A gas respirator is a device used to prevent harmful substances in the air from harming the wearer. It is worn on the face, and it ensures the user is provided with a constant supply of breathable air. Gas respirators are widely used in a number of different fields; soldiers may use them do avoid harm from biological warfare, and car painters may use them to avoid inhaling paint fumes. Another type of gas respirator, called an "escape respirator," is intended to be used only once in an emergency and only lasts long enough to allow one to escape from a contaminated area.
There are two primary mechanisms through which a gas respirator may function, though there are many variants of these mechanisms. The first main category of respirators uses filtration to provide breathable air. The contaminated air is taken into the respirator and the contaminants are filtered out, thereby ensuring the air reaching the individual is at least passably clean. The other category of gas respirators draws breathable air from an external oxygen source, completely preventing all contact with the contaminated air. While these are much more cumbersome, they do remove the need to select the proper filter and to replace filters over time.
The cumbersome nature of respirators with external oxygen sources means that most people are much more likely to use a filter-based gas respirator. Breathing though a filter-based gas respirator is more difficult than breathing unfiltered air because one must draw air through the filter, which is often quite dense. Individuals with weak lungs or breathing problems often find this to be quite challenging, especially if use of the gas respirator is required over a long period of time. To address this problem, many respirators contain powered fans that blow air through the filter to make breathing easier; these are battery powered, though, and only last for a short period of time.
Different types of respirators provide different levels of protection, so it is important to select the correct type of gas respirator. Some only protect against large, hazardous particles in the air and do little to protect against gases or vapors. Filters that do protect against gases and vapors, however, can become clogged if they are used in an area containing a high concentration of airborne particles, such as those in smoke. Great care must be taken before buying a gas respirator, as different types of respirators protect against different hazards.