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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.
For reporting the PM 2.5, PM 10 and ozone air quality indices, this surrogate concentration is called the NowCast. The Nowcast is a particular type of weighted average that provides more weight to the most recent air quality data when air pollution levels are changing. [49] [50]
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]
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]
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 ...
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).
As an example, a measured NO x concentration of 45 ppmv in a dry gas having 5 volume % O 2 is: 45 × ( 20.9 - 3 ) ÷ ( 20.9 - 5 ) = 50.7 ppmv of NO x. when corrected to a dry gas having a specified reference O 2 content of 3 volume %. Note: The measured gas concentration C m must first be corrected to a dry basis before using the above equation.
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