air, and the outdoors is very beautiful. Particularly since the country is very mountainous, many of the mountains are clean and great for hiking and visit.
Hiking along the Russian border is very nice.