My parents were always really strict about the air quality in our home when us kids were growing up.
Eventually I learned this was because my younger brother had severe allergies.
They would always be changing out the air filters with those expensive high MERV rated air filters that were designed for people with allergies. Eventually it became my chore to change all the air filters in the house. There was an air purifier in every single room and I would have to change all those air filters. There was a time when I thought it was overkill until I saw my brother suffer from some really bad allergy attacks. He never was able to go outside much and he had to be homeschooled. He became rather depressed because of his condition, but I started spending my time with him. I even introduced my brother to a lot of my friends and they would hang out with him all the time. My parents appreciated the fact that I was looking out for my brother like that. He was a lot more happy because of it and this made me happy. We never really fought at all, we actually got along very well. I would say for a lot of siblings this is not the case. He always tells me these days how much he appreciates me looking out for him and that he probably wouldn’t have any friends if it weren’t for me. I always shrug it off like there’s nothing to it, but I really appreciate it when he tells me things like that.