Anything that has superfine particles/fibers (such as asbestos) can cause lung problems, because some particles can make it down into the alveoli, and your lungs aren't able to expell it with coughing. Some small particles are captured and expelled with mucous. It's the ones that aren't that cause the problems. Your body then tries to dissolve remaining foreign substances, and this causes scar tissue in the lungs, which leads to breathing troubles, and in some cases, cancer.

If particles on the weed are large enough to be visible, they are too large to get lodged in the alveoli.


Sand/Silica is what glass is made of. If it gets hot enough to melt, it won't "turn to mucous"... It will turn to glass particles. BUT... Silica has a melting point of about 2000 degrees C (about 3630 degrees F)... So unless you've got one crazy-ass lighter, you're not going to convert any sand/silica to glass!


If people are having problems with bleeding lungs, it's more likely due to a bacteria, or possibly even a mold.

Good rule of thumb: Don't smoke weed that appears to have ANYTHING weird on it!