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  2. Air quality guideline - Wikipedia

    en.wikipedia.org/wiki/Air_quality_guideline

    The guidelines stipulate that PM 2.5 should not exceed 5 μg/m 3 annual mean, or 15 μg/m 3 24-hour mean; and that PM 10 should not exceed 15 μg/m 3 annual mean, or 45 μg/m 3 24-hour mean. [2] For ozone (O 3 ), the guidelines suggest values no higher than 100 μg/m 3 for an 8-hour mean and 60 μg/m 3 peak season mean. [ 2 ]

  3. National Ambient Air Quality Standards - Wikipedia

    en.wikipedia.org/wiki/National_Ambient_Air...

    0.5 ppm (1,300 μg/m 3) 3-hour Not to be exceeded more than once per year 40 CFR 50.5: Particulate matter (PM 10) Primary and Secondary 150 μg/m 3: 24-hour Not to be exceeded more than once per year on average over 3 years 40 CFR 50.6: Fine particulate matter (PM 2.5) Primary 9.0 μg/m 3 (12 μg/m 3 prior to May 6, 2024) [25] annual

  4. Particulates - Wikipedia

    en.wikipedia.org/wiki/Particulates

    The CCME standard for particulate matter 2.5 (PM 2.5) as of 2015 is 28 μg/m 3 (calculated using the 3-year average of the annual 98th percentile of the daily 24-hr average concentrations) and 10 μg/m 3 (3-year average of annual mean). PM 2.5 standards will increase in stringency in 2020. [275]

  5. Clean Air Act (United States) - Wikipedia

    en.wikipedia.org/wiki/Clean_Air_Act_(United_States)

    The 1977 CAA Amendments created a process for regular review of the NAAQS list, and created a permanent independent scientific review committee to provide technical input on the NAAQS to EPA. [7] EPA added regulations for PM2.5 in 1997 (62 FR 38652), and updates the NAAQS from time to time based on emerging environmental and health science.

  6. List of most-polluted cities by particulate matter concentration

    en.wikipedia.org/wiki/List_of_most-polluted...

    This list contains the top 500 cities by PM2.5 annual mean concentration measurement as documented by the World Health Organization covering the period from 2010 to 2022. The January 2024 version of the WHO database contains results of ambient (outdoor) air pollution monitoring from almost 5,390 towns and cities in 63 countries.

  7. Air quality index - Wikipedia

    en.wikipedia.org/wiki/Air_quality_index

    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.

  8. Is It Safe to Use Expired Vitamins? The Truth About Vitamin ...

    www.aol.com/vitamins-expire-nutritionists-weigh...

    When you buy a bottle of vitamins from a nutrition store, you’ll probably notice a best-by date on the bottom of the jar. But that inscribed number isn’t a hard-and-fast rule—there is some ...

  9. List of countries by air pollution - Wikipedia

    en.wikipedia.org/wiki/List_of_countries_by_air...

    The following list of countries by air pollution sorts the countries of the world according to their average measured concentration of particulate matter in micrograms per cubic meter (μg/m 3). The World Health Organization's recommended limit is 5 micrograms per cubic meter, although there are also various national guideline values, which are ...