On the outer edge of the forest, Mammoth Cave National Park’s air quality manager Bob Carson shows off an elaborate monitoring station. In this fenced-off clearing, two humble-looking sheds house super-sensitive pollution detectors. One keeps tabs on how much soot—or particulate matter– is in the air. Carson says the instruments tell him not only how much particulate matter is in the air but what’s in that matter.
“Today is a sampling day. We measure particulate matter in the air one in three days. So every three days we get a 24-hour sample,” says Carson