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  2. Parts-per notation - Wikipedia

    en.wikipedia.org/wiki/Parts-per_notation

    At 1 ppm the solution is a very pale yellow. As the concentration increases the colour becomes a more vibrant yellow, then orange, with the final 10,000 ppm a deep red colour. 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 ...

  3. Useful conversions and formulas for air dispersion modeling

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

    As an example, given a concentration of 260 mg/m 3 at sea level, calculate the equivalent concentration at an altitude of 1,800 meters: C a = 260 × 0.9877 18 = 208 mg/m 3 at 1,800 meters altitude Standard conditions for gas volumes

  4. Air pollutant concentrations - Wikipedia

    en.wikipedia.org/wiki/Air_pollutant_concentrations

    where: mg/m 3 = milligrams of pollutant per cubic meter of air at sea level atmospheric pressure and T: ppmv = air pollutant concentration, in parts per million by volume

  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

    An individual score (Individual Air Quality Index, IAQI) is calculated using breakpoint concentrations below, and using same piecewise linear function to calculate intermediate values as the US AQI scale. and The final AQI value can be calculated either per hour or per 24 hours and is the max of these six scores.

  7. Temperature coefficient - Wikipedia

    en.wikipedia.org/wiki/Temperature_coefficient

    The thermal coefficient of electrical circuit parts is sometimes specified as ppm/°C, or ppm/K. This specifies the fraction (expressed in parts per million) that its electrical characteristics will deviate when taken to a temperature above or below the operating temperature .

  8. 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

  9. Permissible exposure limit - Wikipedia

    en.wikipedia.org/wiki/Permissible_exposure_limit

    Chemical regulation is sometimes [clarification needed] expressed in parts per million (ppm), but often [clarification needed] in milligrams per cubic meter (mg/m 3). [2] Units of measure for physical agents such as noise are specific to the agent.