Table 2.
Air pollutants and meteorological factors in Shenzhen (2013–2015).
| Indicator | Mean | Standard Deviation | Minimum | Q1 | Q2 | Q3 | Maximum | No. of Days of Exceeding Grade 1 Criterion * | No. of Days of Exceeding Grade 2 Criterion ** |
|---|---|---|---|---|---|---|---|---|---|
| Air pollutants | |||||||||
| PM2.5 (μg/m3) | 35.0 | 21.9 | 7.1 | 17.4 | 29.9 | 47.1 | 137.1 | 458 | 58 |
| PM10 (μg/m3) | 55.6 | 30.2 | 10.9 | 31.4 | 47.7 | 71.6 | 181.8 | 513 | 11 |
| SO2 (μg/m3) | 10.4 | 4.8 | 3.5 | 7.4 | 9.2 | 11.9 | 54.8 | 1 | 0 |
| NO2 (μg/m3) | 43.8 | 17.5 | 14.7 | 31.9 | 39.7 | 51.6 | 133.7 | 47 | 47 |
| CO (μg/m3) | 1061.9 | 259.7 | 542.9 | 857.1 | 1034.1 | 1239.1 | 1930.4 | 0 | 0 |
| O3 (μg/m3) | 55.2 | 22.3 | 16.4 | 37.6 | 50.8 | 70.0 | 143.3 | 42 | 0 |
| Meteorological factors | |||||||||
| Daily average temperature (°C) | 23. 5 | 5.5 | 6.0 | 19.2 | 24.8 | 28.2 | 33.0 | ||
| Daily average RH (%) | 73.3 | 13.3 | 19.0 | 67.0 | 75.0 | 82.0 | 100.0 | ||
| Daily average atmosphere pressure (kpa) | 1005.6 | 6.4 | 986.8 | 1000.7 | 1005.5 | 1010.8 | 1019.9 | ||
| Daily average wind speed (m/s) | 2.1 | 0.8 | 0.3 | 1.5 | 2.0 | 2.5 | 5.5 |
Q1, Q2, Q3 are equal to the 25%, 50% and 75% number of all values in the sample arranged from small to large, respectively. * The number of days for average daily concentration exceeded the national Grade 1 criterion of China. ** The number of days for average daily concentration exceeded the national Grade 2 criterion of China. The formula for calculating the standard deviation of pollutants is as follows: Standard Deviation is represented by σ. xi represents the average concentration of seven air quality monitoring sites on a given day. µ indicates the daily average concentration of seven air quality monitoring sites in three years. N = 1095. PM2.5 = particulate matter with a particle size below 2.5 microns. PM10 = particulate matter with particle size below 10 microns. RH = relative humidity.