I know and do carry Ventolin. Perhaps my comment was not clear. If a volume of, say, 125 mils is filled with a product of 125 mils it leaves no room for the propellent gas. However looking belatedly at the technicalities of 'aerosols cans' it would seen the propellent is within the product and released only when the pressure in the container is reduced as the release valve is operated. A good anology would be a bottle or can of Coca Cola when the cap ortab is opened.