Gas mask

A gas mask is a air-filtration device worn on the face capable of protecting a wearer against contact with and inhalation of airborne particles and chemical gas agents. Many different types of gas masks exist. A half-mask air-purifying respirator covers only the nose and mouth, which is effective against contaminants strictly dangerous only through inhalation. Since most chemical attacks are dangerous to the eyes, a full-face respirator is designed to cover the wearer's entire face. A gas mask is not to be confused with a SCBA system, common to firefighters, which provides clean air to a user via a tank; a gas mask filters the air around a user to make it safer to breathe. Gas masks are available to the general public through military surplus stores and medical supply shops.

Filtration
Air passing through a gas mask first goes through a filter which separates clean air from airborne contaminants. Gas masks designed to filter out unsafe particles, such as germ or bacteria attack, typically make use of some form of cloth to trap the bacteria. These cloths must be replaced often to ensure efficient breathing. Chemical threats however, are not easily trapped by simple cloth. To protect against deadly chemical vapors, activated charcoal is typically used to chemically bond with the dangerous chemical. The vapor is then forbidden to continue. Activated charcoal is a very porous substance which has been “activated” by the addition of oxygen. When chemicals pass through the pores on activated charcoal, the carbon is able to bond with and hold the chemical in place. When the activated charcoal eventually fills with absorbed chemicals, it too must be replaced.

While effective on some chemicals, activated charcoal does not bond and trap all chemical threats. In order to protect against these types of chemicals, a different filter must be used. Depending on the specific type of chemical encountered, the chemical-composed filter of a gas mask can be switched out for another depending on the specific chemical it must bond to. The chemical then reacts with the specific filter and is neutralized, leaving the remaining air safe to breathe. To protect against leakage issues, some gas masks take advantage of a battery-powered fan to force air from a canister into the filter (supplied air respirator). If any part of the mask is punctured, clean air escapes as opposed to toxic air enter.

Flaws
Although the use of a gas mask can greatly reduce the amount of harmful chemicals or gases from being inhaled or touched, some flaws and inconveniences do exist. Debris filters can easily become clogged and require occasional replacement. If no replacement can be found breathing may become difficult and even impossible. Chemicals designed to absorb harmful gaseous elements are only effective on a select variety of agents and may not provide any protection from other chemicals. In the case of a supplied air respirator, the life of the battery determines the efficacy of the mask. If the battery runs out of power, the masks ceases to provide protection against leaks or puncture. The fact that the filter in a supplied air respirator is constantly in use means the filter requires replacement far more frequently.

History
The first patent for the gas mask was filed by Lewis Haslett in 1849 in Louisville, Kentucky. Very little is known about the design and effectiveness of this early prototype. Garrett Morgan, an American inventor, filed the patent for one of the earliest effective and well-known respirators in 1914. The initial device utilized two breathing tubes with wet sponges at one end and the other attached to a hood made out of cotton. The hoses stretch to the ground, where cleaner air typically resides. Morgan's “safety hoods” garnered reasonable amounts attention initially and even won first place at the Second International Exposition of Safety and Sanitation held in New York City. Two years later, Morgan's invention attained national popularity when it was used in a rescue operation to recover thirty-two men from an underground tunnel. The rescue operation was conducted by a crew of volunteers, including Morgan himself. Shortly after the successful rescue, fire departments and police stations across the nation sent in request orders for the new device. . Gas masks used in World War I follow a modified blueprint from Morgan's original respirator.

Uses
World War I:

The United States entered the first World War without any form of protection against chemical gas attacks. In desperation, some soldiers urinated on rags and held them close to their mouths and noses to prevent inhalation of gas-based weapons. Urine's high ammonia content neutralized most chemical weapons of the time, including chlorine gas. Eventually in June of 1917, the United States government issued two types of foreign gas masks to American soldiers, the British Small Box Respirator and the French M2. Although the British mask provided better filtration, the French model supplied a higher level of comfort for the wearer. Soldiers switching from the British to the French model on occasion inhaled the deadly chemicals accidentally and suffered injuries and death. Months later, the USA developed a modified version of the British Small Box Respirator which provided both better filtration and high comfort. New models were continually being produced until the armistice of November 11, 1918.

World War II:

Despite the fact that several precautions were made against poison gas attacks, gas was hardly used as a weapon in World War II. While the United States, Britain, Germany, and many other nations stockpiled nerve agents and other gases, such weapons were almost never used by any nation. Gas masks manufactured during World War II provided little protection for the user and in some cases actually harmed the wearer. Some models of the World War II gas mask contained two types of asbestos as a filtration agent, blue and white. White asbestos is considered a carcinogenic material and blue asbestos has shown links to Mesothelioma development. In most cases, however, these masks were not necessary. The fear of a gas attack on civilian areas prompted many citizens to practice the use of a gas mask. In school systems, children engaged in regular gas attack drills, in which gas masks would be distributed among students. Civilian gas masks were produced in adult, child, and infant sizes. To make gas masks less intimidating to children wearers, a mask resembling the face of cartoon character Mickey Mouse were produced. When the war ended in 1945, so did the need for the gas mask in combat for several years.

Other Uses:

Although the use of chemical weapons was greatly decreased after World War I, gas masks remained in use throughout many major conflicts. During the Vietnam and Korean War, the M-17 Gas Mask remained the main method of air purification. In modern times, Israeli households oftentimes contain gas masks in preparation for a possible Syrian chemical gas attack.

Video
A 1961 US Army training film for the M/17 Gas Mask fitting and drill. UVCeYXtXmvQ