Air pollution in the city had reached four times the acceptable levels.

这座城市空程度曾高达可接受标准四倍。

There are many sources of air pollution; exhaust fumes, for example.

空有许多来源, 例如废。

Setting off firecrackers makes a tremendous noise and causes serious air pollution.

放鞭炮会产生巨大噪声,严重大。

California's air pollution guidelines are stringent.

加州制定空标准很严格。

This article summarized the indicating function of bryop hyte to air pollution, heavy metal pollution and mineral resources.

综述了苔藓植物对大、重金属和矿监测指示作用。