That Old Forest Fire Smell

The sky suddenly became smoggy this weekend and smelled like a forest fire. But there aren't any forests nearby and the land is so crowded with people that I can't imagine a big countryside fire. Any fire would kill so many people that I would surely have heard about the catastrophe. Walking outside was akin to smoking several cigarettes. But what was the source of the pollution?

Today, a Chinese friend told me the smog and smell were due to farmers burning rice husks both for energy and waste removal. I'll have to look further into this to see if there is validity to his claim.