secondary pollutants

例句：

1. 1. The city's air quality has improved significantly since the implementation of stricter emission standards.
   自从实施了更严格的排放标准以来，城市的空气质量已经显著改善。
2. 2.The factory produces a significant amount of secondary pollutants, which can harm the environment.
   这个工厂生产了大量的次要污染物，这会对环境造成伤害。
3. 3. To reduce pollution, governments around the world are implementing measures to control and reduce the production of secondary pollutants.
   为了减少污染，世界各国政府正在实施措施来控制和减少次要污染物的生产。