UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION

7 The Honorable Jay Nixon Governor, State of Missouri State Capitol Building, Room 216 P.O. Box 720 Jefferson City, Missouri 65102 Dear Governor Nixon:

11201 Renner Boulevard Lenexa, Kansas 66219 

## FEB 1 6 2016

OFFICE OF THE REGIONAL ADMINISTRATOR Thank you for your staffs recommendations dated September 25, 2015, on air quality designations
for the state of Missouri for the 2010 revision
to the primary National Ambient Air Quality Standard for sulfur dioxide. Reducing levels of sulfur dioxide pollution

is an important part of the U.S. Environmental Protection Agency

' s commitment

to a clean, healthy environment. Exposure

to sulfur dioxide can cause

a range of adverse health effects, including narrowing
of the airways which can cause difficulty breathing and increased asthma symptoms. This letter is to notify you of our preliminary intentions regarding your staffs recommended designations. On June 3, 2010, the EPA strengthened
the health-based

or primary standard for
s ulfur dioxide by establishing

a standard for one-hour average sulfur dioxide concentrations

at a level of75 parts per billion. Within one year after
a new or revised standard

is established, the Clean Air Act requires the governor of each state to submit to the EPA

a list of all areas in the state, with recommendations

for whether each area meets the standard. Through an interactive process, the EPA considers the recommendations
and then promulgates designations
for all ar e a s across the countr

y . On July 25, 2013

, the EPA designated
29 areas in 16 states as nonattainment,
but did not at that time designate other areas

. Pursuant
to a March
2, 2015, court-ordered schedule,

1 the EPA must complete the remaining sulfur dioxide designations
by three specific deadlines: July 2, 2016

, December

31

, 2017

, and December 31, 2020. This current round of designations,

to be completed by July
2 , 2016, addresses two groups of areas:

( 1) areas that have newly monitored violations
of the 2010 sulfur dioxide standard based on the most recent three calendar years of certified monitored ambient air quality data, and (2) areas that contain any stationary source that had not been announced

as of March
2, 2015, for retirement and that according

to the EPA's Air Markets Database emitted in 2012 either (i) more than 16,000 tons of sulfur dioxide or (ii) more than 2,600 tons of sulfur dioxide with an annual average emission rate of at least 0.45 pounds of sulfur dioxide per one million British Thermal Units. 1 

### Sierra Club
v. McCarthy, No. 3-13-cv-3953 (SI) (N

. D
. Cal. Mar

. 2, 2015)

. *Printed

on Recycled PaperAfter carefully considering Missouri's recommendations

and other available teclmical information, the EPA intends
to designate

as nonattainment

or unclassifiable/attainment

the following areas, including the following counties or portions of counties: Intended Nonattaimnent Area Franklin County* Intended Unclassifiable/ Attaimnent Area Scott County Intended Nonattainment County **Fra~lin** County (p)* St. Charles (p)* (p) indicates portion of county Intended Unclassifiable/ Attainment Area County Scott County The asterisk (*) indicates the designation

or boundary for this intended nonattainment area represents

a modification

to the designation

or boundary that you have recommended. Because,

at this time, the EPA does not have conclusive information

to determine whether the following areas are meeting or not meeting the sulfur dioxide standard, the EPA intends to designate these areas as unclassifiable: Intended Unclassifiable Area Jackson County* Intended Unclassifiable County Jackson County (p) (p) indicates portion of county The asterisk (*) indicates the designation
for this intended unclassifiable area represents

a modification to the designation that you have recommended. Based on ambient air quality data collected between 2012 and 2014 indicating

a violation of the 2010 S02 NAAQS, the EPA initially identified
an area in Missouri
as one that would potentially create the obligation for us to designate by July 2, 2016. The consent decree directs the EPA to evaluate data collected for the most recent three years (i.e., between 2013 and 2015), and Missouri has submitted

to the EPA complete, quality assured and certified data for calendar year 2015 for Iron County indicating compliance with the 2010 S02 NAAQS. As a result, the EPA intends
to designate this area by either December 31, 2017, or December 31, 2020. The enclosed teclmical support document provides

a detailed analysis that supports our intended designation decisions.
If your state has additional information that we should consider prior to finalizing these designations, please submit

it to us by Apri119, 2016. We also will be publishing

a notice in the Federal Register announcing

a 30-day period for the public to provide input on our intended designation decisions. We will promulgate the designations
for these areas by July 2, 2016. We will designate
all other previously undesignated areas in the state on a schedule consistent with the prescribed timing of the court order, i.e., by December 31, 2017, or December 31, 2020.Welookforwardtoacontinueddialoguewithyouandyourstaffasweworktogethertocompletetheareadesignationsandimplementthe2010primarysulfurdioxidestandard.Foradditionalinformationregardingdesignationsunderthesulfurdioxidestandard,pleasevisitourwebsiteatwww.epa.gov/sulfurdioxidedesignations.Shouldyouhaveanyquestions,pleasedonothesitatetocallme,orhaveyourstaffcontactDavidPeterofmystaffat(913)551-7397orpeter.david@epa.gov.Sincerely,MarkHagueEnclosurecc:SarahParkerPauley,MissouriDepartmentofNaturalResourcesKyraL.Moore,MissouriDepartmentofNaturalResourcesJanetG.McCabe,USEPAHeadquartersStephenD.Page,ResearchTrianglePark