| in cities all over the world | 6 | location |
| increasingly | 3 | degree |
| as tools | 2 | manner |
| pollution → be → important | 8 |
| pollution → be among → important issues | 4 |
| pollution → highlight → the importance | 3 |
| pollution → become → important | 3 |
| negative | neutral | positive |
| 0.334 | 0.532 | 0.134 |
| Raw frequency | 18 |
| Normalized frequency | 0.489 |
| Modifier score | 0.500 |
| Perplexity | 39.393 |