Notice of Public Comment for Wildfire Exceptional Event on August 7 - September 21, 2018

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 (c)(3)(i)) 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.

The Spanish Fork filter exceeded the PM2.5 24-hour standard (in micrograms/m ³ ).

Date        Value        Wildfire Sources

8/7/2018    37.8         Coal Hollow

8/9/2018    50.8         Coal Hollow and other western state(s) fire(s)

8/10/2018   68.8        Coal Hollow and other western state(s) fire(s)

8/11/2018   49.6        Coal Hollow and other western state(s) fire(s)

8/13/2018   58.1        Coal Hollow and other western state(s) fire(s)

9/14/2018   71.5        Pole Creek and Bald Mountain

9/15/2018   42.6        Pole Creek and Bald Mountain

9/17/2018   74.5        Pole Creek and Bald Mountain

9/18/2018   57.7        Pole Creek and Bald Mountain

9/19/2018   76.3        Pole Creek and Bald Mountain

9/21/2018   39.3        Pole Creek and Bald Mountain

Additional exceedances measured by continuous monitors are provided in the documentation report.

The documentation for public review and comment to support removing these data from use in regulatory determinations will be available before February 15, 2019 at https://deq.utah.gov/legacy/programs/air-quality/exceptional-events/ 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 [phone] (TDD 536-4414).

The comment period will close at 5:00 p.m. on March 18, 2019. 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:

ATTN: Wildfire Exceptional Event

Bryce Bird, Director

Utah Division of Air Quality

PO Box 144820

Salt Lake City, UT 84114-4820