When you squeeze the rubber bulb of a perfume atomizers how do you change the air pressure at the top of the tube?

When you squeeze the rubber bulb of a perfume atomizer, you decrease the volume of air inside the bulb, which increases the air pressure within it. This higher pressure forces air up the tube and into the perfume reservoir. As the air pressure at the top of the tube decreases, it creates a vacuum that draws the liquid perfume up through the tube and disperses it as a fine mist when released.