gas mask, breathing device designed to protect the wearer against harmful substances in the air. The typical gas mask consists of a tight-fitting facepiece that contains filters, an exhalation valve, and transparent eyepieces. It is held to the face by straps and can be worn in association with a protective hood. The filter elements in the cheeks of the mask remove contaminants from the air that is drawn through the mask by the wearer’s inhaling. The filters, which can be replaced, clean the air but do not add oxygen to it (some masks are connected by a hose to a separate tank of oxygen). The most common filters employ fibre screens (to strain out finely divided solid particles) and chemical compounds such as charcoal (to capture or chemically alter poisonous gases in the air). Charcoal absorbs and holds a fairly large volume of poisonous gases.
gas masks in World War I
gas masks in World War I
Observe English schoolchildren practicing using gas masks in case of a chemical attack amid World War II
Observe English schoolchildren practicing using gas masks in case of a chemical attack amid World War II
See all videos for this article
Gas masks are widely used by the world’s armed forces. Although it is possible to design filtering devices that will neutralize almost any specific toxic substance in the air, it is impossible to combine in one mask protection against all toxic substances. Military gas masks are accordingly constructed with a view to counteracting those chemicals that are thought most likely to be used in wartime. Gas masks are effective only against those chemical-warfare agents that are dispersed as true gases and are injurious when breathed. Agents such as mustard gas that are dispersed in liquid form and attack the body through the skin surface necessitate the use of special protective clothing in addition to gas masks.
safety, those activities that seek either to minimize or to eliminate hazardous conditions that can cause bodily injury. Safety precautions fall under two principal headings, occupational safety and public safety. Occupational safety is concerned with risks encountered in areas where people work: offices, manufacturing plants, farms, construction sites, and commercial and retail facilities. Public safety involves hazards met in the home, in travel and recreation, and other situations not falling within the scope of occupational safety.
Safety was not considered to be a matter of public concern in ancient times, when accidents were regarded as inevitable or as the will of the gods. Modern notions of safety developed only in the 19th century as an outgrowth of the Industrial Revolution, when a terrible toll of factory accidents aroused humanitarian concern for their prevention. Today the concern for safety is worldwide and is the province of numerous governmental and private agencies at the local, national, and international levels.
The frequency and severity rates of accidents vary from country to country and from industry to industry. In the industrialized nations of the world, accidents now cause more deaths than all infectious diseases and more than any single illness except those related to heart disease and cancer. Accidents in the home, in public and private transportation, and on farms and in factories are by far the predominant cause of death in the population under 35 years of age in industrialized nations. In the United States each year, about six times as many persons receive nonfatal injuries in accidents in the home as in motor-vehicle accidents, and about twice as many at home as in industrial accidents. On a worldwide basis, motor-vehicle accidents tend to be the primary cause of accidental deaths, followed by those in industry and in the home.
Industrial accidents can occur because of improper contact with machinery, the lifting or other handling of bulk materials, and contact with electrical, chemical, or radiation hazards. The mining and lumbering industries are among those that have the highest rate of severe accidents. High-technology industries such as electronics have relatively low accident rates.
Several international organizations provide means by which national safety organizations can exchange information and pass on new ideas. Among the bodies serving in this capacity are the International Social Security Association (ISSA) and the International Labour Organisation (ILO). These two bodies have sponsored international safety congresses every three years since 1955. Every four years a congress is held by the Permanent International Association of Road Congresses, a body that is maintained by the transport ministries of its member countries and by groups representing the highway-construction industry. The World Touring and Automobile Organization (OTA) holds a safety congress every other year.
A number of organizations, including the ILO, ISSA, the World Health Organization, and the European Economic Community, maintain a joint information bureau in Geneva. The International Organization for Standardization, which is also based in Geneva, helps establish safety codes and standards for numerous areas of activity (such as nuclear energy) among the many nations that sponsor it.
National-level safety organizations tend to deal with safety questions most closely associated with the economic structure of the country concerned. Nations having limited industrial development tend to concentrate on road safety, for example. At the local level many groups exist that specialize in one aspect or another of safety. Much of their activity is conducted by professionals whose jobs relate closely to questions of safety, among them policemen, firemen, medical officers, and others concerned with health and with accident prevention. These groups seek to enlist the cooperation of educators, local governments and officials, industrial associations, and trade unions and to effect liaison with professional safety groups such as the American Society of Safety Engineers in the United States or the Institution of Occupational Safety and Health in the United Kingdom. In the United States, local safety councils may be accredited to the National Safety Council, the world’s largest safety body. In the United Kingdom the Royal Society for the Prevention of Accidents performs a role comparable to that of the National Safety Council.
Among the chief activities of individuals and organizations concerned with safety are the collection of statistics on accidents and injuries and the publication of analyses of those statistics; the study of hazardous situations and environments and the development of safer designs, procedures, and materials; the development of educational programs for employers, workers, drivers, and other groups at risk; and the design, through safety engineering, of machines, workplaces, and safety equipment that minimize the risk of injury. In recent years much activity has centred on identifying and preventing risks posed by such hazards as ionizing radiation and a wide array of chemicals and hazardous industrial wastes. The greatest challenge in the field of safety is to keep legislation and public awareness in step with the rapid development of technology and with the fresh hazards that it constantly presents.
security and protection system, any of various means or devices designed to guard persons and property against a broad range of hazards, including crime, fire, accidents, espionage, sabotage, subversion, and attack.
Most security and protection systems emphasize certain hazards more than others. In a retail store, for example, the principal security concerns are shoplifting and employee dishonesty (e.g., pilferage, embezzlement, and fraud). A typical set of categories to be protected includes the personal safety of people in the organization, such as employees, customers, or residents; tangible property, such as the plant, equipment, finished products, cash, and securities; and intangible property, such as highly classified national-security information or “proprietary” information (e.g., trade secrets) of private organizations. An important distinction between a security and protection system and public services such as police and fire departments is that the former employs means that emphasize passive and preventive measures.
Security systems are found in a wide variety of organizations, ranging from government agencies and industrial plants to apartment buildings and schools. Sufficiently large organizations may have their own proprietary security systems or may purchase security services by contract from specialized security organizations.
Development of security systems.
The origins of security systems are obscure, but techniques for protecting the household, such as the use of locks and barred windows, are very ancient. As civilizations developed, the distinction between passive and active security was recognized, and responsibility for active security measures was vested in police and fire-fighting agencies.
By the mid-19th century, private organizations such as those of Philip Sorensen in Sweden and Allan Pinkerton in the United States had also begun to build efficient large-scale security services. Pinkerton’s organization offered intelligence, counterintelligence, internal security, investigative, and law enforcement services to private business and government. Until the advent of collective bargaining in the United States, strikebreaking was also a prime concern. The Sorensen organization, in contrast, moved toward a loss-control service for industry. It provided personnel trained to prevent and deal with losses from crime, fire, accident, and flood and established the pattern for security services in the United Kingdom and elsewhere in western Europe.
World Wars I and II brought an increased awareness of security systems as a means of protection against military espionage, sabotage, and subversion; such programs in effect became part of a country’s national-security system. After World War II much of this apparatus was retained as a result of international tensions and defense-production programs and became part of an increasingly professionalized complex of security functions.
he development and diffusion of security systems and hardware in various parts of the world has been an uneven process. In relatively underdeveloped countries, or the underdeveloped parts of recently industrializing countries, security technology generally exists in rudimentary form, such as barred windows, locks, and elementary personnel security measures. In many such regions, however, facilities of large international corporations and sensitive government installations employ sophisticated equipment and techniques.
Since the 1960s, crime-related security systems have grown especially rapidly in most countries. Among contributing factors have been the increase in number of security-sensitive businesses; development of new security functions, such as protection of proprietary information; increasing computerization of sensitive information subject to unique vulnerabilities; improved reporting of crime and consequent wider awareness; and the need in many countries for security against violent demonstrations, bombings, and hijackings.
Security systems are becoming increasingly automated, particularly in sensing and communicating hazards and vulnerabilities. This situation is true in both crime-related applications, such as intrusion-detection devices, and fire-protection alarm and response (extinguishing) systems. Advances in miniaturization and electronics are reflected in security equipment that is smaller, more reliable, and more easily installed and maintained.
Types of security systems.
Security systems can be classified by type of production enterprise, such as industrial, retail (commercial), governmental, government contractor, or hospital; by type of organization, such as contract security or proprietary; by type of security process, such as personnel or physical security; or by type of security function or emphasis, such as plant protection (variously defined), theft control, fire protection, accident prevention, protection of sensitive (national security or business proprietary) information. Some of these categories obviously overlap.
Security for small businesses constitutes a special situation. Because small firms cannot afford specialized proprietary security staffs, measures must be incorporated into regular routines and staff training or be purchased from outside organizations. Theft, both internal and external, is a prime concern.
Residential security constitutes another special category. Sizable housing or apartment complexes, especially if under one management, can employ sophisticated security measures, including, for example, closed-circuit television monitoring of elevators and hallways and trained security guards. Relatively simple equipment for houses or small apartment buildings, as, for example, exterior lighting and alarms, is increasingly used. Some neighbourhoods of large cities cooperatively employ patrol services or organize resident volunteer patrols.
Some of the most effective advances in security technologies during the past few decades have been in the area of physical security—i.e., protection by tangible means. Physical security has two main components: building architecture and appurtenances; equipment and devices.
A building can be designed for security by such means as planning and limiting the number and location of entrances and by careful attention to exits, traffic patterns, and loading docks.
Equipment and devices may be classified in various categories depending on the criteria used. If the criterion is purpose, some of the principal categories are record containers, including safes and files; communications, such as two-way radios and scrambler telephones; identification, including badges and automatic access-control systems requiring the use of a code; investigation and detection (e.g., lie detectors) and intrusion-detection devices, such as photoelectric cells and ultrasonic-wave-propagating equipment; observation and surveillance, including listening and recording devices, cameras, closed-circuit television, and one-way mirrors; countermeasures for observation and surveillance, such as equipment designed to detect electronic surveillance devices; and fire protection. A classification system based on process results in another set of categories. Examples include perimeter barriers (e.g., fences, walls) and locks to prevent or control access, as well as lighting systems to aid surveillance and to deter illegal entry.
Advances in security equipment technology Gas Mask have been numerous. Some of the more noteworthy examples include sensor devices that report unauthorized removal of items; personal-identification and access-control systems that directly “read” unique personal characteristics such as voice quality and hand geometry; surveillance devices that can scan premises at night; and devices that permit surveillance at considerable distances, making entry to the premises unnecessary.
A major part of security programs consists of measures designed to recruit and effectively use trustworthy personnel. “Personnel security” is a term often used to include measures designed to select only those people for whom there is a good prognosis for trustworthiness, on the premise that losses from employee trustworthiness are more frequent and usually larger than losses from outside the system (e.g., burglary, robbery, shoplifting, espionage) and that one of the best predictors of future behaviour is past behaviour.
Common synonyms are “screening” and “vetting.” The most common technique is the background investigation, which involves obtaining all relevant available data about a person’s past education, employment, and personal behaviour and making judgments concerning the individual’s likely future loyalty and honesty. Thus, the dossier and computerized national data banks exemplify a response by a society in which great geographic mobility necessitates record keeping as a basis for judgments. Another technique is the polygraph, or lie-detector, examination. Research has also been directed to the possible capabilities and limitations of pencil-and-paper psychological tests and stress interviews. In addition to selection techniques there are other measures designed to keep personnel trustworthy after they have been brought into the system—for example, employee indoctrination programs and vulnerability testing.
Systems and procedures constitute another area of the personnel-administration approach to security. It is possible to devise work methods and management controls in such a way that security is one of the values sought along with maximizing productivity and minimizing cost. Examples include the use of automated record-keeping systems, the use of forms and reports periodically checked against physical inventories, and the application of the principle of dual responsibility, whereby work is so subdivided that the work of one employee checks the accuracy of the work of another.
Because control systems are not self-administering, they must be periodically tested and policed. A typical procedure is the vulnerability test, or “created-error” check, in which an error or breach, such as an erroneous invoice, is deliberately planted in the system to see if it is detected and reported. Undercover investigators, such as hired “shoppers” who check on the honesty of sales personnel, also play a role in monitoring the operation of control systems.
Guard-force training, supervision, Gas Mask and motivation are other important aspects of the personnel-administration approach to security. The use of operational personnel to attain security objectives is still another. Examples include engineers, production workers, and clerical staff applying government security regulations for the safeguarding of classified information, and salespeople cooperating with security staff in the detection of shoplifters. The cooperation of operational personnel to attain security objectives along with production objectives demands an interplay between knowledgeable training and communication programs, supervision, employee motivation, and management example.
The personnel-relations approach implicit in much of the above recognizes that the attitudes of rank-and-file employees and the social climate that they create can either be conducive to security or constitute its greatest enemy. Therefore, if security programs are to be successful, they must be carried out in a context of considerable understanding and cooperation of virtually the entire work force. The security program is apt to be only as good as the overall pattern and climate of social relations and loyalties of workers and executives of all ranks.
A gas mask is an item of personal protective equipment used to protect the wearer from inhaling airborne pollutants and toxic gases. The mask forms a sealed cover over the nose and mouth, but may also cover the eyes and other vulnerable soft tissues of the face. Most gas masks are also respirators, though the word gas mask is often used to refer to military equipment (such as a field protective mask), the scope used in this article. The gas mask only protects the user from digesting,[clarification needed] inhaling, and contact through the eyes (many agents affect through eye contact). Most combined gas mask filters will last around 8 hours in a biological or chemical situation. Filters against specific chemical agents can last up to 20 hours.
Airborne toxic materials may be gaseous (for example, chlorine or mustard gas), or particulates (such as biological agents). Gas Mask Many filters provide protection from both types.
The first gas masks mostly used circular lenses made of glass, mica or cellulose acetate to allow vision. Glass and mica were quite brittle and needed frequent replacement. The later Triplex lens style (a cellulose acetate lens sandwiched between glass ones) became more popular, and alongside plain cellulose acetate they became the standard into the 1930s. Panoramic lenses were not popular until the 1930s, but there are some examples of those being used even during the war[clarification needed] (Austro-Hungarian 15M). Later, stronger polycarbonate came into use.
Some masks have one or two compact air filter containers screwed onto inlets, while others have a large air filtration container connected to the gas mask via a hose that is sometimes confused with an air-supplied respirator in which an alternate supply of fresh air (oxygen tanks) is delivered.
is the process of being drawn into a (usually larger) body or substrate, and adsorption is the process of deposition upon a surface. This can be used to remove both particulate and gaseous hazards. Although some form of reaction may take place, it is not necessary; the method may work by attractive charges. For example, if the target particles are positively charged, a negatively charged substrate may be used. Examples of substrates include activated carbon, and zeolites. This effect can be very simple and highly effective, for example using a damp cloth to cover the mouth and nose while escaping a fire. While this method can be effective at trapping particulates produced by combustion, it does not filter out harmful gases which may be toxic or which displace the oxygen required for survival.Gas Mask