Hi there, thanks for the great question.

Sounds like Dad is a regular user of cannabis and is trying not to smoke in front of you. But you have clearly worked out what he is up to so might be good to talk with him about your concerns. If he is interested, there are many sources of help to stop using cannabis—this website or his GP would be good places to start. This site can also give you lots of useful information about the harms of cannabis use so you can understand the negative effects on your health (check the Facts, help and information section).

There is definitely second-hand smoke from cannabis and also from the tobacco which most people mix their cannabis with—both cannabis and tobacco smoke pose some health risks to others who inhale the smoke. Second-hand smoke from tobacco has been well studied and is dangerous to your health in the same way that the direct use of tobacco is dangerous. Cannabis has a pungent smell that can bother non-smokers, and it can linger a long time. There is evidence that people who are exposed regularly to large amounts of second-hand cannabis smoke show levels of cannabis in their urine—levels similar to low level use by direct smokers.

As you are only 13 and your brain is still developing it's a good idea to limit your exposure to cannabis and tobacco as much as possible. If Dad has a garage or shed outside it would be better if he smoked there instead. If that's not possible, ask Dad to keep the laundry door closed to stop smoke going through the house. If the weather is okay, open all the windows to clear out all the smoke and spend time in a room that is smoke free. Hope these suggestions help.