Re: What does unit mg/Nm3 mean?

Hello Stefano,

     We literally had people searching from all over the world (England, 
Germany, Australia, Spain, and The USA) for the definition of the mg/Nmc 
units and finally have a definitive answer for you !!!  The mg is, of 
course, milligrams.   The mc term was a new one for me in the US.  A 
Spanish scientist that I work with reminded that cubic meters is 
represented as metrico cubico, hence the mc can also be written as m^3 or 
cubic meters.  
     The N term was the hardest to "nail down."  The IUPAC definiton of 
the symbol N is a Newton (kg X m/s^2.)  The IUPAC definiton of an 
italicized N is used to define Normality (the number of equivalents of 
solute per liter of solution.)  However, when you put the term Newton into 
the formula, you have a unit that does not make any sense in this 
context.  I have also never seen Normality used for any application other 
than for solution chemistry.  
    I then contacted an editor at Pollution Engineering Magazine (E-mail: 
KCanning@cahners.com) who refered me to a Ph.D. in Germany named Dr. 
Thomas Schmidt (E-mail: schmidt@mpi-muelheim.mpg.de), who explained that 
the N term is an abbreviation of norm or normal.  He continued to explain 
that "Normal, in this connection, means a temperature of 0 degrees Celsius 
and a pressure of 1.013 bar, the conditions at which one mole of an ideal 
gas has a volume of 22.413837 liters."  This definition makes sense to me 
in conjunction with a flue gas measurement.  Ken Johnson, an administrator 
with the MadSci Network (E-mail: kayjay45@home.net) confirmed this 
explantion with an environmental scientist in Australia.  By comparison, 
we routinely use ppm (parts per million)in the USA for this type of 
measurement.
     I want to Thank You, Stefano, for helping me learn something new in 
the world of Chemistry.  I would also like to thank all of the scientists 
that helped me to define this unit of measurement for you.