Policy Relevant Background (PRB) ozone was introduced for the purposes of informing decisions about the National Ambient Air Quality Standard (NAAQS) of ozone. It is defined by USEPA as the background ozone level in absence of anthropogenic emissions from continental North American. In other words, it represents the best achievable ozone condition and “how much controllable ozone is available through emission reduction”. In ambient environment, ozone is produced from both natural and anthropogenic processes. It is clear that many processes including local emission-induced ozone, longrange transport of air pollution, stratospheric ozone intrusion and photolysis are contributed to the overall tropospheric ozone in North America [He et al., 1999; Price et al., 2004; Wang et al., 2009]. To evaluate PRB ozone in the United States, chemical transport modeling is required for simulating the condition of the where absence of North American (NA) anthropogenic emissions while including all the natural processes and NonNA emission influences

Pat Dolwick

Papers

Evaluation of effects of stratospheric ozone to policy relevant background ozone