Why are gas masks alone not enough protection against chemical agents that harm the skin?

Gas masks alone are insufficient protection against many chemical agents because they are specifically designed to filter contaminants from the air to protect the respiratory tract, rather than to shield the entire body surface.12

While gas masks effectively neutralize toxic substances that are inhaled, they do not prevent exposure to agents that attack the body through the skin. Certain chemical-warfare agents, such as mustard gas, are often dispersed in liquid form and can be absorbed directly through the skin. The skin, while an effective barrier to many substances, can be penetrated by chemicals that are highly lipid-soluble or have low molecular weights. Once these substances cross the epidermis, they can be absorbed into the circulatory system via capillaries.13

Because of this, comprehensive protection against such threats requires the use of specialized protective clothing in addition to a gas mask. Relying solely on a mask leaves the skin vulnerable to contact-based chemical injury or systemic poisoning.124