Some of these fine particles--suspended in air as primary organic aerosols--are tiny flecks rich in carbon, often from sources such as diesel exhaust.

• 在这些作为初级有机气溶胶悬浮在空气中的细微颗粒当中，有些是富含碳元素的小尘粒，来源是柴油车尾气之类的排放。