The U.S. Environmental Protection Agency (EPA) published a on October 3 to make it easier to exclude tainted data from the agency鈥檚 future assessments of compliance or non-compliance with its National Ambient Air Quality Standards (NAAQS). EPA also finalized guidance for states seeking to demonstrate that a wildfire event affected monitored ozone concentrations. This could be critical for states looking for all possible options to help them attain EPA鈥檚 tighter ozone NAAQS issued in October 2015.
Specifically, EPA has revised its 鈥淓xceptional Events Rule鈥 (EER) to streamline the process for excluding from regulatory decisions air quality data attributable to events such as wildfires, dust storms, and stratospheric ozone intrusions. Business groups in the western states are concerned, however, that the revised rule still does not provide a clear path to exclude transported background ozone from future designations; as previously reported by 麻豆视频, this issue is of particular importance to 麻豆视频 Chapters in the intermountain states.
The EER is intended to allow state and local air agencies to avoid punishment or other regulatory action for individual events beyond their control. (Note that 鈥渘onattainment鈥 designations can have serious implications for construction, including emissions offsets/restrictions and the potential loss of highway funds 鈥 click here.) Interpretation and application of the EER has proven difficult for both state air agencies and EPA.
EPA鈥檚 most significant change to the EER was to eliminate the requirement that state air agencies demonstrate that, 鈥渂ut for鈥 the exceptional event, the state or relevant area would have complied with the applicable NAAQS. As EPA notes, this provision has been interpreted as requiring a 鈥渟trict quantitative analysis鈥 of the impacts from the event. Instead in the 2016 revisions, EPA finalized language requiring a state to demonstrate that an event has a clear causal relationship to a monitored exceedance based on a "weight of evidence" approach.
EPA also released the Guidance on the Preparation of Exceptional Events Demonstrations for Wildfire Events that May Influence Ozone Concentrations. This non-binding guidance document will assist agencies and EPA in preparing and reviewing these types of events.
EPA has also signaled that it will consider exclusion of air quality data influenced by exceptional events in the construction permitting process, including in the development of background concentrations. EPA plans to release more detailed guidance on the role of data influenced by exceptional events in the major source permitting process in the near future.
For more information, including the link to an EPA webinar audio recording and a quick-reference guide to exception events determinations, . If you still have questions, contact 麻豆视频鈥檚 Leah Pilconis at pilconisl@agc.org.