The best replacement for o3 is o2.

The best alternatives to o3 are rated as following:
★★★★★  o2
★★★★★  o2 optimization
★★★  cointreau
★★★  exo3
★★  ofast
★★  o2 gcc
★  h2o2
★  ozone

Your alternative for o3 is not listed? Suggest!
Speaking about o3, one probably shouldn't forget about alkene.

Other search terms related to o3 and their ratings are:
★★★★★ alkene
★★ h2o2
You have in mind a companion for o3 and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of o3 in all years. Click on graph for more.
o3
o2
o2 optimization