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  2. Parts-per notation - Wikipedia

    en.wikipedia.org/wiki/Parts-per_notation

    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 ...

  3. Immediately dangerous to life or health - Wikipedia

    en.wikipedia.org/wiki/Immediately_dangerous_to...

    The NIOSH definition does not include oxygen deficiency (below 19.5%) although atmosphere-supplying breathing apparatus is also required. [3] Examples include high altitudes and unventilated, confined spaces .

  4. Total dissolved solids - Wikipedia

    en.wikipedia.org/wiki/Total_dissolved_solids

    Fresh water: TDS is less than 1,000 ppm. Brackish water: TDS = 1,000 to 10,000 ppm. Saline water: TDS = 10,000 to 35,000 ppm. Hypersaline: TDS greater than 35,000 ppm. Drinking water generally has a TDS below 500 ppm. Higher TDS Fresh Water is drinkable but taste may be objectionable.

  5. Liquefied petroleum gas - Wikipedia

    en.wikipedia.org/wiki/Liquefied_petroleum_gas

    The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 1000 ppm (1800 mg/m 3) over an 8-hour workday. At levels of 2000 ppm, 10% of the lower explosive limit, LPG is considered immediately dangerous to life and health (due solely to safety considerations pertaining to risk of explosion). [43]

  6. Fresh water - Wikipedia

    en.wikipedia.org/wiki/Fresh_water

    Fresh water can be defined as water with less than 500 parts per million (ppm) of dissolved salts. [6] Other sources give higher upper salinity limits for fresh water, e.g. 1,000 ppm [7] or 3,000 ppm. [8]

  7. Indoor air quality - Wikipedia

    en.wikipedia.org/wiki/Indoor_air_quality

    The UK standards for schools say that carbon dioxide levels of 800 ppm or lower indicate that the room is well-ventilated. [92] Regulations and standards from around the world show that CO 2 levels below 1000 ppm represent good IAQ, between 1000 and 1500 ppm represent moderate IAQ and greater than 1500 ppm represent poor IAQ. [88]

  8. Air quality index - Wikipedia

    en.wikipedia.org/wiki/Air_quality_index

    The definition of the AQI in a particular nation reflects the discourse surrounding the ... 0.12 ppm 1 year 0.03 ppm Ozone ... 1000 (3) 350 500 2620 (2) ...

  9. RoHS - Wikipedia

    en.wikipedia.org/wiki/RoHS

    The maximum permitted concentrations in non-exempt products are 0.1% or 1000 ppm (except for cadmium, which is limited to 0.01% or 100 ppm) by weight.