This would be where we give essential gases like ozone to the outside of Mars. This would be in the atmosphere, of course. Maybe if we were to observe that oxygen has mass, and, Mars has gravity too, then we could easily pump Mars with an ozone layer.
[1] This could be done by bonding nitrogen to hydrogen, of course. This would be apparent because the two major gases of our solar system are these two gases. Then, we could bond them by letting loose a electrical storm on Mars, or,
[2] We could observe that usual way ozone forms is to shine u.v. lights at the atmosphere. This could also be done to create ozone.