emission level

例句：

1. 1. The factory has been operating at a high emission level for years.
   这家工厂多年来一直以很高的排放水平运行。
2. 2.The government has set a target to reduce the emission level by 20%.
   政府设定了一个目标，到2020年将排放量减少20%。
3. 3.The new policy aims to improve the emission level of vehicles on the road.
   新政策旨在提高道路上车辆的排放水平。