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Contact This site works better with javascript enabled.     Concentrations of chemicals in the air are usually measured as the mass of chemicals (milligrams, micrograms, nanograms or picograms) per volume of air (cubic meters or cubic feet). Concentrations can also be expressed as parts per million (ppm) or parts per billion (ppb) by using a conversion factor. This conversion factor is based on the molecular weight of the chemical and it is different for every chemical. The temperature of the atmosphere also has an influence on the calculation.

## CONVERT PPM TO MG/M3

Formula: concentration (mg/m3) = 0.0409 x concentration (ppm) x molecular weight

For example: 100 ppm of NH3 (17.03 g/mol)
0.0409 x 100 ppm x 17.03 = 69.652   Enter the number of mg/m3.
Gas Output Molecular Weight
Ammonia [NH3] M = 17.03 g/mol
Carbon monoxide [CO] M = 28.01 g/mol
Carbon dioxide [CO2] M = 44.01 g/mol
Chlorine [Cl2] M = 70.9 g/mol
Formaldehyde [CH2O] M = 30.026 g/mol
Hydrogen [H2] M = 2.02 g/mol
Methane [CH4] M = 16.04 g/mol
Hydrogen Sulfide [H2S] M = 34.08 g/mol
Nitrogen Dioxide [NO2] M = 46.01 g/mol
Ozone [O3] M = 48.00 g/mol
Perchloroethylene [C2Cl4] M = 165.822 g/mol
Sulfur dioxide [SO2] M = 64.06 g/mol
VOC M = 78.9516 g/mol   ## CONVERT MG/M3 TO PPM

Formula: concentration (ppm) = 24.45 x concentration (mg/m3) ÷ molecular weight

For example: 50 mg/m3 of NH3 (17.03 g/mol)
24.45 x 50 mg/m3  / 17.03 = 71.785ppm   Enter the number of mg/m3.
Gas Output Molecular Weight
Ammonia [NH3] M = 17.03 g/mol
Carbon monoxide [CO] M = 28.01 g/mol
Carbon dioxide [CO2] M = 44.01 g/mol
Chlorine [Cl2] M = 70.9 g/mol
Formaldehyde [CH2O] M = 30.026 g/mol
Hydrogen [H2] M = 2.02 g/mol
Methane [CH4] M = 16.04 g/mol
Hydrogen Sulfide [H2S] M = 34.08 g/mol
Nitrogen Dioxide [NO2] M = 46.01 g/mol
Ozone [O3] M = 48.00 g/mol
Perchloroethylene [C2Cl4] M = 165.822 g/mol
Sulfur dioxide [SO2] M = 64.06 g/mol
VOC M = 78.9516 g/mol   Source: Kansas State University understanding-units-of-measurement.pdf        