I live in Rancho Cucamonga myself, and yes the air quality can be bad on certain days. The weather on the news usually tells when it is too bad to go outside and do aerobic activities. I have friends with asthma and they do just fine. If they want to work out they just go inside to a gym. I ride my horse in the mountains on during the summer I can see a haze, but the rest of the year is fine. We are up higher than say Norco etc when tend to sit in the bad air.
If I can help you find a home, feel free to call me or visit my website to search the MLS at www.inlandempirehouse.com
Joan Patterson, B.A., G.R.I., A.S.P., Realtor, License #01431647
Keller Williams Realty
8250 White Oak Avenue, Ste 102
Rancho Cucamonga, CA 91730