House dust too. I had terrible asthma as a teenager from living in a dusty home that wasn't cleaned. Once I moved out it was much better and I didn't need to use a daily preventative.

Since 2020 I've been wearing a mask when out and noticed my asthma is better than its ever been. For the first time in my life I'm having to get new puffers when they go out of date, not when they run out of doses.