Is it possible to come up positive on a drug test for marijuana without having smoked it- just being in the room with pot smokers?

Yes, it’s possible. She did inhale the smoke, same as anyone who actually put the joint to their lips.

Whether she’s telling the truth or not, I have no way of knowing.

…that seems a very brief period of time for a contact high that would register on a test, doesn’t it?

the amount of smoke needed to be inhaled to produce a high has nothing to do with the amount of smoke needed to be inhaled to show positive test results.

Most of the time when someone has weed in their system, it’s because they were smoking it recently.

Anytime I hear the whole schpiel about “oh I was in the room but I didn’t smoke” I’m immediately skeptical.

I don’t buy that story. It seems far more likely she was hanging out with some friends smoking.

A friend of mine is in the Airforce, and cannot smoke weed. He was paranoid that it would show up on his drug tests from when he hung out with us while we were smoking. It didn’t. So I’m with @The_Compassionate_Heretic; I’m skeptical of this woman’s story.

According to this source, it would require some pretty intense passive exposure:

“Is it possible for secondhand marijuana smoke in a car to cause you to fail the next day? It is possible that secondhand marijuana smoke will raise someone to the 50 ng/mL level, however, extreme exposure is required.

For instance, a closed car full of marijuana smokers and a non-smoker may render the non-smoker positive for both urinalysis and the hair test, provided that they are sealed in the car for a while. The United States army did a case study where volunteers were put in a room pumped full of smoke for an hour, five time daily. Subjects started testing positive after the second day. The non-smoker would have to take in virtually as much second hand smoke as a smoker. Non-smokers are safe in a ventilated area, as long as they don’t get a hair test.”

Yes…contact high is a reality, not a myth.

It is a non-zero chance, yes. What really matters most here is the test threshold for detection, it should be able to tell the concentration of the drug that’s required for a positive reading. Some factors that could influence her reading include the concentration of cannabis smoke in the room, the time from when it was smoked, and the number and depth of breaths the mom took while in that atmosphere. You can see there are many variables here, much too many for any internet folk to definitively proclaim innocence or guilt.

There a big difference between spending time in a closed car with pot smokers and walking into your daughter’s room to send her pot-smoking friends home, and the question detail implies.