For  most of my life, my cats were allowed outdoors. That was the norm in  the era and area I lived in. My epiphany came when I realized that my  Shannon's FIV was the result of fight with an infected neighbor cat when  he was younger. I hope you will learn from mine and others'  experiences, and never have to face the cold, hard truth by losing a  beloved cat.
If you feel that cats really need that fresh air and  sunshin, there are safe alternatives for the outdoor experience. My  Jenny is perfectly happy just sitting on my lap on our deck. She never  wanders out of my site, and our deck is secure from intrusion by other  animals.