with surgical mask an infographic on the difference between surgical masks and n95 respirators a surgical mask is a loose-fitting, disposable device that creates a physical barrier between the mouth and nose of the wearer and potential contaminants in the immediate environment. if worn properly, a surgical mask is meant to help block large-particle droplets, splashes, sprays, or splatter that may contain viruses and bacteria. surgical masks may also help reduce exposure of the wearer's saliva and respiratory secretions to others. a surgical mask, by design, does not filter or block very small particles in the air that may be transmitted by coughs, sneezes, or certain medical procedures. surgical masks also do not provide complete protection from germs and other contaminants because of the loose fit between the surface of the face mask and the face. collection efficiency of surgical mask filters can range from less than 10% to nearly 90% for different manufacturers’ masks when measured using the test parameters for niosh certification. however, a study found that even for surgical masks with "good" filters, 80–100% of subjects failed an osha-accepted qualitative fit test, and a quantitative test showed 12–25% leakage. the u.s. centers for disease control and prevention recommends surgical masks (over no mask) in procedures where there can be an aerosol generation from the wearer, if small aerosols can produce a disease to the patient. history n95 respirators have several historical predecessors. in the late 19th century, miles philips began using a "mundebinde" ("mouth bandage") of sterilized cloth which he refined by adapting a chloroform mask with two layers of cotton mull. paul berger, a paris surgeon, likewise investigated the protective effect of masks during surgery. another mask design was a cloth facemask by lien-teh wu, who was working for the chinese imperial court in the autumn of 1910 during the manchurian plague outbreak. it inspired masks used during the 1918 flu pandemic. another predecessor was gas masks developed during world war i, which were adapted for use by miners. they were reusable but bulky and uncomfortable due to their fiberglass filters and heavy rubber construction. mass production of filtering facepieces was started in 1956 in the soviet union (the first mass-produced model was called "lepestok" meaning "petal" in russian). the air was purified with nonwoven filtering material consisting of polymeric fibres carrying a strong electrostatic charge. respirator was used in nuclear industry (as single-used ppe), and then in other branches of economy. in about 60 years, more than 6 billion respirators were manufactured. unfortunately, the developers overestimated the efficiency (apf 200–1000), which led to serious errors in the choice of personal protective equipment by employers. in the 1970s, the us bureau of mines and niosh developed standards for single-use respirators, and the first single-use n95 "dust" respirator was developed by 3m and approved in 1972. 3m used a melt blowing process that it had developed decades prior and used in products such as ready-made ribbon bows and bra cups; its use in a wide array of products had been pioneered by designer sara little turnbull. originally designed for industrial use, n95 respirators became a healthcare standard subsequent to virus-blocking technology invented by university of tennessee professor peter tsai, and patented in 1995. the novel material consists of both positive and negative charges, which are able to attract particles (such as dust, bacteria and viruses) and trap at least 95% of them by polarization before the particles can pass through the mask. the anti-viral technology was first developed to prevent the spread of drug-resistant tuberculosis. following the onset of the covid-19 pandemic, tsai ended his retirement to help alleviate shortages related to the covid-19 pandemic by researching n95 mask decontamination. many american companies stopped producing n95 respirators in the 2000s due to litigation costs and foreign competition. global shortages during the covid-19 pandemic main article: face masks during the covid-19 pandemic § n95 and ffp masks on january 24, 2020, taiwan announced that it was imposing a temporary ban on the export of masks. the respirators came to be in short supply and high demand during the covid-19 pandemic, causing price gouging and hoarding, often leading to confiscation of masks. production of n95 respirators was limited due to constraints on the supply of nonwoven polypropylene fabric (which is used as the primary filter) as well as the cessation of exports from china. in canada, amd medicom began making masks in 1997 through an agreement with united medical enterprises in atlanta, georgia, us. medicom added factories in shanghai in 2002, yilan taiwan in 2010 and france in 2011. as the pandemic escalated, china, france and taiwan either prohibited the export of masks, or requisitioned medicom's output for local use. the federal government of canada came to an agreement with medicom to buy millions of masks over the next ten years, leading to medicom announcing plans to open a new factory; in montreal. novo textiles in british columbia quickly acquired a surgical mask making machine, and announced plans to acquire an n95 making machine as well. in march 2020, us president donald trump applied the defense production act (dpa) against the american company 3m that allows the federal emergency management agency to obtain as many n95 respirators as it needs from 3m. also in early april 2020, the united states federal government, invoking the dpa, ordered 3m to stop exporting n95 respirators to customers in canada and latin america, and to keep them within the u.s. instead. however, 3m refused, citing humanitarian implications, and the possibility of backfire: "ceasing all export of respirators produced in the united states would likely cause other countries to retaliate and do the same, as some have already done. if that were to occur, the net number of respirators being made available to the united states would actually decrease. that is the opposite of what we and the administration, on behalf of the american people, both seek." selected patents us patent 3333585, robert j barghini, walter m westberg, patrick h carey jr, "cold weather face mask", published 1967-08-01, issued 1967-08-01, assigned to 3m co us patent 3971373a, david l. braun, "particle-loaded microfiber sheet product and respirators made therefrom", published 1976-07-27, issued 1976-07-27, assigned to 3m co us patent 4215682a, donald a. kubik & charles i. davis, "melt-blown fibrous electrets", published 1980-08-05, issued 1980-08-05, assigned to 3m co us patent 4536440a, harvey j. berg, "molded fibrous filtration products", published 1985-08-20, issued 1985-08-20, assigned to 3m co us patent 4807619, james f. dyrud, harvey j. berg, alice c. murray, "resilient shape-retaining fibrous filtration face mask", published 1989-02-28, issued 1989-02-28, assigned to 3m co us patent 4850347, martin r. skov, "face mask", published 1989-07-25, issued 1989-07-25, assigned to moldex metric inc us patent 4856509, jerome h. lemelson, "face mask and method", published 1989-08-15, issued 1989-08-15 us patent 5307796a, joseph p. kronzer, roger j. stumo, james f. dyrud, harvey j. berg, "methods of forming fibrous filtration face masks", published 1994-05-03, issued 1994-05-03, assigned to 3m co