Lung cancer occurs slightly more frequently in the right lung than in the left lung (about 53% versus 47% of the time). the most logical explanation for this is that

I believe that the most logical  explanation for this is that the right primary bronchus is wider than the left one (and the right lung is larger than the left lung), therefore the right lung receives slightly more carcinogenic cigarette smoke with each puff. In lung cancer. the cancer cells usually arise from the epithelium lining of large bronchus. 

2hydrogen and 1 covalent