Firefighters testing<unk> s, for light use in non-oxygen-deficient environments<unk>  masks are part of the equipment worn in mining Making logs from rice chaff First responders may use<unk> s, including during smoke simulation exercises. Air-purifying<unk> s are not effective during firefighting, in oxygen-deficient atmosphere, or in an unknown atmosphere; in these situations an air-supplying<unk>  such as a self-contained breathing apparatus is recommended instead. Gas masks are extensively used in mining and construction. They are used against paint vapors, solvents, silica dust, and other hazardous particles and gasses. Masons and carpenters use them against dusts and adhesives.<unk> s may be used to protect against welding fumes. Different welding processes may produce different fumes, both particles and gasses such as carbon monoxide. Oxygen displacement by otherwise-harmless shielding gasses is also a risk. A self-contained breathing apparatus may be needed.<unk> s used by welders must fit under a welding mask.<unk> s are also used in demolition to protect against asbestos, mould, and other hazardous waste.<unk> s are used for cleaning up after oil spills.<unk> s are used against chemical aerosols and toxic gases. They are used in the chemical industry when handling hazardous materials; workers are usually issued escape<unk> s as a precaution against leaks. Workers are instructed to put their mask on and leave immediately to sound the alarm if they detect a leak. Other<unk> s may be used for making repairs to leaking equipment.<unk> s may be worn in agriculture, for instance when using agricultural chemicals, solvents, fish meal, silage, mold spores and dust. Manufacturing also uses<unk> s, for instance on assembly lines.<unk> s are worn by many employees in the nuclear industry. Medical use CDC video on the use of<unk> s in healthcare<unk> s have historically rarely been used in medicine, though this may change; the possibility of wider use was being investigated in the US in 2017.<unk> s were used as a substitute for N95<unk> s among shortages during the 2020 COVID-19 pandemic. In medical use, the<unk>  portions of the mask must also be cleaned and disinfected, as some germs can survive on them for weeks. Conventionally, the filter cartridges are discarded. Filter cartridges can be hard to find amidst shortages. In emergency situations, if the filters are unclogged and unsoiled but contaminated with germs, the filters could be sterilized and re-used, although the filtration efficiency may be degraded by some forms of disinfection. , the available filter materials would be damaged by being dipped or submerged in cleaning fluid, but the outside of the filter cartridges can be cleaned and disinfected by wipes (pancake-style filters cannot be disinfected). During the COVID-19 pandemic, public health authorities issued guidelines on how to save, disinfect and reuse standard mechanical filters, warning against the disinfection methods that damaged filtration efficiency. Limited research failed to find evidence that<unk> s caused more patient anxiety than FFR masks, including in children and disoriented patients. A single air-filtering<unk>  cost about as much as 40 disposable filtering facepiece<unk> s, and a medical worker uses about 20 disposable masks per day, according to a 2018 publication. The particulate cartridges cost about as much as six disposable masks. Air-supplying<unk> s may be easier for hospital personnel to use; they can be worn for longer periods. Source control<unk> s with one-way valves that release unfiltered exhaled air are not recommended in disease-control settings where the unfiltered exhaled air might infect others, but can be used in some other settings. In pandemics, masks with exhalation valves may not meet the requirements of some public-health orders. If<unk> s with filtered exhalation valves are not available, those with unfiltered exhalation valves may be altered to filter exhalation air, e.g., by using an anesthesia circuit filter. Or the wearer may simply cover the exhalation valve with a surgical mask or other suitable source control material. Care must be taken so that the additional filtration does not impede exhalation to the point that breathing becomes restricted or that excessive CO2 buildup occurs. CBRN defense<unk> s may be used for protection from chemical, biological, radiological, and nuclear agents (CBRN). Some<unk> s are specifically certified for such use. Gas masks were initially widely used in chemical warfare, against the effects of war gas. Chemical and biological weapons are prohibited by customary international humanitarian law, in international and non-international conflicts. Use is considered a war crime. During demonstrations and protests where tear gas (such as CS gas) is employed by riot police, gas masks are commonly used by police and demonstrators alike. Journalists covering these events also use<unk> s, and where use of tear gas spreads into residential areas, even those not on the front lines may buy them. Access to<unk> s has been restricted by authorities who regard them as tools of resistance, causing circumvention and smuggling. File:A mother and baby both in gas-masks during 1941. D3918.A mother and baby, both in gas masks, during WWII. File:Emergency personnel respond to the Tokyo subway sarin attack.Japan Self-Defense Force chemical troops respond to the Tokyo subway sarin attack in 1995 File:2020-08-23 PPB North Precinct Protest (50274961266).A protester at a demonstration in 2020
Elastomeric respirator
Bubble oxygenator
Venturi mask
Negative pressure ventilator
N95 respirator
Laryngeal mask airway
Tracheotomy
Gas mask