Carbon monoxide

carbonyl sulfide

Presumably by "COS" you mean Carbonyl Sulfide. US-EPA lists carbonyl sulfide as a "hazardous air pollutant". So presumably emitters of this compound (other than cabbage farmers) are required to self measure, and describe how they are controlling its emission. I find no direct reference to a limit on emissions.

Carbonyl sulfide: molecular structure: linear
C is central with double bond to sulfur and also to oxygen


http://en.wikipedia.org/wiki/Carbonyl_sulfide

This is a linear molecule.