Which chemical is known that your mask cannot protect you from?

A mask provides varying levels of protection against different chemicals, but certain gases and vapors may pass through the filter materials. Chlorine is a potent gas that can cause respiratory problems and is difficult for standard masks to filter effectively due to its small molecular size and high reactivity. While some masks can offer limited protection against particulates, gases like chlorine often require specific types of respirators equipped with chemical cartridges designed to neutralize or filter out the gas.

This makes chlorine particularly problematic as a hazard that a typical mask is not equipped to handle adequately. Other substances may have their own protective requirements, but chlorine stands out as one that standard masks do not effectively protect against.