The Science of the Total Environment, 116 (1992) 159-167 Elsevier Science Publishers B.V., Amsterdam
159
Monitoring of air for microbial and metal contamination at selected sites in the vicinity of Johannesburg, South Africa V. Y o u s e f i a n d D . B . K . R a m a * National Centre for Occupational Health, P.O. Box 4788, Johannesburg 2000, South Africa
(Received February 7th, 1991; accepted May 4th, 1991)
ABSTRACT A preliminary survey was undertaken to identify air contamination in the vicinity of industrial, residential and hospital sites. In many developing countries, poor town planning has resulted in growth of residential and commercial sites in close proximity to the industrial works, without the provision of a buffer zone. As prevailing winds blow across the industrial works to the other areas, undesirable pollution may be experienced. Before steps are taken to reduce factory emissions, the impact of the industry on the surrounding area needs to be clearly defined. In this study, the total particulate matter and the level of microbial contamination at the selected sites is reported. The elemental composition of the particulate matter is described. Key words: air pollution; microorganisms; metals
INTRODUCTION C o n t a m i n a t i o n is a social a n d historical p h e n o m e n o n . E n v i r o n m e n t a l cont a m i n a t i o n is an inevitable c o n s e q u e n c e o f the activities o f man. We live in a p o t e n t i a l l y hostile w o r l d filled with a bewildering a r r a y o f p o l l u t a n t s o f diverse shape, size, c o m p o s i t i o n a n d chemistry. F u r t h e r m o r e , the physical processes o f the e n v i r o n m e n t c o n t i n u a l l y cause c h a n g e by removing, replacing and redistributing an e n o r m o u s v o l u m e a n d variety o f materials. T h e physical e n v i r o n m e n t is, in fact, d y n a m i c , a n d t h e r e f o r e c o n s t a n t l y cont a m i n a t i n g a n d d e c o n t a m i n a t i n g itself. C o n t a m i n a t i o n m u s t be c o n s i d e r e d an a m o r a l p h e n o m e n o n . It is neither right n o r w r o n g - - it is simply a c o n s e q u e n c e o f living. H o w e v e r , excessive c o n t a m i n a t i o n is t h a t which interferes with ecology; this is p o l l u t i o n and this is wrong. M a n a g e m e n t o f c o n t a m i n a t i o n , so that it does n o t b e c o m e pollution, is essential. H o w e v e r , a n a t i o n a l m a n a g e m e n t p r o g r a m m e , designed to avoid adverse *To whom all correspondence should be addressed. 0048-9697/92/$05.00 © 1992 Elsevier Science Publishers B.V. All rights reserved
160
v. Y O U S E F I A N D D.B.K. R A M A
effects from contamination, starts with the recognition, description and understanding of the effects of the contaminants themselves. Industrial products and a host of other activities inevitably entail the emission of contaminants. One of the transport mediums of contaminants is air which moves omnidirectionally and knows no boundaries. The atmospheric quality at industrial, residential and hospital locations, depends on meteorological, geographical and geological factors. At each site the existence of a multi-source of pollutants with different strengths make air quality evaluation difficult. Water, soil and air are the interconnected recipients of contaminants. Each of these recipient bodies has a limited capacity of tolerating the additives. Mankind should be constantly aware of their responsible position to control this delicately balanced environment. History proves that the penalty of polluting the environment is high, and the damage is virtually irreversible. In this light it is important that proper recognition, evaluation of pollutant, and sincere commitment to control the problem, be undertaken. In the Republic of South Africa the Atmospheric Pollution Prevention Act, Act 45 of 1965 [1], and its Amendment, Act 17 of 1973, are legal means of control. There exists a similar Act for the prevention of pollution of water and soil which has the provision of co-operation with all the other control bodies. The requirements and the philosophy of the Atmospheric Pollution Act is based on the best practicable means (BPM) of controls. Notes on BPMs are normally applicable to new works. Existing works are approached by earlier, less stringent standards. As the public have become more aware and concerned about the quality of air, the authorities are under increasing pressure to control pollution. Today's air pollution control is a very complex issue. No longer are the pollutants directly traceable to individual sources. Control is being achieved, not at high level but at high cost. Thus, a sensible approach to the air pollution problem is desirable. Emotive issues need to be treated objectively. MATERIALS AND METHODS In this preliminary study an attempt was made to evaluate residential, industrial and hospital environments. The following environments were taken into consideration. --
-
--
-
Two hospitals Three waste water works (sewage plants) One used oil re-refinery and chemical plant One ceramic/sanitary ware plant
MONITORING OF AIR FOR MICROBIAL AND METAL CONTAMINATION
---
-
161
One metal works plant One cigarette manufacturing plant One residential site
The main monitoring factors considered were total particulate matter [2] and airborne micro-organisms [3]. The particulate matter was analyzed for metal concentrations by ICP-spectrometry [4]. Bio-aerosols were evaluated for colony-forming units per cubic meter (CFU/m 3) of air.
Airborne particulate monitoring Total airborne particulate was sampled for nearly 24 h, using a high volume suction p u m p and an open face filter holder with a membrane filter of 0.45 or 0.8 #m pore size of 37 m m diameter. Sampling was in accordance with Health and Safety Executive (1986) guidelines [2].
Airborne micro-organisms evaluation Air sampling for micro-organisms (bio-aerosol) is governed by the same principles that affect the collection of any particulate. The collection of micro-organisms is, however, complicated by the viability of the sample. Special handling, processing and analytical techniques are needed for the enumeration and identification of collected micro-organisms. The centrifugal sampler draws the air by impeller into the sampler where the microorganisms are impacted by centrifugal force onto the surface of nutrientcoated plastic strips. In this study the Reuter Centrifugal Sampler (RCS) was used [3]. This is a battery-operated, portable instrument. After sampling at preset (lowest 0.5 to the highest 8 min) time and flow rate (40 I/min based on average 4 #m particle size), the strip is removed and transported to a central laboratory for evaluation. The strips were incubated at 30-35°C for 48-120 h and the resultant colony-forming units (CFU) counted. The number of organisms per unit volume of air was calculated (CFU/m 3) using the air flow rate and sampling time data.
Inductively coupled plasma optical emission spectroscopy An A R L 34000 ICP instrument consisting of inductively coupled argon plasma operating at 27 MHz with direct reading on a 29-channel spectrometer was used. The polychromator is thermostatted, under vacuum, and has a 1.0-m focal length system. A 1080 lines/mm grating is used in conjunction with metal-dielectric-metal-narrow band-pass (10-20 mm) filters for order sorting. The operating conditions involved an incident power of 1.25
162
v. Y O U S E F I A N D D B . K . R A M A
kW, viewing height of 15 mm above the load coil, a plasma argon flow-rate of 0.8 1/min, a coolant argon flow rate of 12 l/rain and the nebuliser argon flow rate of 1 l/min. Aspiration was through an all-glass concentric Meinhard type pneumatic nebuliser without pumping with an uptake rate of 2.3 ml/min. A Gilson autosampler was used. The ICP is operated and controlled with DEC PDP 11/03 computer. The analytical wavelengths for which the instrument is fitted and the average detection limits measured are summarised in Table 1. Standards and calibration Standards were prepared from 1000 ppm stock solutions (BDH/Merck) in 2% nitric acid. Owing to the linearity over the concentration range for the sample types analysed, a two-point calibration was used. Double distilled water was used for all preparations. Interferences in measurements
Spectral interferences due to the influence of major concomitants, and for TABLE 1 Analytical operating conditions and detection limits (DL) for the ICP Element
Emission wavelength (nm)
DL (/zg/ml)
Zn Cd Co W Fe Mg As Sn Hg Mo A1 Cu Pb Ni Si Mn Cr
213.9 226.5 228.6 239.7 259.9 279.0 189.0 190.0 194.2 202.0 308.2 324.8 220.3 231.6 251.6 257.6 267.7
0.01045 0.00777 0.00468 0.06641 0.00305 0.08719 0.09044 0.12834 0.03659 0.05644 0.04323 0.00514 0.07659 0.03256 0.03949 0.00074 0.00665
MONITORING OF AIR FOR MICROBIAL AND METAL CONTAMINATION
163
any potential spectral interferences based upon known unresolved spectral line overlaps were qualitatively checked for by wavelength scans of the background structure near the analyte wavelength. The on-peak and offpeak spectral interference was determined when the analyte was present at 2 ppm and each concomitant at 500 ppm in the solvent of interest.
Measurement of samples Three separate and successive 10-s integrations of photomultiplier current were acquired for the elements of interest in each solution. The mean of the three determinations were transformed to concentration units using the software supplied. Internal standardization was not used. Between the analysis of two samples, double distilled water was aspirated for - 1 5 s for adequate washout. RESULTS A N D DISCUSSION
The results are summarized in Tables 2-4. Identification of bio-aerosols (micro-organisms) in air is often overlooked. In this study an attempt was made to evaluate the extent of prevalence of airborne organisms. Table 4 is a summary of this finding. Due to the wide range of industry, the emission of contaminants would be different at different sites. Refuse incineration is a major source of air pollutants. The meteorological, geological and geographical factors at each site are the major influencing factors for the accumulation, dispersion and dilution of contaminants. Table 2 shows the mass concentration of total particulates at different sites.
TABLE 2 Mass concentration of total particulates in ambient air Site
Concentration (mg/m 3)
Residential Hospital No. 1 Hospital No. 2 Industrial Used-oil refinery Metal works Ceramics Tobacco
0.21 0.03 (in city) 0.09 (close to industry and residential) 0.06 0.23 0.64 1.06
Hospital No. 1 Hospital No. 2 Residential Chemical Industrial Ceramic Metal works 1/50th TLV
Hospital No. 1 Hospital No. 2 Residential Chemical Industrial Ceramic Metal works 1/50th TLV
Source
409 215 322 121 6674 343 604 3000
Pb
5 6 12 7 581 38 69 1000
Co
629 281 924 394 19805 2225 2265 --
K
5 6 12 6 465 34 55 1000
Cd
109 31 256 152 11716 916 1542 4000
Se
18 64 103 29 823 85 155 1 x 104
Cr
Concentration of trace elements ng/m 3
Trace elements of ambient air at the selected sites
TABLE 3
938 1233 2702 502 13178 10079 1276 2 × 105
Si
45 52 49 16 4815 85 105 2 x 104
Cu
116 182 225 94 3332 1002 154 2 x 105
Zn
13 13 24 16 1556 97 116 1000
Hg
416 634 779 547 3934 912 592 1.04 × 105
S
2114 2989 7552 1488 6603 6724 8996 5 x 105
Fe
371 444 874 248 6448 1123 4793 2 × 105
Mg
132 749 1282 97 247 1860 163 1 × 105
Mn
105
274 136 392 195 9336 934 861 93 182
1 x
Na
12 18 42 12 859 10 105 2 x 104
Ni
W
6 4 30 5 368 25 45 1 × 105
Mo
MONITORINGOF AIR FOR MICROBIALANDMETALCONTAMINATION
165
TABLE 4 Bio-aerosol evaluation at different sites Site
Sewage Plant Sewage Plant Sewage Plant Hospital No.
CFU/m 3
No. 1 No. 2 No. 3 2
Indoor environment
Outdoor environment
Distant location (distance in brackets)
825 50-250 25 650-1050
3700 8500 850 950
3700 a (2 km) 175 (1 km) 225 (0.5 km) 375 (0.1 km)
aprobably high due to sprayers used at this site (instant lawn farm). Both raw sludge and the final effluent is used for spray irrigation.
The chemical analysis of this particulate matter indicates the presence of a variety of metals. Table 3 is a summary of this analysis. The sources of these metals are not known, but some are from vehicle exhaust emissions and some are from the effluents of incineration stacks. However, the locality of the site and an observation of its surroundings, suggest that the magnitude of contaminants observed correspond to the type of environment and the density of traffic at that vicinity. Waste water treatment processes involving bubble aeration results in ejection of biological aerosols into the ambient atmosphere [5]. It has been defined that a viable particle is one containing at least one bacterial cell capable of forming a colony under the conditions selected by the investigator [6]. In this study, colony-forming units per cubic meter of air (CFU/m 3) was the basis of our bacterial evaluation. Table 4 describes the recovery of bacterial aerosols from its sources. Also it has been stated that there is little quantitative information on the spread of viable aerosols downwind [6]. Table 4 shows wide differences in CFU/m 3. High CFU/m 3 at Works No. 1 and its nearby lawn farm, needs no explanation. Residents near Works No. 3 often complain about offensive odours, especially during the windy season. They also report frequent occurrences of sore throats and headaches. This offensive odour and the airborne microorganisms may be transported at considerable distance from the very same plant. In the case of Works No. 3, the high colony count (225 CFU/m 3) near the fence, between the school and the plant, is significant. As far as the hospital
166
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RAMA
is concerned, both inside and outside, there are potential sources at each sampled position. CONCLUSION In this paper we have tried to inform rather than to judge. Our purpose is to present facts and to underline problems, not to suggest solutions. We regard contamination as inevitable. Its management depends upon an understanding of its effects. Understanding the effects requires a knowledge of the kind of contamination, the dose, as well as the sensitivity of the receptor system. The Republic of South Africa, like other nations in the world, inherited many intractable problems from past planning decisions, which were probably based on the best available evidence at that time. Caution should be exercised not to make the same mistake again. This aspect should be given careful consideration and it should be common practice to have certain areas zoned for different types of industry, while housing, commercial and residential areas be advantageously situated. More attention should be paid to meteorological factors, atmospheric chemistry, oxidation, hydrocarbons and photochemical reactions. Some industries are relocating into the neighbouring states due to tax benefits, cheap labour and other economical benefits. The approach to air pollution control in these states is different. However, it should be borne in mind that trans-frontier pollution is inevitable. Hence, the whole subcontinent will be affected. A common policy on air pollution prevention needs to be adopted. Information on acceptable concentrations of some materials, in terms of environmental impact are sparse. In deciding upon the BPM, the pollution control authorities do not permit any emission which may result in public health hazard. The strategy is to ensure a margin of safety. In order to achieve this, decisions have to be made about acceptable levels of exposure for many substances. There is little scientifically-based information available on this topic where it is specifically designed to protect the public as distinct from occupational health. Fractions of occupationally derived limits are therefore used for guidance. One such set of standards is the Threshold Limit Values and the Biological Exposure Indices published by the American Conference of Governmental Industrial Hygienists [7]. Whilst the policy of avoiding demonstrable public health hazards has been achieved, the BPM cannot guarantee that local environments are fully acceptable in terms of amenities and therefore free from public complaints. Many complaints are triggered by abnormal conditions. If an investigation of the cause of the problem is made, where possible, the aim should be to prevent or minimize the likelihood of its recurrence.
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The pollution control authority should consult with industry in formulating the relevant BPM. Control requirements are of no value whatsoever if they cannot be implemented. Therefore, pollution control authorities must gather information from industry both locally and internationally. Notes on BPMs are primarily applicable to new works. Existing works usually operate to satisfy earlier, less stringent standards than are set out in newly developed notes. They are normally allowed to continue to operate according to those requirements if no public health hazard exists or no public complaint emerges. Furthermore, there is no specific legislation for the control of airborne micro-organisms. We feel that such legislation should be prepared. The scheduled processes list needs to be amended accordingly. In order to properly conserve our environment, it is necessary to evaluate accurately the present state of the natural environment, so as to form a clear picture of the future direction of its change. Furthermore, now is the time to design and introduce the strategy of 'Pollution-related Health Damage Compensation Law' based on the Polluter-Pays-Principle (PPP) as adopted by the Japanese [8]. ACKNOWLEDGEMENT
The authors wish to thank the staff of the Microbiology Department at the National Centre for Occupational Health for their assistance, and Dr. A.C. Cantrell for editorial comment. REFERENCES 1
A t m o s p h e r i c Pollution Prevention Act, 1965 (Act 45 o f 1965), as a m e n d e d by the Atmospheric Pollution P r e v e n t i o n A m e n d m e n t Act, 1973 (Act 17 o f 1973).
2 Health and Safety Executive, General methods for the gravimetric determination of respirable and total inhalable dust, MDHS 14, Her Majesty's Stationery Office, London, 1986. 3 A.M.Placencia and G.S. Oxborrow, Technical Report, Use of the Reuter Centrifugal air sampler in good manufacturing practices investigations: Referencematerials and training aids for investigators, US Department of Health and Human Services, Public Health Service, Food and Drug Administration, Minneapolis, 1984. 4 Peter M. Eller (Ed.), NIOSH Manual of Analytical Methods, Vol. 1, NIOSH Method 7300. Elements (ICP). 7300(1)-7300(5). U.S. Dept of Health and Human Services, National Institute for Occupational Safety and Health; Cincinnati, Ohio, 3rd edn., 1984. 5 LawrenceSlote, Viral aerosols: a potential occupationally related health threat in aerated waste water treatment systems. J. Environ. Health, 38 (1976) 310-314. 6 J.L.S. Hickey and P.C. Reist, Health Significanceof airborne micro-organismfor waste water treatment plant processes. Part II, Summary of investigations. J. Water Pollut. Control Fed., 47 (1975) 2741-2772. 7
Threshold Limit Values a n d Biological Exposure Indices for 1989-90, A m e r i c a n Conference of G o v e r n m e n t a l Industrial Hygienists, Cincinnati, Ohio, USA, 1989.
8 Quality of the Environment in Japan 1983, Environment Agency, Government of Japan, 1983, pp. 256-257.
159
Monitoring of air for microbial and metal contamination at selected sites in the vicinity of Johannesburg, South Africa V. Y o u s e f i a n d D . B . K . R a m a * National Centre for Occupational Health, P.O. Box 4788, Johannesburg 2000, South Africa
(Received February 7th, 1991; accepted May 4th, 1991)
ABSTRACT A preliminary survey was undertaken to identify air contamination in the vicinity of industrial, residential and hospital sites. In many developing countries, poor town planning has resulted in growth of residential and commercial sites in close proximity to the industrial works, without the provision of a buffer zone. As prevailing winds blow across the industrial works to the other areas, undesirable pollution may be experienced. Before steps are taken to reduce factory emissions, the impact of the industry on the surrounding area needs to be clearly defined. In this study, the total particulate matter and the level of microbial contamination at the selected sites is reported. The elemental composition of the particulate matter is described. Key words: air pollution; microorganisms; metals
INTRODUCTION C o n t a m i n a t i o n is a social a n d historical p h e n o m e n o n . E n v i r o n m e n t a l cont a m i n a t i o n is an inevitable c o n s e q u e n c e o f the activities o f man. We live in a p o t e n t i a l l y hostile w o r l d filled with a bewildering a r r a y o f p o l l u t a n t s o f diverse shape, size, c o m p o s i t i o n a n d chemistry. F u r t h e r m o r e , the physical processes o f the e n v i r o n m e n t c o n t i n u a l l y cause c h a n g e by removing, replacing and redistributing an e n o r m o u s v o l u m e a n d variety o f materials. T h e physical e n v i r o n m e n t is, in fact, d y n a m i c , a n d t h e r e f o r e c o n s t a n t l y cont a m i n a t i n g a n d d e c o n t a m i n a t i n g itself. C o n t a m i n a t i o n m u s t be c o n s i d e r e d an a m o r a l p h e n o m e n o n . It is neither right n o r w r o n g - - it is simply a c o n s e q u e n c e o f living. H o w e v e r , excessive c o n t a m i n a t i o n is t h a t which interferes with ecology; this is p o l l u t i o n and this is wrong. M a n a g e m e n t o f c o n t a m i n a t i o n , so that it does n o t b e c o m e pollution, is essential. H o w e v e r , a n a t i o n a l m a n a g e m e n t p r o g r a m m e , designed to avoid adverse *To whom all correspondence should be addressed. 0048-9697/92/$05.00 © 1992 Elsevier Science Publishers B.V. All rights reserved
160
v. Y O U S E F I A N D D.B.K. R A M A
effects from contamination, starts with the recognition, description and understanding of the effects of the contaminants themselves. Industrial products and a host of other activities inevitably entail the emission of contaminants. One of the transport mediums of contaminants is air which moves omnidirectionally and knows no boundaries. The atmospheric quality at industrial, residential and hospital locations, depends on meteorological, geographical and geological factors. At each site the existence of a multi-source of pollutants with different strengths make air quality evaluation difficult. Water, soil and air are the interconnected recipients of contaminants. Each of these recipient bodies has a limited capacity of tolerating the additives. Mankind should be constantly aware of their responsible position to control this delicately balanced environment. History proves that the penalty of polluting the environment is high, and the damage is virtually irreversible. In this light it is important that proper recognition, evaluation of pollutant, and sincere commitment to control the problem, be undertaken. In the Republic of South Africa the Atmospheric Pollution Prevention Act, Act 45 of 1965 [1], and its Amendment, Act 17 of 1973, are legal means of control. There exists a similar Act for the prevention of pollution of water and soil which has the provision of co-operation with all the other control bodies. The requirements and the philosophy of the Atmospheric Pollution Act is based on the best practicable means (BPM) of controls. Notes on BPMs are normally applicable to new works. Existing works are approached by earlier, less stringent standards. As the public have become more aware and concerned about the quality of air, the authorities are under increasing pressure to control pollution. Today's air pollution control is a very complex issue. No longer are the pollutants directly traceable to individual sources. Control is being achieved, not at high level but at high cost. Thus, a sensible approach to the air pollution problem is desirable. Emotive issues need to be treated objectively. MATERIALS AND METHODS In this preliminary study an attempt was made to evaluate residential, industrial and hospital environments. The following environments were taken into consideration. --
-
--
-
Two hospitals Three waste water works (sewage plants) One used oil re-refinery and chemical plant One ceramic/sanitary ware plant
MONITORING OF AIR FOR MICROBIAL AND METAL CONTAMINATION
---
-
161
One metal works plant One cigarette manufacturing plant One residential site
The main monitoring factors considered were total particulate matter [2] and airborne micro-organisms [3]. The particulate matter was analyzed for metal concentrations by ICP-spectrometry [4]. Bio-aerosols were evaluated for colony-forming units per cubic meter (CFU/m 3) of air.
Airborne particulate monitoring Total airborne particulate was sampled for nearly 24 h, using a high volume suction p u m p and an open face filter holder with a membrane filter of 0.45 or 0.8 #m pore size of 37 m m diameter. Sampling was in accordance with Health and Safety Executive (1986) guidelines [2].
Airborne micro-organisms evaluation Air sampling for micro-organisms (bio-aerosol) is governed by the same principles that affect the collection of any particulate. The collection of micro-organisms is, however, complicated by the viability of the sample. Special handling, processing and analytical techniques are needed for the enumeration and identification of collected micro-organisms. The centrifugal sampler draws the air by impeller into the sampler where the microorganisms are impacted by centrifugal force onto the surface of nutrientcoated plastic strips. In this study the Reuter Centrifugal Sampler (RCS) was used [3]. This is a battery-operated, portable instrument. After sampling at preset (lowest 0.5 to the highest 8 min) time and flow rate (40 I/min based on average 4 #m particle size), the strip is removed and transported to a central laboratory for evaluation. The strips were incubated at 30-35°C for 48-120 h and the resultant colony-forming units (CFU) counted. The number of organisms per unit volume of air was calculated (CFU/m 3) using the air flow rate and sampling time data.
Inductively coupled plasma optical emission spectroscopy An A R L 34000 ICP instrument consisting of inductively coupled argon plasma operating at 27 MHz with direct reading on a 29-channel spectrometer was used. The polychromator is thermostatted, under vacuum, and has a 1.0-m focal length system. A 1080 lines/mm grating is used in conjunction with metal-dielectric-metal-narrow band-pass (10-20 mm) filters for order sorting. The operating conditions involved an incident power of 1.25
162
v. Y O U S E F I A N D D B . K . R A M A
kW, viewing height of 15 mm above the load coil, a plasma argon flow-rate of 0.8 1/min, a coolant argon flow rate of 12 l/rain and the nebuliser argon flow rate of 1 l/min. Aspiration was through an all-glass concentric Meinhard type pneumatic nebuliser without pumping with an uptake rate of 2.3 ml/min. A Gilson autosampler was used. The ICP is operated and controlled with DEC PDP 11/03 computer. The analytical wavelengths for which the instrument is fitted and the average detection limits measured are summarised in Table 1. Standards and calibration Standards were prepared from 1000 ppm stock solutions (BDH/Merck) in 2% nitric acid. Owing to the linearity over the concentration range for the sample types analysed, a two-point calibration was used. Double distilled water was used for all preparations. Interferences in measurements
Spectral interferences due to the influence of major concomitants, and for TABLE 1 Analytical operating conditions and detection limits (DL) for the ICP Element
Emission wavelength (nm)
DL (/zg/ml)
Zn Cd Co W Fe Mg As Sn Hg Mo A1 Cu Pb Ni Si Mn Cr
213.9 226.5 228.6 239.7 259.9 279.0 189.0 190.0 194.2 202.0 308.2 324.8 220.3 231.6 251.6 257.6 267.7
0.01045 0.00777 0.00468 0.06641 0.00305 0.08719 0.09044 0.12834 0.03659 0.05644 0.04323 0.00514 0.07659 0.03256 0.03949 0.00074 0.00665
MONITORING OF AIR FOR MICROBIAL AND METAL CONTAMINATION
163
any potential spectral interferences based upon known unresolved spectral line overlaps were qualitatively checked for by wavelength scans of the background structure near the analyte wavelength. The on-peak and offpeak spectral interference was determined when the analyte was present at 2 ppm and each concomitant at 500 ppm in the solvent of interest.
Measurement of samples Three separate and successive 10-s integrations of photomultiplier current were acquired for the elements of interest in each solution. The mean of the three determinations were transformed to concentration units using the software supplied. Internal standardization was not used. Between the analysis of two samples, double distilled water was aspirated for - 1 5 s for adequate washout. RESULTS A N D DISCUSSION
The results are summarized in Tables 2-4. Identification of bio-aerosols (micro-organisms) in air is often overlooked. In this study an attempt was made to evaluate the extent of prevalence of airborne organisms. Table 4 is a summary of this finding. Due to the wide range of industry, the emission of contaminants would be different at different sites. Refuse incineration is a major source of air pollutants. The meteorological, geological and geographical factors at each site are the major influencing factors for the accumulation, dispersion and dilution of contaminants. Table 2 shows the mass concentration of total particulates at different sites.
TABLE 2 Mass concentration of total particulates in ambient air Site
Concentration (mg/m 3)
Residential Hospital No. 1 Hospital No. 2 Industrial Used-oil refinery Metal works Ceramics Tobacco
0.21 0.03 (in city) 0.09 (close to industry and residential) 0.06 0.23 0.64 1.06
Hospital No. 1 Hospital No. 2 Residential Chemical Industrial Ceramic Metal works 1/50th TLV
Hospital No. 1 Hospital No. 2 Residential Chemical Industrial Ceramic Metal works 1/50th TLV
Source
409 215 322 121 6674 343 604 3000
Pb
5 6 12 7 581 38 69 1000
Co
629 281 924 394 19805 2225 2265 --
K
5 6 12 6 465 34 55 1000
Cd
109 31 256 152 11716 916 1542 4000
Se
18 64 103 29 823 85 155 1 x 104
Cr
Concentration of trace elements ng/m 3
Trace elements of ambient air at the selected sites
TABLE 3
938 1233 2702 502 13178 10079 1276 2 × 105
Si
45 52 49 16 4815 85 105 2 x 104
Cu
116 182 225 94 3332 1002 154 2 x 105
Zn
13 13 24 16 1556 97 116 1000
Hg
416 634 779 547 3934 912 592 1.04 × 105
S
2114 2989 7552 1488 6603 6724 8996 5 x 105
Fe
371 444 874 248 6448 1123 4793 2 × 105
Mg
132 749 1282 97 247 1860 163 1 × 105
Mn
105
274 136 392 195 9336 934 861 93 182
1 x
Na
12 18 42 12 859 10 105 2 x 104
Ni
W
6 4 30 5 368 25 45 1 × 105
Mo
MONITORINGOF AIR FOR MICROBIALANDMETALCONTAMINATION
165
TABLE 4 Bio-aerosol evaluation at different sites Site
Sewage Plant Sewage Plant Sewage Plant Hospital No.
CFU/m 3
No. 1 No. 2 No. 3 2
Indoor environment
Outdoor environment
Distant location (distance in brackets)
825 50-250 25 650-1050
3700 8500 850 950
3700 a (2 km) 175 (1 km) 225 (0.5 km) 375 (0.1 km)
aprobably high due to sprayers used at this site (instant lawn farm). Both raw sludge and the final effluent is used for spray irrigation.
The chemical analysis of this particulate matter indicates the presence of a variety of metals. Table 3 is a summary of this analysis. The sources of these metals are not known, but some are from vehicle exhaust emissions and some are from the effluents of incineration stacks. However, the locality of the site and an observation of its surroundings, suggest that the magnitude of contaminants observed correspond to the type of environment and the density of traffic at that vicinity. Waste water treatment processes involving bubble aeration results in ejection of biological aerosols into the ambient atmosphere [5]. It has been defined that a viable particle is one containing at least one bacterial cell capable of forming a colony under the conditions selected by the investigator [6]. In this study, colony-forming units per cubic meter of air (CFU/m 3) was the basis of our bacterial evaluation. Table 4 describes the recovery of bacterial aerosols from its sources. Also it has been stated that there is little quantitative information on the spread of viable aerosols downwind [6]. Table 4 shows wide differences in CFU/m 3. High CFU/m 3 at Works No. 1 and its nearby lawn farm, needs no explanation. Residents near Works No. 3 often complain about offensive odours, especially during the windy season. They also report frequent occurrences of sore throats and headaches. This offensive odour and the airborne microorganisms may be transported at considerable distance from the very same plant. In the case of Works No. 3, the high colony count (225 CFU/m 3) near the fence, between the school and the plant, is significant. As far as the hospital
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is concerned, both inside and outside, there are potential sources at each sampled position. CONCLUSION In this paper we have tried to inform rather than to judge. Our purpose is to present facts and to underline problems, not to suggest solutions. We regard contamination as inevitable. Its management depends upon an understanding of its effects. Understanding the effects requires a knowledge of the kind of contamination, the dose, as well as the sensitivity of the receptor system. The Republic of South Africa, like other nations in the world, inherited many intractable problems from past planning decisions, which were probably based on the best available evidence at that time. Caution should be exercised not to make the same mistake again. This aspect should be given careful consideration and it should be common practice to have certain areas zoned for different types of industry, while housing, commercial and residential areas be advantageously situated. More attention should be paid to meteorological factors, atmospheric chemistry, oxidation, hydrocarbons and photochemical reactions. Some industries are relocating into the neighbouring states due to tax benefits, cheap labour and other economical benefits. The approach to air pollution control in these states is different. However, it should be borne in mind that trans-frontier pollution is inevitable. Hence, the whole subcontinent will be affected. A common policy on air pollution prevention needs to be adopted. Information on acceptable concentrations of some materials, in terms of environmental impact are sparse. In deciding upon the BPM, the pollution control authorities do not permit any emission which may result in public health hazard. The strategy is to ensure a margin of safety. In order to achieve this, decisions have to be made about acceptable levels of exposure for many substances. There is little scientifically-based information available on this topic where it is specifically designed to protect the public as distinct from occupational health. Fractions of occupationally derived limits are therefore used for guidance. One such set of standards is the Threshold Limit Values and the Biological Exposure Indices published by the American Conference of Governmental Industrial Hygienists [7]. Whilst the policy of avoiding demonstrable public health hazards has been achieved, the BPM cannot guarantee that local environments are fully acceptable in terms of amenities and therefore free from public complaints. Many complaints are triggered by abnormal conditions. If an investigation of the cause of the problem is made, where possible, the aim should be to prevent or minimize the likelihood of its recurrence.
MONITORINGOF AIR FOR MICROBIALAND METALCONTAMINATION
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The pollution control authority should consult with industry in formulating the relevant BPM. Control requirements are of no value whatsoever if they cannot be implemented. Therefore, pollution control authorities must gather information from industry both locally and internationally. Notes on BPMs are primarily applicable to new works. Existing works usually operate to satisfy earlier, less stringent standards than are set out in newly developed notes. They are normally allowed to continue to operate according to those requirements if no public health hazard exists or no public complaint emerges. Furthermore, there is no specific legislation for the control of airborne micro-organisms. We feel that such legislation should be prepared. The scheduled processes list needs to be amended accordingly. In order to properly conserve our environment, it is necessary to evaluate accurately the present state of the natural environment, so as to form a clear picture of the future direction of its change. Furthermore, now is the time to design and introduce the strategy of 'Pollution-related Health Damage Compensation Law' based on the Polluter-Pays-Principle (PPP) as adopted by the Japanese [8]. ACKNOWLEDGEMENT
The authors wish to thank the staff of the Microbiology Department at the National Centre for Occupational Health for their assistance, and Dr. A.C. Cantrell for editorial comment. REFERENCES 1
A t m o s p h e r i c Pollution Prevention Act, 1965 (Act 45 o f 1965), as a m e n d e d by the Atmospheric Pollution P r e v e n t i o n A m e n d m e n t Act, 1973 (Act 17 o f 1973).
2 Health and Safety Executive, General methods for the gravimetric determination of respirable and total inhalable dust, MDHS 14, Her Majesty's Stationery Office, London, 1986. 3 A.M.Placencia and G.S. Oxborrow, Technical Report, Use of the Reuter Centrifugal air sampler in good manufacturing practices investigations: Referencematerials and training aids for investigators, US Department of Health and Human Services, Public Health Service, Food and Drug Administration, Minneapolis, 1984. 4 Peter M. Eller (Ed.), NIOSH Manual of Analytical Methods, Vol. 1, NIOSH Method 7300. Elements (ICP). 7300(1)-7300(5). U.S. Dept of Health and Human Services, National Institute for Occupational Safety and Health; Cincinnati, Ohio, 3rd edn., 1984. 5 LawrenceSlote, Viral aerosols: a potential occupationally related health threat in aerated waste water treatment systems. J. Environ. Health, 38 (1976) 310-314. 6 J.L.S. Hickey and P.C. Reist, Health Significanceof airborne micro-organismfor waste water treatment plant processes. Part II, Summary of investigations. J. Water Pollut. Control Fed., 47 (1975) 2741-2772. 7
Threshold Limit Values a n d Biological Exposure Indices for 1989-90, A m e r i c a n Conference of G o v e r n m e n t a l Industrial Hygienists, Cincinnati, Ohio, USA, 1989.
8 Quality of the Environment in Japan 1983, Environment Agency, Government of Japan, 1983, pp. 256-257.
