Table 1.
Pollution level classification according to Pi.
| Pi | Pollution level |
|---|---|
| Pi ≤ 1.0 | clean |
| 1.0 < Pi ≤ 2.0 | trace |
| 2.0 < Pi ≤ 3.0 | light |
| 3.0 < Pi ≤ 5.0 | moderate |
| Pi ＞ 5.0 | severe |
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