Transcript Exceptional Events Elements of an Effective Demonstration

Exceptional Events
Elements of an Effective Demonstration
Darren Palmer
US EPA Region 4
Exceptional Events Rule
The Basics
• Sets criteria and process for EPA to agree to exclude eventinfluenced data when determining NAAQS compliance and design
values.
– Section 319 of the Clean Air Act, as amended by the SAFE-TEA-LU Act
of 2005 required EPA to promulgate a rule to govern the review and
handling of exceptional events data.
• Final rule published March 22, 2007 (Effective date = May 21, 2007)
• Scope: General rule which applies to all NAAQS.
– CFR language defining NAAQS for ozone, PM2.5, PM10, and Pb
explicitly provides for exclusion of event-influenced data.
– Preamble states EPA intention to effectively apply same scheme for
other NAAQS also, via 107(d)(3) discretion.
– EPA will formally extend the rule to other pollutants as NAAQS are
revised, in time for new mandatory designations.
• Replaces previous EPA policy/practices.
How to Justify Data Exclusion
40 CFR 50.14(a)
• A State may request that EPA exclude data
related to exceedances or violations of a
NAAQS that are directly due to an exceptional
event from use in regulatory determinations
• Demonstration to justify data exclusion
– May include any reliable and accurate data
– Must demonstrate a clear causal relationship
between the measured exceedance or violation of
the affected standard and the event.
Notification of the Public and EPA
1.
Notify public of the
occurrence (or anticipated
occurrence) of the event
Notify EPA by Flagging
the data.
2.
–
Flag data in AQS and
provide event description by
July 1 of following year.
•
–
Also provide initial event
description
Give public notice and 30
day comment period.
The Exceptional Event
Demonstration
• Must be submitted to EPA not later than the
lesser of:
– 3 years following the end of the calendar quarter in
which the event occurred
– or 1 year before EPA plans to use the data for a
regulatory decision.
• A State must submit the public comments it received
along with its demonstration to EPA.
• In general, the type, amount, and detail level for
presentation of evidence will vary by the circumstances
for each event.
The Exceptional Event Demonstration
The Four-Part Test [§ 50.14(c)(3)(iii)]
•
Demonstration to justify data exclusion shall provide evidence
that:
1.
2.
3.
4.
•
The event satisfies the Statutory Definition of Exceptional Event
There is a clear causal relationship between the measurement under
consideration and the event that is claimed to have affected the air
quality in the area
The event is associated with a measured concentration in excess of
normal historical fluctuations, including background; and
There would have been no exceedance or violation “but for” the event.
Provided that all the Exceptional Event Rule requirements are
met, EPA shall exclude such data from use in determinations of
a NAAQS violation.
Note: The rule has special provisions regarding fireworks and prescribed fires.
The preamble discusses other situations of interest.
Definition of “Exceptional Event”
40 CFR 50.1(j)
• Event affected air quality
• Event was either
– Natural or
– Caused by human activity and unlikely to
recur at a particular location
• Event was not reasonably controllable or
preventable
• Event was not related to:
–
–
–
–
–
Air mass stagnation
Inversion
High temperature
Lack of precipitation
Source noncompliance
• EPA Administrator has determined through
the process established in the rule that it
was an exceptional event.
Clear Causal Relationship Between
Measurement and the Event
• Can be demonstrated using data
from a variety of sources
• Several online tools are available
on Datafed website:
http://datafedwiki.wustl.edu/index.php/Data_View
s_Catalog
• Products by Dr. Rudy Husar,
Washington University
• Compiles data and generates
maps from multiple sources,
including EPA, NASA, NOAA,
Navy, and others.
• Tools available to assist in
evaluating several types of events
including wildfires, dust, and
fireworks
Clear Causal Relationship Between
Measurement and the Event (cont.)
• Other useful data sources include:
– Trajectories
– Surface weather maps
– Wind profiler data
– Windroses
– Satellite data
– Air Quality Monitors
– Newspaper reports
– Maps of networks, fires, etc.
Comparison to Historical Data
• In order for a measurement to be excluded, it must be “in excess of
normal historical fluctuations, including background.”
47-065-0031 2003-2007
60
Observed PM2.5 concentration
over historical 95th percentile
50
40
All other dates
30
June 19 - July 19
20
10
0
9/1/2002
3/20/2003 10/6/2003 4/23/2004 11/9/2004 5/28/2005 12/14/200
5
7/2/2006
1/18/2007
8/6/2007
2/22/2008
Comparison to Historical Data
EPA Region 4 two-step analysis for PM2.5
• Step 1: Is the flagged measurement greater
than the historical 84th percentile for the site
for the month?
• Step 2: If the flagged value is not an
exceedance of the 24-hr PM2.5 NAAQS, is the
historical monthly average for the site below
the annual PM2.5 NAAQS?
• If either of these conditions is not met, then the
burden of proof needed in the demonstration is
much greater
No Exceedance “But For” the Event
• EE Demonstration must quantitatively show that
without impact from EE, no exceedance would have
occurred.
This is the only scenario in
which data may be excluded
No Exceedance “But For” the Event
How To Demonstrate Using PM2.5 Speciation Data
• For wildfires, calculate an Organic Mass Increment (OMI):
OMI  ( OC
observed
 OC
average
)  2 .0
OC is Organic Carbon
OCaverage is the average OC observed at the site during
the month over the past 3 years
A multiplier of 2.0 is used to estimate total organic mass
from smoke (Turpin and Lim 2001)
Note: Similar approaches can be taken for other events
such as Saharan dust or fireworks.
80
70
60
Observed
50
Adjsuted
OMI
ug/m3
40
30
20
10
0
-10
The orange line approximates what the observed PM2.5
concentration would have been “but for” the event.