Actually depends on the state. Colorado uses grams per mile (GPM) which is what the EPA uses. Just Googled around for MOT samples and it looks like MOT does use % and PPM though.If you have a full report of the emissions we'd love to see it. US goes on % CO, PPM for HC, and PPM for NOx so some translation may be needed.
I don't think there is a conversion since PPM is based on a single point in time whereas GPM is over a measured distance.