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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 ]
Worldwide, PM 10 concentrations of 70 μg/m 3 and PM 2.5 concentrations of 35 μg/m 3 have been shown to increase long-term mortality by 15%. [29] More so, approximately 4.2 million of all premature deaths observed in 2016 occurred due to airborne particulate pollution, 91% of which occurred in countries with low to middle socioeconomic status.
Particulates or atmospheric particulate matter (see below for other names) are microscopic particles of solid or liquid matter suspended in the air.The term aerosol refers to the particulate/air mixture, as opposed to the particulate matter alone, [1] though it is sometimes defined as a subset of aerosol terminology. [2]
Long-term exposure to PM 2.5 (fine particulates) increases the overall risk of non-accidental mortality by 6% per 10 μg/m 3 increase. Exposure to PM 2.5 is also associated with an increased risk of mortality from lung cancer (range: 15–21% per 10 μg/m 3 increase) and total cardiovascular mortality (range: 12–14% per 10 μg/m 3 increase).
US counties that are designated "nonattainment" for the Clean Air Act's NAAQS, as of September 30, 2017. The U.S. National Ambient Air Quality Standards (NAAQS, pronounced / ˈ n æ k s / naks) are limits on atmospheric concentration of six pollutants that cause smog, acid rain, and other health hazards. [1]
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.
Portable room air cleaners with HEPA filters can be used if ventilation is poor or outside air has high level of PM 2.5. [122] Air filters are used to reduce the amount of dust that reaches the wet coils. [citation needed] Dust can serve as food to grow molds on the wet coils and ducts and can reduce the efficiency of the coils. [citation needed]
Various definitions of pollution exist, which may or may not recognize certain types, such as noise pollution or greenhouse gases.The United States Environmental Protection Administration defines pollution as "Any substances in water, soil, or air that degrade the natural quality of the environment, offend the senses of sight, taste, or smell, or cause a health hazard.