The pressure used in the air leak test is the atmospheric pressure (or air pressure). Atmospheric pressure is the pressure generated by the weight of air. As we live on earth, atmospheric pressure is constantly applied to us and everything around us. The atmospheric pressure at sea level is 101325Pa (1013hPa) which means that we are pressed by a force of 1013hPa.The level of atmospheric pressure changes depending on the altitude. The uncomfortable feeling we get on our eardrum when we ride in an elevator to the highest floor of a high-rise building is the effect of the atmospheric pressure.