| Share | Phrase |
|---|
| 21.59% | harmless [producing effect] gas |
| 18.13% | harmless [producing effect] compound |
| 15.86% | harmless [producing effect] render |
| 12.70% | harmless [producing effect] by-product |
| 11.64% | harmless [producing effect] hydrocarbon |
| 11.56% | harmless [producing effect] component |
| 8.48% | harmless [producing effect] substance |