One good thing about all your children having asthma is that they can't be in the military. I don't have to worry about my three asthmatic sons.
Life is dangerous no matter where you are. I have read that life in the military may actually be less dangerous then in the 'real' world. College is a very dangerous place. We live in famiy housing while I was a graduate school at two major universities. Kids die drinking, using drugs, and doing stupid stuff. I was worried when my oldest went off to live in a dorm and am glad my current college age son decided to live at home while going to college. The campus he goes to is crime-free (the last crime was over 10 years ago - no car breakins or even bookbags being taken) but there is still the worry of car accidents.
My oldest son was in a very bad car accident during Christmas break in Florida with his college friends. They were waiting in a stopped car line for a concert in Florida. He got tired and decided to take a nap in the trunk on top of their camping gear (he is an Eagle Scout). A drunk, drugged driver in a big truck started running over cars and drove over my son (sleeping in the trunk). He was airlifted to Ft. Lauderdale with brain trauma. Somehow his head sunk into the sleeping bags and stuff and he has had a full recovery (scars from a lot of stitches are pretty scarry looking).
The point is that we can't be sure our kids are safe anywhere and we have to hope for the best. It has been a couple years since my son's head was run over by a truck and I still get worried when the two oldest travel far by car. One of my worries is that I can't get to them if they are far away. But I've learned not to make it get me having anxiety attacks. I use deep breathing and daily meditation to break the stress/anxiety cycle. There is a lot of good info on stress reduction on the web.