parts per million


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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.
References in periodicals archive ?
At 700 parts per million, pilots were 69 percent more likely to correctly perform the maneuvers compared to when they were breathing carbon dioxide at 2500 parts per million.
When considering only the top two inches of testing in the park, and only considering arsenic, there are 16 spots that have more than 250 parts per million for arsenic now, according to the county's data.
According to the study, sea level stays more or less constant for CO2 changes between 400 and 650 parts per million and it is only for CO2 levels above 650 parts per million that the researchers again saw a strong sea level response for a given CO2 change.
The current aim is to limit atmospheric C[O.sub.2] levels to 450 parts per million, but in light of this study, scientists have voiced concerns that this threshold isn't low enough.
A person who smokes a pack of cigarettes per day will commonly have a CO level of about 20 parts per million. A two-pack-a-day smoker may have a level of about 40 parts per million.
Parts per Million raises important questions concerning civic and corporate responsibility, environmental toxicity, oil dependence and the restriction of public information.
Lab tests indicate that nahcolite would precipitate out of salty, alkaline lakes only if atmospheric concentrations of carbon dioxide were above 1,125 parts per million (ppm), Tim K.
The carcinogenic effects were evident at daily doses as low as 400 parts per million, equivalent to an assumed daily human intake of 20 milligrams per kilogram body weight (mg/kg).
The old nickel deposits were found from outcrops, but when one is looking for PGMs that are only a few parts per million, one has to use advanced studies to further identify the mineral composition.
The new EPA guidelines mean that sulfur in gasoline must be reduced from 80 parts per million to 30 parts per million.
Hayes Montague is focused on further automation throughout the plant, improving product rates while increasing quality and reducing defect parts per million. The question is--where will they be 18 months from now?
The MOST team argues that the oscillations seen in radial-velocity studies of Procyon imply that the brightness variations should amount to 15 or 20 parts per million, within range of the satellite's sensitivity.