How much reduction can the booster achieve in exhaust emission?

按装汽车省油器之后会减低多少排放废气量？

Thus there must be a big discrepancy in the exhaust emission testing data.

因此在废气数据的测试中存在较大的误差。

Besides, exhaust emission from cars and buses has made the situation even worse.

除此之外，从汽车和公共汽车的废气排放也使得情况更糟。

Exhaust emission of vehicle engines is one of the primary air pollution sources.

车用内燃机的废气排放是大气污染的主要污染源之一。

Exhaust emission of vehicles is one of the main sources that cause serious atmosphere pollution.

汽车尾气污染是造成严重空气污染的主要因素之一。