Oh, btw, .5 ng/ml just means .5 nanograms of cannabinoid metabolities per millilitter of blood, I think.

I've also heard that hair can have up to a 10 year memory, but I think with the hair tests they use now its 90 days, again, I'm not sure, I hope you're alright, I think you might be, but I ain't too sure. I'm assuming that if the cutoff is .5 ng than your hair wouldn't have a permanent memory, because if it did they would just say, "Any metabolites found, you fail. Period." not "If its less than .5 you pass."

Btw, just FYI.... .5 is the standard now, it usually is written as .50, but the point is is that to put that in perspective, when I got drug tested for court, my level was .647 or something and after two or three weeks it went down to .212. I smoked pretty much every day before that, but that was a urinalysis.
I still think you should be fine.

But, tell me how it goes! Good luck, God bless!