Spatial and temporal patterns of ozone at Great Smoky Mountains National Park and implications for plant responses

Ozone levels at Great Smoky Mountains National Park (GRSM) have significantly decreased since the early 2000s, correlating with reduced nitrogen oxide emissions from regional power plants. This study analyzed ozone trends from 1989 to 2016 across six monitoring sites, revealing that while exposure increased with elevation up to 823 meters, it plateaued afterward. Ozone episodes (consecutive hours with concentrations ≥ 60 ppb) have declined in frequency and duration, with the highest recorded concentration of 135 ppb occurring in 1998. The shift from mid-summer to spring for maximum ozone exposures suggests seasonal changes influenced by regional emissions controls. These reductions, linked to the Clean Air Act Amendments, appear to benefit park vegetation, marking a period of the cleanest air in GRSM's recorded history.

Neufeld, H. S., Sullins, A., Sive, B. C., & Lefohn, A. S. (2019). Spatial and temporal patterns of ozone at Great Smoky Mountains National Park and implications for plant responses. Atmospheric Environment: X, 2, 100023. https://doi.org/10.1016/j.aeaoa.2019.100023