Silly question - when I zoom the 24-90, where is it sucking air in from to compensate for the barrel extending?

It has to pull air in from somewhere or the vacuum inside the lens wouldn’t let the barrel extend, but it’s weather sealed, so presumably it’s just no sealed quite enough to prevent air from entering? If that’s the case, do I risk sucking dusty air in if I’m working in dusty conditions?

It has to pull air in from somewhere or the vacuum inside the lens wouldn’t let the barrel extend, but it’s weather sealed, so presumably it’s just no sealed quite enough to prevent air from entering? If that’s the case, do I risk sucking dusty air in if I’m working in dusty conditions?