Table 2.
Number of days/per annum with air pollutants exceeding the standard limits and annual average concentration of the pollutants.
| PM10(μg/m3) | SO2(μg/m3) | NO2(μg/m3) | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Year | Grade II (≥150) | Grade III (≥250) | Annual average concentration | Grade II (≥150) | Grade III (≥250) | Annual average concentration | Grade II (≥80) | Grade III (≥120) | Annual average concentration |
| 2003 | 133 | 27 | 136.05 | 26 | 26 | 129.12 | 117 | 5 | 70.24 |
| 2004 | 134 | 42 | 141.61 | 8 | 8 | 73.55 | 93 | 14 | 69.47 |
| 2005 | 135 | 43 | 148.97 | 21 | 21 | 128.28 | 84 | 12 | 66.59 |
| 2006 | 127 | 51 | 160.66 | 28 | 28 | 156.47 | 93 | 13 | 66.59 |
| 2007 | 127 | 47 | 149.11 | 19 | 19 | 117.58 | 85 | 5 | 66.38 |
| 2008 | 94 | 28 | 122.06 | 9 | 9 | 69.75 | 44 | 2 | 49.77 |
| Total | 750 | 238 | 111 | 111 | 516 | 51 | |||
Note: Air Quality Standards: Grade I for areas such as nature reserves and other areas that need special protection. Grade II is the standard for mainly residential area, commercial areas and mixed use urban areas as well as the rural areas. Grade III standard applies to specific industrial zones [48].