I didn't think that the filler could affect my asthma, but after reading this article https://pacoandpepper.shop/blog/can-cat-litter-cause-allergies-in-humans , everything fell into place. It explains how dust and odors from regular fillers can worsen the condition even for those who have mild breathing problems. Especially if the apartment has poor ventilation. The information is structured, without fluff, and even gives advice on how to choose a safer product. A very useful article - I didn't even expect it.