Vapor-compression refrigeration replaced, such as sulfur dioxide. Haloalkanes are also an order(s) of magnitude more expensive than petroleum derived flammable alkanes of similar or better cooling performance. Unfortunately, chlorine- and fluorine-bearing refrigerants reach the upper atmosphere when they escape. In the stratosphere, CFCs break up due to UV radiation, releasing their chlorine free radicals. These chlorine free radicals act as catalysts in the breakdown of ozone through chain reactions. One CFC molecule can cause thousands of ozone molecules to break down. This causes severe damage to the ozone layer that shields the Earth's surface from the Sun's strong UV radiation, and has
Zombies of the Stratosphere and viewers found the serial to be relatively dull and unimaginative, not as interesting as "Radar Men from the Moon". The use of stock footage from earlier serials is not quite as overwhelming as seen in the earlier or later Cody outings, as greater emphasis is placed on fistfights rather than scenes using the rocket back-pack. Holdren's performance is often stiff and amateurish, especially when compared to the professionalism of the old Republic pros who surround him on screen. Cline describes this serial as just a "quickie." Zombies of the Stratosphere Zombies of the Stratosphere is a 1952 black-and-white Republic