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nitrogen oxide
窒素酸化物を減らす技術が進んだ。
Technology to reduce nitrogen oxides has advanced.
排気ガスの窒素酸化物が大気汚染を引き起こす。
Nitrogen oxides in exhaust gases cause air pollution.
工場の窒素酸化物排出量が基準値を超えた。
The factory's nitrogen oxide emissions exceeded the standard.