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One time use of marijuana is unlikely to be detected by urine drug screening beyond 3 to 4 days at the most. Typically a chronic user may test positive for up to 7 to 10 days, and rarely as long as 30 days.
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Thank you. Sorry for the delay to reply, I was assisting another customer.
The thresholds are lowered enough in testing that you should not test positive if there is a very slight amount of exposure (in passing by a person smoking), but if you are in an enclosed area where people are smoking, it is very possible for you to be intoxicated and even if only mildly so, it could show a positive on a urine test.