Analysis and comparison of available data on air quality criteria in Member countries: inter-regional symposium on criteria for air quality and methods of measurement, Geneva, 6-12 August 1963

V.l n R I n !.' C"' ·~ • ·r ··-' f'. \,. t ""- - , I \...,. r\. . ..,.. • I 1- . ORGANIZATION f', ,, - - DE LA SANTE ,, ..... ~ OO'ER-REG IONAL SYMPOSIUM ON CRIT'ERIA FOR~. . v!HO/AP/11 AIR QUALITY AND METHODS OF MEASUREMENT 19 July 1963 Geneva, 6-12 August 1963 ORIGINAL: ENGLISH ANALYSIS AND COMPARISON OF AVAILABLE DATA ON AIR QUALITY CRIT'ERIA IN MEMBER COUNTRIES by August T. Rossano, jr, Sc.D. Research Professor, Department of Civil Engineering University of Washington, Seattle 5 Interest in ruabient air quality standards is of relatively recent origin. It is now generally recognized that progress in protecting the air resource can be greatly enhanced by the establishment of targets or guides for acceptable air quality. Very few countries have made any seious attempts at deriving air standards, thus information and data in this field are quite limited. The objective of this presentation is to review air quality standard-setting activities of Member countries. In addition, an analysis and comparison will be made of criteria and maximum allowable concentrations developed by these countries. Since the terms criteria and standards will be encountered throughout this discussion it may be well to define these terms to avoid possible confusion. For the purposes of this discussion standards will refer to the values established by a legally responsible authority. In contrast, criteria will represent yard-sticks, rules or tests with which standards are selected. Thus it is possible for different governmental authorities to adopt different legal standards even though the criteria used in each case are the same. AMBIENT AIR STANDARDS IN ME7V1BER COUNTRIES Great Britain The industrial revolution of the eighteenth to nineteenth century had its birth in Great Britain. This was made possible largely because of their abundant supply of coal which became such an important source of fuel for producing the power demanded by the newly emerging industrial economy. AP/11 page 2 Coal smoke and gases soon became th~ major form of air pollution in Great Britain. To a large extent coal smoke, grit and oxides of sulfur still characterize the principal pollution problem in the large metropolitan and industrial centres of England. ·t;::-lile air quality standards were not employed as an approach towards preventing and abating air pollution, England was the first country to pass legislation aimed at ccnt:;."olling air pollution. In the Public H~alth Act of 1936 smcke was declared to be a public nuisance which, if it wont unabated nfter due notice by a local authority, could result in trial. The guilty violator could be fined up tc £50. Under this act, local authorities could pass regulations pr0scribing the permissi~l~ amount of smoke 2missions in terms of colour, d~nsity and content, from all sources except private residences. In general it was an offence to discharge black smoke for d. total of ",xo r;;ir.t;.tes 1dthin any tbirty-mi_nute period. The disastrous smog of December 1952 resulted in the appointment of a Committee on Ai~ Pollution to investigate the nature, causes and eff~cts of air pollution, as well as the efficacy of existing central measures. The recommendatior13 is;:,uin,_, f:·~u .. , th;_s study arc contained in the Clean Air Act of 1956. One of the most important features of this Act is the stipulation concerning "smokeless zones". Local authorities can define such areas in which the emission of dar~c smoke is str:.ctly regulated. Dark smoke including soot, ash and grit is defined by the Ministry of Housing and Local Government as being as dark or darker th::m Shade No. 2 of the Ringlemann Chart. The maximum frequency and duration of emission of s-_vh .:::n'J:.;:e is also specified. The Minister may require the installation of apparatus for indicating or recording the smoke donsity. The information so obtained shall at all tines be made a·!ailable to local authorities. Pollution from chemical and ether processes is regulated, not by local authorities, 1:-ut by the Alkctli Inspectors from the Ministry of Housing and Local Government. 'Ihe Alkalj_ Act of 1906, and zubsequcnt amendments, contains a list of o:-noxious pollutants o.s we2.1 as a schedule of processes which must be registered annually. Such industr:i.es are r·equirt-d to employ the "best practical means" for preventing the escape of undesi~ablc pollut~~ts to the atmosphere. Maximum concentrations of total acidity in the waste gases are stipulated for certain processes. AP/11 page 3 With the exception of West Germany and Czechoslovakia, other countries of western Europe likewise h2.ve not ~dQpted ~ir quQlity standards. In general they control of air pollution in Europe relies heavily upon regulations prohibiting the discharge of pollutants which may endanger the public health, or may be detrimental to safety, crops and public monuments or maybe constitute a public nuisance. Though regulations·do not stipulate the maximum permissible ambient air concentration of a pollutant, some countries like France and Belgium specify the percentage of sulfur dioxide or amount of particulate matter permitted in the flue gases. West Germany Air quality standards for six specific gases have been developed by the Western German Commission. The specifications for each gas were developed by a separate committee under the supervision of the Committee for Clean Air of the VDI (Verein Deutscher Ingineure) • - The standards are based on criteria relating types of effects on positive receptors to specified concentrations of the pollutant. in Table 1. These criteria are shown Listed in Table 2 8.re; the 2-ir quc.li ty standards themselves for the six gases, according to a single short exposure or one of thirty minutes duration. As published, the standards are accompanied by supporting information outlining the objectives and limitations of the standard, the properties of the pollutant and its effects. on-man, plant and animals. USSR Soviet hygienists can justifiably claim the distinction of being the first to develop maximum allowable concentrations of air pollutants, their first publications in this field dating back to 1949. The air quality standards employed in Russia are developed by a permanent committee appointed by the Ministry of Health. Various portions of the standards are assigned to qualified members of the committee. The standards as finally adopted by the Ministry are based on the recommendations of the entire committee. AP/11 page 4 In Table 3 are listed the criteria upon which the USSR air quality standards are based. Table 4 represents the latest Russian compilation of maximum allowable concentrations of air pollutants. It can be seen that two quantitative indices are used, namely, maximum concentration for any single instantaneous exposure, and average 24-hour exposure. The first index is based on the reflex reaction of the respiratory system and odour to any one exposure. The second index is concerned with the development of chronic effects from long-term exposures. Czechoslovakia Czechoslovakia has established air quality standards for a large number of pollutants. In general their values are similar to those in the Soviet standards. A nQ~ber of them however differ, and these are shown in Table 5. United States of America In the United States definitive progress in developing air quality standards has been made in only two states, Oregon and California, although other states are considering action in this regard. The air quality standards in Oregon pertain only to suspended particulate matter. The Oregon State Sanitary Authority, a division of the State Board of Health, has developed specifications in connexion with two types of land usage, namely, residential-co.-·1:·t;~l'ci:,.l ancJ hc~nry inJustry. In ac.~_d.i.tion a standEJ.rd for CaO has b~2n set for residential-co>:1:'1.;:r•ci3.l Rr<.::as. The vRlucs s-2t n.ro not s.l)'o:ulutc ntuab,.;rs but rather concentrations above the normal background. in Table 6. These specifications are listed In addition, Oregon also has adopted standards for particle- fn.J.l-out in accordanco with Table 7. AP/11 page 5 TABLE 1. -CRITERIA FOR Am QUALITY STANDARDS FOR WEST GERMANY Pollutant Concentration - .. i_n p_.p_.m. Chl,or~ne .900 . ·- 10-100 1 -. 0.3-3.0 0.05 Hydrochloric acid 100-1000 10-50; 10 5 Hydrogen sul- fide 700 400-700 170-300 100-300 ... 70-150 20-30 1.5 o.3 0.1 0.025 Nitric acid 25 Nitrous oxides 40-80 10-20 1-2 0.1 Sulfur c.~io:.::id0 lOO 10-50 1-10 1-2 0.3-1.0 0.15 Source: 11 Stern, A. c. -- --- Effect Species .. -- . De~th .. -· Animals Siclmess Animals Irritation Man . pamage Plants .. Olfactory threshold Man Leaf damage Plants No damage Plants Irritation Man No organic damage Man Quickly fatal Man Dangerous (30 min. or less) Man Intense local irr'itation Man Spontaneous Animals _Sl:i.ght symtrtgn!3 . -- ·- . .. Man Strongly perceptible odour Man Toxic l:UJ:lit Plants Definitely perceptible odour Man . Slightly perceptiqle odour Man Olfactory threshold Man Damage Plants Pulmonary ocde::o1a Animals Methemoglobin formation Man Minor irritation Man Olfactory threshold Man Strong irritation Man Irritation Man Contradictory findings Man Damage Plants Perception threshold Man Tolerance limit Plants AP/11 page 6 TABLE 2. AIR QUALITY STANDARDS FOR WEST GERMANY (parts per mill-ien--by volume) -· .. Ambient c~i:, cstc.nc1arct . . Pollutant Average for 30 min • .!?. Single a measurement- exposure Chlorine 0.5 0.1 Hydrogen chloride 1.0 0.5 Hydrogen sulfide 0.2 0.1 Nitric o.cid 1.0 0.5 Oxides of nitrogen 1.0 o.so Sulfur dioxide 0.3 0.3 a - Permissible excess over half-hour average value. E. Not to be exceeded in more than three half-hour periods daily. Source: 11,10 Stern. A. c. TABLE 3. Substance Notes Animal Human clinical electrocortical experience reflex threshold i I --- --- ' Acrolein -- --- --- Arsenic a --- --- Benzene -- --- --- Carbon disulfide -- --- --- Carbon monoxide -- --- --- Chlorine -- --- --- Dichloroethane -- --- --- Fluorine b 0.07 - --- Hydrogen chloride -- --- --- Hydrogen sulfide -- --- --- Lead -- --- --- Manganese -- --- --- Mercury -- --- --- Methanol -- --- --- Nitrogen oxides -- 1.0 --- Phenol -- --- --- Phosphorus oxides c --- --- .Sulfuric acid aerosol -- --- 0,4 Sulfur dioxide -- --- 0.6 ~ Arse~ious acid not included b - As F ~As P205 THRESHOLD VALUES USED IN FORMULATING USSR AIR QUALITY STANDARDS (Values are in mc/m3 ) Values consicler·cd in establis.l1ing air qu01lity standards Single exposure Human odour Human rcspir~tory Human d2rk Hurnan Human perception c;da.pto.tion chron1.Ximctric clinico.l threshold response threshold threshold rosponsG threshold expc;ric.nce --- --- --- --- --- 0.8 1.5 0.6 1.75 --- --- --- --- --- --- 3.0 --- --- --- --- 0.05 --- (J,04 o.ol~ --- --- --- --- --- lOO 0.8 1.5 1.0 1.5 --- 12.2 6.0 6.0 --- --- --- --- --- --- 0.2 0.1 0 'l . "'· 0.2 0.6 --- 0.01 --- --- --- --- ' ' --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- 4.3 --- 3.3 --- --- --- --- --- --- --- 0,02 --- --- --- --- --- --- --- --- 2.0 0.6 1.0 0.7 --- --- 1.6 --- 0.6 --- --- AP/ll page ·7 /8 Average for 24-hour daily exposure lmimal Animal cc•nditioned Water quality std. rc·flcx iDhibitlon clinical (inhalation experience: threshold equivalent) (humon equivalent) --- --- --- '~---- --- --- --- --- --- 0.007 --- 3.2 --- --- --- --- --- 20 --- --- --- --- --- --- --- 0.02 --- 0.13 --- --- --- --- --- --- 0.02 --- 0.013 --- --- --- --- --- 0.0003 50 --- --- --- --- --- --- --- --- --- --- --- --- ---· --- --- --- --- --- Source: Stern A. C. Air Pollution Standards in Stern A. C. (Ed.) AIR POLLl~ION of Vol. II, Academic Press, New York, 1962 I I I ! I I AP/11 page9 TABLE 4. LIMrrs OF ALLOWABLE CONCENTRATIONS OF ATMOSPHERIC POLLUTANI'S IN THE USSR 1. 2. 3· 4. 5- 6. 7. 8. 9· 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27· 28. 29. 30· 31. 32. 33. 34. 35· Air· pollutant Acetone Acrolein Amylacetate Arsenic and ·its inorganic compounds (as As) Benzene (benzol) Benzine (as C) Butylacetate Carbon disulfide Ca;rbon monoxide Chlorine Ch;Lor:-9_pr~n~ . . . Chroma~e (as Cro3) Dichlorethane Diphenyl Dust-(non-toxic) Ethylacetate Fluorine and its Formaldehyde _ Furfural compounds (as F) Hydrogen chloride··· · · · Hydrogen sulfide Lead and its compounds (as Pb) Lead· sulfide (a:s Pb) ·· -· · · Manganese and its compounds (as Mn) Mercury Methanol Methylacetate Nitrogen oxides Phenol Phosphorus anhydride Soot Styrene Sulfuric acid Sulfur dioxide Vinyl acetate 9 Source: Ryazanov, V. A. Max. cone. at 1 time 0.35 0.3 0.1 2.4 5-.0 0.1 0.03 6.0 0.1 0.25 0.0015 3.0 0.01 ... - 0.5 . 0.1 0.03 .. 0.035 . --- 0.05 0.05. -. 0.008 ---- ---- 0.03 _..., __ 1.5 0.07 0.30 0.01 0.15 0.15 0.003 0.3 0.5 0.2 Average during 24 hours 0.35 0.1 0.1 .0.003 0.8 1.5 0.1 0.01 l .• o. 0.03 o.o8. 1.0 0.01 0~15 0.1 0.01 0.012 0.05 - - 0~015 0.008 0.0007 . . --- 0.0017 ·- ... 0.01 0.0003 0.5 0.07 0.10 0.01 0.05 0.05 0.003 0.1 0.15 0.2 . AP/11 page 10 .. TABLE 5. CZECHOSLOVAK Affi QUALITY STANDARDS WHICH DIFFER FROM USSR STANDARDS (maximum allowable concentration in p.p.m.) Pollutant One time exposure 24 hr - mean .. cs2 -HCl NO + N02 Tar (mg/m3) Source: . 10 Stern, A. C. 0.16 0.05 0.07 0.02 0.2 o.w 3.0 1.00 TABLE 6. OREGON STANDARDS FOR SUSPENDED PARI'ICUI.ATE MATTER (mg/m3 above normal background) Type of land use Total suspended matter CaO Residential-corrmercial 0.15 0.02 Heavy industry 0.25 ---- Source: Stern, A. c. 10 TABLE 7. OREGON STANDARDS FOR PARTICLE FALL-OlJI' Land use Existing areas: Residential or commercial Industrial Future zoning: Industrial parks Light industry Hea, vy industry SourC!e: 10 Stern, A. c.· Tons/square mile/month (above normal background) 15 45 10 20 35 • California .'\P/11 page U/12 The most extensive development of air quality standards in the United States has occurred in California. The action was initiated by a mandate from the 1959 California legislature to the state department of public health. The legislature specified th::;.t the standards of air quality "shall be so developed as to reflect the relationship between the intensity and composition of air pollution and the health, illness, including irritation to the senses, and death of human beings, as well as damage to vegetation and interference with visibility". The California ambient air quality standards are shown in Table 8. Accompanying the specificatio~s is a set of thirteen explanatory footnotes. It will be noted that a graded set of standards ':3.s established in which the concentration determines the seriousness of the effect. Each pollutant specification is expressed in terms of a concentration and time period, the latter being either of one hour or eight hours' duration. 'I'he criterion for each standard is shown in the accompanying parenthesis. In recognition of the fact that the California air pollution problem stems in large measure from atmospheric reactions between certain hydrocarbons and oxides of nitrogen in the presence of sunlight, considerable attention was given to the primary pollutants which are involved in these reactions, as well as those secondary reaction products which cause the characteristic effects of eye irritation, vegetation damage, visibility restriction, rubber cracking and odour. An l:ldi:i'ect i~d5.cator, oxidant index, was used in place of specific pollutants, such as oxides of nitrogen and hydrocarbons since extensive and reliable data on oxidant levels existed ar:d since oxidants were previously shown to correlate reasonably well with the effects mentioned above. It is important to note that these standards provided the basis upon which to calculate the required reduction of motor-vehicle emissions which are regarded as the major source of pollution in the metropolitan areas of California. Such calculations in turn yielded the data required for developing the California motor- vehicle emission standards in terms of maximum allowable concentrations of hydro- carbon vapours and carbon monoxide gas. POLLUTANT Photochemical Pollutants Hydrocarbons _ dioxide Oxidant Ozone Photochemical ~erosolG Carbon monoxide Ethylene Hydrogen sulfide Particular matter Sulfur dioxide Sulfuric acid Carcinogens Hydrogen fluoride Lead TABLE 8. CALIFORNIA STANDARDS OF AMBIENT Ail'. (lUALITY1 "ADVERSE" Lw~L Level at vrhich there Hill be se-nsory irritation, damage to vegetation, reduction in visibility or similar effects 110xident Index 0.15 p.p.m. for 1 hour by the potassium iodide method (eye irritation, damage to vegetation and visibility reduction) Not applicable 0.5 p.p.m. for l hour or 0.1 p.p.m. for 8 hours (damage to vegetation) 0.1 p.p.m. for 1 hour (sensory irritation) Sufficient to reduce vlsl- bility to less than 3 miles when relative humidity is less than 70 per cent. 1 p.p.m. for 1 hour or 0.3 p.p.m. for 8 hours (damage to ve.::;etation) Footnote 8 Not applicable Footnote 11 Not a~-'Plicable "SERIOUS 11 LEVEL Level c:.t wh:Lch th·.crc will be altc:cation of bodily func- tjon or vfuich is likely to l~ad to chronic disease Footnct~ l Footnct~ 2 Not applicahlc Footnot~ ~ Not applicable 30 p.p.m. for J :1.:mr2 or 120 p.p.m. for 1 hour (interference with oxy,::•.:::n transport by blood) Not arplicabl= Footnote S Not appli.ca1Jl,_ 5 p.0.1:1. f~,r 1 hcur (broncho- con;·tr_iJ;-Li·!l~ in hurnarc. : .1Jb- J·,-,~+--) .._.v ....,.._., Footnot,_ '- Footnc:tc 10 Footn~..-1~.: 12 Footnote 13 "EMERGENCY11 LEVEL AP/11 page 13 Level at which it is likely that acute sickness or death in sensitive groups of per- persons will occur Footnote 1 Footnote 2 Not applicable Footnote 4 Not applicable Footnote 5 Not applicable Footnote 7 Not applicable 10 p.p.m. for 1 hour (severe distress in human subjects) Footnote 9 Not applicable Not applicable Footnote 13 1 As amended by State Board of Public Health, 16 March 1962 and incorporated into Ul' Cu.ll~·,·rnl_-:., /,dmlnL::trative Code, Title 17, Chapter 5, Subchapter 5, Article 1. Source: California Department of Public Health2 AP/11 page 14 Footnotes 1. Hydrocarbons are a group of substances most of which, normally, arc toxic only at concentrations in the order of several hundred "'arts pel' million. HowevE.r, a numbt.:r of hydrocarbons can react photochemically at very low concentrations to produce irritatL1g and toxic s~bstances, Be;causc of the large nc<mber of hydrocarbons invol':ed, tht.· complexity of the photochemical reactions and the reactivity of other compounds such as nitrogE.n dioxide and ozone, it is not yt:t possible to est:~blish "serious" and "emergency" levels for hydrocarbons. From the public health standpoint, the concentration of those hydrocarbons which react photoch0.-mically should h:; mainto.ined at or below the level associated v>lith the oxidant index defined in the "adverse" standard. 2. Five p.p.m. nitrogen dioxide for eight hours will produce temporarily decreased respiratory function in anim:J.ls. High l<.JVGl:::: (150-220 p.p.m") in short t:;xposures produce fibrotic changes in the lungs of man that may end fatally. More data on human exposures will be nE.cded prior to setting a standard. 3. Ozone, at 1 p.p.m. for eight hours daily for about a year, has produced bronchioliti~ and fibrositis in rodents, impairment data have been reported; at 1.25 p.p.m. some effect is obscrveci on residual volume :md diffusing capacity. would be needed oefore a standard is set. ExtrapolatLon of these data to man is difficult. The varic..bility of the tests was not reported. Functional Additional data 4. A value of 2.0 p.p.m. of ozone for one hour may produce serious interference with fw.1ction in h<.:althy persons c.nd the assumption i:3 made that this might cause acute illness in sensitive persons. 5. Given certain assumptions concerning ventilatory rates, acute sicl-mess mic:£ht result from a carbon monoxide level of 240 p.p.m. for one hour in sensitive groups becausE of inactivation of ten per cent. of the body's haemoglobin. In any event it is clear that when a population exposure limit has been set for carbon monoxide, because of E.xposures from other sources, community air pollution standards should be based on some fraction of' this limit. 6. Hydrogen sulfide is not knovm to produce chronic disease in humans but there may be durable sequelae from acute exposures. The disagreeable odour may interfere with appetite in sensitive groups of persons at about 5 p.p.m. At high concentrations loss of the sons~ of smell occurs. This has bel?n reported at 100 p.;:-,.m, for expo.sures lastlng two to 15 minutes. Conjunctivitis and mild resplratory tract irritation have been reported at levels of 50-100 p.p.m. for one hour. 7. Acute sickness and death with neurotoxicity may occur at concentrations of' several hundred p.p.m. It is 'icry unlikely th,~se leveL:; will occur in community air pollution. 8. A sulfuric acid mist level of 1 mg/m3 v1ith an average particle size of 1 micron vdll produc<e 3. respiratory response in me,n. It is not possible to generalize from this for all air pollution conditions, because under natural conditions, particle size will vary. Only with large droplets would sensory irritation be produced without other physiological effects. g. A level of 5 mg/m3 of sulfuric acid mist for a few minutos produces coughin:; and irrits.tion in normal individuals. Presumably, it could cause acute illness in sensitive groups of persons in a period of one h01.1r. 10. Carcinogens include a fc:w organic compounds such as some polycyclic hydrocarbons and some metals such as arsenic and chromium. Studies on effects of such substances are currently under way, bL1t there are not sufficient data, at present, to set standards. In the m·2antimc::, it is recommended -;;ilat concentrations of carcinogens in air should be kept as lov1 as possible. 11. Hydrogen fluoride and other airborne fluorides settle upon and some- are ai)sorhc:d into vegetation. When forage crops containing 30-50 p.p.m. of fluoride measure-d on a dry weight basis are regularly consumed over a long period the teeth and bones of cattle may show changes, depending upon age, nutritional factors and the form of fluoride ingested. Such changes may or may not have :my economic effect. Fluorides at these levE:ls do not necessarily cause injury to the forage plants themselves. However, injury may be produced in certain species of vegetation upon long-term exposure to low levels of atmosphGric fluorides. 12. The irritating properties of hydrogen fluoride in experimental human -::xposure hav._ ix;en manifested by desquamation of the skin, at concentrations of 2-5 p.p.m. irritation also occurs from hydrogen fluorides but quantitative data are not c.dcquc.tc to support a standard. Mucous membrane 13. It is clear that lead levels should be set on the ~Jo.sis r_:,f avc-rage values for long periods. While data arc abundant coll.cerning human response to sic;ht-hours-a-day, five-days-a- week exposures, data are insufficient for the effects of the continuous exposure inhE.:rent in community c.ir pollution. \~hile laboratory studies 'tlill be pursued with vigour, it becomes very important that local agencies collect data on existing lead Jcvels. Since l~ad exposures are from multiple sources, community air pollution standards should be based on a portion of the total limit for population exposure. Los Angeles County AP/ll· page 15 As early as 1954 there was considerable public concern in Los Angeles that air pollution could reach levels high enough to crcat~ a Donora- or-London-typc disaster. As a consequence of this, in 1954 the Los Angeles County Air Pollution Control Board established a programme which called for the declaration of public alerts when specified air pollutants reach~d predetermined levels. Table 9 indicates the three alert stages for the four selected pollutants. While the alert stages do not constitute air quality standards, they did provide a valuable protective mechanism during th€ period prior to tho establishment of the California ambient air quality standards. The objective of the ~lert programme is to prevent the uncontrolled build-up of air pollution to levels high enough to cause a general catastrophe. It must be pointed out that the feasibility of the Los Angeles alert programme depends in a very large measure on the existence of an extensive air-monitoring network capable of providing continuous and immediate data on the concentrations of the selected contamir~ts. TABLE 9. ALERT STAGES FOR TOXIC CONTAMINANTS (P.P.M.) Alert stages Contaminant First alert Second alert Third ::::.lert Carbon monoxide lOO 200 300 Nitrogen oxides 3 5 10 Sulfur oxides 3 5 10 Ozone 0.5 1.0 1.5 '1 Source: Rossano, A. T. Jr: San Francisco Bay Area For the control of sulfur dioxide pollution many American communities rely on a stipulation regarding the maximum permissible concentration of so2 in the stack emissions. Frequ0ntly the figure used is 0.2 per cent. by volume of the stack gases. AP/11 page 16 The Air Pollution Control District of the San Francisco Bay Area has taken a unique approach to the control of so2 • Their regulations allow the 0.2 per cent. figure to be exceeded provided the operator of the process can demonstrate that the ground-level concentration of sulfur dioxide at the plant boundaries does not exceed certain specified levels and durations. The standard is expressed in terms of equations relating the maximum permissible concentration c (in p.p.m.) with duration t (in hours). Four equations are used to cover the case of daylight as well as all hours of the day, and daily as well as monthly occurrences, as follows: l. t 0.8 During the daylight hours of any day ---c-0.2 2. t = 1.6/c-0.2 During all hours of any day 3. t = 10/c 2 During the daylight hours of any month 4. t = 20/c2 During any hours of any month For example, during daylight hours a 0.3 p.p.m. average concentration is permissible for a continuous eight-hour period, while a 1.0 p.p.m. average concentration is permitted for only one hour. Over the entire day a 0.3 p.p.m. average concentration is acceptable for 16 hours, while a 1.0 p.p.m. average concentration may exist over a two-hour period. These concentrations are permitted for relatively longer periods when averaged over a month. The criteria for these· standards are based on visible damage to highly sensitive vegetation and are belov< odour thresholds. In this novel approach to air quality standards the process operator bears the burden of proof. He is therefore required to maintain a limited network of continuous so2 nnalysers which can provide a time record of so2 concentrations. This type of standard has appeal to the majority of operators vvhO feel that the expenditures for the monitoring equipment and its operation are justifiable on economic grounds. COMPARISON AND ANALYSIS AP/ll page 17 Direct comparisons between ambient air quality standards of the various Member countries :::.re not fee:.sible for the follovling reasons: 1. The objective and criteria are different for each country. 2. The selected time exposure period varies in each country. Moreover such comparisons must, out of necessity, be quite limited in scope since only four countries have established ambient air quality standards. At present there are only four pollutants for which each of these countries has developed a standard. A limited comparison of air quality standards for some air pollutants from the USSR, West Germany and the United States can be made by referring to Table 10. The pollutants selected were the only ones for which specifications had been set by the three countries. Country USSR ,_ West Germany (V .D. I.) United States (Calif.) TABLE 10. COMPARISON OF SOrJIE AMBIEl\lT AIR QUALITY .STANDARDS FROM THREE COUNTRIES Air quality standard (p.p.m.) Time period Carbon Nitrogen Sulfur monoxide oxides dioxide 24 hr.-mean 0.9 0.05 0.06 one-time ex- 5.4 0.16 0.17 posure 30 min.-mean --- 0.5 0.2 8 hr - mean 30 --- 0.3 l hr --- --- l.O Source: Stern, A. C., ll Ry~·.z·nov, v. ; .. 9 Hydrogen sulfide .006 .oo6 0.1 --- O.l The Czechoslovak standards for the four pollutants selected are the same as those for the USSR with one exception; the standard for oxides of nitrogen in Czechoslovakia is 0.2 p.p.m. for a one-time exposure and 0.07 for a 24-hour mean. /AP/ll page 18 Obviously the actual numerical value of a standard will depend upon the criteria c,nployed. A brief review of the objectives and bases used by the Member countries is offered for the purpose of assisting in understanding the apparently wide divergence in nume~ical values ~n the standards used in the USSR and the United States. The Russian standards which are discussed in this paper are hygienic standards. The values were determined by rese~rch utilizing special toxicological experiments involving animals and hum:;ms. Certain studies involved the measurement of excitation of reflexes including respiratoPy movement, contraction of vocal chords and bronchial musculature, changes in the tonus of the blood vessel walls, and alteration of cerebral functions. Additional studies pertained to the influence of gas inhalation on optical chronaxy demonstrating the reflexive inhibition of one area of the cerebral corte;~ because of excitation by a toxic substance of another area of the cortex. It was found that these changes occurred at or above the threshold limit of odour, and thus such a te,.,h.:ique was not sufficiently sensitive. Light excitation of the eye was found to be markedly affected by inhalation of gas. Some of these chc.nges occurred belm'l the odour threshold of a substance and· therefore were considere::l to represent subsensor:r exc:.tatiun: Electro-encephelographic methods proved to have the sensitivity and convenience needed for observing sub- sensory responses. In settiag the sJ-.anc:..:..rds two :n.d.ices i'7ere usc;d, (1) values capab:..E: of preventing reflex reactions of the ~espiratory organs including the nose to one-time exposures, and (2) levels preventing the chronic absorption of toxic substances on a long-term exposure basis. It is the Soviet pre:-1ise -chc:.t ve_~;,; low concentrations of toxic substances can produce sub-pathological effects which are regarded c.-:> functione.l alterations.. These constitute protective adaptational reactions indicating that the external environment has dev~.ated from phys iologic norm. Such concentrations therefore a.re intolerable since they place limitations upon the freedom of the organis1n and reduce its capability to adapt to other unfavourable environmental conditions which may arise. AP/11 page 19 On the basis that sub-sensory excitations are harmful, the Russians decide~ that maximum allm·1able concentrations must be set at levels \'l'hich are not only below odour - ' - . . .. perception thresholds, but indeed below thresholds of sub-conscious reflex reaction especially those affecting the cerebral cortex. The Soviet scientists believe there are three types of air pollution standards. The first are called hygienic standards and are based on experimentally derived information. The criteria for these standards specify that the external environment shall: (l) have no direct or indirect adverse effect on man, and (2) maintain his physiological well-being. Such standards are absolute and unalterable except as scientific knowledge advances through improvements in precision of scientific measurements. The second set of standards are termed sanitary standards. Thase are based on hygienic standards, but deviate from them sufficiently to effect a compromise between what is desirable and what is economically expedient and technically feasible. Sanitary--standards are temporary and can be altered according to current technological and socio-economic conditions. The third set of standards art technological standards. These are essentially emission standards. Their objective is to limit the amount of pollution which is emitted to the atmosphere from specific sources. In contrast, the objectives of the California air quality standards are to provide a sound basis for efforts to control or abate an existing and worsening air pollution problem in certain of its large metropolitan areas. The standards are based upon estimates of levels of various pollutants at which certain specified effects begin to occur. The followin~ effects of air pollution on sensitive persons v1ere considered: ''1. . ,..cut<:: sickr).ess and deD..th. 2. Insidious or c~onic disease. AP/11 page 20 3. Alteration of important physiological functions. 4. Untoward symptoms. 5. Discomfort from air pollution sufficient to lead individuals to change residence or place of employment." Possible effects of community air pollution upon sensitive types of crops included: "1. Acute damage leading to unmarketability. 2. Insidious or chronic effects, leading to impaired yield. 3. Alteration of fundamental biochemical process~s without overt damages." Because these effects could vary both in type and. severity a graded set of standards was adopted defined as follows: Adverse Level, Serious Level and Emergency Level. Although it was recognized that there could be a number of co-existing factors which would modify the effects, it was stated that existing knowledge was sufficient to take into account only some of these. Admittedly the standards set for a specific pollutant would not necessarily apply to situations involving more than one pollutant. The established valJes are based on sound data derived from tecnnical publications and other existing sources, and concurred in by panels of qualified scientists. It was admitted that the level of control achievable by such standards would not guarantee that every single individual including the most sensitive would be free of effects. The compromise adopted was to aim the standards at protecting the health and well-being of the most sensitive population groups, definable in terms of age and medical status. Finally, the standards are not intended to represent a sharp line of division between satisfactory and unsatisfactory air quality. The levels represent concen- trations which if exceeded would be expected to produce the stated effects. In converse, the effects would not ordinarily occur below the levels shown. The California standards also include information on methods of measuring the pollutants and criteria for determining the most sensitive group in the community. f AP/11 page 21 As mentioned previously although direct comparisons are inappropriate because of differences ~n criteria, objectives and format of the standards it is quite apparent that the standards of the USSR are considerably below those of California and West Germany. This is due mainly to the fact that the USSR standards are based primarily on human sub-conscious thresholds while those of California, and to a great extent West Germany, are based on human conscious thresholds. This wide difference in standards is due in part to differences in medical and public health philosophy as to what constitutes a threat to health and well-being. A formi~~ple barrier to progress in achieving agreement on this question is the lack of sufficient technical information on the relation between air pollution and health, especially in regard to long-term exposures. A considerably greater effort in terms of research and investigation is necessary in order to achieve reliable criteria. The entire movement towards the determination of a satisfactory set of ambient air qual~ty .~tandards which tak8 into account the questions of health, well-being, economics, nesthetics, engineering and la•• could be greatly accelerated through closer co-operation and commUnication among qualified air pollution workers around the world. The World Health Organization is to be commended for providing excellent leadership on an international scale and more specifically for sponsoring symposia such as this. AP/11 page 22 REPERET\JCES 1. Air Pollution Control Association ( 1963) Bases a:.:.d types of air quality criteria, unpublished report of Task Group 2 of Committee TR-5, Ambient Air Standards 2. California Department of Public E-:;c.J.th. ':l'echnical report of California standards for Ambie~~ Ai~ Quality and Motor Vehicle Emissions. 3. Goldsmith, J. R. (1963) !3~ses and criteria _for· ~ir quality standards, presented at the Fifty-sixth Ar~~al :1eeting of the Air Pollution Control Association, Detroit, f\Uc~1igan 4. MacKenzie, V. G. (1963) Eutu~~-~~~look_fo~_the deveJ.~0~ent and application of air qua~i ty stancJ_~.rd~, presen7.ed at the Fj_fty--sixth Annual Meeting of the Air Pollution Control ftf:'sor::c:--.tion, Detroit, Michigan 5. Parker, A. (1957) Air pollut~_on lec;isla~ioE_, s~andards, and enforcement, World · Health Organization ExperT. Ccmmittoe on Air Pollution report, Geneva, Switzerland 6. Porter, R. (1963) Definition of terms relat<:d to ai.r quaJ.it:v, United States Public Health Service, Division of Air Pollution memorandum 7. Rossano, A. T. jr (1962) Air quality and emission criteria as bases for air pollution control, Eighth European Seminar for Sanitary Engineers sponsored by the World Health Organization in Brussels, Belgiun 8. Ryazanov, V. A. (1962) Criteria and methods -~o~~st~~lishing maximum permissible concentrations of air pollutants, Eighth European Seminar for Sanitary Engineers sponsored by the World Health Organization in Brussels, Belgium 9. Ryazanov, V. A. (1962) Sen~y physiology as basis for air quality standards, Archives of Envi.ronmental 1iealth 10. Stern, A. C. (1962) Air pollutj_on standards. In: 11ir pollu~icn, II, Stern, A. C._. cd., 1\crcdc:uir: Pr,_,;o;·;_. \'l·':i York 11. Stern, A. C. (1963) SU:'!l~T.I~~y of_ex.~.sti!2'3.~i.r_pol_lutlon_stB:nr:1~rds, paper presented at the "5'ift;r-s:!.xth Annunl ~k:et.Lnr:; of the; J-'\ir Pollution Control Association, Detr>oit _, r-1ic::,iF~.n 12. Yocom, J. E. (196?) i'.ir ;-;'JJ:l~J.t io:1. reg-u.:!.a-'-.ions - their growinf' impact on enginee:;:>ing C.ecisions_, Cbe~_ic~__I::ng~neerin~ •