A study shows that early morning smoking may increase the risk of developing lung cancer.

A research team at Pennsylvania State University said that smokers who light up cigarettes within five minutes of waking had higher levels of the lung cancer-related carcinogen than those who smoke a half hour after waking.

The finding was made by analyzing the smoking habits and urine samples of two-thousand smokers.

Researchers attributed the higher levels of the carcinogen to the possibility that people who smoke sooner after waking inhale more deeply and more thoroughly.