Technical Details

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: https://www.epa.gov/pm-pollution/particulate-matter-pm-basics 

How do we monitor PM?  We monitor PM using a light scattering laser photometer known as the DustTrak™ DRX Aerosol Monitor Model 8533EP (http://www.tsi.com/dusttrak-drx-aerosol-monitor-8533/). 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: http://www.tsi.com/.   

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 1-hr interval. The 1-hr 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.  We use EPA's Air Quality Index to assign context to our measured values, see: https://www.airnow.gov/aqi/aqi-basics/

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.