There are studies which state marijuana does not have the same effect on the lungs as tobacco. However, marijuana smoke contains many of the same particles found in tobacco smoke. Marijuana has approximately three times the amount of tar found in tobacco smoke and 50 percent more carcinogens. Also, hand rolled marijuana joints are not filtered and the smoke is inhaled deeply which results in greater exposure. So why, according to studies, does marijuana not have the same effect? Well, individuals typically smoke far less marijuana than tobacco which leads to tobacco having a greater effect on the lungs. Most individuals included in the study smoke maybe 1-3 joints a month, compared to packs of cigarettes a day. So long story short, marijuana smoke can have the same effect on the lungs as tobacco in those who smoke marijuana frequently. Please do not take this as an excuse to smoke marijuana! There are other medical consequences linked to marijuana smoke, such as psychological disorders, and there are even studies linking marijuana to decreased testosterone production.