I went south and south again, and took out my katana. Selecting the sharper and straighter edge of the two, I carefully swept the inside of the air vent. Continuing on, I managed my way through the entire vent, slowly but thoroughly removing the needles.

@Stratn- yes, but a needle that's sideways is rather hard to poke yourself with, seeing as it is parallel to the floor and you don't see people cutting themselves on the floor much. Plus sweeping the inside of the vent would naturally build all the needles up at the edges, and thus they could be easily avoided.