Document 1gYd3m2R37a9E94RQ4JkGRb9X

1957 National Safety Congress Chemical Industries breathing problems 'would be cuufinrd to underwater or to travel m high altitudes. Unfortunately, pure air is a relatively rare commodity, and is much harder to obtain pure than many chemical elements and com sources and appended to tins paper shows that respiratory problems have occurred in many diverse activities. Specialized knowl edge ad action in advance is essential if such injuries are to be prevented. pounds. It is glamorous or unusual in Soane variations of the air are canvrf by natural forces (such as moisture from xaio or dust from winds on dry earth), while $nm^ are due to TM>n (such as combustion products, unburaed or incompletely burned fuels, solvents, vapors, dusts, fumes, inert and toxic gases). When these variations are email, we say that the air as "pore,** but when the variations, either alone or in com bination, exceed our ability to adapt to them, or our abilhy to tolerate them, wc say the air is "had.** cidents which produce serious results; fail ure of a pressure system in an airplane at high altitudes will cause blackouts m sec onds; above 43,000 feet, even breathing pure oxygen is not adequate-- a pressure suit or a pressurized cabin is essential. On the other hand, no less serious are the problems when commonplace materials, such as a few sausages overheating and burning on a fry ing pan on a kitchen range produced suffi cient smoke and toxic gases to overcome the occupants; firemen required respiratory pro tective apparatus to effect a rescue of the air pollution unconscious victims. So simple yardstick has yet been devised to tell us when air ceases to be "pure," although numerous air pollution studies are underway, and threshold limit values (maxi mum allowable concentrations for industrial exposures) are available as a guide. We have just begun to realize that air pollution control may be even snore important than stream pollution control. When extreme conditions exist, as in London, Meuse, Danora or Los Angeles, we know that /taw arwf smokes resulting fran fires have been studied for years, and excellent reports are available, but it is impossible tc predict what gases may be encountered or in what concentrations in a give: fire. A large number of different flammable chemi cal compositions or chemical combinations that change with heat, such as plastics, fab ric*. insulation, refrigerants, solvents, paints. trwfttcitfcE and building materials, play im portant roles in our daily lives. foiman life is more difficult thzn other times when smog is not present. VARIETY OF GASS IN FIRES On a minor scale, every year a serious problem exists from dost or pcBat (such as rose fever, hay fever, or ragweed fever) for allergic persons, and we have found that respirators are frequently considered a a welcome supplemoU to dedication for the relief of such conditions. Jn OfMrtirm tO CZlboU mOQOXidc, OtrboO dioxide, and water (presort in nearly all fires), one may expect ammonia from burn ing wool, cyaoogqi from burning silk, ac rolein from burning fats, sulfur-containing gases from burning rubber and leather, and chknine-eontainmg gases from burning or smouldering chlorinated plastics. Tram paled Most breathing air supply problems can newspapers smouldering m limited oxygen, be controlled with adequate ventilation. If 41 per roe of the total gases given off was air could be properly treated to remove par found to be carbon monoxide, and 43 per ticulate natter, noxious vapors, and toxic cent was carbon dioxide. gases, bested or cooled, and then distributed A pole of newspapers in a large open ballas required, breathing can be reduced to a tray would give an entirely different concen minor problem insofar as purity of air is tration of carbon monoxide and carbon concerned Unfortunately, adequate remUa- dioxide tritfim the breathing zone than the tion and air treatment is sometimes impos eymg pfo burning in a small enclosed base sible or impractical where emergency action ment. 'Determinations ranging from two most he taken to preserve life and property. per fT* to lour per cent carbon monoxide Therefore, we must provide man with have been trade using Ttcogtuued CO de respiratory protection if we expect him to tectors in the smoke of balding fires in the survive. A glance at the case histories of same room in which firanen were engaged incidents collected at random from many in extinguishment, by a medical doctor 12 wearing self-contained breathing apparatus. Pneumonokonioses (Greek for lung dust) A vigorous movement is now underway to or pneumoconioses are a group of lung encourage fire and other rescue services to conditions which result from the inhalation use adequate respiratory protection more of dust Silicosis is one of the most common effectively. types of pneumoconiosis, and is caused by AIR CONTAMINANTS The convent!anal classification of air con taminants follows: the inhalation of "free" or "unromhined" silica, sudb as quartz, opal flint and crystobalhe. Many other dusts may produce long involvement such as ahsestos, talc, the de A. Aerosols (dispersoids) (particulate contaminants)--dusts, fumes and mists. A better classification of aerosols is hosed on ph)*siologia] effects: A. Nuisance and Inert: produce no known injuries: calcium carbonate, magnesium carbonate, gypsum rates, carbon, iron and barium. Other dusts cause chemical irritation, such as the adds, alkali substances, fluorides and chromates. Allergic reactions may be caused by common dusts such as pollens, synthetic resins, plastics, felt, fur, gums, spices, to bacco, paper, rubber, wood, starch, floor, and wooL The Bureau of Mines groups alt the B. Inert pulmonary reactions: produce non-specific pulmonary reactions: sili cates, aliwrwmtrn C Minimal pulmonary fibrosis-producing barium compounds, tin, iron oxides D. Extensive pulmonary fibrous-producing silica, asbestos E. Chemical Irritants: produce inflamma tion or ulceration alkaline reactions: adds, fluorides, chromates above dusts as "Fneumocomosis-Produang and Nuisance Dusts-** TOXIC OUSTS Another classification of dusts refers to `Toxic Dusts." Some have a lower thres hold limit or maximum allowable concentra tion dan does lead, although the Barcas of Mines classification uses lead as a reference. Among aerosols more toxic than lead are: cadmium oxide fame, chromic arid and F. Toxic systemic poisons: produce patho logic^ reactions: lead, manganese, anti mony, arsenic (not more toxic than chromates, mercury, mercury (organic), yellow phosphorus, picric arid, selenium, tellurium, calcium arsenate. Pb), arsenates, organic-phosphates, Respirators approved for all the above rarfinium, radicBcZjv^ bayBiam (more dusts (both toxic and jmniuKXtMUosfe-pTP- toxic than lead) ducing and nuisance dusts) are called "dust" G. Allergic manifestations: produce aller gic reactions: pollens. H. Fever-producing reaction: action un known or allergen: metal fumes, cer tain textile dust, (hemp, cotton, jute, bagasse) respirators. A few substances, such as beryl lium and radioactive substances, are not currently covered by Bureau of Mines schedules. "Fumes" include aerosols formed by the condensation of vapors from heated metals. Mdti&g. cutting, and welding of zinc, lead. A. AEROSOLS i-admiu w and other produce such Formerly called dispersoids or particulate fumes. contaminants, these are substances present in "Mists" and uSpraysn include liquid drop- the air as minute particles (such as dusts), jets formed wfiox liquids are carried into as fumes (such as metal fumes), or as ousts the air or are formed by a reaction with (such as chromic-add mists). In grouping the moisture in the air. An interesting ex these together, it is recognized that they ample is OJ parts per minion sulfur dioxide, may be physically filtered, screened, or ad with sunlight, forms 20,000 particles per cc sorbed from the air until properly d^g**** of sulfuric arid mist. filters. Aerosols may range in sue item The avaSahafity of filters with pore sites \50 microns to a fhoisandtii of at micron m sze (1 micron equals 39.37 millionths of an inch mix 10-4 centimeter'). Many tinsts are aim fire and explosion hazards. iTom lti milVrmicroas (apprommalely the size of the polio virus) to five microns (the tiie of common contaminants in liquids) has greatly improved and speeded up analyses 13