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2. Useful conversions and formulas for air dispersion modeling

   en.wikipedia.org/wiki/Useful_conversions_and...

   Atmospheric pollutant concentrations expressed as mass per unit volume of atmospheric air (e.g., mg/m 3, μg/m 3, etc.) at sea level will decrease with increasing altitude because the atmospheric pressure decreases with increasing altitude.

3. Air pollutant concentrations - Wikipedia

   en.wikipedia.org/wiki/Air_pollutant_concentrations

   Some express the concentrations as ppmv (parts per million by volume) and some express the concentrations as mg/m 3 (milligrams per cubic meter), while others require adjusting or correcting the concentrations to reference conditions of moisture content, oxygen content or carbon dioxide content.

4. Parts-per notation - Wikipedia

   en.wikipedia.org/wiki/Parts-per_notation

   The difference is quite significant when dealing with gases, and it is very important to specify which quantity is being used. For example, the conversion factor between a mass fraction of 1 ppb and a mole fraction of 1 ppb is about 4.7 for the greenhouse gas CFC-11 in air (Molar mass of CFC-11 / Mean molar mass of air = 137.368 / 28.97 = 4.74 ...

5. Threshold limit value - Wikipedia

   en.wikipedia.org/wiki/Threshold_limit_value

   Its units are in parts per million (ppm) for gases and in milligrams per cubic meter (mg/m 3) for particulates such as dust, smoke and mist. The basic formula for converting between ppm and mg/m 3 for gases is ppm = (mg/m^3) * 24.45 / molecular weight. This formula is not applicable to airborne particles.

6. Air quality index - Wikipedia

   en.wikipedia.org/wiki/Air_quality_index

   Air pollutants vary in potency, and the function used to convert from air pollutant concentration to AQI varies by pollutant. Its air quality index values are typically grouped into ranges. Each range is assigned a descriptor, a color code, and a standardized public health advisory. The AQI can increase due to an increase of air emissions.

7. Volume units used in petroleum engineering - Wikipedia

   en.wikipedia.org/wiki/Volume_units_used_in...

   Note that the m³ gas conversion factor takes into account a difference in the standard temperature base for measurement of gas volumes in metric and imperial units. The standard temperature for metric measurement is 15 degrees Celsius (i.e. 59 degrees Fahrenheit) while for English measurement the standard temperature is 60 °F.