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  2. Air quality index - Wikipedia

    en.wikipedia.org/wiki/Air_quality_index

    An air quality index (AQI) is an indicator developed by government agencies [1] to communicate to the public how polluted the air currently is or how polluted it is forecast to become. [2][3] As air pollution levels rise, so does the AQI, along with the associated public health risk. Children, the elderly and individuals with respiratory or ...

  3. Air pollution in the United States - Wikipedia

    en.wikipedia.org/wiki/Air_pollution_in_the...

    Anthropogenic air pollution has affected the United States since the beginning of the Industrial Revolution. [2] According to a 2024 report: "39% of people living in America—131.2 million people—still live in places with failing grades for unhealthy levels of ozone or particle pollution."

  4. List of countries by air pollution - Wikipedia

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

    Air pollution can affect nearly every organ and system of the body, negatively affecting nature and humans alike. Air pollution is a particularly big problem in emerging and developing countries, where global environmental standards often cannot be met. The data in this list refers only to outdoor air quality and not indoor air quality, which ...

  5. How to understand the Air Quality Index - AOL

    www.aol.com/news/how-to-understand-the-air...

    The AQI uses a scale that typically ranges from zero to 500 to denote air quality. If your area has an AQI of 50 or below, you're in a green zone. You should have good air quality and little or no ...

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

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

    The 2018 version of the WHO database contains results of ambient (outdoor) air pollution monitoring from almost 2700 towns and cities in 91 countries. Air quality in the database is represented by the annual mean concentration of particulate matter (PM10 and PM2.5, i.e. particles smaller than 10 or 2.5 micrometers, respectively). [1] [2] [3]

  7. Clean Air Act (United States) - Wikipedia

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

    The Clean Air Act (CAA) is the United States' primary federal air quality law, intended to reduce and control air pollution nationwide. Initially enacted in 1963 and amended many times since, it is one of the United States' first and most influential modern environmental laws. As with many other major U.S. federal environmental statutes, the ...

  8. United States vehicle emission standards - Wikipedia

    en.wikipedia.org/wiki/United_States_vehicle...

    Two sets, or tiers, of emission standards for light-duty vehicles in the United States were defined as a result of the Clean Air Act Amendments of 1990. The Tier I standard was adopted in 1991 and was phased in from 1994 to 1997. Tier II standards were phased in from 2004 to 2009. Within the Tier II ranking, there is a subranking ranging from ...

  9. Air pollution measurement - Wikipedia

    en.wikipedia.org/wiki/Air_pollution_measurement

    Air quality monitoring sensors in Port Pirie, South Australia. Air pollution measurement is the process of collecting and measuring the components of air pollution, notably gases and particulates. The earliest devices used to measure pollution include rain gauges (in studies of acid rain), Ringelmann charts for measuring smoke, and simple soot ...