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Table 2: Average Annual Air Quality Index, Delhi (2016-2021)

Year (no. of days) 2016 2017 2018 2019 2020 2021
Category (354) (365) (365) (365) (366) (365) 2016 2017 2018 2019 2020 2021
Good (0–50) 0 2 0 2 5 1

Satisfactory (51–100) 25 45 53 59 95 72 108 152 159 182 227 197
Moderate (101–200) 83 105 106 121 127 124
Poor (201–300) 120 115 113 103 75 80

Very Poor (301–400) 101 89 73 56 49 64 246 213 206 183 139 168
Severe (>401) 25 9 20 24 15 24

Source: Ministry of Environment, Forest and Climate Change
6.45 In addition, Continuous Ambient Air Quality Monitoring Stations (CAAQMS) data
for Delhi reveals that annual concentration of PM has decreased gradually since 2016. Delhi
achieved approximately 22 per cent reduction in PM2.5 and 27 per cent reduction in PM10 in
2021 as compared to 2016.

6.46 Figure 27 shows the average monthly air quality (PM2.5) for Delhi during 2017-21. In
2021, nine months registered an improvement over 2017, with the largest improvements seen in
October (54 per cent), May (50 per cent) and September (48 per cent). In 2021, average monthly
air quality in Delhi declined in January (17 per cent), February (15 per cent) and March (one per
cent) as compared to corresponding months in 2017, indicating an area of concern.

Figure 27: Average Monthly CAAQMs of Delhi (2017-2021) (PM2.5 in µg/m3)

300 2017 2021
Average Monthly Air Quality (PM2.5 µg/m3) 200
250

150

100

50
0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Source: Ministry of Environment, Forest and Climate Change

6.47 Figure 28 shows the average monthly air quality (PM10) for Delhi during 2017-21. In
2021, nine months registered an improvement over 2017, with the largest improvements seen
in September (66 per cent), October (49 per cent) and May (48 per cent). In 2021, average
monthly air quality in Delhi declined in January (five per cent), February (seven per cent) and
March (four per cent) as compared to corresponding months in 2017, indicating an area of
concern.