Search results
Results from the WOW.Com Content Network
= 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
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.
One part per billion (ppb) denotes one part per 1,000,000,000 (10 9) parts, and a value of 10 −9. This is equivalent to about three seconds out of a century . One part per trillion ( ppt ) denotes one part per 1,000,000,000,000 (10 12 ) parts, and a value of 10 −12 .
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).
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 ...
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 ...
The examples don't seem to be too accurate. A drop is usually defined as 0.05 ml, which then gives;. 1 drop in 50 ml = 1‰, 50ml is a very small cup 1 drop in 50 l = 1ppm 50 l is about 11 gallons, not 40 1 drop in 50 cubic metres = 1 ppb 1 drop = 1ppt, a 50 m swimming pool is 50*25*2 = 2,500 m^3 1 drop in 50,000,000 cubic metres = 1ppq, 50,000,000 m^3 is equivalent to a lake covering a square ...
In October 2008, the US EPA reduced the allowable lead level by a factor of ten to 0.15 micrograms per cubic meter of air, giving states five years to comply with the standards. [225] The European Union's Restriction of Hazardous Substances Directive limits amounts of lead and other toxic substances in electronics and electrical equipment.