VEREIN
DEUTSCHER
INGENIEURE
Maximale Immissions-Konzentrationen
(MIK)
Schwefeldioxyd
VDI 2108
VDI-RICHTLINIEN
November ]?96l
PERMISSIBLE IMMISSION CONCENTRATIONS OF
SULPHUR DIOXIDE
This publication, translated from the German, was prepared by
the Subcommittee on Sulphur-Dioxide Effects of the Committee
on Gas and Dust Action of the VDI Committee on Air Purification.
All rights reserved.
Reproduced with permission by the
U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Washington, D. C.
VDI-Handbuch Reinhaltung derLuft
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Foreword
This is one of several dozen VDI Clean Air Committee specifications
on air purification which the Division of Air Pollution of the U.S. Public
Health Service has obtained permission to translate, publish, and distri-
bute in limited quantity. A complete list of the VDI publications being
published by the Division of Air Pollution appears on the inside back
cover. Because the VDI Committee from time to time revises these
specifications, this and other publications in the series may be super-
seded by later publications.
The VDI Clean Air Committee specifications are compiled by trade
or professional associations and published by the Committee. The Com-
mittee has neither official status nor regulatory authority, although West
German governmental agencies participate in its activities. Air quality
specifications published by the Committee are therefore advisory, rather
than regulatory. They may however later be adopted by West German
governmental authorities.
The English translations were done by the Joint Publications Research
Service of the Office of Technical Services, U.S. Department of Commerce.
It should be borne in mind that various terms literally taken from the Ger-
man do not have the same connotation in English; for example, the word
"standard" frequently appears where the word "criteria" might better
reflect the comparable American meaning, since in this country "standard"
is generally meant to imply a legally enforceable value, while "criteria"
usually means a recommended value upon which standards may be based.
The publication and distribution of these translations by the Public
Health Service constitutes neither endorsement of the specifications nor
of the air quality or emission limitations recommended in them. We
believe that they contain much useful information that would otherwise
not be available to non-readers of German and for this reason have made
them available to workers in the air pollution field in the United States.
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PERMISSIBLE IMMLSSION CONCENTRATIONS OF
SULPHUR DIOXIDE
Prepared by:
Subcommittee on Sulphur-Dioxide Effects
of the Committee on Gas and Dust Action
of the VDI Committee on Air Purification
VDI No. 2108, November 1961
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TABLE OF CONTENTS
Page
VDI 'Committee for Air Purification ........ ... iii
INTRODUCTION: Permissible Immission Concentrations ... 1
General Remarks . „ ............ . ...... 3
1. Occurrence of Sulphur Dioxide ..... .........
1.1 Occurrence in Nature , . ....... „ ......... 3
1.2 Occurrence in Technical Installations .......... 3
1.3 Utilization in Technical Installations .......... 3
2.
Properties of Sulphur Dioxide
2.1 Physical and Chemical Properties ..... ...... . . k
2.2 Demonstration and Determinat :>n ............. 1;
3. Effects of Sulphur Dioxide ............ c ... 5
3.1 Effect on Man . ....... ..... ........ , 5
3.2 Effect on Animals. .................... 6
3.3 Effect on Plants ........ r , ....... 7
3*31 Manifestations of Plant Damage ..„,,. ^ ..„. , , "(
3.32 Reactions of Plants ............ , . ,. 7
3.1; Effects on Buildings ........ , - . . , „ 9
1;. Exposure Limits ..... ..... ..... . „ . 9
References ................... „ . . . 11
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VDI Committee for Air Purification
The VDI Committee for Air Purification is composed of experts
in all fields of importance for air purification. These experts col-
laborate with the Committee on their own responsibility and without
compensation and are proposed for the Committee by the following
societies and institutions:
German Society for Hygiene and Microbiology
German Society for Oil and Coal Chemistry
German Society of Gas and Water Experts
German Meteorological Services
Society of German Chemists
Society of German Iron Mine and Steel Mill Experts
Association of Anthracite Mines
Technical Inspection Associations
Society of German Steel Mill Experts
Society of German Foundry Experts
VDI Trade Section on Dust Technology
Association of Steam Boiler Owners
Scientists from Universities and Institutes in Biology,
Chemistry, Forestry and Agriculture, Human and Veterinary
Medicine, Metallurgy, Physics and Technology
Research Institute of the Cement Industry
Federation of German Industry (Chemical Industry, Oil Industry,
Automobile Industry, etc.)
German Federal Railroads
Federation of German Farmers
Federation of Community Associations
Settlement Federation of the Ruhr-Coal District
Competent Federal and State Ministries
Institute for Water, Soil and Air Hygiene of the Federal
Public Health Service
Public Inspection Services
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INTRODUCTION
Permissible Immission Concentrations
The VDI Specifications on Air Purification are divided into
the following groups:
1. Permissible Immission Concentrations (PIC-values)
2. Calculation of the Distribution of Dust and Gas
3. Restriction of the Emission of Dust and Gas
ii. Dust and Gas Measuring Techniques.
In the evaluation of problems of air pollution, the inner rela-
tion of these four groups of specifications must be considered.
The VDI Specifications for Permissible Immission Concentrations
(PIC) concern the determination of limit values for given types of air
pollution. The PIC-values of air-polluting substances are defined as
those concentrations in layers of the open air close to the ground
and/or, for dust, also as those quantities of deposition on the ground
which may be considered in general as harmless, according to present
experience, for man, animal or plant when exposed for a given duration
and frequency. (The present PIC-Specifications on sulphur dioxide are
an interim solutionj cf. sec. ii)»
The concentrations of air-polluting substances in the open air
vary greatly. For reasons of measuring methodology, the limit con-
centrations are determined as mean values for given periods of time.
As a rule, one limit value each is determined for continuous or inter-
mittent exposure to gaseous substances.
The limit value for continuous exposure (PICC) is the maximum
mean concentration in a given measured interval (e.g., half/hour mean
value) under continuous exposure.
During shorter periods, the limit value, for many substances,
in continuous exposure can be exceeded without danger. Duration,
extent and frequency of possible excess exposure cannot be uniformly
determined because of the varying character of the effect of such
substances as well as for reasons of measuring methodology.
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Concentration is indicated in mg/rrP oi' air and/or cra^/m^ of
air (ppm » parts per million),.
In the determination of PIC-values for dust deposition, different
assumptions are applicable on the basis of present experience. Measuring
intervals must extend in principle over longer periods. The limit
value for dust deposition is indicated in g/m2/time,,
PIC-values are valid only within certain ranges because of
individual differences of constitution and surroundings,, In them-
selves, they are not a scale for the evaluation of suspected damage ,
from emission. If PIC-values are referred to in such cases, then
this must be done in consideration of all accompanying circumstances
and only by experts familiar with the pertinent factors.
In the determination of PIC-values, the experiences and findings
are decisive which were gained for cases where only one type of air-
polluting substance is involved* It is known that the simultaneous
existence of several such polluting substances changes the combined
effect but we are able only in special cases to develop specifica-
tions for combined factors of pollution because of the great number
of possible combinations.,
As a rule, the PIC-values are valid only for the open air out-
side of an emitter., For purposes of comparison, the PIC-values are always
contrc'Oted vith the permissible work-station concentration (PWC-
value) of the respective gas, aerosol or dust, i«e», the present limit
value for the mean concentration of the substance in the respiratory
air at the work-station per 8-hour shift (German Research Federation,
Committee on Testing of Industrial Materials Injurious-to-Health.
First Communication, December 1958. Cf. Federal Ministry for Labor
and Social Matters, "Worker Protection" No. 12, 19£8).
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General Remarks
Air pollution by sulphur dioxide gas is widespread. It
is produced by the oxidation of sulphur and sulphur-containing com-
pounds in many technical processes and acts as an irritant gas of
pungent odor primarily on the mucosae of the nose, the throat and the
respiratory tract. The relatively strong irritation of high con-
centrations constitutes an effective warning sign and generally pre-
vents more serious intoxication. Some animals are as sensitive as
man. Plants may already be damaged by concentrations which cannot
be perceived by the human sensory organs.
1. Occurrence of Sulphur Dioxide
1.1 Occurrence in Nature:
In nature, sulphur dioxide occurs in volcanic gases.
1.2 Occurrence in Technical Installations:
Sulphur dioxide is created by the combustion of sulphur-con-
taining fuels (coal, oil) in the furnace installations of power plants
and industrial enterprises, domestic furnaces and steam engines. It
is also formed during the roasting of sulphur-containing ore and in
the combustion of sulphur, especially for the production of sulphuric
acid. It may also occur in the processing (roasting and direct-
process methods) and/or the sintering of sulphur-containing fine-
metal ores.
1«3 Utilization in Technical Installations;
Among other purposes, sulphur dioxide is used for bleaching,
for the production of sulphuric acid and other sulphur-containing
compounds, of sulphite liquor in the cellulose industry, for refrigera-
tion, for the sterilization of vessels (e.g., vine barrels and bottles),
for the conservation of fruit pulp and for the bleaching of dried fruit.
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2. Properties of Sulphur Dioxide
Sulphur dioxide is a colorless gas of pungent odor heavier
than air. It dissolves in water with the formation of sulphurous
acid. The extent of solubility depends in inverse ratio on the
degree of partial pressure and of temperature.
Sulphur dioxide is oxidized in the atmosphere gradually to
sulphur trioxide which converts with the air moisture to sulphuric
acid. Oxidation is accelerated by such catalyzers as soo&.and par-
ticles of heavy-metal oxides. In addition to sulphur dioxide, there
are always small amounts of sulphuric acid in the air for this
reason. In technical processes at high temperatures, sulphur dioxide
is therefore quickly oxidized to sulphur trioxide on special contacts
such as vanadium oxide, platinum-asbestos or iron oxide.
2.1 Physical and Chemical Properties
Chemical formula SC^
Molecular weight 6U.06
Density (°C, ?60 Torr) 2.926 kg/Nra^
Boiling Point -10.02° C
Solubility in water of sulphur dioxide at 10° C and partial
pressures of
760 Torr 153.9 g/kg HgO
10 Torr 3.7 g/kg H20
1 Torr 0.63 g/kg H20
Solubility in water of sulphur dioxide at 30° C and partial
pressures of
760 Torr , 75.6 g/kg HgO
10 Torr 1.85 g/kg HgO
1 Torr 0.31 g/kg H20
2«2 Demonstration and Determination
Qualitative demonstration:
Pungent odor combined with specific taste;
Decoloration of pigments, e.g., malachite green;
Decoloration of starch-iodide solutions;
Red staining of fuchsine-aldehyde solutions;
Red staining of sodiumnitroprusside.
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Quantitative determination:
Cf . VDI Specifications No. 2111.
3. Effects of Sulphur Dioxide
3.1 Effect on Man;
In concentrations of about 100 cn/m and over, sulphur dioxide
causes strong irritation of the mucosae and a consequent immediate
interruption of respiration and sometimes spasms of the glottis which
may produce acute asphyxiation under intensive exposure. Normally,
the strong irritation compels the individual affected to immediately
leave an atmosphere containing a high concentration of sulphur dioxide
so that serious or fatal intoxications through this gas — in contrast
to most other irritant gases — are very infrequent. If appreciable
amounts of sulphur dioxide enter the median and lower respiratory
tracts, this will produce inflammatory swelling of the mucosae and
muscular spasms of the bronchi as well as possibly a laryngeal edema.
The effect on the respiratory surface of the lung is generally
secondary. Sequels in the wake of non-fatal serious intoxication may
be persistent inflammations of the throat, of the larynx, of the
trachea and the bronchi with mucous secretion and coughing as well
as distention of the lung and a temporary high increase of the red
blood corpuscles. Clouding of the cornea occurs only at very high
concentrations and will disappear after appropriate treatments .
In concentrations of about 10-50 cm^/rn^, sulphur dioxide becomes
immediately perceptible by its strong pungent odor and disagreeable
taste and causes throat irritation and a burning sensation on the
raucosae of the upper respiratory tract as well as the cornea and, under
continued exposure, bronchitis and finally a greater or lesser degree
of distention of the lung. Subjects by occupation frequently exposed
to the gas may develop a limited tolerance.
The indications on the effect of concentrations of about 1 to
10 cm3/m3 on respiration are contradictory.
In tnan, 1, 2, 5 and 8 cm^/m^ are supposed to accelerate
pulse and respiratory rate and produce shallow breathing (l). In
similar experiments with J>, 10 or 20 cm3/m3 of sulphur dioxide, how-
ever, no such changes were observed but 10 cm^/nP are supposed to pro-
duce bronchial spasms in particularly sensitive subjects (2)e Nothing
is known on injury through continued daily inhalation in the range of
the so-called maximum work-station concentration (PWC-value) of 5 cm^/m
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The threshold value for the perception of sulphur dioxide by
smell and taste is indicated as 0.3-1.0 cm3/m3 (3, I|, £). Sensitive
subjects perceive 0.3 cm-ym^ by taste (5) and the olfactory threshold
lies between 0.3 and 1.0 cnvVm * depending on individual sensitivity
(li). In testing analytically controlled sulphur-dioxide concentrations
on twelve individuals, the taste and sometimes the smell of 0.5 cm3/m3
was noticed by four individuals, seven individuals noticed 1.1 cm3/m3
and all subjects recognized 2.6 cm3/m3. In these ranges, the initial
perception of smell gradually recedes and is increasingly replaced
by the specific taste which increases in intensity with continued
exposure. The rapid habituation more or less inherent in other
typical irritant gases is absent with sulphur dioxide. Sensitive sub-
jects mav find 1 cm3/m3 already disagreeable in continued inhalation
and h cm3/m3 may already produce minor throat irritation, after a
short time, in subjects not accustomed to the gas (3).
On the effect of continued inhalation of sulphur dioxide in
concentrations between 0.5 and 5'0 cm3/m3, there are at present rela-
tively few experiences extant. An increased effect through conversion
to sulphuric acid and enriching in and on simultaneously present
aerosols has been discussed (6, 7) but the question of such injury in
man from concentrations of such, combinations occurring in practice has •
not yet been solved. In the animal experiment, respiratory interference
was increased by sulphur-dioxide concentrations as low as 2 cm3/m3 if
finely dispersed aerosols of a neutral salt were inhaled simultaneously
(6).
The significance of sulphur dioxide and its conversion products
for an epidemic of respiratory diseases during certain fog periods in
London and some industrial centers has not yet been clarified. Under -
weather conditions with increased smoke density and simultaneous rise
of the sulphur-dioxide concentration to more than 0.2 cm3/m3, the con-
dition of patients with chronic bronchitis appeared to worsen (8).
It should be noted that the unpleasant smell of S02 becomes apparent
sligrtly above the threshold of perceptibility.
. Nor
should we forget that the genesis and the cause of certain respiratory
diseases are certainly influenced by certain forms of air pollution
and that it has not yet been definitely established in this connection
what the content of sulphur dioxide and its conversion products is
which can be regarded as riot constituting a risk.
3.2 Effect on Animal;
There are definite differences in the effect of sulphur dioxide
on different animal species. In general, older animals are more
resistant than young animals. Domestic animals are as sensitive to
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sulphur dioxide as man. Among laboratory animals, guinea pigs are con-
sidered as more and rats as less sensitive species (9). Continued
exposure to 10 cn-> of the gas in one cubic meter of air for a period
01 ninety days was tolerated by rabbits, rats and mice without apparent
symptoms (10). Experiences on the reaction of lower organisms, e.g.,
insects, to low sulphur dioxide concentrations do not yet exist.
3.3 Effect on Plan-;,r •
The high sensitivity of many plants to the effect of sulphur
dioxide has induced extensive research in recent decades. The findings
so obtained are of considerable importance for the national economy.
3.31 Manifestations of Plant Daniage;
Sulphur dioxide concentrations of 1-2 cra^/m^ often cause in a
few hours acute damage, especially to leaves, through localized destruc-
tion of tissue (necrosis) t^Lth subsequent discoloration, primarily from
grayish-green into ivory, brown or reddish-brown. Preferred points
of attack consist, in dicotyledons, of the intercostal fields and
leaf edges and, in the monocotyledons, of the tips of the leaves.
Coniferous needles frequently become discolored from the tip inward.
As a consequence of the decay of the leaf surface, growth and yield
reductions as well as the death of the plant may occur.
Through long continued exposure to low sulphur dioxide concentra-
tions, chronic damage is possible which is represented by yellowing of
the leaf (chlorosis) and/or inhibition of photosynthetic metabolism
which also reduces growth and yield as well as resistance against
certain parasites (11).
3.32 Reactions of Plants;
The reactions of plants are definitely dependent upon concentra-
tion of and duration of exposure to sulphur dioxide. Since damage
increases progressively with concentration at the same amount of sulphur
dioxide, peaks of concentration beyond certain values are potentially-
dangerous (16). In regard to this, the time of day — most plants are
several times more resistant by night than in the day — as well the
frequency and chronological distribution of the exposure to the gas
must be taken into consideration. The different plant species possess
different degrees of resistance to sulphur dioxide. Coniferous plants,
the butterfly-blossom fodder plants (clover and alfalfa) and the cereals,
especially barley, are among the most sensitive. To this should be
added that the sensitivity of each individual plant changes during the
course of its development (16). Shoots and young plants are in general
more resistant than older plants, The developing light-green shoots
of fir and spruce in the spring are riot damaged but the needles of the
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preceding year are affected. However, in the summer, the fully de-
veloped new shoots ara more sensitive than those of last year. Whereas
fir and spruce drop acutely damaged needles, scotch pine retains them
generally quite obstinately and continues to assimilate with the still
green part of the needle. Under chronic effects, damaged coniferous
plants have a lesser number of normal annual needle growth because of
dropped needles and therefore present a less dense appearance.
Where climate factors of light, temperature, air and soil
moisture require maximum physiological activity, risk to the plants is
greatest. Woods generally stiffer most in the stages of early growth,
i.e., the age where mass growth culminates. During the winter, the
bare plants tolerate stronger effects. Because of the reduced .tempera-
ture and light intensity in the winter, this is also true for ever-
greens to a certain extent.
Plants well supplied with nutrients, especially nitrogen, are
more resistant than those insufficiently supplied. Any plant is most
resistant when it grows under optimum ecological conditions.
In the evaluation of damage to vegetation, the reduction of
either the esthetic or the economic use-value of the respective
planting is decisive (16).
Any plant will tolerate a certain amount of sulphur dioxide which
will produce no damage under continued exposure. This concentration is
designated as the first tolerance limit. In order to prevent damage
to all culture plants, the concentrations occurring would have to remain,
at all times, below the tolerance limit applicable to the most sensitive.
plants. According to present investigative findings, this corresponds
to a figure of about O.ii mg of sulphur dioxide in 1 cubic meter of air
(approximately 0.15 cm3/m3 of air) but more detailed experience on
tolerance limits under exposure to sulphur dioxide for several years
of non-seasonal plantings (orchards and woods) are not yet available
to an adequate extent.
Whether damage to plants occurs from temporarily exceeding
the first tolerance limit depends primarily upon the respective degree
of resistance of the exposed culture and the conditions of action
(climate, nutrition, emission factors). This complex of factors is
expressed explicitly in the second tolerance limit. The second tolerance
limit therefore comprises all the factors which influence the reactions
of plants from exposure to sulphur dioxide (12).
All observations and measurements to date have shown clearly
that the first tolerance limit may be exceeded for short periods within
certain intervals of time and to a given extent, without necessarily
producing damage in the plants. The reasons for this lie in the fact
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that, according to all available observations, only a slight probability
exists for a concurrence of the most critical situations in regard to
the effects of exterior and interior factors (climate, soil condition,
plant development) on the plant reactions. Moreover; the sulphur
dioxide emissions occurring are not always uniform but vary more or
less so that, in intermediate periods with slight or no emission, the
plants are afforded periods of recovery (13, 15)«
3.it Effects on Buildings;
Sulphur dioxide gas does little damage to buildings. Sulphurous
acid and/or the sulphuric acid created from it through slow oxidation
favors the corrosion of metals and the weathering of building stone,
especially limestone and marble.
1|. Exposure Limits
In view of the emission of concentrations of sulphur dioxide
already reached in many areas through industrial discharge and waste
gases from other combustion processes (domestic furnaces, traffic, etc.)
arsd in view of the technical and economic difficulties existing at
present for an effective reduction of these emission components, pro-
visional permissible inmiseion concentration values (PIC-values) have
been established for the immission of sulphur dioxide, without con-
sideration of other air-polluting substances. Efforts must be made
•ho create, through technical measures, the prerequisites for a reduc-
tion of the indicated PIC-values.
The PIC-values for sulphur dioxide established from these view-
points are therefore guide values which principally serve the purpose
of attempting control of the immission of sulphur dioxide. Because
these values lie for certain plants beyond the tolerance limits de-
tervnined experimentally to date, there is no certa'inty that their
observance will guarantee the protection of the most sensitive plant
species (cf. sec. 3.32).
On the basis of the assumptions quoted under section 3 and
in consideration of viewpoints of measurement techniques, the provi-
sional tolerance limits for sulphur dioxide are determined as half-
ho-Jir mean values as follows:
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PICC - continuous exposure value » 0.5 mg/m^ 'ZZ 0.2 cm3/m3 of airj
PICj = intermittent exposure value
(within in two hours, once
each a half-hour mean value
of) • 0.75 mg/nr -^0.3 cm3/m3 of airj
PWC-value (permissible work-
station concentrationj
Ik} as comparison • 13.0 mg/m3 ^ 5.0 cm3/m3 of air.
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REFERENCES
1. Amdur, M. 0., W. W. Melvin Jr. and Ph. Drinker: Effects on
Inhalation of Sulphur Dioxide by Man. Lancet (1953) II,
p. 758/9.
2. Lawther, P. J. s Effects of Inhalation of Sulphur Dioxide on
Respiration and Pulse-rats in Normal Subjects. Lancet (1955)
II, p. 758/9.
3. Henschler, D., A. Stier, H. Beck and W. Neumann: Olfactory
Threshold of Some Important Irritant-gases • (Sulphur Dioxide,
Ozone, Nitrogen Dioxide) and Manifestations in Man by Low
Concentrations. Arch, f . Gewerbepathologie and Gewerbehygiene
17 (I960), p. 51*7/70.
h» Johnstons, P.. T. : Occupational Diseases. Philadelphia 19l|2.
5. Thoraas, M, D., J. 0. Ivie, J, II. Abersold and R. H. Hendrickss
Automatic Apparatus for Determination of Small Concentrations
of Sulphur Dioxide in Air, Industr. Engin. Chem., analyt, Edit.
15, p. 287/90 (19143).
6. Amctar, M. 0.: The Physiological Response of Guinea Pigs to
Atmospheric Pollutants. Itn. J. Air Poll, 1 (1959), p. 170/83.
7. Hettchs, H. O.s Contributions to the r'smog" problem. Proceed,
Internet. Clean Air Gonf., Nat, Soc, for Clean Air, London
(I960) p. 139/la.
8. Lavbher, P, J, : Climate, Air Foliation and Chronic Bronchitis.
Proc, Roy. Soc, Med, 51, p. 262/4 (1958),
9. Greenwald, I,: Effects of Inhalation cf Low Concentrations of
Sulphur Dioxide Upon Man and Other Mammals. Arch, of Ind, Hyg.
10 (195U, p. U55/75.
10. Vedder, E. B. and G. C, Armstrong: Toxicity of Sulphur Dioxide.
E.A.T.R., U. S. Department of the Army, Chemical Warfare Service,
1918 . - Zit. n. Greenwald,
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11. Wentzel, K. F.: Air Pollution as Local Factor in Silviculture
Close to Industrial Areas, "Principles of Silviculture"
Hanover 1959.
12. Stratmann, H.s The Utilization of Air Analysis for the Evaluation
of the Effect of Sulphur Dioxide on Vegetation. Staub 21 (1961)
Nr. 2, p. 61/6U.
13. Zah, R.s Effect of Sulphur Dioxide on Vegetation - Findings from
Experimental Exposure to Gas. Staub 21 (1961) Nr. 2, p. 56/60.
111. German Research Federation, Committee on Testing Industrial
Materials Injurious -to-Health, Communication 1, December 1958,
cf . Federal Ministry for Labor, "Worker Protection", No. 12,
1958.
15. Guderian, R. and H. Stratmanns Annual Reports on Cultivation
Experiments in the Open at Biersdorf 1958/59.
16. Van Haut. H. and H. Stratmanns Experimental Investigations on
the Effect of Sulphur Dioxide on Vegetation. Research Reports
of the Land Nordrhein-Westfalen Nr, 88U (I960).
17. Katz, M. : Sulphur Dioxide in the Atmosphere and Its Relation
to Plant Life. Ind, and Eng. Chem, XL (19ii9) No. 11, p. 2U50/55.
18. Katz, M. and A. W, McCallum: The Effect of Sulphur Dioxide on
Conifers,, In; Air Pollution. Louis C. McCabe, New
York, Toronto., London 1952j pp." 84/96 ••'-
19. .Keller, H.: Contributions to the Determination of Smoke Damage
on Coniferous Plants Produced bv Sulphur Dioxide. Beiheft
zum Forstwiss. Zentralblatt, Nunchen 1958.
20. Scheffer, T. C. and G. G0 Hedgcock: Injury to Northwestern
Forest Trees by Sulphur Dioxide from Smelters. Techn. Bull.
No. 1117, U. S. Dept. of Agr. 1955-
21, Swain, R. and A. B. Johnson: Effect of Sulphur Dioxide on Wheat
Development, Ind. and Eng. Chem. 28 (1936), p.
22. Thomas, M. D.: Gas Damage to Plants. Annual Review of Plant
Physiol. 2 (1951), p. 293/322.
23. Thomas, M. D., R. H. Hendricks and G, R. Hill: The Action of
Sulphur Dioxide on Vegetation, Proceedings of the First Air
Pollution Symposium (Nov. 19^9) No. 10 and 11, Pasadena
(Calif. )
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2h. Thomas, M. D., R. H. Hendricks and G. R. Hill: Sulphur Metabolism
of Plants, Ind. and Eng. Chem. 1*2 (1950), No. 2, p. 2231/35.
25. Zimmermann: Effects on plants of impurities associated with air
pollution. In: Air Pollution. Hrsg. Louis C. McCabe. New
York, Toronto, London 1952$ darin p. 127/30.
26. Application of Air Quality Standards to a Community Problem:
Bernard D. Tebbens and Dale H. Hutchison, Journal of Air
Pollution Control Assoc. 11 (1961).
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VDI CLEAN AIR COMMITTEE SPECIFICATIONS, PUBLISHED IN ENGLISH
BY THE DIVISION OF AIR POLLUTION, U.S. PUBLIC HEALTH SERVICE
VDI No.
Title
2090 Sources of Air-Polluting Substances
2091 Restricting Dust Emission From Forced-Draft Boiler Installations,
Capacity 10 Ton/Hr and Over, Hard-Coal Fired with Mechanical
Grates
2092 Restricting Dust Emission From Forced-Draft Boiler Installations,
Capacity 30 Ton/Hr and Over, Hard Coal-Dust Fired with Dry Ash
Removal
2093 Restricting Dust Emission From Forced-Draft Boiler Installations,
Capacity 30-600 Ton/Hr and Over, Hard Coal-Dust Fired with liq-
uid Ash Removal
2094 Dust Prevention - Cement Industry
2095 Dust Emission From Induced-Draft Ore-Sintering Installations
2098 Restricting Dust Emission From Natural-Draft Steam Generators,
Capacity 25 Ton/Hr and Less, Lignite-Fired with Stationary or
Mechanical Grates
2099 Restricting Dust Emission in Blast-Furnace Operation
2101 Restricting Dust Emission From Copper-Ore Smelters
2102 Restricting Emission of Dust From Copper-Scrap Smelters
2103 The Restriction of Chlorine Gas Emission
2104 Terminology in Air Purification
2106 Permissible Immission Concentrations of Chlorine Gas
2107 Permissible Immission Concentrations of Hydrogen Sulphide
2108 Permissible Immission Concentrations of Sulfur Dioxide
2109 Restricting Emission of Hydrogen Sulphide and Other Sulphur-Con-
taining Compounds, Except Sulphur Dioxide, From Gas Generators
in Coke, Gas, and Coal-Constituent Processing Plants
2110 Restricting Emission of Sulphur Dioxide From Coke Ovens and Gas
Plants
2115 Restricting Emission of Dust From Manually Operated Central -
Heating Boilers, Capacity 600, 000 KCAL/Hr and Less, Fired with
Solid Fuels
2281 Restricting the Emission of Fumes From Diesel-Engine Vapors
2284 Restricting Emission of Dust and Sulphur Dioxide in Zinc Smelters
2285 Restricting Dust and Sulphur-Dioxide Emission From Lead Smelters
2290 Restricting Emission From Gas Generators in Coke and Gas Plants
2292 Restriction of Dust Emission in Anthracite-Briquet Factories
2293 Restricting Emission of Dust in Anthracite Processing Installations
2302 Restricting Emission of Dust, Tar Mist and Gas when Charging Coke
Ovens
2105 Permissible Concentrations of Nitrous Gases
GPO 869- 179
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