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Air monitoring

Under the National Air Monitoring Programme (NAMP) there are four monitoring stations in Nagaland i.e. two stations at Dimapur and two stations at Kohima. Under this programme three air pollutants are monitored and analyzed viz., Respirable Suspended Particulate Matter (RSPM), Nitrogen dioxide (NO2) and Sulphur dioxide (SO2). The monitoring of pollutants is carried out for 24 hours and 8 hourly sampling for particulate matter (RSPM) and 4 hourly sampling for gaseous pollutants (NO2 & SO2)  twice in a week.

The Nagaland Pollution Control Board regularly monitors ambient air quality of Dimapur and Kohima city throughout the year using manually operated Respirable Dust Samplers. The data generated in the NAMP stations are uploaded in the Environmental Air Quality Data Entry System of the Central Pollution Control Board.

The readings and data comparison of Dimapur and Kohima NAMP stations for the year 2014 to 2017 are given in the table below.

STATUS OF AMBIENT AIR QUALITY AT KOHIMA CITY

Monthly average concentration of Respirable Suspended Particulate Matter (RSPM) at two stations                                  viz Opposite N.S.T office (609) and Opposite War Cemetery (610) during 2014 to 2017

Sl. No

Month Opp. NST office

(609)

Opp. War Cemetery

(610)

2014

2015 2016 2017 2014 2015 2016

2017

1

January

87 87 102 87 127 127 145

144

2

February 84 84 115 96 131 131 165

147

3

March 88 88 83 109 133 133 158

161

4

April 84 84 59 84 118 118 122

170

5

May 64 64 56 59 122 122

126

136

6

June 42 42 39 49 94 94 88

128

7

July 44 44 28 53 86 86 74

102

8

August 44 44 28 55 74 74 84 108

9

September 50 50 30 48 91 91 84

95

10

October 66 66 38 69 119 119 110

157

11

November 86 86 62 95 122 122 147

203

12 December 109 109 98 142 139 139 147

247

Annual Average 71 71 62 79 113 118 121

150

 

AMBIENT AIR QUALITY STATUS OF DIMAPUR CITY

Monthly average concentration of Respirable Suspended Particulate Matter (RSPM) at two stations                                 viz. Bank Colony (317) and Dhobinala (448) during 2014 to 2017

Sl. No

Month Bank Colony (317) Dhobinala (448)

2014

2015 2016 2017 2014 2015 2016

2017

1

January 221 182 199 189 296 218 207 194
2 February 165 201 158 143 205 218 202

195

3

March 134 163 154 160 218 215 236

245

4 April 133 93 93 141 240 123 135

194

5

May 73 60 84 93 130 110 131 165

6

June 42 46 92 92 82 79 112 99

7

July 36 44 36 77 67 80 74

104

8 August 38 39 49 107 64 83 73

118

9 September 48 51 52 145 69 82 80

122

10

October 101 94 89 141 132 97 105 138

11

November 146 132 145 110 184 192 167 127
12 December 196 201 152 148 214 211 172

136

Annual Average 96 108 109 128 158 142 141

153

The Annual average values for Respirable Suspended Particulate Matter (RSPM) depicted in the table above shows that particulate matter increases during the dry season starting from October to April.

Annual average concentration of Respirable Suspended Particulate Matter in Kohima

Sl.No.

Year Annual average concentration of RSPM in Kohima (µg/m³)

1

2014 92

2

2015

95

3 2016

92

4 2017

115

 

Annual average concentration of Respirable Suspended Particulate Matter in Kohima

Sl.No.

Year Annual average concentration of RSPM in Dimapur (µg/m³)

1

2014 127
2 2015

125

3 2016

125

4 2017

140

Inference:

The analysis for the past 4 years from 2014 – 2017 shows that in both Kohima and Dimapur the concentration of RSPM values had exceeded the prescribed National Ambient Air Quality Standards (NAAQS) of 60 (µg/m³). The Central PollutionControl Board has categorized both Kohima and Dimapur falls under “Non Attainment Cities & Towns” due to high level of RSPM concentration.

NATIONAL AMBIENT AIR QUALITY STANDARDS (2009)

Pollutants Time weighted average Concentration in Ambient Air
Industrial, Residential, Rural and Other Areas Ecologically Sensitive Area (notified by Central Government)
Sulphur Dioxide (SO2), µg/m3 Annual * 50 20
24 hours ** 80 80
Nitrogen Dioxide (NO2), µg/m3 Annual * 40 30
24 hours ** 80 80
Particulate Matter (Size less than 10µm) or PM10 , µg/m3 Annual * 60 60
24 hours ** 100 100
Suspended Particulate Matter (SPM), µg/m3 Annual *     140*** 70
24 hours **     200*** 100

 

*    Annual Arithmetic mean of minimum 104 measurements in a year at a particular site taken twice a week 24 hourly at uniform intervals.
** 24 hourly or 8 hourly or 1 hourly monitored values, as applicable, shall be complied with 98 % of the time in a year.2% of the time, they may exceed the limits but not on two consecutive days of monitoring.
*** The values under industrial area for Suspended Particulate Matter (SPM) is 360 µg/m3 (Annual Average) and 500 µg/m3 (24 Hourly)