INTRODUCTION:

The origin of urban air pollution is mainly in anthropogenic emission sources, which include automobiles, Industries and domestic fuel combustion. The air pollutants so generated are detrimental to human health (Sarala Thambavani and Saravanakumar, 2011).

In addition, they cause negative impacts directly or indirectly, if at elevated concentrations, on vegetation, animal life, buildings and monuments, weather and climate, and on the aesthetic quality of the environment (Stern, 1976; Godish, 1985; Takemura et al., 2007, Shen et al., 2009). Rates of increase in air pollutant concentrations in developing countries such as India are higher than those in developed countries and hence atmospheric pollution is often severe in cities of developing countries all over the world (Mage et al., 1996). India and other developing countries have experienced a progressive degradation in air quality due to industrialization, urbanization, lack of awareness, number of motor vehicles, use of fuels with poor environmental performance, badly maintained poor roads and ineffective environmental regulation (Joshi and Chuhan, 2008). Apart from local effects, air pollutants can travel long distances and cause impacts far from its source (Agarwal, 2005). Indian cities are facing serious problem of airborne particulate matter (Agarwal et al, 1999) and the United Nations estimated that over 600 million people in urban areas worldwide were exposed to dangerous levels of traffic generated air pollutants (Cacciola et al, 2002). The high concentration of particulate matter in the environment has become a problem for many countries (Elbir et al., 2000). PM consists of primary aerosols as well as secondary aerosols such as sulfate, nitrate, sulfur dioxide (SO₂) and oxides of nitrogen (NO_x), if present in excess in ambient air, affect the respiratory tract causing irritation and increasing airway resistance (Tsai et al, 1991). Air pollution can directly affect plants via leaves or indirectly via soil acidification (Steubing, et al., 1989, Sarala Thambavani and Saravanakumar, 2011). Atmospheric particulate matter is the major air pollutant in India. In many Indian cities, the levels of particulate pollutants in the ambient air have been found to be above the permissible limit (Meenakshi and Saseetharan, 2004). Concentration of ambient air particulates has been found to be associated with a wide range of effects on human health (Dockery and Pope, 1994; Gold berg, 1996; Schwartz, 1991; Schwartz, 1994). Approximately 50,000 premature deaths occur annually due to PM10 pollution in India. In the present study, the levels of particulate air pollutants were measured at three stations within Madurai city and these particulate pollutants concentrations were statistically compared with secondary aerosols such as Sulphur dioxide and Oxides of nitrogen. This paper is organized Data and analysis techniques, including the geography of the study area, the data collection method, data processing, and analytical techniques and Air Quality Index (AQI) and Major Conclusions are presented.

Air Quality Sampling and Analysis:

Suspended Particulate Matter:

Sampling was done with the handy and personal samplers manufactured by Envirotech. Small circular filter disc of Whattman GF/A 42 filter paper was used for SPM sampling. Dry weight of the above-mentioned filter paper was taken after drying in an oven at 105^oC. This process was repeated thrice and the average weight was taken. The dry weight of filter papers were determined before and after sampling and the difference of weight constituted the suspended particulate matter.

Sulphur Dioxide:

Sampling was done with the Envirotech make handy sampler (APM 820). The sampling and analysis were done as per IS 5182 (part II) 1969. Sodium tetrachloride mercurate was used to absorb SO₂ at a constant flow rate of 1 ppm for 90 minutes. Spectrophotometric analysis using sample of sodium tetrachloromercurate containing SO₂, absorbed from air was analyzed in GBC-Cintra Ultra Violet spectrophotometer at a wavelength of 560 nm.

Oxides of Nitrogen:

Sampling was done with the Envirotech make handy sampler (APM 820). The sampling and analysis were done as per IS 5182 (part VI) 1975. Sodium hydroxide was used to absorb NO₂ at a constant flow rate of 1 ppm for 90 minutes. Spectrometric analysis with sample of sodium tetrachloromercurate containing SO₂, absorbed from air was analyzed in GBC-Cintra Ultra Violet spectrophotometer at a wavelength of 540 nm. Monitored pollutants and the methodologies employed for ambient air quality study are listed in table 1.

Data and Analysis Techniques:

Madurai city is one of the important cities in South India. It is the seventh largest city in Tamil Nadu, situated at the banks of river Vaigai and its terrain is mostly flat. The ground rises from the city, towards outward, on all sides except the south, which is a gradually sloping terrain. It is surrounded on the outskirts by small and prominent hills. The city is about 100 meters above mean sea level and it is situated on 9⁰55’ NL and 78⁰7’ EL and the city is covering 51.96 sq.kms that comprises of a total population of 25,78,201 persons (Census 2011) whereas the Madurai

Urban agglomeration comprising the city and surrounding settlements accommodates a population of 12,03,095 persons. The climate of Madurai city is hot and dry and the temperature range between a maximum and minimum of 42⁰C and 21⁰C respectively. The city has emerged as an important center for textiles and engineering industries. The sampling stations were selected keeping in view the important zone and the nature of activity. A total of three sampling stations, consisting of industrial, residential and traffic cum commercial were chosen for the present study. The description of sampling station is given in table 2.

For the present study, all the primary pollutants data were collected by the Central Pollution Control Board (CPCB) at three sampling sites in Madurai city during the year of 2002 to 2009. Then the observed annual average concentrations of ambient air pollutants over Madurai city has been compared with the respective Indian National Ambient Air Quality Standards (INAAQS) are listed in table 3.

A basic statistical analysis was carried out for all the pollutants in all the sampling stations. These basic statistics include maximum, minimum, mean, standard deviation and coefficient of variation of each variable during the study period shown in the table 4. The Pearson correlation analysis has also been performed between particulate and gaseous pollutants to investigate the relationships between them.

Fig-1: Trend of Gaseous pollutants over Madurai city during 2002-2009.

Fig-2: Trend of Particulate Matter over Madurai city during 2002-2009.

Analysis of Air Pollution Indices:

An environmental index is a tool that is used to report overall environmental status and trend based on a specific standard (Thomas and Ott, 1976). It has been found that the rate of progress among countries towards producing indices is highly uneven. Ambient air quality standards impart an idea about the ambient air quality status. Evaluating overall air pollution due to various air pollutants is a complex understanding. It consists of an ill-defined mixture of several pollutants from different sources. Additional secondary pollutants are created in the atmosphere. Synergism can occur among certain pollutants. Despite these complexities, efforts are made to evaluate the combined effects of the individual pollutants. There are several methods and equations used for the determination of the Air pollution indices (API). The relative scale of API is given in table 5.

TABLE 5: Relative scale of Air Quality Index:

Index Value Category

<25 Clean air

26-50 Light air Pollution

51-75 Moderate air Pollution

76-100 Heavy air Pollution

>100 Severe air Pollution

Air Quality Index:

Air Quality Index (AQI) is the number indicating the air quality at a particular time in a particular area. Air pollution indices are used to provide accurate, timely and easily understandable information about daily levels of air pollution. Index figures enable the public to determine whether air pollution levels in a particular location are good, moderate, unhealthful, or worse. In addition, the relevant authorities can use the indices as public information tool to advise the public about the general health effects associated with different pollution levels and to describe whatever precautionary steps may need to be taken if air pollution levels rise into the unhealthful range (Air pollution indices in the ASEAN region, (2004); Department of Environmental science UPM). The pollutants included for the Indian air quality index are SPM, SO₂, NO_x, PM10 (RSPM), CO and O₃. The standard level of Central pollution control board (CPCB) are 200 µg/m³ for SPM, and 80 µg/m³for SO₂ and NO_x have been considered for arriving at the AQI (Dayal and Nandini, 2000).

For urban areas in India, an equation has been developed to determine AQI. In India, generally four pollutants (SO₂, NO_x, SPM and RSPM) are monitored continuously in urban areas. For the proposed equation, these four pollutants have been considered. Equal weight age is given to all pollutants (that is n_i=1). For each pollutant there is individual pollutant index (Pi), which is defined as:

Pi = [C_i/C_s]ⁿⁱ ………………..(1)

Where, C_iis the current concentration level of a pollutant, C_s is standard for that pollutant for the same average time period, and n_i is the weighting for that pollutant (n=1 if all pollutants have equal importance). An individual pollutant index is greater than 1; it means that actual concentration level has exceeded the standard value. The equation for AQI can be written in generalized form as:

AQI = [A ∑P_i] B ………………… (2)

Where, A and B are constants to be selected on the basis of past history and the classification of air quality. The background levels for the four pollutants considered are: NO₂- 0.001 ppm, SO₂- 0.0002 ppm, SPM – 37 μg/m³ and RSPM- 14 μg/m³. The equation developed for calculation of AQI is as follows:

AQI = [13.7 ∑C_i/S_i]^1.15 ……………. (3)

The national ambient air quality standards for these pollutants in India are given in table 6 (CPCB, 2004).

TABLE 6: Air quality categories based on air quality index

AQI Values Ambient air quality status

<20 Excellent

20-39 Good

40-59 Low

80-99 High

>100 Critical

Air quality index was calculated based on Tiwari and Ali (1987) method. The air quality was categorized as per Mudri (1990). The air quality rating if each parameter is considered is obtained by q= V/Vs, where ‘q’ is the quality rating, ‘V’ is observed value of the parameter and ‘Vs’ is standard value recommended for the parameter. If ‘n’ number of parameter is considered, the arithmetic means of these ‘n’ number of quality rating is found out.

AQI = ¼ [∑ⁿCi/Cs] 100 …………….. (4)

TABLE 7: Air Quality categories based on AQI

Index Value Category

Below 10 Very clean

10-25 clean air

26-50 fairly clean

51-75 Moderately Polluted

76-100 Polluted

>100 heavily polluted

Oak Ridge Air Quality Index (ORAQI):

In this study, Oak Ridge Air Quality Index (ORAQI) has been used for the relative ranking of overall air quality status at different study locations (Ghose, 2004: Inhabier; 1974). All the parameters required for this meet the requirements of CPCB, Govt. of India. ORAQI can be calculated using the following formula:

ORAQI = 9.61 x x 1.37 ……… (5)

Where, Ci – concentration for pollutant i

Si – standard pollutant i

Oak ridge air quality index was chosen for relative ranking of different pollution with respect to air quality status. Oak Ridge Air quality Index helps in assessing the ambient air quality status. The suggested ranking for ORAQI readings is tabulated in table 8.

TABLE 8: Air quality categories based on ORAQI values

ORAQI Values Condition

<20 Excellent

20-39 Good

40-59 Fair

60-79 Poor

80-99 Bad

100 and above Dangerous

The AQI values obtained by equation (4) are compared with ORAQI equation modified for the four pollutants in the present study, keeping the exponent same as 1.37. The modified ORAQI equation has been developed as:

Modified ORAQI = [7.21 ∑ C_i/S_i] ^1.37 …………(6)

TABLE 9: AQI calculated using the formula

Location	Years								Average AQI	Category
Location	2002	2003	2004	2005	2006	2007	2008	2009	Average AQI	Category
Fenner (I) Ltd	38	34	30	21	24	21	21	18	25.88	Good
Highwaybuilding	112	67	48	42	45	40	38	42	54.25	Low
Kunnathurchatram	126	169	170	74	47	43	44	45	89.75	High

TABLE 10: AQI calculated using the formula ¼ [∑ⁿCi/Cs] 100

Location	Years								Average AQI	Category
Location	2002	2003	2004	2005	2006	2007	2008	2009	Average AQI	Category
Fenner (I) Ltd	44	40	35	26	29	26	26	26	31.12	Fairly clean
Highway building	110	71	53	48	50	46	44	47	58.63	Moderately polluted
Kunnathurchatram	123	158	159	77	52	49	49	50	89.63	Polluted

TABLE 11: AQI calculated using the formula ORAQI = 9.61 xx 1.373

Location	Years								Average AQI	Category
Location	2002	2003	2004	2005	2006	2007	2008	2009	Average AQI	Category
Fenner (I) Ltd	23	21	18	13	15	14	14	12	16.25	Excellent
Highwaybuilding	58	37	28	25	26	24	23	25	30.75	Good
Kunnathurchatram	65	83	84	41	28	26	26	26	47.38	Fair

TABLE 12: AQI calculated using the formula Modified ORAQI = [7.21 ∑ C_i/S_i] ^1.37

Location	Years								Average AQI	Category
Location	2002	2003	2004	2005	2006	2007	2008	2009	Average AQI	Category
Fenner (I) Ltd	32	28	24	15	19	16	16	13	20.38	Good
Highwaybuilding	114	62	42	36	38	34	32	35	49.13	Fair
Kunnathurchatrm	132	187	189	70	41	37	38	38	91.5	Bad

TABLE 13: Geometric Mean value of AQI in Madurai city using all AQI equation

Sites	AQI = [13.7 ∑C_i/S_i]^1.15	AQI=¼ [∑ⁿCi/Cs] 100	ORAQI =9.61 1.37	M.ORAQI=	Mean AQI	Category
Fenner (I) Ltd	25.88	31.12	16.25	20.38	22.72	Clean air
Highway building	54.25	58.63	30.75	49.13	46.82	Light air Pollution
Kunnathur chatram	89.75	89.63	47.38	91.50	76.85	Heavy air Pollution

Fig. 3: AQI values over Madurai city based on Equation-3

Fig.4: AQI values over Madurai city based on Equation 4

Fig. 5: AQI values over Madurai city based on Equation 5.

Fig. 6: AQI values over Madurai city based on Equation 6.

Figure 7: Comparisons of Mean AQI Values of Sampling Sites over Madurai city.

RESULTS AND DISCUSSION:

Annual Distribution of Particulate Pollutants:

Primary statistics of pollutants SO₂, NO_x, SPM and RSPM are listed in Tables3. The statistics include maximum, minimum, mean, standard deviation and coefficient of variation. The overall annual average SO₂ concentrations varied from 8 μg/m³ to 20 μg/m³ in 2002 to 2009 at all three stations. The highest annual average 20 μg/m³ was recorded in the years 2003 and lowest annual average, 8 μg/m³ was recorded in the year 2007.The annual average concentration of NO_x varied from 20 to 40 μg/m³ in all the study period. The maximum and minimum value of NO_x 40 μg/m³ and 20 μg/m³were recorded in2002 and 2004 respectively. As far as SPM is concerned, annual average concentrations varied from 65 to 397μg/m³. Highest value of SPM 397 μg/m³ was recorded in the year 2004 and lowest value 65 μg/m³ was recorded in the year 2002. The annual average concentrations of RSPM varied from 29 to 183 μg/m³ in 2002 to 2009. The highest and lowest concentration was recorded in 2003 and 2005 respectively. Out of three stations kunnathur chatram has highest annual average for both RSPM and SPM. Lowest concentration of both particulate matters was noted in the Fenner(I)Ltd and highway building. So, the particulates and gaseous pollutants generated due to photochemical reactions may also be correlated with the recorded concentrations. Figure1 and 2 showed the trend of Gaseous pollutant and particulate matter over Madurai city during the study period. It was noted that both kind of pollutants have decreasing trend. The decreasing concentrations of these pollutants exhibit due to the decreasing usage of petrol and diesel in most of the automobiles within the city. The Tamil Nadu Pollution Control Board has implemented many action plans to bring down the particulate pollutants level over Madurai city. In a comparison of annual SPM averages with ambient air quality standards, it is observed that pollutant concentrations have often crossed the permissible limit. Automobiles and industries are the major sources for atmospheric particulate pollution in Madurai. Except automobiles, operation of diesel-powered generators (which are used in commercial establishments during electricity supply failures), emissions from paved roads, and background concentrations from industrial and semi industrial areas of the city are the other important sources of particulate pollution. Cooking in houses, school and commercial establishments; and refuse incineration in houses, public places, and municipal incineration in open grounds offer their own contributions to the total load as well as the atmospheric particulate matter concentrations all over the city. The other important reason for the recorded concentrations in the sampling sites may be combustion of conventional fuels like firewood, charcoal, dry cow dung, biomass materials and agro residues not only at the nearby slum areas but also at the commercial centers especially in the roadside hotels. These sources emit large amount of particulates in to the atmosphere (Carvacho et al., 2004; Monna et al., 2006). It is noted that the sand along the sides of the roads, which are dusty in nature, is not removed frequently. The road dust re suspension through mechanical and thermal turbulence also constitutes a source of primary atmospheric particles (Weckwerth, 2001; Sternbeck et al., 2002; Adachi and Tainosho, 2004). Both particulate pollutants (SPM, RSPM) showed maximum standard deviations in traffic cum residential area because emissions are high due to maximum number of point sources, and also emissions from the other sources like area sources and line sources. Minimum standard deviations are noticed in industrial areas because of nature of the sampling sites and sources are less when compared with commercial cum traffic areas.

The Coefficient of Variation (CV) is defined as the ratio between the standard deviation to mean. The CVs of the recorded concentrations of SO₂ are 26.32%, 11.40% and 7.56% and NO_x are 9.02%, 10.72% and 24.80% for the three sites respectively (table 4). Similarly, calculated CVs of the recorded concentrations of SPM are 24.24%, 37.00% and 62.12% and RSPM are 54.96%, 61.78% and 72.13% for the three sites respectively. The calculated CVs of the recorded concentrations range from 24.24% to 72.13% for particulate matters and from 7.56% to 26.32% for Gaseous pollutants.

Air Quality Index:

An air quality index (AQI) is defined as a numerical rating that reflects the composite influence on overall quality of a number of air quality parameters which will be helpful not only for advising the public but also for urban planning (Inhaber, 1975; Kassomenos et al., 1999; Srivastava and Sarkar, 2006; Bishoi et al., 2009). The AQI focuses on health effects we may experience within a few hours or days after breathing polluted air. The higher the AQI value, the greater the level of air pollution and the greater the health concerns. An AQI value of 100 generally corresponds to the national air quality standard, which is the level set to protect public health in India. AQI values below 100 are generally considered satisfactory. When AQI values are above 100, air quality is considered to be unhealthy at first for certain sensitive groups of people, then for everyone for higher AQI values (Mohan and Kandya, 2007). In the present study, the annual average value of SO₂, NO_x, SPM and RSPM in the ambient air of Madurai city at three sites, namely industrial, residential and commercial cum traffic areas were considered to determine the short-term air quality indices. The AQI levels for these activities were illustrated in the table 9 to 12. This shows that AQI values are highest in commercial area followed by industrial area and residential areas over the study period from 2002-2009. These high AQI value in commercial area is attributed by vehicular emission. It is also proved by the mean AQI values taken for each site.

The AQI are analyzed by considering annual averaged values of each pollutant during year 2002 to 2009 at three sampling sites using the proposed equation 3 to 6 and reported in tables 9 to 12 and figures 3 to 6. The geometric mean value of all AQI equations for the study area is also reported as mean AQI value for Madurai (table 13, fig. 7). Pollution status and AQI for different locations are discussed below. The AQI trends are decreased over the time at all activity zones. AQI values varied from 16.25 to 91.50. It is to be noted that highest AQI values were observed in traffic cum commercial area which have low levels of permissible limits. Lowest AQI values were observed in industrial areas because they have high permissible limits. The categories of AQI values in the sampling sites are good, fair and bad at industrial, residential and commercial areas respectively. This indicates that air quality in commercial area is dangerous over the study period compared with other two sites. In the Fenner (I) Limited, the level of SPM is highest and SO₂ is lowest. The trend of pollutants levels is SO₂<NO_x<RPM<SPM. The AQI value is continuously decreasing from 2002 (38) to 2009 (12) in all the equations. The mean value of AQI for the last eight years is 23. This showed that the ambient air quality is good and clean.The residential area of highway building the AQI Values are continuously decreasing from 2002 to 2009 in all the equations. The mean AQI value for the last nine years is 47, which showed that ambient air quality is light polluted in the study region. At Kunnathur chatram, the level of SPM and RSPM is higher than the level of sulphur dioxide and oxides of nitrogen. The trend of pollutant levels are SPM>RSPM>NO_x>SO₂.The pollutantSO₂-SPM, SO₂- RSPM, NOx-RSPM and SPM - RSPM are positively correlated with r-values 0.22 to 0.93 for each. This shows that RSPM concentration increases with the concentrations of SO₂and SPM. The average AQI value is 77, which reveals that the ambient air quality is heavily polluted.

From these AQI estimates, it is amply clear that ambient air pollutants are emerging as critical pollutants for urgent attention because they are degrading air quality in Madurai city with consequent effects on public health. On the basis of the rating scale in table 6, it is found that the atmospheric environment of Madurai is polluted from moderate to unhealthy levels. This indicates an urgent need for systematic control of atmospheric pollutants from anthropogenic sources especially the particulate pollutants to safeguard the human population, flora, and fauna as well as social assets such as cultural sites in the city. Therefore, stringent air quality control options to specific sources are to be adopted for reductions of ambient levels.

CONCLUSION:

The present study shows that particulate pollutants SPM and RSPM are mostly above permissible limits at kunnathur chatram in Madurai city. In Madurai SO₂, NOx and SPM concentrations are continuously decreasing but there are no substantial changes in PM10 concentrations. This implies that fine-mode particles are still produced by vehicles, industrial activities, and combustion of conventional fuels for domestic and commercial purposes. The results of this study will be useful for further research on interactions between atmospheric aerosols, and local and regional weather and climate in Madurai. On the basis of the AQI rating scale, we found that the atmospheric environment of Madurai is in moderately polluted to unhealthy range due to the city is expanding rapidly human and animal populations, vehicular traffic and industrialization. These developments are increasing atmospheric aerosol concentrations which in turn, are increasing ambient air pollution substantially. It is certain that these increases will make adverse effects on climate as well as health. Hence it can be concluded that a strict implementation of adequate abatement measures and environmental regulations is urgently necessary.

REFERENCES:

1. Adachi, K. and Tainosho, Y . Characterization of Heavy Metal Particles Embedded in the Tyre Dust. Environ. Int. 30:2004, 1009–1017.

2. Agarwal A, Narain S, Sen S. State of India’s environment. The Citizens Fifth Report. Part I: National Overview. Centre for Science and Environment, New Delhi. In A. Agarwal (Eds.) 1999; PP. 167-206.

3. Agarwal M. Effects of air pollution on agriculture: An issue of national concern. National Academy of Science Letter. 23 (3and4):2005 93-106.

4. Air pollution indices in the ASEAN region. Department of Environmental Science UPM 2004.

5. Bishoi, B., Prakash, A. and Jain, V.K. A Comparative Study of Air Quality Index Based on Factor Analysis and US-EPA Methods for an Urban Environment. Aerosol Air Qual. Res. 9:2009, 1–17.

6. Cacciola RR, Sarva M, Polosa R. Adverse respiratory effects and allergic susceptibility in relation to particulate air pollution: Flirting with disaster. Allergy. 57:2002, 281-286.

7. Carvacho, O.F., Trzeple–Nabaglo, K., Ashbaugh, L.L., Flocchini, R.G., Melin, P. and Celis, J. Elemental Composition of Spring Time Aerosol in Chillan, Chile. Atmos. Environ. 38: 2004, 5349–5352.

8. Central Pollution Control Board, New Delhi.URL: http://www.cpcb.delhi.nic.in/as.htm. 2004.

9. Dayal, H.V. and S.N. Nandini. Vehicular emissions and ambient air quality in Mangalore city. Poll Res.19 (2):2000, 205-209.

10. Dockery, Ward.D, Pope. C.A. Acute respiratory effects of particulate air pollution, Annu. Rev. Public Health, 15; 1994: 104-132.

11. Elbir.T, Muezzinoglu.A and Bayram.A. Evaluation of some air pollution indicators in Turkey, Environmental International. 26; 2000: 5-10.

12. Ghose, M.K. Assessment of air pollution indices in opencast coal mining complex- An Indian case study. J. Env. Sci. Eng. 46; 2004: 21-32.

13. Godish, T. Air Quality. Lewis Publishers, Inc. Chelsea, USA 1985.

14. Godberg.K. Particulate air pollution and daily mortality: Who is at risk? Journal of Aerosols Med. 9; 1996: 43-53.

15. Inhaber, H. A Set of Suggested Air Quality Indices for Canada. Atmos. Environ. 9; 1975: 353–364.

16. Joshi PC, Chauhan A. Performance of locally grown rice plants (Oryza sativa L.) exposed to air pollutants in a rapidly growing industrial area of district Haridwar, Uttarakhand, India. Life Science Journal. 5(3); 2008: 41-45.

17. Kassomenos, P., Skouloudis, A.N., Lykoudis, S. and Flocas, H.A. Air Quality Indicators for Urban Indexing of Atmospheric Pollution over Large Metropolitan Areas. Atmos. Environ. 33; 1999: 1861–1879.

18. Mage D. Ozolins G, Peterson P, Webster A, Orthofer R, Vandeweerd V, Gwynne M. Urban air pollution in mega-cities of the world. Atmospheric Environment; 30; 1996: 681-686.

19. Meenakshi P and Saseetharan M.K. Urban Air Pollution Forecasting with Respect to SPM using Time Series Neural Networks Modelling Approach – A Case Study in Coimbatore City. J. Environ. Sci. Eng. 46; 2004: 92–101.

20. MoEF. Annual report. Ministry of Environment and Forests, Government of India, New Delhi, 2000-2001.

21. Mohan, M. and Kandya, A. An Analysis of the Annual and Seasonal Trends of Air Quality Index of Delhi. Environ. Monit. Assess. 131; 2007: 267–277

22. Monna, F., Poujol, M., Losno, R., Dominik, J., Annegarn, H. and Coetzee, H. Origin of Atmospheric Lead in Johannesburg, South Africa. Atmos. Environ. 40; 2006: 6554–6566.

23. Mudri, S.S. Categorisation of ambient air quality on the basis of air quality index. Indian J. Env. Prot., 10(6); 1990: 424-427.

24. National Ambient Air Quality Statistics of India. Central pollution Control Board, 1997.

25. Sarala Thambavani D, Saravana Kumar R. Correlation Analysis and Exceedence Factor among the Ambient Gaseous Pollutants and Particulate Matter in Urban Area. Journal of research in Biology. 3; 2012: 232-240.

26. Sarala Thambavani. D, Saravanakumar. R. Pigment Profile and Chlorophyll degradation of selected road side Plant Species. Asian Science .6 (1and2); 2011: 93-102.

27. Schwartz.J. Particulate air pollution and daily mortality: A Synthesis Public health Rev. 19;1991: 39-60.

28. Schwartz.J . Air pollution and daily mortality: A review and metal analysis. Environmental Research. 64;1994: 39-60.

29. Shen Z.X., Cao, J.J., Tong, Z., Liu, S.X., Reddy, L.S.S., Han, Y.M., Zhang, T. and Zhou, J. Chemical Characteristics of Submicron Particles in winter in Xi’an. Aerosol Air Qual. Res. 9; 2009: 80–93.

30. Srivastava, R.K. and Sarkar, R. Air Quality Index: A Brief Review. Indian J. Environ. Prot. 26; 2006: 344–347.

31. Stern, A.C. Air Pollution. Academic Press, New York, USA.1976; Vol. 1, 3rd edn.

32. Sternbeck, J., Sjodin, A. and Andreasson, K. Metal Emission from Road Traffic and the Influence of Resuspension – Results from Two Runnel Studies. Atmos. Environ. 36; 2002: 4735–4744.

33. Takemura, T., Kaufman, Y.J., Remer, L.A., Nakajima, T. Two competing pathways of aerosol effects on cloud and precipitation formation, Geophys. Res. Lett. 34:2007: L04802. doi: 10.1029/2006GL028349.

34. Thomas G.C and W.R. Ott. Preliminary communication- A proposed uniform air pollution index. Atmos. Env. 10; 1976: 261-264.

35. Tiwari, T.N. and Manzoor Ali. Air quality index for Calcutta and its monthly variation for various locations. Indian J. Env.Prot. 7(3); 1987: 172-176.

36. Tsai.Y and Cheng.M.T. Visibility and aerosol chemical compositions near the coastal area in Central Taiwan, Scientific Total Environment. 231; 1991: 37-51.

37. Weckwerth, G. Verification of Traffic Emitted Aerosol Components in the Ambient Air of Cologne (Germany). Atmos. Environ. 35; 2001: 5525–5536.

Received on 21.09.2012 Modified on 03.10.2012

Asian J. Research Chem. 5(10): October, 2012; Page 1242-1250

Methodology	SO₂	NO_x	SPM	RSPM
Indian standard number	IS-5182 (part-II) 1989	IS-5182 (part-II) 1982	IS-5182 (part-IV) 1987	--
Sampling equipment	High volume sampler with impinge	High volume sampler with impinge	High volume sampler	--
Duration sampling	8 hour	8 hour	8 hourly for 24 hour	8 hourly for 24 hour
Collection media	TCM	NaOH	GF/A Filter paper	Thimble

Sites	Location	Description	Category
Site-1	Fenner (I) limited	Industrial, residential area	Industrial
Site-2	Highway building	Less traffic, residential area	Residential
Site-3	Kunnathur chatram	Heavy traffic, residential, commercial area and shopping complex	Commercial cum traffic

Pollutants	Time weighted average	Concentration in ambient air
Pollutants	Time weighted average	Industrial areas	Residential, Rural and other areas	Sensitive areas
Sulfur dioxide (SO₂) (μg/m³)	Annual*	80	60	15
Sulfur dioxide (SO₂) (μg/m³)	24 hours**	120	80	30
Oxides of Nitrogen as NO_x (μg/m³)	Annual*	80	60	15
Oxides of Nitrogen as NO_x (μg/m³)	24 hours**	120	80	30
Suspended Particulate Matter (μg/m³)	Annual*	360	140	70
Suspended Particulate Matter (μg/m³)	24 hours**	500	200	100
Respirable Particulate Matter (μg/m³)	Annual*	120	60	50
Respirable Particulate Matter (μg/m³)	24 hours**	150	100	75

Air Quality Index Value of an Ambient Air Pollutants and their Relationship in Urban Area

Years