Table 1.
Summary statistics of air quality index (AQI) and air pollutants from 1st January 2018 to 31st July 2020.
| 2018–2019 |
2020 |
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|---|---|---|---|---|---|---|---|---|
| The same calendar with the lockdown duration in 2020 |
The same calendar with the duration after lockdown in 2020 |
During Lockdown |
After Lockdown* |
|||||
| Mean | SD | Mean | SD | Mean | SD | Mean | SD | |
| AQI | 85.5 | 59.1 | 60.2 | 41.9 | 67.7 | 50.4 | 51.7 | 35.2 |
| PM10(μg/m3) | 92.0 | 65.1 | 64.8 | 50.6 | 66.4 | 51.9 | 52.8 | 40.8 |
| PM2·5(μg/m3) | 57.8 | 48.2 | 32.2 | 26.2 | 46.9 | 42.7 | 26.7 | 22.3 |
| O3(μg/m3) | 53.3 | 32.9 | 77.7 | 48.0 | 58.9 | 29.5 | 74.3 | 44.1 |
| SO2(μg/m3) | 16.4 | 21.0 | 11.0 | 12.9 | 10.6 | 13.2 | 9.0 | 9.3 |
| NO2(μg/m3) | 32.5 | 23.8 | 25.5 | 20.3 | 20.7 | 16.4 | 22.8 | 18.0 |
| CO (mg/m3) | 1.0 | 0.6 | 0.7 | 0.4 | 0.8 | 0.5 | 0.6 | 0.3 |
SD: Standard deviation; *: After lockdown was the duration from the lift date of lockdown to 31st July 2020. The dates for lockdown and lift were different among provinces in China.