how long does it take for the smell from anaesthetic to go away?

my 4yr old had dental surgery this morning (exactly 12hrs ago). she's fine - except for being a bit more clingy and cranky than usual, she's basically back to normal (20min after leaving the dentist, she was knocking back honey-garlic meatballs and an apple juice).

thing is, her breath REEKS like a chemical factory - it's the gas they used to knock her out.

i've been put under any number of times (numerous facial operations) and i don't remember it taking this long for it to clear, but then i was put under with a needle, not a mask, and i don't remember from when i was her age.

she's been asleep for a couple hours and i've been checking her every 30 minutes (which i will do until she wakes up on her own) but that smell just gets to me - i can smell it as soon as i get near the bed. i'm wondering if it's an indicator that her body is not clearing the stuff from her system as well as it should.