PM data is the near real-time measurement of particulate matter 10 microns or less in size from the surrounding air.
But the report also shows that the concentration averages for those pollutants around the nation are creeping back up. The only two cities not to show an upward trend in ozone days were Bloomington, where the number of ozone days fluctuated, and New Castle, whose monitors did not track ozone days.
EPA data shows concentration averages for some air pollutants have stopped decreasing or begun increasing. The EPA is also attempting to: weaken fuel-economy standards for cars and light trucks; eliminate restrictions for new, modified and reconstructed coal plants to capture carbon dioxide emissions, change emissions rules for power plant startups, shutdowns and malfunctions; change rules that cut methane emissions from landfills and weaken a rule that limits mercury emissions from coal power plants.
These particles come in many sizes and shapes and can be made up of hundreds of different chemicals. The following table shows the various breakpoints used in calculating the AQI.
An ozone exceedance day is counted if the measured eight-hour average ozone concentration exceeds the standards.
In Columbus, reported ozone days rose from in to in