Frequent Questions

  • What is air pollution? Generally any substance that is introduced into the atmosphere that has damaging effects on living things and the environment is considered air pollution. Smog hanging over cities is probably the most familiar example; however, there are many different kinds of pollution—some visible, some invisible - that contribute to make air pollution a complex problem. Common air pollutants include:
              • Carbon Monoxide (CO)
              • Lead (Pb)
              • Nitrogen oxides (NOx)
              • Ground-level Ozone (O3)
              • Particulate matter (PM)
              • Sulfur Oxides
  • What do we monitor? We monitor an air pollutant known as particulate matter (PM). PM is used to define a mixture of solid particles and liquid droplets found in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope. Particles with a diameter of less than 10 microns (PM10), including fine particles less than 2.5 microns (PM2.5) pose the greatest risks to health, as they are capable of penetrating peoples’ lungs and entering their bloodstream. Sources of PM include combustion engines (both diesel and petrol), solid-fuel (coal, lignite, heavy oil and biomass) combustion for energy production in households and industry, as well as other industrial activities (building, mining, manufacture of cement, ceramic and bricks, and smelting). To learn more see:

*Image provided by EPA

  • How do we monitor PM? We monitor PM using a light scattering laser photometer known as the DustTrak™ DRX Aerosol Monitor Model 8533EP ( The DRX is an active monitoring device that draws air through a measurement chamber using an electric pump in order to provide concentration levels for particulate mass across multiple size fractions. The DRX is developed by TSI, Inc. and more information can be found at:

*Image provided by TSI

  • What are the resulting data? Each data point on our plots represent the mean concentration of PM2.5 micrograms per cubic meter (ug/m3) measured over a 30-minute interval. This is a measure of particulate matter based on size and how the particle moves through air. The 30-min average summarizes observations collected every 30 seconds for particles ranging from 1 to 15 microns in diameter.
  • How do I interpret the data? Air pollution monitors like the ones used here provide high resolution snapshots of air pollution levels. Such snapshots are very useful for providing 'instant' understanding of air quality conditions and thus can be very useful for planning activities. That said, it’s important to note that scientific studies to date have yet to establish what such snapshots of exposure to outdoor air pollution means for health. In order to provide guidance on such air pollution measures, the EPA has developed a sensor scale to help determine whether air quality values fall into low, medium or high ranges using snapshot measures from non-reference sensor devices. We note we present this for guidance only as we continue to work on a scale for MCAMN.
EPA Pilot Air Quality Scales.docx
  • How do our monitors compare to regulatory grade monitors? In order to better understand how and why our data results may differ we have placed our DRXs near a regulation grade monitor managed by the South Carolina Department of Health and Environmental Control (DHEC). By collecting co-located data air quality with both technologies and assessing the results we can compare how accurate and reliable our lower cost technologies are when compared to traditional methods. Our results are presented in the DRX Comparison report below.
DRX Comparison Report.docx