Comment by mrguyorama

This is because it's an airport and there are tens of thousands of gallons of kerosene around, including several gallons per minute per running jet engine actively burning and turning into combustion products.

Even in a perfectly working bleed air system, the air comes from outside the plane, which on the tarmac of an airport, is god awful, shitty, and not at all healthy.

Lot's of other commenters talking about how the smell goes away at altitude.

Because it doesn't come from the packs (except in fume events), and what people are usually smelling is that airports have very bad air, and that air is much cleaner at 30k feet.

The miniscule oil vapor/droplets that are making their way into the bleed air system from engine compressor seals will still happen at 30k feet. If you don't smell something at all times on a plane, it cannot be coming from that.

This level of contamination would be like working at a gas station, which can be a health hazard. OSHA regulates air quality for employees working around hydrocarbons.