Causing harm; hazardous or injurious, often used for things dangerous to health or environment.
その化学物質は有害なので取り扱いに注意してください。
That chemical is harmful, so please handle it with care.
長時間の紫外線曝露は皮膚に有害だ。
Prolonged UV exposure is harmful to the skin.
有害な影響を避けるために規制が設けられた。
Regulations were put in place to avoid harmful effects.