In a new paper published in Elementa, Dan Jaffe and his coauthors look at background ozone in the US and how it influences whether states can meet air quality standards. Background ozone (O3) includes “contributions from natural and foreign sources of O3 that cannot be controlled by precursor emissions reductions solely within the US.” Understanding background O3 is necessary for air quality management overall and for states and municipalities to meet national air quality standards.
They examined over 100 published studies in order to assess what is the current knowledge about the distribution, trends, and sources of background ozone in the continental US. They found that “noncontrollable O3 sources, such as stratospheric intrusions or precursors from wildfires, can make significant contributions to O3 on some days, but it is challenging to quantify accurately these contributions.” In order to address this shortcoming, they recommend a more coordinated and focused approach to understanding background ozone in the US: improvements in the monitoring network, large-scale field experiments, more accurate and consistent chemical transport models, and more detailed observations of wildfires.