Air is an essential component of life, and there are situations where this important component might become scarce. It is for times like this that various inventors spent days and nights creating respirators and face masks. An Overview of The Background It was in the 16th century, that Leonardo Da Vinci suggested that a finely-woven cloth dipped in water could protect sailors from a toxic weapon that he had designed. It was again, in 1799, that Alexander von Humboldt introduced a primitive respirator when he was working as a mining engineer in Prussia. Most of the early respirators were made up of a bag that was placed completely over the head and fastened around the throat with windows which enabled the wearer to see. Some of these respirators were made up of rubber, while others of rubberized and impregnated fabric. In most of the cases, a tank of compressed air, or a reservoir of air under slight pressure, was carried by the wearer. This tank supplied the wearer with necessary breathing air. There were other devices too, some of which were provided with means for the absorption of carbon dioxide in exhaled air, and the re breathing of the same air many times, while other devices were fitted with valves, for the exhalation of used air. Lewis P. Haslett was granted the first US patent for an air purifying respirator in 1848. His creation, the "Haslett's Lung Protector" filtered dust from the air, with the help of one-way clapper valves and a filter made of moistened wool, or a similar porous substance. It was this patent that gave way to a long string of other patents for air purifying devices, including patents for the use of cotton fibers as a filtering medium, for limestone and charcoal absorption of poisonous vapors, as also for improvements on the eyepiece and eyepiece assembly. It was in 1879, that Hutson Hurd patented a cup-shaped mask. This mask became widespread in industrial use. Things were changing across the Atlantic too, where a Scottish chemist, named John Stenhouse, was investigating the power of charcoal and its various forms in order to capture and hold large volumes of gas. John Stenhouse, used the knowledge he had about science, for building one of the first respirators that was able to remove toxic gases from the air. This invention paved the way for activated charcoal to become the most widely used filter for respirators. John Tyndall, a British Physicist, improved upon Stenhouse's mask by adding a filter of cotton wool, saturated with charcoal, glycerin, and lime. Respirators A respirator is used when the user is likely to be exposed to gas, or in situations where he/she might be exposed to some airborne material. The market today has a large number of different masks available, with one to suit every condition. Basically, there are 3 types of respiratory masks, which are used under different circumstances, and require different training and precautions to be taken.

• Self Contained Breathing Apparatus (SCBA) This type of respirator is used in industrial circumstances, where the user requires a guaranteed safe supply of air. As the name implies, this equipment provides a micro environment that is cut off from any external pollutants or chemicals. A large tank of air and an airtight mask, make up this apparatus. The tank of air is under high pressure and usually provides enough air for about an hour. In case this is not enough, there are larger versions available. The SCBA respirator resembles the equipment worn by a diver. There are two main types of masks available under this category, one is the open circuit system, in which once air is exhaled, it will be released into the environment and the other is called closed circuit, and it is used where the environment must not be contaminated. In a closed circuit SCBA system, the exhaled air is stored and can later be reprocessed, to allow the user more time to work.
• Powered Air Purifying Respirator (PAPR) The PAPR is designed to be worn under circumstances where particulate matter needs to be removed from the air, which is otherwise safe to breathe. The PAPR respirator is helpful when using a paint sprayer or an industrial sanding, grinding device, as the air becomes contaminated with paint or fine dust, that can cause problems if inhaled. This respirator has an air pump attached to the belt. This pump provides a steady flow of filtered air to a separate mask. The various filters available are sorted by the minimum size of particle that they filter out of the air supply, with the coarser ones designed to get rid of relatively large dust particles and the fine filters for items as small as virus particles. It is essential to use the correct filter as the efficiency of the air pump will be governed by the ease with which it can push air through the breathing mask.
• Escape Breathing Devices The escape breathing device is designed in order to provide the user with a temporary supply of clean and safe air, in case of an emergency, such as in an environment where some poisonous gas can leak.

Face Masks The face mask is a loose-fitting disposable mask that covers the mouth and the nose. This mask helps germs from being spread by the person wearing it. Apart from that, it also keeps splashes or sprays from reaching the nose and the mouth of the person. It is important to remember that these are not designed to protect the user from breathing in very small particles. Also, these should be discarded after use! The face mask is used by professional surgeons and dentists. It can be affixed to the wearers head using a loop strap, tie-on strap, or a single headband. These masks are available in pleated, flat, and single styles, in colors like blue, white, pink, and green. Face masks are smooth and comfortable to wear. Some of the ones available in the market have an aluminum nosepiece that helps secure the mask to the face. All the dental and medical masks are made up of high quality non-woven materials and are latex-free.