| detect negative ions | 0.50 |
| neutralize positive ions | 0.31 |
| increase alkalinity | 0.25 |
| spread in every directi… | 0.25 |
| disperse into the air | 0.25 |
| feel good | 0.16 |
| remove the pollution | 0.16 |
| increase the flow of ox… | 0.16 |
| produce biochemical rea… | 0.16 |
| purify the air | 0.16 |
| many diseases | 0.16 |
| dangerous effect | 0.16 |
| beneficial | 0.35 |
| abundant | 0.16 |
| invisible | 0.16 |
| electron | 0.25 |
| oxygen atoms | 0.25 |
| atom | 0.25 |
| odorless | 0.16 |
| formed | 0.68 |
| allowed to enter on oth… | 0.36 |
| polarized | 0.25 |