A lot of the info in the Discover article cited above #8 comes from the Children’s Health Study, conducted at USC in the mid 90s. A followup to that study (results published in 2015) confirm that air quality has continued to improve, and that the lung function of children was improved over the previous study. The bottom line is that air quality in the LA basin is significantly better now. There is still air pollution in the area, though. Since asthma may be triggered by a variety of means, the OP can’t really know how his/her child’s asthma will react to the air at USC or the Claremonts unless they visit, as indicated in #10 above.