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EL CENTRO, CA 92243-2850 FAX: (760) 353-9904

AIR POLLUTION CONTROL DISTRICT

STAFF REPORT

FINAL DRAFT

Imperial County 2013 State Implementation Plan for the 2006 24-Hour 

PM2.5 Moderate Nonattainment Area (2013 PM2.5 SIP)

I Executive Summary

Since 1997 the United States Environmental Protection Agency (U.S. EPA) has 

released two National Ambient Air Quality Standards (Standard) for particulate matter or 

PM. The PM Standards included PM10 and PM2.5.

For PM2.5, U.S. EPA determined, using monitoring data, that Imperial County attained or 

met the 1997 standard (65μg/m3). However, on October 17, 2006, U.S. EPA

strengthened the primary and secondary 24-hour PM2.5 NAAQS from 65ug/m3 to 

35ug/m3. The U.S. EPA designated Imperial County as “Moderate” Nonattainment for 

the 2006 PM2.5 NAAQS and required Imperial County to submit a PM2.5 SIP to the U.S. 

EPA by the end of December 2014.

The Clean Air Act requires a PM2.5 SIP to address certain elements affecting an 

identified nonattainment area (NA). They are, 1) an emission inventory; 2) an 

attainment demonstration 3) transportation conformity budgets; 4) New Source Review 

updates; 5) an analysis of Reasonably Available control Measures and Technologies 

(RACM/RACT); 6) an assessment of Reasonable Further Progress (RFP); and 7) 

Contingency Measures.

Finally, in order not to unduly burden border regions that are significantly impacted by 

international emissions, the Clean Air Act allows “States” to demonstrate, to the 

satisfaction of U.S. EPA, that the area qualifies for treatment under section 179B, which 

provides that areas which would have attained the standard by the attainment date but 

for emissions from outside the U.S. are not to be subject to reclassification (i.e. from 

Moderate to Serious)

II Final Draft Imperial County 2013 PM2.5 SIP (Plan) Description

The 2013 PM2.5 SIP (Plan) for Imperial County is a highly technical and scientific plan 

developed cooperatively with the California Air Resources Board and U.S. EPA. The 

PM2.5 SIP demonstrates that emissions originating in Mexico impacted the Calexico 

area during five exceedance days between 2010 and 2012. The PM2.5 SIP 

demonstrates that Imperial County would have attained the 24-hour PM2.5 standard “but 

for” emissions from Mexicali. Each chapter addresses specific elements required by the 

Clean Air Act.

I Staff Report for the 2013 PM2.5 SIP
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Chapter One - Introduction and Background

This chapter introduces the reader to the pollutant in question, PM2.5. The chapter gives 

the reader the necessary regulatory background, identifies the regulatory agencies 

affected, a general description of the nonattainment area identified in Imperial County 

and gives a general overview of the nature, components and the affects of PM2.5. 

Essentially, this chapter brings together the necessary data and discussion in 

presenting the PM2.5 SIP for the 2006 NAAQS. 

Chapter Two – Ambient and Air Quality Data

This chapter introduces the reader to the concept of ambient air, its collection and use 

of data. It gives the reader information regarding the nature of the interaction between 

the identified pollutant, meteorology, climate, and location. This chapter provides an 

overview of impact of climate and meteorology on the dispersion of particulate matter, a 

description of the local air monitoring network and an overview of PM2.5 data collected 

and its temporal and spatial patterns within Imperial County. Essentially, the air quality 

data demonstrates that air quality in Brawley and El Centro has improved showing a 

reduction of the average design value; however, in Calexico, air quality has not improved 

and remains above the PM2.5 standard of 35μg/m3.

Chapter Three – Emissions Inventory

This chapter explains and introduces the reader to the concept of an “Emissions 

Inventory”. The chapter explains what an emissions inventory is, an accounting of the 

amount of a given pollutant that is emitted into the atmosphere by various sources over 

a specific time period. It also explains how a given pollutant is classified or categorized, 

either a “stationary source”, “area-wide source” or “mobile source”. The chapter further 

explains and discloses the pollutants under review, PM2.5 (known as direct PM2.5) and 

its precursors (NOx, SOx, VOC’s, and ammonia) and provides the reader the time 

period used to analyze the Plan, 2008, 2011 and 2012. To complete the cycle the 

chapter discloses the actual concentrations per classification for each of the identified 

years, 2008, 2011 and 2012. Finally, because emissions inventories are an accounting 

of the concentrations of a given pollutant the chapter discusses the pollutants within the 

context of “significance”. Overall the chapter identifies the significant sources of direct 

PM2.5 as unpaved road dust, fugitive windblown dust, farming operations (tilling), 

managed burning and disposal and emissions from aircraft. No significant sources 

were identified for precursor emissions.

Chapter Four – Attainment Demonstration

Chapter 4 is an overview of the 179B analysis, “But-for” emissions from Mexicali, 

Mexico found in “Attachment A”. Chapter 4 summarizes the technical and scientific 

evidence analyzed within the 179B analysis which demonstrates that the Imperial 

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County nonattainment area (NA) would have timely attained the PM2.5 standard “but for” 

emissions from Mexicali, Mexico.

Summary of the 179B Analysis for PM2.5 Emissions Impacting Calexico in Imperial 

County

The 179B Analysis utilized techniques referenced in U.S. EPA guidelines for areas 

impacted by emissions originating outside the U.S. Taking a scientific view point, with 

no preconceived notions, the analysis consisted of assessing emission inventories from

Imperial County and Mexicali; evaluating samples collected from the Calexico monitor 

on exceedance days; reviewing meteorology; and performing what is known as a 

directional analysis which is an analysis that begins at the monitor and follows back to 

the direction that it came from.

The technical analysis (Attachment A) indicated that the violations which occurred in 

Calexico for the 24-hour PM2.5 were due to emission sources not found in California. 

The analysis further found that PM2.5 concentrations at El Centro and Brawley, which 

are more representative of local emissions within Imperial County, were significantly 

lower during those Calexico violation days. Overall, violations in Calexico occurred 

during stagnant conditions, where pollution from holiday activities in Mexicali, including 

extensive firework displays and bonfires containing plastics, tires and other refuse 

materials filled the entire air shed and drifted into Calexico. The analysis indicated that 

“but for” increased pollution emissions from the Mexicali Metropolitan area the Calexico 

PM2.5 levels would have attained the 24-hour PM2.5 standard.

The 179B Analysis demonstrates that emissions originating in Mexico impacted the 

Calexico area during five exceedance days between 2010 and 2012. The analysis also 

demonstrates that Imperial County would have attained the 24-hour PM2.5 standard “but 

for” emissions from Mexicali.

Chapter Five – RACM/RACT, RFP, Contingency Measures and Transportation 

Conformity

Chapter 5 provides the reader with the methodology, summary and analysis of the 

Reasonable Available Control Measures (RACM), Reasonable Further Progress (RFP), 

Contingency Measures and the Transportation Conformity budgets, all requirements of 

moderate nonattainment areas. Chapter 5 explains to the reader the why’s, how’s and 

results of the RACM analysis required by the Clean Air Act. Without a proper RACM 

analysis, RFP, Contingency Measures and Transportation Conformity budgets become 

difficult to assess.

Chapter 5 explains the regulatory background and requirements associated with any 

RACM analysis. It further summarizes the current measures and programs that are 

being implemented to address those significant sources of direct PM2.5. As mentioned 

within the Chapter 3 summary no significant sources of PM2.5 precursor emissions were 

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identified. Chapter 5 summarizes the current rules applicable to unpaved road dust, 

fugitive windblown dust, farming operations (tilling), managed burning and disposal and 

describes the state mobile program which addresses emissions from aircraft. Chapter 5 

refers the reader to “Attachment B” for detailed rule comparisons. The RACM analysis 

(which includes RACT) demonstrates that the emissions of the collective existing control 

measures are sufficient to maintain attainment “but for” emissions from an international 

source. However, in order to further protect the public health and to prepare for the 

newly adopted annual PM2.5 standard Chapter 5 includes a commitment by Imperial 

County to further study sources of ammonia, i.e. Beef Feedlots, Composting Facilities 

and Agricultural Fertilizers.

In addition, Chapter 5 explains that RFP and Contingency Measures are met. The first 

year that the Imperial County NA would attain is 2012, therefore the milestones, which 

is required for any RFP demonstration, shows emissions decreasing linearly or staying 

the same from 2008 to 2012 (the attainment year), meeting the original intent of 

demonstrating progress towards attainment. Contingency measures are met because 

the attainment and RFP years are in the past. Since the Clean Air Act only requires 

contingency measures when RFP is not met, an RFP is met, then the requirement for 

contingency measures is met. Finally, Chapter 5 establishes the Transportation 

Conformity Budgets for PM2.5 and NOx.

Chapter Six – Border Strategic Concepts

This Chapter provides evidence to the reader of ongoing efforts at the federal, state and 

local level to implement different programs to achieve mutual international goals 

oriented at education and protection of the public health and welfare. Generally the 

chapter provides the reader a complete overview of the programs associated with 

improving air quality in both Mexicali and Imperial County. This chapter introduces and 

describes the organizations and programs currently implemented for the benefit of both 

the Imperial and Mexicali valleys, such as: the web-based air quality and health 

information center, the school flag alert program, the Mexicali and Imperial education 

media campaign and the vehicle idling emissions study at the Calexico East and 

Calexico West ports of entry. 

Chapter Seven – Conclusion and SIP Checklist

Chapter 7 provides the reader a checklist with a general description of the Clean Air Act 

requirement for Moderate Nonattainment Areas. The chapter provides a description 

and/or location to the reader where that identified requirement is found within the 2013 

PM2.5 SIP.

III California Environmental Quality Act (CEQA)

The Final Draft Imperial County 2013 PM2.5 SIP (Plan) is a “project” as defined by the 

CEQA. Since the Plan imposes the greatest discretionary authority of approval upon 

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the ICAPCD it is therefore the lead agency for this project. As part of the review 

process the ICAPCD examined the Plan for applicability to CEQA. Because the Plan 

does not proposed or imposed any new regulation and in fact demonstrates attainment 

of the Standard “but for” emissions from an international source a class “8” categorical 

exemption applies. However, in order to provide for optimum public participation and 

involvement the ICAPCD opted not to utilize the exemption and instead provide an 

additional resource for the identification of any potential environmental impacts 

associated with the Plan. Thus, in order to fulfill the purpose and intent of CEQA the 

ICAPCD prepared an Initial Study to help identify and address any potential 

environmental impacts associated with the Plan.

In accord with the Imperial County Planning and Development protocols for CEQA the 

Environmental Evaluation Committee (EEC) met October 23, 2014 at 1:30pm to discuss 

and review the prepared Initial Study. After discussion, review and input from the public 

the EEC made a “mandatory finding” of “No Impact” to the degradation to the quality of 

the environment. The EEC “[f]ound that the proposed project COULD NOT have a 

significant effect on the environment, and a NEGATIVE DECLARATION ...” was 

proposed based on the evidence on record. The final “finding” was signed by the 

Assistant Air Pollution Control Officer Reyes Romero on October 23, 2014 indicating 

that the ICAPCD would prepare a Negative Declaration.

The Public Notice of a proposed Negative Declaration was released for a 30 day 

comment period by the ICAPCD October 23, 2014. The transmittal list included 86 

postal mailing as well as e-mails to local, federal, state, libraries, cities, school districts, 

special districts and others. In addition, the ICAPCD posted the Public Notice on the 

home page for the ICAPD, outside the main Administration building and outside the 

ICAPCD building. Comments are due by close of business November 25, 2014.

IV Final Draft Imperial County 2013 PM2.5 SIP (Plan) Development

The Plan development extended over a period of five years with a cooperative triagency effort including the CARB, U.S. EPA and the ICAPCD to address the intricate 

technical aspects of the Plan. In order to engage additional perspectives and to gain 

insight into public opinion the ICAPCD introduced a draft version of the Plan October 1, 

2014. Two workshops were held to afford the greatest amount of participation, an 

afternoon workshop in El Centro and an evening workshop in Calexico. CARB was 

present at both workshops to help explain the technical aspects of the Plan. Translation 

services, both in English and Spanish, were available for both workshops. The public 

notice inviting the community to participate was released in Spanish and English 

September 26, 2014. Two comments were received that were general and broad in 

nature. One comment was a statement that the commenter observed burning in 

Imperial County. The second comment asked about the servicing, operation and 

function of a monitor, no specific monitor was mentioned. Both comments were duly 

noted and discussed during the workshop in detail. The response by CARB and 

ICAPCD during the workshop was detailed and informative.

V Staff Report for the 2013 PM2.5 SIP
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The Public Hearing notice was released and published in the Imperial Valley Press legal 

section on October 24, 3014 and November 2, 2014. All interested parties were notified 

of the Public Hearing notice via e-mail and provided a link to the Plan on October 24, 

2014.

V Recommendations

ICAPCD ADVISORY BOARD

The ICAPCD Advisory Board met to discuss and review the Imperial County Draft 

Imperial County 2013 State Implementation Plan for the 2006 24-Hour PM2.5 Moderate 

Nonattainment Area on November 10, 2014. The ICAPCD Advisory Board 

recommended the approval of the Draft Imperial County 2013 State Implementation 

Plan for the 2006 24-Hour PM2.5 Moderate Nonattainment Area, the staff report and it’s 

findings.

ICAPCD STAFF

ICAPCD staff recommends adoption of the attached Draft Imperial County 2013 State 

Implementation Plan for the 2006 24-Hour PM2.5 Moderate Nonattainment Area and 

associated findings. Concurrently, the ICAPCD recommends the certification and 

adoption of the Negative Declaration for the Draft Imperial County 2013 State 

Implementation Plan for the 2006 24-Hour PM2.5 Moderate Nonattainment Area.

After addressing the technical and non-technical issues raised by the U.S. EPA, the 

Draft Imperial County 2013 State Implementation Plan for the 2006 24-Hour PM2.5

Moderate Nonattainment Area effectively demonstrates that Imperial County timely met 

attainment of the PM2.5 standard “but for” emissions from Mexicali Mexico.

VI Declaration of Findings

The Imperial County Air Pollution Control District Board hereby finds as follows:

The ICAPCD is a regulatory agency and the public agency with the principle 

responsibility for carrying out the project.

Clean air is a valuable and essential natural resource.

U.S. EPA partially designated Imperial County as a nonattainment area for the PM2.5

24-hr standard, effective December 14, 2009.

The partial PM2.5 nonattainment area includes the majority of the populated area in 

Imperial County.

VI Staff Report for the 2013 PM2.5 SIP
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As a result of a ruling by the United States Court of Appeals for the District of Columbia 

circuit Imperial County was classified by “operation of law” as a “moderate” nonattainment area as required by subpart 4 provisions on June 2, 2014 by U.S. EPA.

The Draft Imperial County 2013 State Implementation Plan for the 2006 24-Hour PM2.5

Moderate Nonattainment Area meets the requirements of the federal Clean Air Act 

(CAA) for areas classified as “moderate” nonattainment for PM2.5. In accordance with 

section 179B of the CAA, this Draft Imperial County 2013 State Implementation Plan for 

the 2006 24-Hour PM2.5 Moderate Nonattainment Area satisfies the attainment 

demonstration requirement satisfying the provisions of subpart 1 and subpart4 of the 

CAA.

Failure to adopt the Draft Imperial County 2013 State Implementation Plan for the 2006 

24-Hour PM2.5 Moderate Nonattainment Area would guarantee that the Imperial County 

would not meet federal PM2.5 standards as required by the CAA.

The Draft Imperial County 2013 State Implementation Plan for the 2006 24-Hour PM2.5

Moderate Nonattainment Area demonstrates attainment as required by the CAA with a 

long-term effect resulting in the reduction/maintenance in emissions from stationary and 

mobile sources.

The Draft Imperial County 2013 State Implementation Plan for the 2006 24-Hour PM2.5

Moderate Nonattainment Area incorporates an updated emissions inventory, the CAA 

section 179B analysis, an analysis of Reasonable Available Control Measures (RACM), 

an assessment of Reasonable Further Progress (RFP) and a discussion of contingency 

measures.

The Draft Imperial County 2013 State Implementation Plan for the 2006 24-Hour PM2.5

Moderate Nonattainment Area satisfies the planning requirements set forth in the 

federal CAA including establishing a transportation conformity budget based on the 

latest planning assumptions.

The continued implementation of the Draft Imperial County 2013 State Implementation 

Plan for the 2006 24-Hour PM2.5 Moderate Nonattainment Area existing control 

measures would provide for continued attainment of the PM2.5 National Ambient Air 

Quality Standard (NAAQS).

The Draft Imperial County 2013 State Implementation Plan for the 2006 24-Hour PM2.5

Moderate Nonattainment Area demonstrates that air quality monitored data for 2010

thru 2012 demonstrates that Imperial County would have been in attainment of the 24-

hour PM2.5 NAAQS “but-for” international emissions emanating from Mexico.

The Draft Imperial County 2013 State Implementation Plan for the 2006 24-Hour PM2.5

Moderate Nonattainment Area is considered a “project” pursuant to the CEQA and that 

VII Staff Report for the 2013 PM2.5 SIP
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EL CENTRO, CA 92243-2850 FAX: (760) 353-9904

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an Initial Study was prepared and presented to the EEC on October 23, 2014 with a 

finding of “No Impact”

Imperial County prepared and subsequently released for a 30 day public comment 

period a Negative Declaration upon the recommendation of the EEC.

That Certification and approval is necessary of the Negative Declaration for the Draft 

Imperial County 2013 State Implementation Plan for the 2006 24-Hour PM2.5 Moderate 

Nonattainment Area because there has been no evidence presented to suggest that the 

Draft Imperial County 2013 State Implementation Plan for the 2006 24-Hour PM2.5

Moderate Nonattainment Area will lead to or result in significant adverse impacts to the 

environment.

The Draft Imperial County 2013 State Implementation Plan for the 2006 24-Hour PM2.5

Moderate Nonattainment Area is technically sound and capable of being understood by 

those persons directly affected by it.

The Draft Imperial County 2013 State Implementation Plan for the 2006 24-Hour PM2.5

Moderate Nonattainment Area does not conflict with or contradict any existing statute, 

court decision, state or federal regulation.

The Draft Imperial County 2013 State Implementation Plan for the 2006 24-Hour PM2.5

Moderate Nonattainment Area is not duplicative of any existing state or federal 

regulation or plan.

The ICAPCD has a population of less than 500,000 people.

VIII Staff Report for the 2013 PM2.5 SIP