The fine particulate matter (PM 2.5) standard was established in 1997 and is health-based – meaning it was designed to establish pollution limits to protect public health. There are two standards for particulate matter less than 2.5 microns in diameter (PM 2.5): annual and daily.
The annual standard is 15 micrograms per cubic meter (m g/m3) and attainment is determined by taking the average of the monitor values over a three-year period. The daily standard is 65 micrograms per cubic meter (m g/m3) and attainment is determined by taking the 98th percentile of the monitor values over a three-year period. Values greater than the annual (15 m g/m3) or daily (65 m g/m3) standards are considered to exceed the standard.
Please visit the Indiana Department of Environmental Management's website for more information about the PM 2.5 standard and how it affects central Indiana.
