PPB to UG/M3 in ArcSkoru

The link below contains a general conversion calculation to conver ppb to ug/m3: https://www2.dmu.dk/AtmosphericEnvironment/Expost/database/docs/PPM_conversion.pdf      

Hi Angela, Could you please explain what those options are?  Thanks.  

Following - I had the same issue, not realizing that my PID was only recording in PPB. The molecular weight of compounds vary. When measuring TVOC, we dont exactly know the breakdown of constituent components, and these arent limited to only the 6 most likely provided in the example.  Is there perhaps a better general conversion acceptable for LEED?  They ask us to explain the conversion - but ther is no explanation of how to convert leaving to the user to figure out.  We could, for example, take the average of the 6 most likely compounds (2.014) to determine ppb conversion? LEED sometimes accepts the worst case as well, which would assume the molecular weight of Benzene at 3.19, but that could easily tip the scale in the negative.  Atmospheric pressure was recorded, but there is no way to know which compound was being detected during increased readings - this could vary depending on location within the building.

According to Arc's Guide to Reentry, TVOC measurements in ppb should be converted to μg/m 3 using a conversion factor of 3.767. https://www.arcskoru.com/sites/default/files/Arc%20Guide%20to%20Re-Entry.pdf