Why was Asbestos used in Gas Mask filters?

Explanation as to why asbestos was used in Gas Mask filters, white and blue asbestos was commonly used in particulate filters of a gas mask during the second world war to help filter out gas, most western masks phased Asbestos out of the filters in the next couple of decades, however we now know that Soviet and Warsaw PACT filters used asbestos in them up until the collapse of the Soviet Union and asbestos may still be present in modern Russian Federation filters. This video explains why asbestos was a good