Pollution or contamination of air, water, soil, etc., by harmful substances that negatively affect health or the environment.
工場の排水が川を汚染した。
The factory's wastewater polluted the river.
大気汚染がひどくて外に出にくい。
Air pollution is so bad that it's hard to go outside.
土壌汚染の調査と対策が急がれている。
Soil contamination surveys and countermeasures are urgently needed.