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Fluorescein aqueous solutions, diluted from 10,000 to 1 parts-per-million in intervals of 10 fold dilution. 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.
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).
Thus, a wet basis concentration of 40 ppmv in a gas having 10 volume percent water vapor would have a dry basis concentration = 40 ÷ ( 1 - 0.10 ) = 44.44 ppmv. Correcting to a reference oxygen content
Criteria can be set in different units (e.g. μg/m 3, parts per billion by volume (ppbv), parts per billion by mass (ppb (mass)), parts per million (ppm)) and it is possible to convert between all of these units if the molecular mass of the pollutant and the temperature are known. Different standard temperatures are used throughout the world ...
When more than 10% of samples exceed the LCR's Action Level (currently 15ppb for lead and 1.3ppm for copper; lead Action Level lowered to 10 ppb in 2027), state and municipal governments must check their plumbing systems semi-annually and intervene by investigating, recommending treatments, identifying the source of contamination, removing lead ...
Mixed Flowing Gas (MFG) test is a laboratory test in which the temperature (°C), relative humidity (%RH), concentration of gaseous pollutants (in parts per billion, ppb or parts per million ppm level), and other critical variables (such as volume exchange rate and airflow rate) are carefully defined, monitored and controlled.
The odor detection threshold is the lowest concentration of a certain odor compound that is perceivable by the human sense of smell.The threshold of a chemical compound is determined in part by its shape, polarity, partial charges, and molecular mass.
9 ppm (10 mg/m 3) 8-hour Not to be exceeded more than once per year 40 CFR 50.8: Ozone (O 3) Primary and Secondary 0.12 ppm (235 μg/m 3) 1-hour a: expected number of days per calendar year, with maximum hourly average concentration greater than 0.12 ppm, is equal to or less than 1 40 CFR 50.9: Primary and Secondary 0.070 ppm (140 μg/m 3) 8-hour