I was a teen in Harrisburg PA in the early 00s and I remember one day in August maybe 2001/2002 when there was a shocking level of wildfire smoke that made the sky brown/visibility terrible. It was much worse than what we currently have. IIRC it was due to some big wildfires in Quebec. But that stood out to me because I had never seen it before. I've been in the DC region 10 years now and I do remember some gray/hazy days due to smoke, but this one seems unique.