need a site explaining new vs old refrigerants?

Question

i need to find a site that explains the difference between old vs new types of refrigerants, and why they changed.

Answer 1

Freon was the refrigerant of choice prior to the 1990's when Freon and Halogenated gases were outlawed due to environmental concerns. The site below is a guide to the various alternative chemical compounds used today.

Answer 2

they changed from R-12 to R-134a in the early 90's (around 1991 or so) because R-134a does not harm the environment as much as R-12 does, and yes, R-134 a does not work as efficiently as R-12 but it helps the environment by not enlarging the hole in the o-zone layer