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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. Parts-per notation - Wikipedia

    en.wikipedia.org/wiki/Parts-per_notation

    At 10 000 ppm the solution is a deep red colour. As the concentration decreases the colour becomes orange, then a vibrant yellow, with the final 1 ppm sample a very pale yellow. In science and engineering , the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities , e.g. mole fraction or ...

  4. Grain per gallon - Wikipedia

    en.wikipedia.org/wiki/Grain_per_gallon

    It translates into 1 part in about 58,000 parts of water or 17.1 parts per million (ppm). Also called Clark degree (in terms of an imperial gallon). Usage.

  5. PPM - Wikipedia

    en.wikipedia.org/wiki/PPM

    Parts-per-million, ppm Carbon dioxide in Earth's atmosphere, CO 2 ppm; Peak programme meter, measuring audio level; Planned Preventative Maintenance of equipment; PPM Star Catalogue of 378,910 stars' positions and proper motions; Proton precession magnetometer, measures small magnetic field variations; Pulse-position modulation of a signal

  6. Air pollutant concentrations - Wikipedia

    en.wikipedia.org/wiki/Air_pollutant_concentrations

    Notes: 1 atm = absolute pressure of 101.325 kPa or 1.01325 bar; mol = gram mole and kmol = 1000 gram moles Pollution regulations in the United States typically reference their pollutant limits to an ambient temperature of 20 to 25 °C as noted above.

  7. 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.

  8. Per mille - Wikipedia

    en.wikipedia.org/wiki/Per_mille

    Visualisation of 1%, 1‰, 1‱, 1 pcm and 1 ppm as fractions of the large block . Percentage point difference of 1 part in 100; Percentage (%) 1 part in 100; Basis point (bp) difference of 1 part in 10,000; Permyriad (‱) 1 part in 10,000; Per cent mille (pcm) 1 part in 100,000

  9. Standard cubic centimetres per minute - Wikipedia

    en.wikipedia.org/wiki/Standard_cubic_centimetres...

    Standard cubic centimeters per minute (SCCM) is a unit used to quantify the flow rate of a fluid. 1 SCCM is identical to 1 cm³ STP /min. Another expression of it would be Nml/min.