How will smoking two cigarettes a day effect CO2 laser resurfacing ?

Although you only smoke two a day, smoking decreases the blood flow to the face which will slow down healing.  Healing from a full face CO2 is difficult enough that you certainly don't want to do anything that would affect the process.  If you really only smoke two a day shouldn't be too hard to quit for a month or two beforehand  

Smoking will negatively effect any surgical procedure, especially those that impact skin. Smoking reduces the concentration of oxygen in regions that are healing from laser treatments and slows the healing of surgical wounds. You must also avoid second hand smoke as this has the ability to further slow the healing process. Furthermore you should consider the benefits of quitting smoking as it will reduce the need for further skin treatments. The combination of sun exposure and smoking has proven to require more intensive treatments with prolonged exposure to either.