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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.
Below is a list of 526 cities sorted by their annual mean concentration of PM2.5 (μg/m 3) in 2022. [1] [2] By default the least polluted cities which have fewest particulates in the air come first.
PM 2.5 AQI of US monitors, calculated utilizing NowCast, courtesy US EPA PM2.5 AQI map, calculated utilizing NowCast, courtesy US EPA. The PM (particulate matter) NowCast is a weighted average of hourly air monitoring data used by the United States Environmental Protection Agency (USEPA) for real-time reporting of the Air Quality Index (AQI) for PM (PM 10 - particles less than 10 micrometers ...
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 ...
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.
Looking down from the Hollywood Hills, with Griffith Observatory on the hill in the foreground, air pollution is visible in downtown Los Angeles on a late afternoon.. Air pollution is the introduction of chemicals, particulate matter, or biological materials into the atmosphere that cause harm or discomfort to humans or other living organisms, or damage ecosystems.
[5] [6] A sub-index value is computed for each pollutant based on the pollutant's ambient air concentration. The highest sub-index value is then taken as the PSI value. In other words, the PSI is determined by the pollutant with the most significant concentration. [7] During haze episodes, PM 2.5 is the most significant pollutant. [8]
In terms of health effects, the guideline states that PM2.5 concentration of 10 is the lowest level at which total, cardiopulmonary and lung cancer mortality have been shown to increase with more than 95% confidence in response to long-term exposure to PM2.5. [2]