In Toronto, it takes two weeks before there is a noticeable change in colour on the filter.
After five nights in Albania and one in Kosovo, the air filter has turned dark grey, nearly black.
Every house here has firewood stacked against the outside walls, under porches, or in sheds. Every car garage has firewood stacked against its back wall. Every large business has an auxiliary diesel generator. I did not know it made such a difference. The smell of woodsmoke in the air was comforting, not an indicator of the danger to people's lungs.
Nearly every street has a carwash consisting of a multi-bayed tent and people with pressure washers. They have plenty of customers. I thought people were just super-fastidious about their cars. Now I know they're blasting the grime off the windows so they can see.
Now I know why I can't seem to keep my glasses clean.
Now I know why I am coughing and have a sore throat.
The sky still seems clear and blue, oddly.