Why does everyone insist on breathing it in out all the time. When it's in the ballon it isn't in your lungs therefore not being absorbed. Best method:
Hyperventilate for a few seconds
Empty lungs
Inhale whole balloon
Hold till dizzy/needing to breathe
Exhale all into ballon
Take 3 deep breaths
Inhale/exhale till you loose the balloon/come back round with it in your pocket etc
Oh, and the oil in the canisters seems really bad, after 360 canisters a few weeks ago I found I had a THICK coating of dark grey particulate filled oil all over the inside of the whipped cream maker. I tried making a filter for it with paper kitchen towels but after 4-5 balloons the contact area becomes saturated then the next canister that goes in dislodges it all into the balloon. This is with the "Best Whip" brand, tastes utterly grim too, the balloon on with the filter failed made me puke.
Also was coughing up grey with bits in for a week and had a really nasty phlegmy cough and very raw throat that seemed directly related to it. I did do about 150 of those canisters myself over the space of 4 days though.