Ok, there are the legal effects which are considerable. They get you involved with dangerous people even if they seem ok they are involved with illegal activities and this gets them into dangerous contexts. You can go to jail from it.
The lung condition can be
pneumonia (there would be cough), can be blood clot to the lung (but frankly
oral contraceptive pills are associated with a small risk of that but marijuana is only associated with that if you lie around not moving your legs for hours at a time). And much more likely is lung inflammation from marijuana.
Asthma and asthma like irritation of the lung can cause a jelly like substance to be secreted and accumulate until it is coughed out. Inflammation causes some bleeding. Mild cases of this occur in at least 1 in six people
smoking marijuana. If it were frequently fatal, it would be more of a health problem than
narcotic overdoses, so we know serious problems from this are RARE and mild cases of it stop within days of stopping/taking a break from the marijuana. A lot of marijuana smokers I see daily have mild to moderate asthma and they take asthma medicine instead of stopping. None of the people I see on
oxygen smoke marijuana; they all smoke cigarettes. So, annoyance effects, even requiring the occaisional ER visit or antibiotics are common with marijuana but serious
lung injury from the marijuana is rare but if someone gets a pneumonia it of course needs treatment.