Often some of the nicest and most affordable (and now the newer) places in Silicon Valley, including Campbell, are located near freeways, railroad tracks and commercial zones.
There are U.S. Dept. of Health studies that show whether there are cancer and/or birth defect clusters in different areas. That may help you.
Thanks for your posting.
To be frank, anytime anyone posts a question that pertains to health, safety or environment, we have to refer you back to your own health care professional. Conversations about how any environment or environmental factors will affect your life is an issue outside of the scope of real estate, and it is the reason that doctors and nurses are licensed to practice in California--only a physician will know enough about your current state of health to tell you and your wife how environmental factors will affect your health and the health of current or future children.
So make a phone call to your doctor and get his/her advice on how these factors will affect you. The Real Estate professionals here--unless also simultaneously licensed as a doctor--have insufficient information to properly provide you with guidance in this matter.
Every person has their own tolerance when it comes to noise and pollution. I used to live near a Freeway and I didn't notice exhaust smell from the cars and Highway 85 was lower than the neighborhood. We did get more dust and there was noise.
If you suffer from asthma or other lung issues, you may want to discuss this with your doctor.