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be between three quarters of a billioh and a billion dollars, and the annual operating charges would he upward of a half a billion dollars annually. The investkatbg did not include the treatment of ssnitmy sewage or the wsstas from miscellanwus small industries which contribute to stream pollution. Certain g r o u p advocating drastic measurea for the cormtion of stream pollution have not clearly recognized the results awmplished by many industries or takenintoaccount theenonnous sums of money that have slready heen expended in the construction and operation of treatment works. For example, the synthetic rubber industry, under the direction of the Office of Rubher Reserve, has spent nearly 14 million dollsrs during the past
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three years in treating wastes from various plants. Similar action has been taken by many private industria, and the installed facilities now total many millions of dollars. It may be expected that industry will continue to install treatment works in grest numbers throughout €he country, snd this program will undoubtedly expand at an increasing rate during the next few years. The adequacy of such treatment work8 t o improve the quality of surface wsters must depend on intelligent planning and on a program of cooperation between industry and federal and state boards which enforce existing or future lam. Paisinr~obefore the Induatnd Wasta Sympasiurn at the 111th Meeting of the A n ~ a r c m Ca~.crca&Born-r. Atlantic Clty, N J.
ATMOSPHERIC POLLUTION W. C. L. HEMEON AND T. F. HATCH Industrial Hygiene Foundation, Mellon Institute, Pittsburgh, Pa.
P
OLLUTION of the community atmosphere by air- or gasborne contgminantS to some degree is an integral part of the industrial scene and will never be entirely eliminsted. One common and extreme view ignores the practical facte and demands the purity of wuntry air in our cities. At the other extreme is the attitude of smugness which associates atmospheric pollution with industrial prosperity and ignores the desirability of ita reduction by technical measures of proved practicability. For the most part, however, there is agteement on the desirahility of minimizing emission of pollutants, disagreement developing only as to the practicality of control in specific circumstances. At the outset it is necemry to dispel one misoanception that often heclouds the problem and is, therefore, a hazard to clear thinking: Rarely do the ascertaioable facts establish that common atmospheric pollutants are hamrdous to health in the sew that demonstrable ill health results from inhaling polluted air. It is a fact that appeala to the courta or to public health autborities are w n U y based on oleims of health impairment and also that public sentiment, as expressed through judicial bodies, is likely to be sympathetic to health arguments. The engineer will do well to translate the terminology so that “hazard to public health” becomes “public nuisance”. This does not alter the problem but does clarify the issue. Thus, be will not waste time and energy in attempting to ohtaiu p m f that a certsjn pollutant “will not hurt you”. Atmospheric pollution does not have to be injurious to health to be socially undesirable. The civic trend is to require more and more from industxy in matters of air polh~tioncontrol. The problem commonly affects a group of plants in the industrial community and is, therefore, B proper subject for regulation by a public agency. The usual pasition of industrial management is a willingness and desire to reduce contamination if management is convinced (a)that there ls, in fact, excessive pollution from plant operations, and (b) that it is economically feasible for the plant to abete the condition. Serious Werences of opinion commonly occur, however, on both these points. The opportunity for realiaing condition (I is much simpler where responsible management is close to the community and its affairs. Industry would be ~ $ advised 1 to take an active rather than passive position in this field and to anticipate the effects of the civic trend by assuming the lead in sponsoring urgently needed research. Clase cooperation with public agencies is ala0 advisable to ensure that any regulatory actions are based on sound engineering principles. The primary basis for wntrol is, of course, the welfare of inhabitants of the community, but gains in this respect will be limited if regulations are h o u n d or impractical.
The limited technological attention given to t the past is reflected in co;;fused thinking on many of i& aspects. This article proposes to outline broadly the nature of the problem and, more particularly, to indicate the present deficiencies in our engineering knowledge and consequent research needs. For this purpose the subject is considered in its two major aspects: Apgmisal.of: (a)Standards of atmospheric cleanliness-what is to e dw?ved? (b) Measurement of atmospheric pollutionbow is achievement measured? Control: ( u ) Kelatim between eommunit standards and permissible disrharge of industrial pollution-low murh polluting material may industry dischnrgr? (b) ,C?ntrol methoda--wahst must industrv do to reduce its load wthin the mllxlmum nermiesible lwei? The legal aspects are not considered because we are not lawyers. Moreover, it is assumed the reader is in favor of air pollution abatement. The discussion is also limited to the problem of industrial pollution per se and i s a o t concerned with coal smoke, which is a vast subject having a wnsiderable m o u n t of literature of its own (combustion engineering a d smoke abatement). *PPB*ISAL OF POLLXITION
A phenomenon fits into engineering science to the extent that it can be measured and appraised, but it can he appraised only if the measurement can be referred to m e framework of experience indicating relative goodness, adequacy, or the like. The development of meaningful standards for evaluation of atmaspheric pollution is, therefore, an essential step in putting the whole problem on a firm engineering basia. One important contaminant, sulfur dioxide, has been studied extensively with Espeot t o its capacity for d a d g i n g vegetation. The madmum safe concentration has been determined. and it is now considered good practice to operate plants producing this gas in such m e r aa to avoid ground-level concentrations in excess of 0.5 to 0.75 part per million. This standard is unique in that no other atmaspheric contaminant has received such scientific &48e88ment. There is clearly a need for additional research in a development of standards for other common air pollutants. Substances like sulfur dioxide that may do specific damage to plant or mind life or to structural materials lend themselves neatly to relatively exact treatment in the development of standmds of permieaibility. On the other hand, thoae pollutants that are primarily offensive to people require entirely ditIerent research techniques for the attainment of realistic standards.
May 1947
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Table 1. Appropriate Procedures for Measurement of Industrial Atmospheric Pollution CHARACTER O F POLLUTION SAMPLING METHOD~ SAMPLEANALWEB CABEB A N D VAPORS
Damage to vegetation, miuterials. etc.: irritation, etc.; where effect is proportional pnmerily to atm. w n c n
Water sol.: standard gas washing Basks or impinger
Microanalytical teohniques
Not water sol.: adsorbents, such BS silica gel or sotivated oarbon; also low temp. oondensation
Weighing or laboratory recovery from adsorbent, then microanalysis
GASEII AND YAPORB. DUST. FUMES, AND MIST
Nuisanoe in which effect is proportional to contact rate snd weather factors, etc., not primarily atm. oonm.
Special tests simulating damaging effects, which integrate factors of concn., wind. rain temp.. etc. M a y use natural or synthetic test surf&oes-.g.. lead peroxide cylinders. fabrics, painted surfaces, etc. DUBT, FUWEB, AND MISTS
Nuisance or heyth haesrd, where effect is ~roportional primarily to atm. oonon. Discoloration, staining: effect proportional to atm. oonon. independent of weather
Imphger: eleotrostatio precipitator; Owens dust sampler; filter paper, eto.' Filter of proper color contrast
Nuisance by deposition by gravity on surfsees. where &eet is not pronortional to atm. conon.
Settling cans; ooated slides
Mioroseopic counting: weighing; ohem. analysis for specific constituents' Comparison with speoially prepared so& of stains for partieulas situation
.
DUST
Weighing: chem. or phya. malyeia (pwtide sine examination)
FUYEB
Measurement of light absorption in situ, and correlation with conon. and westher Light screening effects: ham * Method of choice in both sampling and analysis depends an partide size. eonoentration. and other physical properties.
Prscticd standards must give due weight to the factors of tradition of the community, its socioeconomic status, and history of the industries. For example, one would not expect the same standards for a city of heavy industry as for a New England town accustomed to the operation of light industry. I n the absence of established facts from which to derive standards, it is perfectly proper to adopt vdues which represent simply a ressonable ccmpromise between the ideal cleanliness of oountry air and the high degree of pollution to which some of our cities are now exposed. The develonment of meanindul standards for the community
quired on the performance characteristics of discharge stacks-. concentration, mass rate of emission, etc., and the relation between them and resulting concentrations at ground level. Only by the development of such relations can the basic community requirements be translated into tangible engineering terms for we by industry. It is not sufficient, for example, to specify that B collector for certain fumes must have an efficiency of 90%, when the total rate of emission, height of stack, and other circumstmeea would readily permit 7.5%; in another case, 95% efficiency may be totally inadequate and unfair to the community. If mase
t o do. A plant which is discharging an irritating substanoe, for example, derives no benefit from the maximum allowahle ground concentration fixed at some point acmsa town. What is needed is a statement of the permissible mass rate of discharge of the offending material from the plant stack. Thus, in prder to apply the community standards practically, hasic information is re-
information to use & a guide in designing its control eqlipmenc The need for establishing these relations, so that industry can interpret community standards in terms of what it must do, haa not been adequately emphasized. Until i t is done, confusion and improper interpretation of regulations governing atmospheric pollution control will continue and progress will be halted.
b b The aivie trend is to require more and m o r e fmm industry i n air pollution control. Managemerit generally desires to reduce contamination if it is conrineed t h a t there is excessive pollution from their operations, a n d t h a t i t is economically feasible to a b a t e the condition. I n d u r U y xoulcl he rwll advised to anticipate the effects of the &io trend hy assunxirig the lead in sponsoring urgently needed research. Cooperation wilh puhlie agencies is also advisable to ensure that regulatory actions a m b a s 4 on sound engineering principles. The primary basis for conlrol is the xelfare of inhahitants of the community-, hut gains in this respect will be l i m i t n l if regulations are impractical. Relations permilting interpretation of c o m m u n i t y standards of atniospherio pollution i n terns of %.hat industry should do must be cleveloped and
emphasized. The difficult problem.* in the control of atmospheric pollution a m economic; the most serious are those prohlenis in which the cost of the only k n o w n method is out of proportion to the value of plant operations or to the mognitndc of t h e nuisance. Industrial pollutants arc classified according to their outstailding physical properties. A schome i s presented which is suggestive of procedures for measuring different types of pollution. Control of indiistrial pollution is effected b y tall starkx and by chcmical engineering techniques. Stacks approaching 1000 feet i n height 'nay be practical in certain situations. Meteorology, b y identifying the most effective "air streams" for the dispersal of c o n t a m i n a n t s i n t o t h e atmosphere, oan aid rnaterially in the selection of new p l a n t sites which have difficult problems of gaseous waste disposal.
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Table 11. General Classification of Pollutants, According to Outstanding Phlsical Properties POLLUTIST CHIR.~CTERISTIC A S POLLUT-LXT EXbMPLER REU.LRKS Gases and Sonic deleterious, malodorous. 01' 802 may injure vegetatioil: acid vnl,o~',. > l a y he ful.tl!cr suMivideii iiito oi,g:rnic vapors
Dusrc
Fumes and
smoke
. Mists
irritating property
Solid iiiaterials of large particale size 'relative t o fume), so Trill kettle by gravity onto surfaces near ground
Solids, but without pronounced settling properties; may he irrirating or inert
Liquid droplets; niay be corrosive: usually permanent
corrode materials: nlalotiorou~organic ronipounds in minute concentration
a n d inorganic. acid or neutral, e r r .
I'nel dusrs (coiiihustio~i!: coal. coke. a,41
I n ~ p o r ~ t a ntto tli,tinqui>li betwecu t l i r w and roal ,inoke n-liirh we often grou1,ed a* ">tnoke" i n loo,^ tprr!!inolog:y
Xliiiei~al(IuhtC: nietallir and iioiiiiletallic (cement k i l n , rock w u 4 1 e r . ~ .iiietallurgical furnaces, etc.) .\Iiscellaneou~ducts ~ v i t hcli,.tinmive pt~opei,ties, readily identifying t h e soume (caustic, c h o m e salt-. dyer. allergens. organic dusrs)
\‘cry hroad clas. which. for some ronsiderations, might he broken d o w n
further Materials easily ragged by laymen
1,'unics are result of volatilizarioll and condensation of solids (e.g., zinc oxide!
Smoke included for completeness, but not particularly characteristic of industry
Smoke results from incomplete combustion
Smoke and coal dust may originate from identical furnaces hut have different causes, so should he differentiated
903 is only outstanding. coninio~iexample (steam is a mist, hut impermanent)
This class is logical from atandpoint of collection, even though in nuisance a
