page_title: Respirator
section_title: Earliest records to 19th century
hierarchical_section_title: Respirator / History / Earliest records to 19th century
context_page_description: A respirator is a device designed to protect the wearer from inhaling hazardous atmospheres, including fumes, vapours, gases and particulate matter such as dusts and airborne microorganisms. There are two main categories: the air-purifying respirator, in which respirable air is obtained by filtering a contaminated atmosphere, and the air-supplied respirator, in which an alternate supply of breathable air is delivered. Within each category, different techniques are employed to reduce or eliminate noxious airborne contaminants.
  Air-purifying respirators range from relatively inexpensive single-use, disposable face masks sometimes referred to as a dust mask to more robust reusable models with replaceable cartridges often called a gas mask.
context_section_description: The history of protective respiratory equipment can be traced back as far as the first century, when Pliny the Elder (circa A.D. 23-79) described using animal bladder skins to protect workers in Roman mines from red lead oxide dust. In the 16th century, Leonardo da Vinci suggested that a finely woven cloth dipped in water could protect sailors from a toxic weapon made of powder that he had designed.
  In 1785, Jean-François Pilâtre de Rozier invented a respirator.
  Alexander von Humboldt introduced a primitive respirator in 1799 when he worked as a mining engineer in Prussia.
  Practically all respirators  in the early 18th century consisted of a bag placed completely over the head, fastened around the throat with windows through which the wearer could see. Some were rubber, some were made of rubberized fabric, and still others of impregnated fabric, but in most cases a tank of compressed air or a reservoir of air under slight pressure was carried by the wearer to supply the necessary breathing air. In some devices certain means were provided for the adsorption of carbon dioxide in exhaled air and the rebreathing of the same air many times; in other cases valves allowed exhalation of used air.
  Julius Jeffreys first used the word "respirator" as a mask in 1836. The mask worked by capturing moisture and warmth in exhaled air in a grid of fine metal wires. Inhaled air then was warmed and moistened as it passed through the same metal grid, providing relief to sufferers of lung diseases. The Respirator became popular, and was mentioned in the literature of the day, including in the writings of Elizabeth Gaskell, William Makepeace Thackeray and Charles Dickens.
  In 1848, the first US patent for an air-purifying respirator was granted to Lewis P. Haslett for his 'Haslett's Lung Protector,' which filtered dust from the air using one-way clapper valves and a filter made of moistened wool or a similar porous substance. Following Haslett, a long string of patents were issued for air purifying devices, including patents for the use of cotton fibers as a filtering medium, for charcoal and lime absorption of poisonous vapors, and for improvements on the eyepiece and eyepiece assembly. Hutson Hurd patented a cup-shaped mask in 1879 which became widespread in industrial use, and Hurd's H.S. Cover Company was still in business in the 1970s.
  Inventors in Europe included John Stenhouse, a Scottish chemist, who investigated the power of charcoal in its various forms, to capture and hold large volumes of gas. He built one of the first respirators able to remove toxic gases from the air, paving the way for activated charcoal to become the most widely used filter for respirators. Irish physicist John Tyndall took Stenhouse's mask, added a filter of cotton wool saturated with lime, glycerin, and charcoal, and in 1871 invented a 'fireman's respirator', a hood that filtered smoke and gas from air, which he exhibited at a meeting of the Royal Society in London in 1874. Also in 1874, Samuel Barton patented a device that 'permitted respiration in places where the atmosphere is charged with noxious gases, or vapors, smoke, or other impurities.' German Bernhard Loeb patented several inventions to 'purify foul or vitiated air,' and counted the Brooklyn Fire Department among his customers.
  A predecessor of the N95 was a design by Doctor Lien-teh Wu who was working for the Chinese Imperial Court in the fall of 1910, which was the first that protected users from bacteria in empirical testing. Subsequent respirators were reusable but bulky and uncomfortable. In the 1970s, the Bureau of Mines and NIOSH developed standards for single-use respirators, and the first N95 respirator was developed by 3M and approved in 1972.
caption: Woodcut of Stenhouse's mask
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