Air quality, with regard to Sulphur Dioxide (SO₂), Oxides of Nitrogen (NO₂) and Suspended Particulate Matter (SPM) in industrial and residential locations in various cities/town was monitored during the reported period and evaluated on the basis of Exceedence Factor (EF) in terms of low, moderate, high and critical.

6.1.2 Sulphur Dioxide (SO₂)

The annual mean concentration of SO₂ vis-à-vis number of monitoring stations is depicted in Fig 6.1. It is observed that at one residential location in the city of Dhanbad, high level of SO₂ is reported, whereas rest of the locations conformed to the respective National Ambient Air Quality standard (NAAQS).

Fig 6.1 Range of Annual mean concentration of Sulphur Dioxide
Vis-à-vis Number of monitoring stations

The ten locations depicting highest values of  annual mean concentration of Sulphur Dioxide are listed in Table 6.1. The annual mean concentration of Sulphur dioxide in the city of Dhanbad violeted the standards.

Table 6.1 Ten locations having highest concentration of Sulphur Dioxide during year 1998

S. No	Industrial			Residential
	Location	State	Annual mean SO2 conc. (µg/m3)	Location	State	Annual mean SO2 conc. (µg/m3)
1.	MADA, Jharia	Bihar	76	Regional Office, Dhanbad	Bihar	66*
2.	M.I.D.C. Chandrapur	Maharashtra	67	Grasim Kalyan Kendra, Nagda	M.P.	56
3.	Near Police Station (FCI Main Hospital), Sindri	Bihar	65	S.R Off., Bapat Nagar, Chanderpur	Maharashtra	54
4.	Renusagar Colony, Anpara	U.P.	59	University Gate, Pune	Maharashtra	48
5.	Anpara Colony, Anpara	U.P.	58	Chemiequip Limited, Ambarnath	Maharashtra	43
6.	Chemical Division Labour Club, Nagda	M.P.	55	Anand Rao Circle, Bangalore	Karnataka	42
7.	Poud Phata (Kothrud), Pune	Maharashtra	51	Nasik Municipal Corporation Building, Nasik	Maharashtra	41
8.	PCMC, Chinchwad, Pune	Maharashtra	49	Housing Board's Office, Pondicherry	Pondicherry	38
9.	AMCO  Batteries, Bangalore	Karnataka	37	RTO Colony Tank, Nasik	Maharashtra	37
10	Escorts Medical Centre, Faridabad	Haryana	36	Municipal Office, Rourkela	Orissa	32

*  -   Annual mean concentration of SO₂  exceeded the standard of 60 µg/m³   for Residential areas.

The number of locations, where either annual mean concentration or 24-hourly concentration of sulphur dioxide exceeded the standards for more than 5% of the times, are listed in Table 6.2. Percent violations with respect to 24-hourly standards is depicted in Fig. 6.2. During 1998, at three industrial  and four residential locations, either Annual Mean Concentration or 24-hourly or both the values exceeded the respective standards.

Fig 6.2 Percent violation of 24-hourly standards  (Sulphur Dioxide)

Table 6.2 : Locations where either annual mean or 24-hourly concentration of                Sulphur Dioxide  violated respective standards
LOCATION	STATE	AREA CLASS	ANNUAL MEAN CONC. (µg/m3)	% Exceedence over 24-hourly standards
M.A.D.A., Jharia	Bihar	Industrial	76	13
Near Police Station (FCI Main Hospital), BIT, Sindri	Bihar	Industrial	65	12
M.I.D.C.,  Chandrapur	Maharashtra	Industrial	67	13
Regional Office, Dhanbad	Bihar	Residential	66	27
M/s Chemiequip Ltd, Ambarnath	Maharashtra	Residential	43	14
Sub-Regional Office, Bapat Nagar, Chandrapur	Maharashtra	Residential	54	28
Grasim Kalyan Kendra, Nagda	M.P.	Residential	56	24

Based on the analysis of air quality data at all the monitoring stations and pollution level categorization, the status of SO₂ levels during 1998 is presented in the Fig 6.3. The Annual Mean Concentration of SO₂ has been well within the National Ambient Air Quality Standards limit at all the locations except at one residential location i.e. Dhanbad (Bihar).

Fig 6.3 Status of  Sulphur Dioxide (SO₂) levels in terms of high, moderate and low pollution

6.1.3  Oxides of Nitrogen (as NO₂)

The annual mean concentration  of Nitrogen dioxide  vis-à-vis  number of monitoring stations is presented in Fig. 6.4. It is observed that at one sensitive, two industrial and three residential locations, the NO₂ level exceeded the annual Mean Ambient Air Quality standards limit of NO_2.


Fig 6.4 Range of Annual mean concentration of Sulphur Dioxide
Vis-à-vis Number of monitoring stations

The locations where annual Mean Air Quality standards exceeds are in the city of Alwar (one industrial and one residential),  Udaipur (one industrial and two residential) and Kota (one sensitive). Alwar is a satellite town of Delhi with a high concentration of industries. Due to inadequate power supply, the industrial, commercial and residential activities often resort to captive power generation resulting in high emissions of Oxides of Nitrogen. Table 6.3 enlists ten locations depicting highest values of annual mean concentration of Nitrogen dioxide.

Table 6.3 Ten Locations Having Highest Concentration of Nitrogen Dioxide (NO₂)

*        Locations where annual mean concentration of NO₂  exceeded the respective standards of 80 µg/m³ for Industrial and 60 µg/m³   for Residential areas.

Percent violations with respect to 24-hourly standards is depicted in Fig. 6.5. The number of locations where either annual mean or 24-hourly concentration exceeded the standards of NO₂ for more than 5% times are listed in Table 6.4 During 1998, one sensitive and eight residential locations violated the 24-hourly standards of NO₂ for more than 5% of the times.

Fig 6.5 Percent violations of 24-hourly National Ambient
Air Quality standards for Nitrogen Dioxide