Table 4.
Mean pollutant concentrations in Indian megacities during the COVID-19 pandemic.
| Megacities | Pollutants | Pre lockdown period (Feb 2020) [AM±SD] | Lockdown period (May 2020) [AM±SD] | Unlock period (June 2020) [AM±SD] |
|---|---|---|---|---|
| Bangalore | PM10 (μg m−3) | 97.1 ± 30.2* (n = 679) |
57.0 ± 14.1* (n = 725) |
52.3 ± 32.1* (n = 704) |
| PM2.5 (μg m−3) | 42.0 ± 13.9* (n = 687) |
19.4 ± 4.9* (n = 739) |
11.8 ± 4.9* (n = 709) |
|
| CO (mg m−3) | 1.1 ± 0.4* (n = 672) |
0.6 ± 0.1* (n = 729) |
0.6 ± 0.3* (n = 696) |
|
| O3 (μg m−3) | 36.5 ± 7.8* (n = 567) |
32.4 ± 10.9* (n = 740) |
20.7 ± 9.5* (n = 613) |
|
| Chennai | PM10 (μg m−3) | a | a | a |
| PM2.5 (μg m−3) | 32.5 ± 16.7* (n = 681) |
12.2 ± 5.7* (n = 729) |
16.5 ± 12.5* (n = 714) |
|
| CO (mg m−3) | 0.8 ± 0.2* (n = 691) |
0.8 ± 0.1* (n = 736) |
1.0 ± 0.1* (n = 707) |
|
| O3 (μg m−3) | 32.3 ± 29.9* (n = 689) |
30.8 ± 26.1* (n = 744) |
46.1 ± 23.6* (n = 713) |
|
| Delhi | PM10 (μg m−3) | 202.2 ± 83.3* (n = 689) |
107.1 ± 61.7* (n = 727) |
109.1 ± 42.1* (n = 699) |
| PM2.5 (μg m−3) | 113.7 ± 56.3* (n = 686) |
39.8 ± 15.6 (n = 731) |
43.0 ± 16.3* (n = 701) |
|
| CO (mg m−3) | 1.3 ± 1.1* (n = 692) |
0.5 ± 0.1* (n = 741) |
0.6 ± 0.2* (n = 706) |
|
| O3 (μg m−3) | 19.3 ± 12.3* (n = 654) |
45.7 ± 42.4* (n = 698) |
67.1 ± 54.2* (n = 664) |
|
| Kolkata | PM10 (μg m−3) | 260.0 ± 122.3* (n = 675) |
26.0 ± 9.2* (n = 736) |
36.1 ± 12.4* (n = 697) |
| PM2.5 (μg m−3) | 101.3 ± 43.2* (n = 679) |
14.5 ± 5.1* (n = 741) |
14.9 ± 6.4* (n = 702) |
|
| CO (mg m−3) | 0.7 ± 0.6* (n = 676) |
0.1 ± 0.1* (n = 729) |
0.3 ± 0.1* (n = 711) |
|
| O3 (μg m−3) | 32.3 ± 22.9* (n = 508) |
44.5 ± 17.4* (n = 263) |
53.5 ± 23.4* (n = 640) |
|
| Mumbai | PM10 (μg m−3) | 208.4 ± 80.5* (n = 689) |
80.8 ± 20.0* (n = 731) |
55.5 ± 45.9* (n = 706) |
| PM2.5 (μg m−3) | 75.1 ± 28.9* (n = 684) |
11.7 ± 4.4* (n = 737) |
13.7 ± 7.2* (n = 703) |
|
| CO (mg m−3) | 2.9 ± 0.7* (n = 678) |
0.2 ± 0.1* (n = 731) |
1.0 ± 0.1* (n = 698) |
|
| O3 (μg m−3) | 51.4 ± 41.2 (n = 596) |
a | a |
*PM2.5, PM10, CO and O3 concentrations vary across the three lockdown periods significantly in each city (ANOVA, p ≤ 0.05).
a
Data not available.