Some coal is rich in heavy metals, and burning it in electric power stations, incinerators, steel mills, and motor vehicles may produce air pollution containing the metals.

• 一些煤富含重金属元素，当这些煤在发电站、焚化炉、炼钢厂和机动车里面燃烧时，会造成大气污染，使空气中含有这些重金属元素。