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A normal cubic meter (Nm 3) is the metric expression of gas volume at standard conditions and it is usually (but not always) defined as being measured at 0 °C and 1 atmosphere of pressure. A standard cubic foot (scf) is the USA expression of gas volume at standard conditions and it is often ( but not always ) defined as being measured at 60 ...
Some express the concentrations as ppmv (parts per million by volume) and some express the concentrations as mg/m 3 (milligrams per cubic meter), while others require adjusting or correcting the concentrations to reference conditions of moisture content, oxygen content or carbon dioxide content.
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 ...
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).
The table below lists units supported by {{convert}}. More complete lists are linked for each dimension. For a complete list of all dimensions, see full list of units. {{Convert}} uses unit-codes, which are similar to, but not necessarily exactly the same as, the usual written abbreviation for a given unit. These unit-codes are displayed in ...
Note that the m³ gas conversion factor takes into account a difference in the standard temperature base for measurement of gas volumes in metric and imperial units. The standard temperature for metric measurement is 15 degrees Celsius (i.e. 59 degrees Fahrenheit) while for English measurement the standard temperature is 60 °F.
The World Health Organization guidelines were most recently updated in 2021. [1] The guidelines offer guidance about these air pollutants: particulate matter (PM), ozone (O 3), nitrogen dioxide (NO 2), sulfur dioxide (SO 2) and carbon monoxide (CO). [2]
9 ppm Nitrogen dioxide 1 hour 0.12 ppm 1 year 0.03 ppm Ozone 1 hour 0.10 ppm 4 hours 0.08 ppm Sulfur dioxide 1 hour 0.20 ppm 1 day 0.08 ppm 1 year 0.02 ppm Lead 1 year 0.50 μg/m 3: PM 10 1 day 50 μg/m 3: 1 year 25 μg/m 3: PM 2.5 1 day 25 μg/m 3: 1 year 8 μg/m 3