and the pressure decreases whereby drawing air into the enclosure 10 through the cascade filter 20 the air first passes through the micro porous membrane 27 that is fabricated from ptfe or other such material this membrane 27 filters out particulate matter to a predetermined size typically to sub micron level the membrane also forms a vapour barrier that stops water entering this can include pressurised water and detergents from high pressure cleaners the air then passes through the activated carbon block 26 that strips most corrosive chemicals and free radical oxidants through adsorption after leaving the activated carbon block 26 the air passes through silica gel 25 that dehydrates the air further the air then enters the enclosure 10 at ambient temperature and pressure containing no moisture or corrosive agents when the light is switched on and starts to radiate 80 or more energy as heat into the trapped air the air heats up effectively increasing its temperature and pressure the pressurised internal air now exits the filter 20 until the internal pressure is equal to the ambient pressure when the lamp is switched off the operation is repeated in this manner the cyclic turning on and off of the lamp does not draw moisture or corrosive elements into the enclosure the filter 20 effectively cleans the air mechanically.