Secondhand smoking has always had its myths. Of course, the myths seem to surround cannabis. The famous myth about a contact high only "works" if you are around cannabis smoke for over an hour (2017-2019).
Cannabis seeds found on Japan's Oki Islands date back to roughly 10,000 years ago - 8000 B.C. although this doesn't guarantee that the ancient Japanese people of the Oki Islands used cannabis, historians believe that it is safe to assume that they did, in fact, use the plant.