A report from a New Zealand parliamentary committee recommends decriminalization of marijuana for adults. The report offers the sort of candid advice you never hear from our government, which is currently conducting a campaign aimed at convincing the public that marijuana is "more harmful than we all thought." The New Zealand committee has this to say about the respiratory hazards of pot smoking, for instance:
Smoking cannabis carries a similar risk of lung cancer and other cancers as tobacco. However it must also be recognized that, with the exception of extremely heavy users, cannabis users tend to smoke less than tobacco users….We recognize that the use of high THC cannabis may have the effect of decreasing harm by reducing the amount of smoke inhaled by the users….The current practice in New Zealand of users holding smoke in to maximise the effect of the THC has been shown to increase risk of lung damage without increasing the high. We encourage the provision of harm reduction information that makes this clear.
By contrast, the U.S. Office of National Drug Control Policy warns that "one joint contains as much cancer-causing tar as four cigarettes," without noting that the typical pot smoker does not consume even as much as a joint a day, while the typical tobacco smoker goes through around 20 cigarettes a day. And according to our government, higher THC content makes marijuana more dangerous. In other words, better pot is worse.