Chapter 4-PREVENTIVE ANfD CORRECTIVE DAMAGE CONTROL 



clothing, which includes a parka, trousers, 

 rubber boots, and gloves, is easily decontami- 

 nated. 



Ordinary work clothing (including long under- 

 wear, field socks, coverall, field boots, and 

 watcli cap) is partially effective in preventing 

 droplets of liquid chemical agents and vapors 

 from reaching the skin. However, ordinary work 

 clothing is not as effective as the other types 

 of clothing in preventing contamination. Under 

 some conditions, personnel may wear two layers 

 of ordinary work clothing to achieve greater 

 protection than can be obtained with one layer. 



PROTECTIVE MASKS 



The protective mask is a very important 

 item of protective equipment, since it protects 

 such vulnerable areas as the eyes, the face, and 

 the respiratory tract. The protective mask pro- 

 vides protection against NBC contamination by 

 filtering the air before it is inhaled. 



In general, all protective masks operate on 

 the same principles. As the wearer inhales, air 

 is drawn into a filtering system. This system 

 consists of a mechanical filter which clears the 

 air of solid or liquid particles and a chemical 

 filling (usually activated charcoal) which absorbs 

 or neutralizes toxic and irritating vapors. The 

 purified air then passes to the region of the 

 mask, where it can be inhaled. Exhaled air is 

 expelled from the mask through an outlet valve 

 which is so constructed that it opens only to 

 permit exhaled air to escape. 



Protective masks do not afford protection 

 against ammonia or carbon monoxide, nor are 

 they effective in confined spaces where the 

 oxygen content of the atmosphere is too low 

 (less than about 16 percent) to sustain life. 

 When it is necessary to enter spaces where 

 there is a deficiency of oxygen, the Navy oxygen 

 breathing apparatus (OBA) is used. 



DETECTION OF NBC CONTAMINATION 



The very nature of NBC contamination makes 

 detection and identification difficult. Nuclear 

 radiation cannot be seen, heard, felt, or other- 

 wise perceived through the senses. Biological 

 agents are small in size and have no charac- 

 teristic color or odor to help in identification. 

 Although- some chemical agents do have a char- 

 acteristic color and odor, recently developed 

 nerve agents are usually colorless and odorless. 



It is obvious, then, that with contamination 

 which cannot be seen, smelled, felt, tasted, or 

 heard, specialized methods of detection are 

 required. Mechanical, chemical, and electronic 

 devices are available or under development for 

 the detection of NBC contamination. 



Detection of Nuclear Radiation 



The instruments used for detecting radio- 

 logical contamination are known as radiacs , 

 the name being an abbreviation of radiation , 

 detection, indication, and computation . Various 

 types of radiacs are used aboard ship and at 

 shore stations, since no single type of radiac 

 can make all the radiological measurements 

 that may be required. 



The radiacs used aboard ship include (1) 

 intensity meters for measuring gamma radia- 

 tion; (2) intensity meters for measuring beta 

 and gamma radiation; (3) survey meters for 

 measuring alpha radiation; and (4) dosimeters 

 for measuring accumulated doses of radiation 

 received by individuals. These basic types of 

 radiacs are described briefly here. Specific 

 information on operating principles and detailed 

 instructions for operating the instruments may 

 be obtained from the manufacturer's technical 

 manual furnished with each instrument. 



GAMMA METERS. — Intensity meters for 

 measuring gamma radiation include both port- 

 able instruments and fixed systems installed 

 aboard ship. The intensity of gamma radiation 

 is measured in roentgens per hour (r/hr) or in 

 milliroentgens per hour (mr/hr). The roentgen 

 is a unit of measurement for expressing the 

 amount of gamma radiation or X-ray radiation. 

 A milliroentgen is 1/1000 of a roentgen. Radiacs 

 used for measuring large amounts of gamma 

 radiation are called high- range intensity meters ; 

 these instruments are usually calibrated in 

 roentgens per hour. Radiacs designed for meas- 

 uring smaller amounts of gamma radiation are 

 called low- range intensity meters ; they are 

 usually calibrated in milliroentgens per hour. 

 Both high-range and low-range instruments are 

 likely to have several scales; a range selector 

 switch allows selection of the appropriate scale 

 for each monitoring survey. 



BETA AND GAMMA METERS. -Intensity 

 meters which measure gamma radiation and also 

 detect or measure beta radiation are usually of 

 the Geiger-Mueller type. These instruments can 



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