Concerns About Letting Cats Outside
I own five cats and all go outside although my oldest cat is indoors most of the time unless the weather is nice. Other than my old cat the others were all born wild; ferals whom we have caught and tamed.
I live rurally, I have no neighbors, no rules requiring cats to be inside, and I do have other buildings and places they can go for shelter.
When I lived in the city I had my yard fenced so that the cats could go outside but could not leave the yard. When one cat did figure out how to get out of the yard I built a special cat enclosure next to the house.
Having said that, it is much safer for cats to be indoors only.
When cats are out they are at risk. In some areas there are laws that require cats to be indoors or on their owner's property (which is not easy). Even if legally allowed to roam cats face many dangers, cars, dogs, and people who hate cats and try to poison them or torture them. In some places cats are stolen and used as bait animals for fighting dogs. There are always risks of fights with other cats and concerns related to diseases (even if the cat is vaccinated).
As such, to answer the question of if it is safe to let cats outside, the answer is very simply "no". There are always risks.
If you are going to let your cat outside it should be spayed or neutered first, it should be vaccinated, and wear a collar with identification. It should be tattooed or microchipped in case the collar is lost. It should have food, water, and shelter, when outside, and should not be outside if you are not home. It should be inside in cold weather, and ideally kept in your yard when outside.
Image Credit » Photo by author's husband