These are bad problems on Earth, but would be good on Mars. Also, PFCs do not hurt living things. Also, PFCs do not destroy ozone, which is an important form of oxygen. It would be good to build up an ozone layer in the air of Mars. There's only a very tiny amount of ozone on Mars now, and it needs more, says Margarita.
Sunlight hits a planet's surface, which then radiates warming energy into the atmosphere.
Greenhouse gases prevent that energy from escaping into space. Sunlight hits a planet's surface mostly as visible and ultra-violet light. The planet soaks in this solar energy, and then sends warm infra-red energy back up to space. Greenhouse gases in the air act like a blanket to trap the heat and stop it from escaping. On Mars, we will want to trap as much heat as we can, so adding the right mix of PFCs could do the job well.