Why PM Seems Like a "New" Topic
You’ve heard of ozone, acid rain, carbon monoxide and CFCs. Researchers, scientists and citizens have known for years that these pollutants (and many others) harm our health, so why haven’t we heard as much about PM?
Scientists have monitored PM since the 1960s, when it was then called total suspended particulate (TSP). TSP monitors collected large particles, and did not have the capability to capture particles smaller than 10 microns. At that time, information on the health effects of TSP was limited.
During the 1980s, researchers began to study effects of TSP on the human body. As people learned that TSP can harm lung function, technology improved to allow monitors to collect smaller and smaller samples of TSP.
The U.S. EPA replaced TSP with PM10 as the indicator for health-related standards in 1987. The indicator includes only those particles with an aerodynamic diameter smaller than or equal to a nominal ten micrometers (PM10 - Particulate Matter 10 microns or less).
Scientists developed PM10 (or coarse particulate) monitors, and as technology advanced, monitors began to detect PM as small as 2.5 microns. Studies continued to show that both long term and short term exposure to PM can endanger people’s health. In 1997, the U.S. EPA set a stricter standard for particulate air pollution from 10 microns in size to 2.5 microns.
As studies reinforced the dangers of PM, the U.S. EPA, the Ohio EPA and HCDOES have worked to increase awareness of and create regulations for this pollutant. PM monitors have become so advanced that, upon further analysis of a sample, researchers can determine which chemicals are present and, in some cases, the chemicals’ origins.
