'Light' Cigarettes aren’t safer:

"Light," "mild" or "low-tar" cigarettes are sometimes billed as healthier for people who do not quit. But these cigarettes do nothing for a smoker's health. People who smoke light cigarettes are still at risk for serious health problems, including lung cancer. Nicotine-craving smokers of light cigarettes actually may inhale more deeply, take larger or more rapid puffs, or smoke extra cigarettes to get enough nicotine.

There is no evidence that switching to light cigarettes helps smokers quit.