He found that about 563 metric tons of nitrogen trifluoride was emitted in 2006 .

他发现2006年中有大约563公吨的三氟化氮被排放。

The concentration of nitrogen trifluoride in the atmosphere is about 0.5 part per trillion , making it very hard to measure .

大气中三氟化氮的浓度大约为0.5万亿分之一（ppt），使得它很难测定。