However, smoking half or one cannabis cigarette per day leaves a fraction of the tars deposited by a whole pack of tobacco cigarettes consumed in a day. Also, the condensed smoke from cannabis contains many compounds that are anti-bacterial (and anti-cancer). It is likely that the article authors sought to be misleading.
I don't think it is misleading. After all it is just general and there is a big possibility that people smoke more than half or whole cannabis joint in a day. Just do what you are comfortable with, but it is good to be informed.