Emissions mostly come from vehicle exhausts , factories , artificial fertilisers and manure from intensive farming .
氮排放主要来自汽车尾气、工厂、及集约化农业中使用的化肥和粪肥。
Most environmentalists were pushing a " command-and-control " approach , with federal officials requiring utilities to install scrubbers capable of removing the sulfur dioxide from power-plant exhausts .