Before that, I would sneeze first thing in the morning, then sneeze by rows of 10 times in Spring, 30 times a day, nose bleeding from too much sneezing. I would also have an irritated bronchitis which gave me slight asthma (but enough to make me abandon intensive sports). Now I still have risk of asthma, but at least when I want relief, I close the windows, switch on the Coway, and breathe fresh air. I live in a city center of average density.
However, CO2 fills up quickly. I wish I could find some portable air exchanger: Taking air from outside, exchanging temperature, and filtering. I’ve lodged a bit for a house which has that, I’m hoping I’m selected.