What is the force that drive air in to lungs?

Atmospheric pressure

The force that drives air into the lungs is atmospheric pressure. Atmospheric pressure is the weight of the air above a given point. At sea level, atmospheric pressure is about 14.7 pounds per square inch (psi). This means that there is a force of 14.7 psi pushing down on every square inch of your body.

When you inhale, you are creating a lower pressure in your lungs than the atmospheric pressure. This difference in pressure causes air to flow into your lungs. The greater the difference in pressure, the faster the air will flow into your lungs.

When you exhale, you are creating a higher pressure in your lungs than the atmospheric pressure. This difference in pressure causes air to flow out of your lungs. The greater the difference in pressure, the faster the air will flow out of your lungs.

Atmospheric pressure is not the only force that affects breathing. The elasticity of the lungs and the muscles of respiration also play a role. However, atmospheric pressure is the primary force that drives air into and out of the lungs.