<P> Asbestos can be recycled by transforming it into harmless silicate glass . A process of thermal decomposition at 1000--1250 ° C produces a mixture of non-hazardous silicate phases, and at temperatures above 1250 ° C it produces silicate glass . Microwave thermal treatment can be used in an industrial manufacturing process to transform asbestos and asbestos - containing waste into porcelain stoneware tiles, porous single - fired wall tiles, and ceramic bricks . </P> <P> The combination of oxalic acid with ultrasound fully degrades chrysotile asbestos fibers . </P>

Which of the following is not a kind of air mass found in the united states