Gas masks and filters are used to protect the body from the harmful effects of chemical and biological agents. Many chemicals such as chlorine, hydrogen cyanide, phosgene, mustard agent and others were used during World War I. This caused a number of casualties among allied forces and created the need for the protective masks.
Since then gas masks have evolved and these gas masks protect against all types of known chemical and biological agents. Gas masks use different techniques to protect users. But common components such as the facepiece, hood, eyepieces and filters are present in almost all the masks.
The most basic masks use filtration techniques. Pollutants generally have larger particles than oxygen and by using a fine mesh these can be kept out. The only drawback is that the air supply is also limited in this process. The other process uses the absorbing qualities of certain chemicals such as activated charcoal to control the harmful agents.
Such masks have limited use, as they are able to absorb only a few chemicals. The present-day masks use the method of chemical neutralization. These masks contain chemical filters that neutralize the harmful chemicals present in the air. Some of these also have tubes for drinking water, communication system and winterization kits to prevent fogging during cold weather conditions.