How do Cat soot numbers translate into Percentage?

[silverbox]

I have been getting good reports on my Jetta TDI from Cat but have not been able to get a percentage # for soot is there any way to translate their methodology?

 

[boxcab]

Well, if the report is in parts per million (ppm), divide the number by 10,000. This will give the percentage as a whole number. For example, if the number were 50,000 ppm, divide by 10,000 and get 5%. 5000 ppm is 0.5%, 2500 ppm is 0.25%, etc.