noun which may take the genitive case particle 'no', na-adjective
non-polluting; pollution-free; clean
Describes something that does not cause pollution, especially in environmental contexts. Often used with エネルギー, 車, 技術, etc.
無公害のエネルギー源を開発する必要がある。
We need to develop non-polluting energy sources.
この工場は無公害な生産方法を採用している。
This factory uses pollution-free production methods.
Compound of 無 (mu, 'without') + 公害 (kōgai, 'pollution'). The term became common in the late 20th century with growing environmental awareness.