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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 mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement. Commonly used are parts-per-million (ppm, 10 ...
The permissible exposure limit (PEL or OSHA PEL) is a legal limit in the United States for exposure of an employee to a chemical substance or physical agent such as high level noise. Permissible exposure limits were established by the Occupational Safety and Health Administration (OSHA). Most of OSHA's PELs were issued shortly after adoption of ...
The score for each pollutant is non-linear, as is the final AQI score. Thus an AQI of 300 does not mean twice the pollution of AQI at 150, nor does it mean the air is twice as harmful. The concentration of a pollutant when its IAQI is 100 does not equal twice its concentration when its IAQI is 50, nor does it mean the pollutant is twice as harmful.
Ch. = Concentration, in mass per unit volume at altitude h and specified temperature T. As an example, given an air pollutant concentration of 260 mg/m 3 at sea level, calculate the equivalent pollutant concentration at an altitude of 2800 meters: Ch = 260 × [ { 288 - (6.5) (2.8) } / 288] 5.2558 = 260 × 0.71 = 185 mg/m 3.
Threshold limit value. The threshold limit value (TLV) is a level of occupational exposure to a hazardous substance where it is believed that nearly all healthy workers can repeatedly experience at or below this level of exposure without adverse effects. Strictly speaking, TLV is a reserved term of the American Conference of Governmental ...
Since january 2012, Brazilian service stations started offering two types of Diesel, 50 ppm and 500 ppm on most areas and 1800 ppm in remote areas. Since january 2013 the 10 ppm or EURO V Diesel replaced the 50 ppm Diesel, which is now widely used and can be found in the majority of service stations, and the 1800 ppm was discontinued.
Total dissolved solids (TDS) is a measure of the dissolved combined content of all inorganic and organic substances present in a liquid in molecular, ionized, or micro-granular (colloidal sol) suspended form. TDS are often measured in parts per million (ppm). TDS in water can be measured using a digital meter.
Annual mean, averaged over 3 years 40 CFR 50.18: Secondary 15 μg/m 3: annual Annual mean, averaged over 3 years 40 CFR 50.7: Primary and Secondary 35 μg/m 3: 24-hour 98th percentile, averaged over 3 years 40 CFR 50.18: Carbon monoxide (CO) Primary 35 ppm (40 mg/m 3) 1-hour Not to be exceeded more than once per year 40 CFR 50.8: Primary 9 ppm ...