San Luis Obispo has a very safe feel to it. There are blue-light poles around campus that will connect directly to an emergency dispatcher. With that being said, the biggest crime on campus is bike-seat theft. Every once in a while, something bigger happens, but the severity and frequence of these incidents are both nowhere near what larger cities experience. The nice thing is that there is a PolyAlert text/email system that is well-utilized by the University to make sure that all students can get any pertinent information regarding campus safety. Cal Poly does also have its own police force with fully-sworn officers. University Police Department (or UPD) serves as the first responders for any incidents on campus (e.g., medical emergencies, alcohol violations, etc.). UPD also sponsors an escort van to provide rides home from the University Union or library. Some areas on campus (and also the areas immediately off campus) can have poor lighting, which can lead to a sense of uneasiness. It's important to practice safe behaviors so as to minimize risk, especially when going out at night.
As far as health goes, there is a full-service health center that is available for students to use. Pretty much every nonemergency medical need can be met here. There's also a 24-hour nurse line for when the health center is closed.