A wide range of industries use<unk> s including healthcare & pharmaceuticals, defense & public safety services (defense, firefighting & law enforcement), oil and gas industries, manufacturing (automotive, chemical, metal fabrication, food and beverage, wood working, paper and pulp), mining, construction, agriculture and forestry, cement production, power generation, shipbuilding and the textile industry.<unk> s require user training in order to provide proper protection. User seal check Each time a wearer dons a<unk> , they must perform a seal check to be sure they have an airtight seal to the face so that air does not leak around the edges of the<unk> . (PAPR<unk> s may not require this because they don't necessarily seal to the face.) This check is different than the periodic fit test that is performed by specially trained personnel using testing equipment. Filtering facepiece<unk> s are typically checked by cupping the hands over the facepiece while exhaling (positive pressure check) or inhaling (negative pressure check) and observing any leakage around the facepiece. Elastomeric<unk> s are checked in a similar manner, except the wearer blocks the airways through the inlet valves (negative pressure check) or exhalation valves (positive pressure check) while observing the flexing of the<unk>  or air leakage. Manufacturers have different methods for performing seal checks and wearers should consult the specific instructions for the model of<unk>  they are wearing. Some models of<unk> s or filter cartridges have special buttons or other mechanisms built into them to facilitate seal checks. Fit testing Most types of<unk> s depend upon forming a good seal between the<unk>  body and the face of the wearer. Fit testing procedures have been developed to ensure that the<unk>  is appropriate for the wearer and the wearer's donning technique is capable of creating an adequate seal. Poor fit can have a negative impact on the<unk> 's overall filtering effectiveness by as much as 65%. A study on<unk>  effectiveness conducted in Beijing found that facial fit was the primary contributor to total inward leakage (TIL), based on a test of nine different models. Facial hair such as a beard can interfere with proper fit. Qualitative fit testing typically subjects the wearer to an atmosphere containing an aerosol that can be detected by the wearer, such as saccharin or isoamyl acetate, with the wearer reporting whether detectable levels of the aerosol has penetrated into the breathing area. Quantitative fit testing typically uses a specially prepared<unk>  with an inserted probe. The<unk>  is donned, and aerosol concentrations inside and outside of the mask are compared and used to determine a numerical fit factor. Typical room atmosphere contains sufficient particulates to perform the test, but aerosol generators can be used to improve the test accuracy.Workplace protection factor (PF) of filtering facepiece, measured in real time with two optical dust meters. In-facepiece dust concentration is changed dozens of times in a matter of minutes due to changes of the size of the gaps between the mask and face. A U.S. Department of Labor study showed that in almost 40 thousand American enterprises, the requirements for the correct use of<unk> s are not always met. Experts note that in practice it is difficult to achieve elimination of occupational morbidity with the help of<unk> s: It is well known how ineffective ... trying to compensate the harmful workplace conditions with ... the use of<unk> s by employees. Unfortunately, the only certain way of reducing the exceedance fraction to zero is to ensure that Co (note: Co - concentration of pollutants in the breathing zone) never exceeds the PEL value. The very limited field tests of air-purifying<unk>  performance in the workplace show that<unk> s may perform far less well under actual use conditions than is indicated by laboratory fit factors. We are not yet able to predict the level of protection accurately; it will vary from person to person, and it may also vary from one use to the next for the same individual. In contrast, we can predict the effectiveness of engineering controls, and we can monitor their performance with commercially available state-of-the-art devices. Contrast with surgical mask right 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 from the wearer's saliva and<unk> y secretions to others, especially during surgical procedures. A surgical mask, by design, does not filter or block very small particles from the outside air that may be transmitted by coughs, sneezes, or certain medical procedures to the wearer. 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 (CDC) recommends surgical masks in procedures where there can be an aerosol generation from the wearer, if small aerosols can produce a disease to the patient. Surgical N95 Kate Rubins wearing a 3M 1860 "surgical N95"alt=Head-and-shoulders photo of a middle-aged white woman. Her blonde hair is tied in a bun. Her nose and mouth are covered by a teal<unk>  with head and neck straps. She is wearing royal blue coveralls. Some N95<unk> s have also been cleared by the U.S. National Institute for Occupational Safety and Health (NIOSH) and U.S. Food and Drug Administration as surgical and are labeled "surgical N95", "medical<unk> s," or "healthcare<unk> s". These protect the patient and others from the wearer's<unk> y emissions (as a surgical mask would) as well as protect the wearer from airborne particulates and aerosols (as a standard N95<unk> . Unlike a standard N95<unk> , FDA-cleared "healthcare<unk> s" also provide protection from high-pressure streams or jets of bodily fluid, such as blood. The CDC recommends the use of<unk> s with at least N95 certification to protect the wearer from inhalation of infectious particles including Mycobacterium tuberculosis, avian influenza, severe acute<unk> y syndrome (SARS), pandemic influenza, and Ebola. Escape<unk> s Dräger escape<unk> . This model has no hood, and instead comes with noseclips to ensure the wearer breathes only through the filter. Escape<unk> s or smoke hoods such as Air-Purifying Escape<unk> s are for use by the general public for chemical, biological, radiological, and nuclear (CBRN) terrorism incidents. The American National Standards Institute (ANSI) and the International Safety Equipment Association (ISEA) established the American National Standard for Air-Purifying<unk> y Protective Smoke Escape Devices to define both test criteria and approval methods for fire/smoke escape hoods. ANSI/ISEA Standard 110 provides design guidance to manufacturers of<unk> y Protective Smoke Escape Devices (RPED) in the form of performance requirements and testing procedures. The standard covers certification, ISO registration for the manufacturer, associated test methods, labeling, conditioning requirements, independent process and quality control audits, and follow-up inspection programs. ANSI/ISEA 110 was prepared by members of the ISEA RPED group, in consultation with testing laboratories and was reviewed by a consensus panel representing users, health and safety professionals and government representatives. The U.S. Consumer Product Safety Commission uses ANSI/ISEA 110 as the benchmark in their testing of fire escape masks. Air-purifying<unk> s Air-purifying<unk> s are<unk> s that draw in the surrounding air and purify it before it is breathed (unlike air-supplying<unk> s, which are sealed systems, with no air intake, like those used underwater). Air-purifying<unk> s are used against particulates, gases, and vapors that are at atmospheric concentrations less than immediately dangerous to life and health. They may be negative-pressure<unk> s driven by the wearer's inhalation and exhalation, or positive-pressure units such as powered air-purifying<unk> s (PAPRs). Air-purifying<unk> s may use one or both of two kinds of filtration: mechanical filters retain particulate matter, while chemical cartridges remove gases, volatile organic compounds (VOCs), and other vapors. Additionally, air-purifying<unk> s may come in many forms: filtering facepiece<unk> s consist solely of a disposable mechanical filter; elastomeric<unk> s are reusable but have replaceable filters attached to the mask; and powered air-purifying<unk> s have a battery-powered blower that moves the airflow through the filters. According to the NIOSH<unk>  Selection Logic, air-purifying<unk> s are recommended for concentrations of hazardous particulates or gases that are greater than the relevant occupational exposure limit but less than the immediately dangerous to life or health level and the manufacturer's maximum use concentration, subject to the<unk>  having a sufficient assigned protection factor. For substances hazardous to the eyes, a<unk>  equipped with a full facepiece, helmet, or hood is recommended. Air-purifying<unk> s are not effective during firefighting, in oxygen-deficient atmosphere, or in an unknown atmosphere; in these
Respirator
Ventilator
Aspirator 
Resuscitator
Intensivist
Both respirator
TheraBreath 
Liquid ventilator