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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. The change of atmospheric pressure with altitude can be obtained from this equation: [2]
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 T = ambient temperature in K = 273. + °C 0.082057338 = Universal gas constant in L atm mol −1 K −1: M = molecular mass (or molecular weight) of the air pollutant
However, the names of all SI mass units are based on gram, rather than on kilogram; thus 10 3 kg is a megagram (10 6 g), not a *kilokilogram. The tonne (t) is an SI-compatible unit of mass equal to a megagram (Mg), or 10 3 kg. The unit is in common use for masses above about 10 3 kg and is often used with SI prefixes.
Indoor air particulate samples (<10 um) were collected in Chinese homes from Xuan Wei county burning smokey coal, smokeless coal, and wood in 1983 and 1984; the concentration of 5-methylchrysene was 1.6 to 17 ug/m 3, 0.21 to 3.5 ug/m 3, and 0.03 to 0.05 ug/m 3, respectively. Sampling was conducted in March and September, 2011.
A solution with 1 g of solute dissolved in a final volume of 100 mL of solution would be labeled as "1%" or "1% m/v" (mass/volume). This is incorrect because the unit "%" can only be used for dimensionless quantities. Instead, the concentration should simply be given in units of g/mL.
If you’re stuck on today’s Wordle answer, we’re here to help—but beware of spoilers for Wordle 1252 ahead. Let's start with a few hints.
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.
A headache is a pain in the head, neck or face that is often described as a sensation of pressure that varies in location, frequency and severity, according to the National Institutes of Health.