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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
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
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 ...
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).
O 3 and NO 2 are measured in parts per billion (ppb) while PM2.5 is measured in micrograms per cubic metre (μg/m 3). The AQHI is calculated on a community basis (each community may have one or more monitoring stations).
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.
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 .
The two alternatives are to abbreviate as "mcg" [14] [3] or to write out "microgram" in full (see also List of abbreviations used in medical prescriptions). The alternative abbreviation may be ambiguous in rare circumstances in that mcg could also be read as a micrigram , i.e. 10 −14 g; however the prefix micri is not standard, nor widely ...