危害 (wēihài) means 'to harm, endanger' and focuses on serious threats to health, safety, or the environment — it's more abstract and severe than 伤害 (shānghài 'to injure, hurt'), which is used for physical or emotional injury to a person or animal. 损害 (sǔnhài) is closer but emphasizes gradual damage to something's value or function (e.g., reputation, health).