624 NOTES
The Effects of Air Pollution on Urban Climates by HANS-WALTER GEORGII, Professor of Atmospheric Physics, University of Frankfurt, Germany
Growing cities and growing industrial production Considering the sources of air pollution we see necessarily lead to an increase in the discharge of in Fig. 1 and Fig. 2 the increase in the number of both harmless and noxious substances into the automobiles in the city of Frankfurt-am-Main and atmosphere. These discharges come from the the heavy increase of industrial production which chimney stacks of industrial plants, from domestic has outstripped the linear growth of population. and community heating and from the exhaust gases Urbanization and industrialization are develop- of automobiles. The gaseous and particulate com- ments which are interrelated; that is why the ponents emitted into the atmosphere lead to a change industrial potential of Europe is growing in relation in the composition and transparency of the air over to the population density, as was outlined recently large parts of the world, mainly over the large by Stephany & Roussel.1 While the growth of cities, and in this way nearly every element of the population is more or less linear, the concentration climate in these areas is modified. Investigations of the population in cities leads to a progressively 30 years ago by Linke a and Stummer b in Frankfurt increasing population density in certain urban areas. show clearly the significance of change in the following components of the climate of cities: Extent of air pollution (1) the intensity of solar radiation, The growing rate of discharge of pollutants into the atmosphere, combined with the influence of the (2) the range of visibility, change of topography, leads to an accumulation of (3) the temperature distribution, trace-substances in the air over cities and frequently (4) the relative humidity, to the formation of haze. This haze-dome which (5) the local wind distribution, and builds up over densely populated areas is con- (6) the distribution of precipitation. centrated or dispersed according to rate of discharge, to the wind profile and the vertical temperature Furthermore, the enlargement of cities influences profile. the climate of the more central city areas because of Observations from aircraft, made by the author the progressive transformation of rural countryside and his collaborators in the area over the industrial into built-up areas. We must be fully aware of the region of Mannheim-Ludwigshafen with S02 as fact that the urban climate represents a special tracer for pollution, show very clearly that the direct meso-climatological type which is in most cases influence of locally produced pollutants extends to vastly different from the climatological conditions in an altitude of about 700 m above the industrial the rural surroundings of the cities. centre (Fig. 3). Results from a series of such flights In discussing urban climates we have therefore to showed that the haze and dust layer caused by distinguish between (1) the modification of the pollutants was rarely thicker than 1000 m above the climate by the accumulation of buildings (change of ground, but usually exceeded 500 m. The lateral topography) and (2) the modification of the climate distribution of sulfur dioxide 300 m above a city is by urban air pollution. While earlier literature on demonstrated in Fig. 4. This figure also shows very this subject, as summarized for instance in Kratzer's clearly the magnitude of the difference in S02 monograph,c deals mainly with the influence of the concentration above urban and industrial areas com- built-up areas, more recent investigations show the pared with rural areas. I want to stress this point increasing influence of atmospheric pollution on particularly because the modification of the air layer urban climates. above urban areas is responsible for climatic changes taking place near the ground. a Linke, F. (1940) Das Klima der Grossstadt. In: Biologie der Grossstadt, Leipzig, Th. Steinkopff, pp. 75-90. An example of the degree of pollution of the air b Stummer, G. (1939) Klimatische Untersuchungen in above a densely populated area compared with the Frankfurt/M. und seinen Vororten. In: Ber. Met. Geophys. Inst. Univ. Frankfurt, No. 5. d Stephany, H. & Roussel, A. A. (1966) World review on c Kratzer, A. (1956) Das Stadtklima, Braunschweig, air pollution: Europe. In: Proceedings of the International F. Vieweg & Sohn. Clean Air Congress, London, 1966, p. 25. 2327c FIG. 1 160000 INCREASE IN THE NUMBER OF MOTOR VEHICLES IN THE CITY OF FRANKFURT
140000 52 120000 48
100000 . 40 _ t t \' / +~~~~~~~~~~~~~~~~~36 80000t x' " 32E zX ~~~~~~~28X 60000 . .24
40000 . 16z % /3"o' t12 20000 8
% rL~~~~~~~~~ O I I I I I I 1938 1950 1952 1954 1956 1958 1960 1962 "9042)4
60000- % 24 0 0C§ FIG. 2 INCREASE IN THE CONSUMPTION OF ELECTRIC POWER AND MINERAL OILS IN RELATION TO THE GROWTH 750 300r OF THE30rlPOPULATION IN THE FEDERAL REPUBLIC OF GERMANY'l 20000 i0 0 ooveils
0t k k ______< __,_, 2 0 Z50 -200- OFoTHE~20 POPULATION IN THE FEDERAL_REPUBLIC a IRo
Mineral oil I
E~~~~~~~~~~~~~~~~~~~~~~Electric power I Motor vehicles I
25 100 70 ;'00 80 c Popultc.ion -/..60 -40 20 626 NOTES
FIG. 3 DISTRIBUTION OF SULFUR DIOXIDE CONCENTRATION (Mg/m3) IN THE ATMOSPHERE ABOVE THE INDUSTRIAL AREA OF MANNHEIM-LUDWIGSHAFEN
700- 60 7-__~~ 70 600-
- 500- E
Go X00 0s f ._00 I 300-
200
100k
0. Ludwigshafen - Monnheim 1< -ca 20 km 1
FIG. 4 LATERAL DISTRIBUTION OF SULFUR DIOXIDE CONCENTRATION (LgU/m3) IN THE ATMOSPHERE AT A HEIGHT OF 300 m OVER THE INDUSTRIAL AREA OF MANNHEIM-LUDWIGSHAFEN
150 W - Waldhof M - Mannheim N - Nedarou L - Ludwigshafen //
_ _ ~00
ideLberg
s CHa0toch 0 N EFFECTS OF AIR POLLUTION ON URBAN CLIMATES 627
FIG. 5 CONCENTRATION OF TRACE GASES IN SOME PURE AND POLLUTED ATMOSPHERES a 1.0 SO2 NO2 NH3 C12
098
M 087 I-
I.3-I4
06 I I*5 6 1)0.2 I. Kl.Frnfr/I Wne)4 t oiz(umr 05 Irnfr/ (Smmr 5 ovg .S o itz(umr 0.101 -I C~~~a"Lfl.O O w-V ICOI.' o ba ba ba' Laba bo a 1 2 3 45 67 89 1 2 3 45 6 78 123 4 78 1 23 78 WHO9041N9'1 Continental Maritime Continental Maritime Continental Maritime Continental Maritime 1 a. Frankfurt/M (Winter) 4 St. Moritz (Summer) b. Frankfurt/M (Summer) 5 Corviglia b. St Moritz (Summer) 2 a. K(1. Feldberg (Winter) 6 Capreia/Mittelland Meer (Summer) b. KI. Feldberg (Summer) 7 Florida 3 Zugspitze (August) 9 Meteor Expedition 1965 (400-500 N, Dec.) a The actual concentrations (,Ug/m3) are indicated on each bar. composition of a pure atmosphere is shown below: smell and haze caused by the city of Munich and Component Pure atmosphere Polluted atmosphere touches on the current concepts of diffusion and of Particulate matter 0.01-0.02 mg/m3 0.07-0.7 mg/m3 wash-out of pollutants. Sulfur dioxide 10-3-10-2 ppm 0.02-2 ppm More recent investigations include the monograph Carbon dioxide 310-330 ppm 350-700 ppm by Kratzer,C the very valuable studies by Lands- Carbon monoxide <1 ppm 5-200 ppm berg,e f papers by Emonds g and Kalbh on the Oxides of nitrogen 10-3-10-2 ppm 10-2_10-1 ppm climate of Bonn and Cologne and the work by Total hydrocarbons <1 ppm 1-20 ppm Chandler i on the climate of London, a masterpiece Some information on the concentration of several of skilful and careful research on the climatological trace gases in pure atmospheres compared with properties of a large town. Studies by Clarke j on the polluted atmosphere of the city of Frankfurt is the nocturnal urban boundary layer over Cincinnati, presented in Fig. 5. The concentration in Frankfurt in the USA, constitute one of the very few three- during winter is taken as 1 and the concentrations dimensional investigations over cities, including found at the other locations are given as percentages vertical temperature soundings obtained by heli- of this value. Fig. 6 shows the cumulative frequency copter and pilot-balloon ascents. distribution of concentration of particulate matter in US towns of different size (I, II, III) compared e Landsberg, H. (1966) Air pollution and urban climate. In: Biometeorology, vol. 2, Oxford, Pergamon Press, p. 648. with suburban areas (III a) and the surrounding f Landsberg, H. (1956) The climate of towns. In: W. L. countryside (IV). Thomas, ed., Man's role in changing the face of the earth, Chicago, University of Chicago Press, p. 584. Properties ofurban climates g Emonds, H. (1954) Das Bonner Stadtklima. Arbeiten zur Rheinischen Landeskunde, Vol. 7, Bonn, Selbs tverlag It is clear that urban climates have been the Geographisches Institut, Universitat Bonn. subject of study for a long time: a memorandum by h Kalb, M. (1962) Met. Rdsch., 15, 92. i Chandler, T. J. (1965) The climate of London, London, Mr Franz Xaver Epp to the Bavarian Academy of Hutchinson & Co. Science, dated 28 March 1787, describes the terrible Clarke, J. F., personal communication, 1968.
13 628 NOTES
FIG. 6 CUMULATIVE FREQUENCY DISTRIBUTION OF PARTICULATE MATTER IN AMERICAN CITIES OF DIFFERENT SIZES AND IN RURAL AREAS a 99
95: 90-
80/
-60/
.1- lEa 11 ll I
0 20 30 so / 0 200 3W0 500 1000 Particulate matter content (pg/m3) W,0 901419 I Towns wlth population > I1000000 (11 towns in'USA) II Towns with population ~> 700000 > ; (9500) III Towns with population < 700 000 (117 towns in USA) Illa Suburbs IV Farmland (500) a Arrows indicate the 50% values. The figures in parentheses represent the number of towns In which measurements were made and the total number of measurements.
F Radiation budget. Modifications of the composi- vapour absorption (Wa.) and to extinction of tion of urban atmospheres such as those described radiation by particulate matter (Sa8) then above lead to considerable changes in the radiation aR+ Sa8 + Waw budgets ofdensely populated areas. Taking Linke's k T= Trubungsfaktor (T) as an indicator ofthe atmospheric aR turbidity due to Rayleigh-scattering (aR), to water- A value of T=1 would be found in a completely pure Rayleigh-atmosphere, and higher values would k Linke, F. (1942) Handb. Geophys., 8, 239 indicate larger amounts of trace-substances leading EFFECTS OF AIR POLLUTION ON URBAN CLIMATES 629 to a reduction of incoming direct and scattered solar evidence that the atmospheric transmission of the radiation in the ground layer of the atmosphere. total solar radiation decreases with increasing Measurements of the Linke turbidity factor carried turbidity. A study of turbidity measurements made out in Vienna showed an increase from values at Washington, D.C., and Davos, Switzerland, around 3, in the suburban areas of Vienna, to 8 in suggests a world-wide increase in turbidity over the centre of the city. Average values of Linke's past several decades. While the increase in Davos turbidity factor for Helsinki and Kew, England, may represent the world-wide contamination of the indicate the considerable reduction of solar radiation atmosphere, part of the Washington increase is at Kew, due to industrial activity. probably due to local increase in population and Linke's turbidity factor Average urbanization. There is no doubt that the turbidity- Winter Spring Summer Fall for year network operated in the USA at 35 stations provides Helsinki 2.2 2.9 3.2 2.4 2.7 very valuable information on the total dust content Kew 4.1 4.9 5.1 4.5 4.6 of urban atmospheres and on its fluctuations. Besides the increase of turbidity of incoming Visibility. There is no question that the visibility radiation by atmospheric pollution, a reduction in in cities is greatly reduced under certain conditions. the duration of bright sunshine in large cities is also Accumulation of condensation nuclei produced from found. Chandler i compares the duration ofsunshine many anthropogenous and industrial sources in and at several stations in and around the centre of around cities leads to a decrease of visibility and London. The average duration of bright sunshine often to the formation of fog. Evaluation of the decreased considerably towards Central London as smoke-concentration in London by Craxford & indicated below: Weatherley m shows clearly the increase of airborne Average duration of pollutants towards the centre of the city during bright sunshine, London, 1921-50 (hours per day) winter months. Clcsely correlated with this increase Jan. July Whole of condensat.on products was an increase in the year frequency of fog-occurrence: the data of Chandler ' Surrounding country 1.7 6.6 4.3 Outer suburbs 1.4 6.5 4.1 show that London as a whole has indeed more fog Inner high-level suburbs 1.3 6.3 4.0 than the surrounding country. Also the number of Inner low-level suburbs 1.3 6.3 4.0 days with good visibility is reduced in Central Central London 0.8 6.2 3.6 London compared with the suburbs. It should be noted that the frequency offog in urban environments The loss of sunshine in Central London was is higher in spite of the fact that the air temperature greatest during the winter months, when atmos- is higher and the relative humidity lower in cities pheric pollution was heavy due to the higher level of compared with the countryside. The explanation domestic heating. It is evident that the change of the for this contradiction lies in the mechanism of fog radiation budget in large cities affects the temperature formation. With high concentrations of sulfur distribution compared with that of the countryside, dioxide, the formation of sulfuric acid by catalytic and is the cause of some of the specific characteristics oxidation on the surface of particulate matter in a of urban climates. It is also evident that the effects humid environment leads to the formation of small of a typical urban climate are more marked under droplets of fog under conditions in which fog would calm, sunny weather conditions. not form in a pure atmosphere. This has many With respect to the reduction of incoming solar unpleasant and dangerous consequences with respect radiation due to the haze-dome above cities it is to the harmfulness of urban fog, a problem which generally agreed that the decrease of direct solar will be briefly discussed at the end of this paper. radiation amounts to 10 %-20%, the decrease of In a recent investigation, Georgii & Hoffmanni scattered sky radiation, however, being less. Several determined the correlation between SO2 accumulation authors emphasize particularly the reduction in the and visibility for the German cities of Gelsenkirchen ultraviolet component of solar radiation, a problem and Hamburg. The results show, for a weather which is of special interest to physicians. In this connexion the investigations by McCormick & m Craxford, S. R. & Weatherley, M. L. (1964) Airpollution LudwigI deserve attention. Their paper presents and town planning. In: Proceedings of the Annual Conference of the National Society for Clean Air, Harrogate, 1964, I McCormick, R. A. & Ludwig, J. H. (1967) Science, pp. 1-18. 156, 1358. n1 Georgii, H. W. & Hoffmann, L. (1966) Staub, 26, 511. 630 NOTES situation characterized by (1) an inversion below This is very well demonstrated in Chandler's in- 1000 m, and (2) a ground-level wind velocity below vestigation of the London "heat-island ". He has 3 m/s, that 80% of all cases of excessive SO2 con- found that in some instances the difference in the centration (excess of 90 % of the cumulative frequen- minimum temperature between the suburbs and cy distribution for SO2) occur at visibilities below the centre of London can reach 6degC- 7degC. 5 km and 50% of all cases at visibilities below 2 km. Measurements of the temperature distribution This again shows the existence of a relation between carried out by Stummer b some years ago show air pollution and the meteorological element clearly the increase in temperature towards the centre visibility ". of the city of Frankfurt during calm, cloudless Temperature distribution. The most striking nights in spring. The temperature difference in these feature of the urban climate is certainly the difference cases amounted to nearly 4 deg C (Fig. 7). in temperature distribution between the cities and Fig. 8 shows the average diurnal trend of temper- their rural surroundings. This so-called " heat- ature measured at a height of 2 m during " radiation- island" effect, leading also to the urban wind- days " in the centre of Frankfurt (Rathenauplatz) in system, has been investigated by many authors in a summer and at the boundary of the city close to a great number of cities. Again, the heat-island effect large park (Feldbergstrasse). While the average is a bright-weather phenomenon, which is parti- maximum temperature during the day did not show cularly effective in calm, clear nights. While the much difference between the 2 stations, there was average difference in temperature between a city and considerable difference during the night, with the its surroundings is only ldegC-1.5degC, the dif- higher temperature in the centre of the town; at the ference reaches its maximum during the night and, time of the minimum temperature, a difference of according to our observations, during May and June. about 1.5 deg C is indicated. These findings are in
G. 7 TEMPERATURE DISTRIBUTION IN THE CITY OF FRANKFURT DURING CLEAR CALM NIGHTS
Zeilsheim EFFECTS OF AIR POLLUTION ON URBAN CLIMATES 631
FIG. 8 AVERAGE DIURNAL TREND OF TEMPERATURE IN THE CITY OF FRANKFURT AND ON THE OUTSKIRTS OF THE CITY
27 26 25 \0Ra 24 23 22
~'21 ~20 E 19 18 17/ / 16 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~Feldbergstrasse 15~~~~~~~~~~~~~~~~~~~~ -Rathenauplatz 14- 13 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 AM Midday PM Time of day (h)
good agreement with the extensive results gained by some of the causes of the development of the Chandler who found that the heat-islands of temperature difference between city and its rural London, Manchester or Washington are strongest surroundings: before dawn. We can conclude from these results that firstly the consumption of fuel, which may (1) the thermal capacity of buildings, supply energy equal to one-third of the solar (2) the decrease of outgoing infra-red radiation radiation falling on the city, and secondly the solar during the night due to increased amounts of energy stored during the day in the built-up parts of pollution, and the city and slowly released into the atmosphere (3) the heat contribution from the burning of during the night are responsible for the urban various fuels. temperature pattern. Detailed information on the horizontal distribu- In agreement with Chandler,0 I share the opinion tion of temperature across a city can be gained by that differences in cloud amounts and fog frequencies temperature traverses as carried out by Chandler i are only of secondary importance and only of in London and by Kalbh in Cologne. These occasional significance. Of great importance in traverses project the urban pattern on to the thermal connexion with the accumulation and diffusion of structure. Details of the local urban morphology can pollutants is the thickness of the nocturnal heat- be recognized very clearly in the temperature island which, of course, will vary with the wind speed distribution. Without going into details of the great and the lapse-rate of temperature. As already number of observations on the heat-island effect in different cities, it can be stated that the following are 0 Chandler, T. J. (1967) Met. Mag., 96, 244. 632 NOTES mentioned, very little detailed information is obtain- will probably not reach the ground in the area of the able with respect to the vertical temperature profile " heat-island ". It would be very desirable to have over cities. Chandler assumed a thickness of about more studies of this type carried out in cities with 50 m-150 m, which is obviously in good agreement different topographic patterns. with Clarke'sJ direct measurements in Cincinnati. One phenomenon which is closely connected with Clarke reports on a pronounced modification of the the higher minimum night temperatures in cities, vertical temperature structure. The vertical extent of and the reduced number of nights with frost, was this modification-he calls it the " urban boundary observed by Kalbh while carrying out a pheno- layer "-increases with downwind distance over the logical study in the city of Cologne. Miss Kalb made urban area. Depending on the temperature lapse-rate careful observations of the spatial distribution of Clarke found that the nocturnal boundary layer apple trees in blossom in Cologne. Due to higher extends to an altitude of 300 m or even in some temperatures in the centre of the city the proportion instances to 400 m. Clarke's study demonstrated a of apple trees in blossom increased from the suburbs spatial variation of the temperature profiles within towards the centre of the city. When 50% of the the boundary layer and consequently a spatial trees were in blossom in an area close to the densely variation of the dispersion rate. Above the " heat- built-up parts of the city only 10% of the apple trees plume " there exists a stratified layer, the stability of were in blossom in the surrounding villages. In more which, and the height of which, depend mainly on the distant parts the trees were not blossoming at all. general weather pattern. Pollutants emitted from This study appears to be a unique attempt to relate tall stacks into the stable layer above the boundary the effect of urban temperature distribution to the layer-will experience little vertical dispersion and development of vegetation.
FIG. 9 WIND DISTRIBUTION IN THE CITY OF FRANKFURT DURING CLEAR CALM NIGHTS
Z,ilshuim EFFECTS OF AIR POLLUTION ON URBAN CLIMATES 633
Urban wind systems. The " heat-island " effect is In addition to the temperature difference, the also the main factor leading to the formation of an speed and direction of the geostrophic wind is also urban wind system. But, as is the case with the important in the formation of the urban wind- temperature difference between cities and the sur- system. As result of the studies in the city of Frank- rounding countryside, the development of an urban furt it was found that geostrophic wind speeds above wind-system is associated with low wind speed and 3 m/s-4 m/s near the ground prevent the formation with stable temperature lapse rate, that is, pre- of an urban wind-system in the city. However, wind dominantly with anticyclonic weather situations. direction and wind speed are strongly influenced by From earlier measurements of the local wind- the change of ground-surface roughness when the air distribution in Frankfurt, we know that in calm reaches the city. Nearly all meteorological stations cloudless nights there is a convergence of winds in cities report reduced average wind speed and an towards the centre of the city with velocities up to increased number of days with calms. Fig. 10 shows 2 m/s-4 m/s. In accordance with Clarke's J findings an evaluation of the wind-field in Frankfurt during we can expect a vertical component above the city a day with prevailing strong westerly winds. The centre and downward motion outside the heat- wind direction was changed within the city and island, thus closing the local circulation system. the wind speed was considerably reduced within the Naturally, the intensity of this convective cell will built-up area due to the increased roughness. The depend on the temperature difference between the features of the wind pattern of that particular day surrounding area and the city. Fig. 9 shows the do not reveal an urban circulation system, rather a influx of air near the ground in the city of Frankfurt change of wind velocity and wind direction. Un- on calm summer nights. doubtedly the urban circulation system is very
FIG. 10 WIND DISTRIBUTION IN THE CITY OF FRANKFURT ON A DAY WITH STRONG WESTERLY WINDS
Zeilsheirn 634 NOTES
FIG. 11 FIG. 12 AIR CIRCULATION WITHIN STREETS AT CARBON MONOXIDE DISTRIBUTION AT DIFFERENT DIFFERENT WIND SPEEDS HEIGHTS ABOVE STREET LEVEL IN RELATION TO WIND SPEED T -T 33 m Wind speed co 2m/s 15- 22 10 Ca.
16
.2p 103
36 Leeward Windward 3m E10 33m Wind speed >2 rns s c C3 ~ 33 0 0 * v, . . 6 0 E 22 l *1346m 6 7
C/, ~~~~~7 16 0 _
10 Wind speed (m/s) WHO 90425
3 can be gained on the distribution of pollutants in Leeward 15 1 Windward streets and on their dispersion in relation to wind WH0 90424 velocity and wind direction. Systematic measure- ments on the concentration of carbon monoxide emitted from automobiles in the city of Frankfurt important in connexion with the dispersion and were performed by Georgii, Busch & Weberq at distribution of pollutants produced from sources in different levels above the street. The wind velocity the city-area, as described by Berlyand.P was measured simultaneously at street and roof When we reduce our observations to the micro- level. This investigation showed a significant relation meteorological scale, very interesting information q Georgii, H. W., Busch, E. & Weber, E. (1967) Unter- P Berlyand, M. E. (1968) Meteorological factors in the suchung uber die zeitliche und raumliche Verteilung der dispersion of air pollutants in town conditions. (Unpublished Immissionskonzentration des Kohlenmonoxid in Frank- document WHO/AP/WP/68.2). furt/Main, Ber. Met. Geophys. Inst. Univ. Frankfurt, No. 11. EFFECTS OF AIR POLLUTION ON URBAN CLIMATES 635 between the ventilation of the streets and wind speed Conclusion and wind direction. As can be seen in Fig. 11 at In conclusion it may be said that the city which wind velocities below 2 m/s, ventilation was very produces so many pollutants is itself an obstacle to poor, fresh air which entered the space between the dispersion of these pollutants, and thus increases buildings from above did not reach the street level, the dangers associated with the accumulation of the and the carbon monoxide concentration in- noxious components. Unfortunately, little informa- creased considerably nearer the ground. It required tion is available on the effects of urban climate on a wind speed above 2 m/s (lower part of Fig. 11) for man. There seems to be general agreement that the the vortex which formed within the street to reach increased concentration of pollutants in city air street level but even then there was a great difference constitutes a hazard as far as respiratory diseases are in the rate of ventilation between the windward side concerned, and the results of the smog episodes and the leeward side of the street. This effect in 1952 and 1962 in London, and Western and produced a horizontal gradient of carbon monoxide Central Europe, respectively, have been widely across the street. Complete ventilation of the street reported in the literature. The work by Lawther r and dispersion of the pollutants produced from low on the effects of urban life on bronchitis and lung sources in the street required a wind velocity of cancer deserves a special mention. While eye 5 m/s or more. The accumulation of pollutants in irritation is commonly attributed to the photo- streets also depends on the height of the buildings chemical smog in Los Angeles, the air pollution in and the width of the street. Generally wind velocity this city has so far not been reported to have shown is the most important factor in the dispersion of any direct adverse effects on human health. pollutants in cities. Low wind velocity leads to an Simultaneous investigations of air pollution and accumulation of pollutants in the air as can be seen epidemiological studies are being conducted in many for CO in Fig. 12. New methods and techniques countries and cities all over the world and it must be permit the use of tracers-in this case the carbon hoped that one consequence of these studies will be monoxide-to study the circulation system in cities that the level of air pollution can be gradually and streets and the use of these techniques will reduced despite the rapidly growing populations. certainly increase our understanding of small-scale circulation patterns. r Lawther, P. J. (1966) Postgrad. Med., 24, 703.
Field Tests with Larvicides other than DDT for Control of Blackfly (Diptera: Simuliidae) in New York * by HUGO JAMNBACK, New York State Museum and Science Service, Albany, N. Y., USA
DDT is an unusually stable insecticide that, when ticides have been under way for the past few years. applied to bodies of water, may accumulate to This paper deals with field tests of methoxychlor, injurious levels in fish.a, b, c For this reason, and Abate, Dursban, fenitrothion, and carbaryl,f all of because of evidence of DDT-resistance in black- which have shown some degree of effectiveness flies,d, e investigations of possible alternative insec- against larvae under laboratory conditions.s h, The larvicides were applied by aircraft as 15%- * Published by permission of the Assistant Commisioner, 20% insecticide in oil solution with 0.5 %-0.75% New York State Museum and Science Service. a Anderson, R. & Everhart, W. (1966) Trans. Amer. Fish. f The formulae of these insecticides are given in Kenaga, Soc., 95, 160-164. E. (1966) Bull. ent. Soc. Amer., 12, 161-217. b Burdick, G. et al. (1964) Trans. Amer. Fish. Soc., 93, g Jamnback, H. & Frempong-Boadu, J. (1966) Bull. Wld 127-136. Hlth Org., 34, 405-421. c Burdick, G. et al. (1968) N. Y. Fish Game J., 15. h Travis, B. & Schuchman, S. (1968) J. econ. Ent., 61, d Jamnback, H. & West, A.-unpublished data. 843-845. e Suzuki, T., Ito, Y. & Harada, S. (1963) Jap. J. exp. t Travis, B. & Wilton, D. (1965)fMosquito News, 25, Med., 33, 41-46. 112-118. 2327D