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  2. Parts-per notation - Wikipedia

    en.wikipedia.org/wiki/Parts-per_notation

    In fractions like "2 nanometers per meter" (2 n m / m = 2 nano = 2×10 −9 = 2 ppb = 2 × 0.000 000 001), so the quotients are pure-number coefficients with positive values less than or equal to 1. When parts-per notations, including the percent symbol (%), are used in regular prose (as opposed to mathematical expressions), they are still pure ...

  3. Useful conversions and formulas for air dispersion modeling

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

    0.1 × ( 12 ÷ 8 ) = 0.15 grain per dscf when corrected to a gas having a specified reference CO 2 content of 12 volume %. Notes: Although ppmv and grains per dscf have been used in the above examples, concentrations such as ppbv (i.e., parts per billion by volume), volume percent, grams per dscm and many others may also be used.

  4. Air pollutant concentrations - Wikipedia

    en.wikipedia.org/wiki/Air_pollutant_concentrations

    1 volume percent = 10,000 ppmv (i.e., parts per million by volume) with a million being defined as 10 6. Care must be taken with the concentrations expressed as ppbv to differentiate between the British billion which is 10 12 and the USA billion which is 10 9 (also referred to as the long scale and short scale billion, respectively).

  5. Air pollution measurement - Wikipedia

    en.wikipedia.org/wiki/Air_pollution_measurement

    The amount of pollutant present in air is usually expressed as a concentration, measured in either parts-per notation (usually parts per billion, ppb, or parts per million, ppm, also known as the volume mixing ratio), or micrograms per cubic meter (μg/m³).

  6. List of abbreviations used in sanitation - Wikipedia

    en.wikipedia.org/wiki/List_of_abbreviations_used...

    μg - Microgram; MHM - Menstrual hygiene management; ML - Megaliter or 1 million liter or 1000 cubic meters; MLD - Million liters per day; MOH - Ministry of health (see also List of health departments and ministries) MOOC - Massive open online course; MOS - Manual of style, see also: MOS for WikiProject Sanitation; MoU - Memorandum of understanding

  7. Microgram - Wikipedia

    en.wikipedia.org/wiki/Microgram

    In the metric system, a microgram or microgramme is a unit of mass equal to one millionth (1 × 10 −6) of a gram. The unit symbol is μg according to the International System of Units (SI); the recommended symbol in the United States and United Kingdom when communicating medical information is mcg .

  8. Unlike alcohol, THC impairment is hard to measure — making a ...

    www.aol.com/news/arbitrary-cutoffs-thc-levels...

    His new study found that the number of moderately injured drivers with concentrations of THC above 5 nanograms per milliliter rose from 1.1 percent before cannabis was legalized to 3 percent after ...

  9. Arsenic contamination of groundwater - Wikipedia

    en.wikipedia.org/wiki/Arsenic_contamination_of...

    A drinking water standard of 0.05 mg/L (equal to 50 parts per billion, or ppb) arsenic was originally established in the United States by the Public Health Service in 1942. After the passage of the Safe Drinking Water Act of 1974 (SDWA), the Environmental Protection Agency (EPA) was given the power to set the maximum contaminant levels (MCLs ...