"The haze is coming back again," said Lars-Otto Reiersen, head of the Arctic Monitoring and Assessment Programme (AMAP), which handed a report on acids and haze to officials from eight Arctic Council nations in Salekhard, Russia.
The pollution was originally believed to have been caused by Russian industry to the South, but such industry has declined in recent years meaning other causes are now being considered.
Reiersen told Reuters one theory was that: "The haze might be linked to climate change -- with increased temperatures there are more forest fires. That means more soot in the atmosphere." Warmer temperatures in recent decades mean the forest fire season in northern forests starts earlier and ends later.
Other potential sources of the pollution are the rapidly growing economies of South and East Asia, and particularly China. It's a sobering thought that industrial growth is causing the degradation of some of the world's most pristine environments.