INTRODUCTION TO OCCUPATIONAL HEALTH

mg/m3

The concentration of a gas or vapor in air is usually expressed in parts per million (ppm), but may be converted to mg/m³ at a temperature of 25慢 and a pressure of 760 mm Hg through use of the following relationship:

mg/m³ = ppm x (Molecular Weight / 24.45)

For example:
A 50 ppm concentration of carbon monoxide (molecular weight = 28) is equivalent to a concentration of 57.26 mg/m³ at 25慢 and 760 mm Hg.

Also note that:
Concentration (ppm) = Concentration (%) x 10,000

For example:
A concentration of a gas or vapor equal to 0.01% is equivalent to a concentration of 100 ppm.