Gas masks were designed in the early 1900s to help protect people from toxic smoke released during a fire. It is a device worn to protect the wearer from chemicals and biological agents that may be released from an explosion, fire, or other emergency. 

It is a type of safety equipment used to protect against exposure to harmful gasses. Gas masks are designed to filter out certain types of hazardous gasses, such as chlorine and sulfur dioxide, before they can reach the individual wearing the mask. 

The masks are also designed to provide ventilation and protection from heat and radiation. The design of the gas mask was necessary to protect soldiers from poisonous gas inhalation. The original gas mask was made out of cloth and leather and it was very uncomfortable to wear.

In 1915, a new type of gas mask was invented that used a filter to trap harmful gas particles. Today, gas masks are made out of plastic and metal so they are more comfortable to wear.

The gas mask was designed to protect soldiers from poisonous gas. A filter that sits over the mouth and nose, keeping out harmful particles and gasses. Over time, the mask has evolved to include other features, like eye protection and a transparent cover so that you can see what's happening outside.