What changed my mind about the whole thing was my kids. I may not feel the particulates in the air, but my kids do, especially my eldest daughter (who has early childhood asthma, in remission) - winter comes, particulates go up, they start coughing uncontrollably all day. Particulates go down, suddenly they're healthy again (+/- running nose).
I have limited sympathy for conspiracy theories, and very little for those burning trash in their homes, but I do understand where the smog-skepticism comes from. I still remember when Krakowski Alarm Smogowy became a thing, winter 2012; back then, this felt like a huge fad pushed by young activists on the Internet.