Conversion of air pollutant concentrations

[Milt Beychok]

Various governmental agencies involved with environmental protection and with occupational safety and health have promulgated regulations limiting the allowable concentrations of gaseous pollutants in the ambient air or in emissions to the ambient air. Such regulations involve a number of different expressions of concentration. Some express the allowable concentrations as volume of a specific gaseous pollutant per million volumes of ambient air or, more simply as parts per million by volume (ppmv). Others express the allowable concentrations as mass of a specific gaseous pollutant per volume of ambient air or usually as milligrams per cubic meter (mg/m³).

The equations for conversion between ppmv and mg/m³ depend on the temperature at which the conversion is wanted (usually about 20 to 25 °C). At an ambient air pressure of 1 atmosphere, the general conversion equation is:

ppmv = (mg/m³) × (0.08205) × (T) / (M)

and for the reverse conversion:

(mg/m³) = (ppmv) × (M) (12.187) / (T)

where:
ppmv = air pollutant concentration, in parts per million by volume
mg/m³ = milligrams of air pollutant per cubic meter of air
T = ambient air temperature, in kelvins (K) = 273.15 + °C
0.08205 = Universal Gas Law constant, in [atm·L]/(mol·K)
M = molecular weight of the air pollutant (dimensionless)

Notes:
-- Pollution regulations in the United States typically reference their air pollutant limits to an ambient temperature of 20 to 25 °C as noted above. In most other nations, the reference ambient temperature for pollutant limits may be 0 °C or other values.
-- 1 percent by volume = 10,000 ppmv
-- atm = absolute atmosperic pressure in atmospheres
-- mol = gram mole
-- L = liter

[Alex.11]

Air pollutant concentrations, as measured or as calculated by air pollution dispersion modeling, must often be converted or corrected to be expressed as required by the regulations issued by various governmental agencies. Regulations that define and limit the concentration of pollutants in the ambient air or in gaseous emissions to the ambient air are issued by various national and state (or provincial) environmental protection and occupational health and safety agencies.
Such regulations involve a number of different expressions of concentration. Some express the concentrations as ppmv (parts per million by volume) and some express the concentrations as mg/m3 (milligrams per cubic meter), while others require adjusting or correcting the concentrations to reference conditions of moisture content, oxygen content or carbon dioxide content. This article presents methods for converting concentrations from ppmv to mg/m3 (and vice versa) and for correcting the concentrations to the required reference conditions.
All of the concentrations and concentration corrections in this article apply only to air and other gases. They are not applicable for liquids.

[chempro]

good, can not you develop excel program cover all the unit conversion in air pollution measuring industry? Appreciate if you can