It smells like burning.
You aren't referring to ALL pollution. You are referring to passenger vehicles' smog-forming emissions. Or, that's what the article refers to.
The numbers:
So, the ONLY number of concern for motorcycles are the CO numbers. I mean, we wouldn't worry about any others as they are significantly lower than any other. Right?
You understand that transportation only has a 7% impact on Particulate Matter - which actually has more of an affect on asthma and smog than VOC's. That is OVERALL pollution. And, motorcycles don't come into play there. [referring to the chart] My 7% number comes from my research project and text book used for my class.
Did you notice on their report that lawn and garden equipment actually had a higher output of CO than on-road motorcycles? So, those should have converters too...