And that gives us an inverse relationship between pressure and volume. So as the volume increases inside the intraplural space, by Boils Law, the pressure must decrease. Now, what exactly is the pressure inside the lungs? Well, the pressure inside this space of our lungs is known as the intrapulmonary pressure. And the intrapulmonary pressure is the same as the atmospheric pressure because the lungs are actually exposed to our environment. And what that means is, inside our lungs, if the pressure outside the body is, let's say, one atmospheric pressure, then the pressure inside the lungs is also one ATM.