High from passively inhaling cannabis smoke? According to drug researcher Bernd Werse from Frankfurt's Goethe University, this risk is rather low.

What matters is how much weed is actually smoked in the area. A single joint smoked in a bar probably has no effect on passive consumers. “However, if you are in a small room in which many joints are circulating at the same time, you will probably get a certain intoxication from the passive smoke,” says the drug expert in an interview with the German Press Agency.

Overall, Werse believes that this danger is not very serious; outdoors it “almost doesn’t exist at all”. Independently of this, an experiment at the universities of Mainz and Jena had already shown in 2010 that spending several hours in a Dutch coffee shop did not seriously increase the THC levels in the blood of eight test subjects who did not smoke weed.