| Similarity | Rank | |
|---|---|---|
| dioxide | 0.902 | 4762 |
| monoxide | 0.850 | 12904 |
| nox | 0.839 | 28969 |
| carbon | 0.839 | 3195 |
| nitrogen | 0.829 | 6386 |
| hydrocarbon | 0.827 | 12320 |
| oxide | 0.824 | 7892 |
| particulate | 0.822 | 25930 |
| tetrachloride | 0.821 | 38419 |
| emission | 0.815 | 3620 |
| &sub2; | 0.812 | 34174 |
| nitrous | 0.809 | 29606 |
| pollutant | 0.801 | 10281 |
| hexafluoride | 0.786 | 78594 |
| methane | 0.783 | 11786 |
| trioxide | 0.783 | 83599 |
| chlorine | 0.779 | 10537 |
| dioxin | 0.775 | 17452 |
| co2 | 0.772 | 18793 |
| phosgene | 0.770 | 98640 |
| ozone-depleting | 0.769 | 40272 |
| halon | 0.768 | 27495 |
| nitric | 0.766 | 22052 |
| chlorofluorocarbon | 0.764 | 24061 |
| benzene | 0.764 | 21692 |