Don’t blame the trees: Using data to examine how trees contribute to air pollution

Ground-level ozone is a greenhouse gas, a human health hazard, and negatively affects plant productivity resulting in billions of dollars in crop losses globally. Ground-level ozone is a secondary air pollutant formed through chemical reactions between volatile organic compounds (VOCs) and nitrogen oxides (NOx) in the presence of sunlight. While the emissions of most NOx gasses are the result of anthropogenic activities, VOCs have both anthropogenic and natural sources. In this learning activity, students will evaluate data from governmental reports and peer-reviewed literature to become familiar with factors influencing the production of ground-level ozone with an emphasis on the role of VOC-emitting trees in North America. After completing this activity, students should be able to (1) distinguish between primary and secondary air pollutants and identify precursor chemicals that lead to the formation of ground-level ozone, (2) interpret figures and tables that document temporal and spatial changes in the concentration of ground-level ozone and its precursors, (3) explain the relative contributions of anthropogenic and natural emissions to the formation of ground-level ozone, and (4) evaluate different management approaches for reducing air pollution.