Clean air: pollutants, monitoring and control

Chemistry hands the learner of German a gender rule that holds with unusual reliability. A compound whose name ends in -id is neuter: das Oxid, das Sulfid, das Chlorid, and so das Stickoxid on this list. The trap is the element it is made from. Der Stickstoff, nitrogen, is masculine because its last part is der Stoff, and anyone who has just said der Stickstoff tends to carry the article across. The compound, though, takes its gender from its own ending and not from the element in front of it: das Stickoxid, das Stickstoffdioxid, das Schwefeldioxid. The plural is die Stickoxide, and that is the form a report or a news item usually prefers, because it speaks of the whole family of oxides rather than of any one of them.