parts per million


Also found in: Dictionary, Acronyms, Encyclopedia.

parts per million (PPM, ppm)

the ratio of the amount of one substance to the amount of another, expressed as a unit of solute dissolved in one million units of solution. It denotes the number of units of one substance relative to one million units of another substance. It may be further expressed in terms of mass-to-mass, volume-to-volume, or another relationship of units of measure.

parts per million

(părts),

PPM; ppm

The concentration of a solute in a liquid or gas. For example, a pollutant such as soot may be said to be present in air at a level of 50 parts per million (parts of air). The units also may be expressed as weight of one substance to the weight of another or the volume of a fluid in the volume of another.

parts per million

mg/kg or ml/l; see ppm.
References in periodicals archive ?
EPA didn't order Benny Goodman Park cleaned up because the average number for the park, for arsenic, was below 250 parts per million in 2003.
Sea level rises to these high values will take many centuries, or even millennia, but the implications from the geological record are clear - for a future climate with maximum warming of about two degrees Centigrade, that is with CO2 stabilized at 400 to 450 parts per million, sea level is set to steadily rise for many centuries, towards its natural equilibrium position at around 24 +7/-15 metres, at 68 per cent confidence," Rohling said.
The theories say a star like Procyon should exhibit brightness variations amounting to 60 parts per million, completely at odds with MOST's measurements and estimates from radial-velocity studies.
To date, the electronic tongue has been tested on ions of copper, zinc, lead, and iron, and has detected concentrations as low as about 10 parts per million, according to a report by Buehler and Kuhlman.
The new standards specify diesel fuel sulfur content of 500 parts per million for most nonroad vehicles by 2007, dropping to 15 parts per million by 2010.
Noting that 400 parts per million (ppm) is the EPA limit for material to not be considered a hazardous waste, Cosper said that only paint chips tested alone surpassed this limit, testing at 3,500 milligrams per kilogram following TCLP (toxicity characteristic leaching procedure) testing methods.
The new fuel will meet new EU rules calling for sulphur levels in fuel to be reduced from 50 parts per million to 10 parts per million by January, 2005.
Switching to ultra-low-sulphur petrol (50 parts per million sulphur content) brings immediate reductions in emissions of nitrogen oxides and hydrocarbons by 13% on average.
In the study 95 per cent on swans tested in Stratford had above the acceptable lead level of 25 parts per million in their blood.
In measuring solids such as plastic pellets and thin films, XRF has the same detection sensitivity - down to a few parts per million - as classic elemental analysis techniques such as atomic absorption spectroscopy, which require samples to be dissolved in a solvent before they can be analyzed.
015 parts per million, or 15 parts per billion, which is the New York State's guideline.
According to the report released by the mayor, the tests showed the newspaper contained 950 parts per million of aluminum; 806 parts per million of calcium; 54 parts per million of copper; 16 parts per million of iron; 126 parts per million of magnesium; 33.