air pollution concentration

例句：

1. 1.The city's air pollution concentration has been increasing rapidly in recent years.
   近年来，该城市的空气污染浓度迅速增加。
2. 2. The government is working hard to reduce the air pollution concentration in the city.
   政府正努力减少城市中的空气污染浓度。
3. 3. The study shows that the air pollution concentration in the area is still high.
   研究表明该地区的空气污染浓度仍然很高。