Notice of Public Comment for Wildfire Exceptional Events on August 6 - 7, 2017

Federal regulations, 40 Code of Federal Regulations (CFR) Part 50, allow states to exclude air quality data that exceed or violate a National Ambient Air Quality Standard (NAAQS) if they can demonstrate that an "exceptional event" has caused the exceedance or violation. Exceptional events are unusual or naturally occurring events that can affect air quality but are not reasonably controllable or preventable using techniques implemented to attain and maintain the NAAQS.

Exceptional events may be caused by human activity that is unlikely to recur at a particular location, or may be due to a natural event. The Environmental Protection Agency (EPA) defines a "natural event" as an event in which human activity plays little or no direct causal role to the event in question. For example, a natural event could include such things as high winds, wild fires, and seismic/volcanic activity. In addition, the EPA will allow states to exclude data from regulatory determinations on a case-by-case basis for monitoring stations that measure values that exceed or violate the NAAQS due to emissions from fireworks displays from cultural events.

Federal regulations (40 CFR Part 50.14) require that all relevant flagged data, the reasons for the data being flagged, and a demonstration that the flagged data are caused by exceptional events be made available by the State for 30 days of public review and comment. These comments will be considered in the final demonstration of the event that is submitted to EPA. The following monitoring station air quality exceedances have been attributed to a wildfire exceptional event.

Monitoring Station Date PM2.5 Standard

microgram/m3 microgram/m3

Smithfield 08/06/2017 40.6 35

08/07/2017 39.6 35

The documentation for public review and comment to support removing these data from use in regulatory determinations will be available beginning October 1, 2017 at: https://deq.utah.gov/ProgramsServices/programs/air/exceptionalevents/index.htm or at the Multi Agency State Office Building, 195 North 1950 West in Salt Lake City.

In compliance with the American with Disabilities Act, individuals with special needs (including auxiliary communicative aids and services) should contact Brooke Baker, Office of Human Resources at 801-536-4412 (TDD 536-4414).

The comment period will close at 5:00 p.m. on November 1, 2017. Comments postmarked on or before that date will be accepted. Comments may be submitted by electronic mail to [e-mail] or may be mailed to:

Joel Karmazyn

Utah Division of Air Quality

PO Box 144820

195 N 1950 W

Salt Lake City, UT 84114-4820