Document 8w51ra8L1R5BbGR2Xj4dY48y

350 FRANK A. PATTY irritant gases. Even though this is not approved practice, it has heen.Jretp? and safely used with a modified gas-mask facepiece in certain situatiolw!! apparatus protects the wearer against atmospheres deficient in oxygenjL'as as from contaminants immediately dangerous to life. However, in the usc-ioi device as well as the hose mask, the wearer is limited by what the skin willf either from the standpoint of irritation or absorption--for instance, in atmo^ containing hydrogen cyanide. The oxygen-breathing apparatus is thesipa respiratory protective device, and is a rather complicated mechanical ap`ua\ It requires training and experience in its use and maintenance, and it i *" that the wearer have a clear understanding of its mechanical parts before] at!?? ing to wear it into an immediately dangerous atmosphere. Since all states and the ASA code covering approved respiratory protective devices,$Mj| upon the results of the approval tests of the United States Bureau of Mincsij logical to be guided by the current list of approved devices from th|| S. Newly Developed Air- or Oxygen-Supplying Devices 'C-Ij New and somewhat simplified self-contained air- or oxygen-supply in|^| utilizing compressed air or oxygen, as well as self-contained oxyge^S apparatus having potassium peroxide regeneration cartridges to supp|l|| and remove carbon dioxide, have found useful application. Each canister for these devices is approved for either 30 or 45 minutes use. The?tfi are simplified and more adaptable to certain industrial uses thanfea ccoohnvveenntt'iioorniaalldTyvphee..~HWomwiruRvveerr,~~t3KTenyv rreoqmuiiirme training and experien---c--e-rcf.d-.rm w use and should never be considered as either foolproof or as simple as a; C. UNAPPROVED EQUIPMENT ^ There are many unapproved devices offered for sale to be uicjl^inSl. situations, but before selecting one of these devices it is well to^consufil responsibility involved. If a respiratory protective device is proposed'Vi-,],".? of preserving health, or of saving a life in the event of an emergehjy,>_rn#j something one can take chances with in order to save a few cents or favorite salesman. If the atmospheric contaminant is harmful, being harmful, and United States Bureau of Mines approved';,flSSpipafay tective devices are,provided, there is.evidence of an attempt.;t6.jpot^^M of the persons involved; but if unapproved devices are provided] negligent be inferred. Few employers are in a position to establish the efficiuiiy'j(;f;(IV tory protective equipment by dependable experimentation, -are--theref-ore-:dependen;t--upon--outside--advicer-Tb-use-mippro^OT * - ------------------ ------------------- -- -- --"Fi"" in industrial situations is to assume the role of guinea pig to find possible]; comings. f' 'List of Respiratory Protective Devices Approved by the Bureau of A/t-iinL'onia,' currently from the U. S. Bureau of Mines, 4800 Forbes St., Pittsburgh 13, PeimV.'<%^ .'11 RESPIHATORS AND RESPIRATORY DEVICES 351 Msmiii*, 1- Filtering Efficiency against Paint Mist ^e?centage collecting efficiency of a respirator is perhaps not of as much ^Si?the amount of.contaminant passing through the filter under various *jbes, because the amount passing through the filter determines the | i-workman's exposure. It is only fair to state that practically any Ifilter arrangement will remove some particulate matter from the air ohgh it. Where the exposure is a borderline one, that is, near or only ||||fo\ie accepted "safe" practice, a device of low efficiency may lower the |l||!lfwithin accepted limits. This is, of course, not true of gases or solvent ||||these are not affected by mechanical filters. Table 2 indicates the TABLE 2 Filtering Efficiency of Respirators in Paint Mist Resistance (inches of water) to air flow at Lead 85 liters/min. (mg./cu. m. in air) ir material IflpBer, 4 plies |||?rj?Iies $jisbeesecloth |Mf|ween cheesecloth abridge, with 20 plies pssuSi paper Before test 0.3 1.0 0.2 . -0..5.. . 00..55 00..22 00..0055 00..22 33..55 After test 0.3 1.6 0.6 .0.9 00..88 00..44 ---- 00..22 44.4.4 Before filter 395 397 374 353 449988 445588 445500 335511 5244 After filter 63 10.7 15.0 6.0 3399.8.8 2222.9.9 111177.0.0 2211.1.1 11.6.6 Filtering efficiency (per cent) 84.0 97.3 96.0 98.3 92."'0 9955..00 7744..00 9944..00 9999..77 ||||iency of some unapproved respirators in restraining lead in paint^&he tests upon which the table is based were conducted for approxi||||lf hour at an air flow of 32 liters per minute. ^meach of these materials has an efficiency of 74 per cent or better, r6'iff'!ics-.the requirement of delivering air having less than 0.15 mg. lead ^rniiterfbf Air. These tests indicate that even a layer ofAbsorbent' cotton |||||p|ipth may remove 90 per cent or more of the lead pigment in ^^fe^an isolated short exposure with no other protection available, l|ij^)rti^ while. However, when a workman is exposed to a mist con^^^Sl^^r-lead-per^b'i&^rheterT-^his-exposure^thraughkitheiiespiEatoEg^I||jer 100 times that of accepted safe practice. Obviously, percent|||j|P|j|not an acceptable means of rating respirators. ..The significant, ^^^Ariibunt of leakage through the filter and such is now used in, pp^tkbE. G. Meiter, F. H. Gibson, TJ. S. Pub. Health Service Bull. No. 1,77, 1928,