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Sunland Park One-Hour Ozone Maintenance Plan 

Technical Support Document

I. Background 

The Clean Air Act requires the Environmental Protection Agency (EPA) to establish national 

ambient air quality standards (NAAQS) for pollutants that cause or contribute to air pollution 

that is reasonably anticipated to endanger public health or welfare. These pollutants are referred 

to as criteria pollutants. States must develop a State Implementation Plan (SIP) that identifies 

how these standards will be attained and maintained. The State must submit revisions to the SIP 

to EPA for approval. EPA reviews a revision and approves it if it conforms with the Federal 

Clean Air Act (CAA) and Federal regulations. Approval makes the revisions Federally 

enforceable. If the revision does not conform with the Clean Air Act and Federal regulations, 

EPA disapproves it. Disapproval may lead to further revisions by the State or development of a 

Federal Implementation Plan by EPA. 

 

Ozone is a criteria pollutant regulated under the Clean Air Act (CAA). Sunland Park has 

been designated nonattainment since 1995 for violations of the 1-hour NAAQS for ozone. 

Sunland Park was officially designated as nonattainment for ozone in a Federal Register 

announcement published June 12, 1995 (60 FR 30789). Sunland Park was designated as a 

“marginal” nonattainment area, which is the lowest or least “serious” classification. 

 The Sunland Park nonattainment area is approximately 42 square miles (sq. mi.) in area and 

includes the communities of Sunland Park, Santa Teresa, and La Union. Sunland Park, La Union 

and Santa Teresa are located along the border region of New Mexico and are adjacent to El Paso, 

Texas, and Ciudad Juarez, Mexico, or what is commonly referred to as the Paso del Norte 

Airshed. The Sunland Park ozone nonattainment area is located in southern Doña Ana County, 

New Mexico, and includes the communities, from south to north, of Sunland Park, Santa Teresa, 

and La, Union, New Mexico. The area is largely rural with a small population and 

predominately agricultural land use along the Rio Grande, especially north of Santa Teresa. 

EPA considers an area to be in attainment for the 1-hour ozone NAAQS if the level of 0.12 

parts per million (ppm) for a 1-hour exposure not to be exceeded more than once per year, 

averaged over 3 years. Between the years of 2000 and 2002 there was one monitored level over 

the 1-hour NAAQS, and no monitored exceedances of the 8-hour ozone NAAQS. 

 

The federal requirement for the Sunland Park Maintenance Plan springs from the U.S. 

Environmental Protection Agency’s (EPA) rules for transitioning from a National Ambient Air 

Quality Standard (NAAQS) for ozone, based on a one hour averaging time (“1 hour ozone”) to 

an ozone NAAQS based on an eight hour averaging time (“8 hour ozone”). On April 30, 2004, 

published the first phase of its final rule to implement the 8-Hour NAAQS, called the “phase 1 

rule “ (69 FR 23951). At that same time, EPA also published 8-hour ozone designations for all 

areas of the country. For most areas, the 8-hour ozone designations became effective on June 

15, 2004. The phase 1 rule provided that the 1-hour ozone NAAQS would no longer apply for 

an area one year following the effective date of the area’s designation for the 8-hour ozone 
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NAAQS. As part of this action, all areas that were in nonattainment for the 1-hour NAAQS, but 

in attainment for the new 8-hour NAAQS for ozone areas were required to develop a 

maintenance plan that complies with the requirements of the Federal Clean Air Act Section 

110(a)(1). This plan is due within three years of the revocation of the 1-hour ozone NAAQS. 

This is referred to as an “anti-backsliding” provision by EPA. (40 CFR 51.905(a)(3) and (4)) 

 Sunland Park is one of the few areas in the United States that was nonattainment for the 

revoked 1-hour NAAQS, but in compliance with the new 8-hour NAAQS. New Mexico is 

therefore required to submit a maintenance plan for this area. 

II. Analysis of the State’s Submittals

A. General Requirements of 1-hour ozone Maintenance Plans 

Section 110 of the Clean Air Act provides the general framework for Implementation 

Plans. The EPA document entitled “Maintenance Plan Guidance Document for Certain 8-hour 

Ozone Areas Under Section 110(a)(1) of Clean Air Act” dated May 20, 1995 provides more 

detailed information about maintenance plan requirements. 

The maintenance plan updates submitted by New Mexico meet CAA requirements, and 

follow EPA guidance. 

B. Specific Requirements of 1-hour O3 Maintenance Plans 

Section 110(a)(1) of the CAA does not explicitly state what is required for a maintenance 

plan, so EPA suggested using CAA section 175A, which states the requirements for a 

maintenance plan, as a guidance for states to use in developing their maintenance plans. The 

required components of a Maintenance Plan under CAA Section 175A include: 

 Attainment Inventory 

 Maintenance Demonstration 

 Monitoring Network 

 Verification of Continued Attainment 

 Contingency Plan 

1. Attainment inventory. The federal Clean Air Act requires that an emissions inventory be 

developed to identify the level of emissions in the nonattainment area that is compatible with 

attainment of the NAAQS. For the Sunland Park Ozone Nonattainment area, the attainment 

inventory uses a base year of 2002. The 2002 base year emission inventory is based on all 

actual emissions (area, point, mobile, and biogenic) for the ozone precursors NOx, CO, and 

VOC. Although NOx emissions were not required as part of the emissions inventory, due to the 

NOx waiver, the NMED included it in their inventory to provide EPA with a complete ozone 

inventory for the area. Table 1-1 below lists all actual emissions (area, point, mobile, and 

biogenic) for the base year of 2002 for the ozone precursors NOx, CO, and VOC. 
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Table 1-1. Summary of all source categories for 2002. TPY=tons per year. TPD=ton per day 

Source 

Category 

NOx 

TPY 

TPD 

CO 

TPY 

TPD 

Voc 

TPY 

TPD 

Area 30.40 0.0896 157.94 0.586 193.73 0.553 

Point 1,085.7 3.044 192.38 0.552 94.19 0.331 

Mobile 829.63 2.27 6,040.64 16.55 53014 1.45 

Biogenic 5.74 0.015 n/a n/a 528.08 1.44 

Total 

Emissions 

1,951.47 5.41 6,390.96 17.68 1,342.04 3.74 

NMED described the procedures for developing this in the NMED 8-Hour Ozone 

Maintenance Plan on pages 8-49. The emissions inventory process includes quality assurance 

procedures as a means to verify that data have been reviewed and examined for their source or 

origin, methods of compilation, accuracy, occurrence of errors, and clarity. This is to assure a 

good product and that such procedures can easily be applied to future inventories. EPA’s 

Emission Inventory Improvement Program was used as a guide in developing the 2002 emission 

inventory for the Sunland Park Nonattainment area.

We have reviewed the procedure and find they meet EPA guidance for emission inventory 

and recommend approval. 

2. Maintenance Demonstration. To demonstrate maintenance of the NAAQS for a 

nonattainment area, the CAA requires the state to either show that future emissions of a pollutant 

or its precursor will not exceed the attainment inventory developed for the area, or to provide 

modeling to show that future sources and emissions will not cause an exceedance of the 

NAAQS. Sunland Park, La Union and Santa Teresa are located along the border region of New 

Mexico and are adjacent to El Paso, Texas, and Ciudad Juarez, Mexico, or what is 

commonly referred to as the Paso del Norte Airshed. Sources in Sunland Park, Santa Teresa, 

and La Union are only contributing a small percentage (1.6%) of the CO, NOX and VOC 

emissions in the airshed. A majority of the emissions contributing to ground level ozone in the 

airshed are from the City of El Paso and Ciudad Juarez. Because only a small portion of the 

pollutants affecting the Sunland Park ozone nonattainment area are emitted within that area, it is 
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not possible to demonstrate maintenance for the area based solely on control of emissions 

emitted within the Sunland Park area., The NMED demonstrated the continued maintenance of 

the 8-hour ozone NAAQS through the use of cooperative efforts with the State of Texas and with 

Mexico, as well as current permitting requirements for point sources within the nonattainment 

area. Table 1-2 below shows the contributions from El Paso County and Ciudad Juarez in 

comparison to the Sunland Park nonattainment area.

Table 1-2. Emissions in Paso del Norte Airshed. TPY=ton/year 

Source Ciudad Juarez TPY 

VOC NOx CO 

El Paso County TPY 

VOC NOx Co 

Sunland Park TPY 

VOC NOx Co 

Mobile 20,208 25,590 155,583 9,939 17,122 148,277 530 830 6,040 

Area 68,085 14,082 52,393 8,640 872 5,993 190 30 158 

Point 2,308 18,133 13,821 861 4223 1,704 94 1,086 94 

Total 90,601 57,805 221,797 19,440 22,217 155,974 810 1,946 6,292 

Percentage 81.7 70.5 57.7 17.5 27.1 40.6 .73 2.4 1.6 

* The emissions data for Ciudad Juarez comes from, The 1999 Mexico NEI: Six Border States and are based on the inventory data for the State of 

Chihuahua. This is the only complete emission inventory data currently available for this area. 

** The emissions data for El Paso comes from the, El Paso County 8-Hour Ozone Maintenance Plan and the El Paso Redesignation to 

Attainment for Carbon Monoxide and Maintenance Plan, both submitted to EPA by the Texas Commission on Environmental Quality in January 

of 2006. 

Sunland Park contributes very little to the total air emissions within the Paso del Norte 

Airshed making it very difficult to demonstrate maintenance of the 8-hour ozone standard for 

2014 using only the emissions from the Sunland Park nonattainment area. Table 1-3 shows the 

emissions for the Sunland Park nonattainment area in 2014, based on a projected population 

growth of 3.2% per year (University of New Mexico, Bureau of Business and Economic 

Research). Even with the increase of emissions based on population growth for the year 2014, 

the emissions in the Sunland Park nonattainment area are still only 2.2% of the emissions in the 

Paso del Norte Airshed. In light of the limited amount of pollutants generated within the 

Sunland Park Nonattainment area, it is impossible to base the demonstration of maintenance for 

the area on the limited emissions emitted within the Sunland Park Nonattainment area. 

Table 1-3 Summary of all source categories for 2014. TPY= tons per year, TPD= tons per day 

Source Category NOx 

TPY TPD 

CO 

TPY TPD 

VOC 

TPY TPD 

Area 42.07 0.115 218.59 0.598 262.44 0.719 

Point 1,502.6 4.12 266.25 0.729 130.36 0.357 

Mobile 1,147.96 3.14 8,360.24 22.90 733.71 2.010 

Biogenic 7.94 0.015 n/a n/a 730.86 2.002 

Total Emissions 2,700.57 7.39 8,445.08 24.27 1,857.37 5.088 

Back trajectories on high ozone days confirm that air pollution from Texas and El Paso are 

the major cause of high ozone levels. See figure (XXX) (Attach Marks figure), New Mexico 

discussed in its maintenance demonstration for the 8-hour O3 NAAQS in the Sunland Park 
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Nonattainment area the use of cooperative efforts with the State of Texas and Mexico and 

current permitting requirements for point sources within the nonattainment area. Cooperative 

efforts within the Paso del Norte airshed are accomplished by the Joint Advisory Committee for 

the Improvement of Air Quality in the Ciudad Juárez, Chihuahua, El Paso, Texas, and Doña Ana 

County, New Mexico Air Basin (JAC) was established in 1996 to provide the local community 

with the means to participate as partners in the improvement of air quality in the Paso del Norte 

region. The JAC is a binational committee made up of private citizens, private sector 

representatives, university officials, federal, state, and local government officials, and nongovernmental environmental and public health organizations. The JAC is charged with the 

development and recommendation of air quality improvement projects and programs to the Air 

Work Group established under the 1983 U.S.- Mexico La Paz Agreement. The JAC serves as 

the local community-based organization overseeing the process to achieve cleaner air for the 

Paso del Norte region. New Mexico has been an active participant in the JAC and has worked 

with the committee to assist in decreasing emissions of ozone precursors within the Paso del 

Norte Airshed. 

Maintenance in the air shed is shown if emissions projections for the El Paso area are shown 

in combination with emissions from Sunland Park. (El Paso emissions were obtained from the 

Texas maintenance plan for El Paso approved at (74 FR 2389, January 15, 2009)) to remain less 

than the attainment year inventory for the 10 year period of the maintenance plan. Table 4 shows 

that overall emissions of VOC and NOx on the U.S. portion of the air basin are declining 

substantially for the 10 year period despite the fact that emission grew slightly in the Sunland 

Park area. 

Table 4 Summary of overall emissions of VOC on the U.S. portion of the air basin. 

VOC 

2002 2014 

Sunland Park 3.74 

El Paso 52.44 

Total 56.18 

Sunland Park 5.088 

El Paso 44.61 

Total 49.608 

NOx 

Sunland Park 5.41 

El Paso 60.87 

Total 66.28 

Sunland Park 7.39 

El Paso 36.89 

Total 44.28 

There are currently two major sources of air pollution that have permitting requirements; El 

Paso Electric – Rio Grande Generating Station and FOAM –EX, Santa Teresa Plant, in the 

Sunland Park O3 Nonattainment area. Both of these facilities have Title V permits with the 

State of New Mexico (see Appendix F). The purpose behind Title V permits is to reduce 

violations of air pollution laws and improve enforcement of air quality control laws. This is 

accomplished through enforceable emission limitations and standards; a compliance schedule; a 

requirement that the permittee submit to the permitting authority, no less often than every 6 

months, the results of any required monitoring; and such other conditions as are necessary to 
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assure compliance with applicable requirements of their permit. Permit conditions for the El 

Paso Electric and FOAMEX, along with state regulations will ensure that future sources and 

emissions of VOC and CO in New Mexico will not cause an exceedance of the NAAQS (see 

appendix G for current state regulations pertaining to VOC and CO emissions and permit 

conditions). The Sunland Park O3 Nonattainment area currently has a NOx waiver, see 

Appendix D for that waiver. 

3. Monitoring Network. To verify compliance with the NAAQS for ozone once an area has 

been redesignated to attainment/maintenance, an appropriate air quality monitoring network 

needs to be maintained by the state. The AQB will continue to use the ozone monitoring 

network already established in the Sunland Park nonattainment area to verify attainment of the 

NAAQS in the area. The monitoring network is in accordance with 40 CFR 58. Table 1-4 

below, contains information on the current ozone monitoring network in the Sunland Park 

nonattainment area. 

Table 1-4. Monitoring Stations in the Sunland Park nonattainment area. 

Name AIRS Monitor ID County Site ID Monitoring Period 

Sunland Park, NM 35-013-0017 0071 1989-Present 

Desert View, NM 35-013-0021 0021 1996-Present 

Santa Teresa, NM 35-013-0022 0022 1996-Present 

La Union, NM 35-013-0008 0008 1974-Present 

4. Verification of Continued Attainment. To guarantee that attainment will be continued in 

the future, the state needs to ensure that they have the legal authority to implement and enforce 

all air quality measures needed to attain and maintain the 8-hour NAAQS for ozone. The current 

permit conditions for El Paso Electric and FOAM-EX and state regulations NMAC 20.2.70 – 

Operating Permits and NMAC 20.2.72 – Construction Permits verify that New Mexico has the 

continued legal authority needed to implement and enforce air quality controls to maintain the 

NAAQS for ozone in Sunland Park in the future. New Mexico will also provide the EPA with 

an interim emissions inventory report for point, area, mobile and biogenic emissions of VOCs 

and CO in the Sunland Park maintenance area. 

5. Contingency Plan. As a requirement of section 175A of the CAA, a contingency plan 

must be developed to correct any violations of the O3 NAAQS in Sunland Park, Santa Teresa, 

and La Union after the area has been redesignated. The plan should be an enforceable part of the 

SIP and should ensure that the appropriate measures will be adopted in the event that the 

NAAQS are exceeded for ozone. As discussed previously, New Mexico has very little to no 

control over a majority of the ozone precursor emissions in the Paso del Norte Airshed, thus 

making it difficult to provide contingency measures for any future violations of the O3 NAAQS 

in the Sunland Park area. 
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Although New Mexico does have little control over the emissions within the airshed, it has 

committed to development of an education and outreach campaign as a means of protecting 

public health if there are any future violations of the ozone NAAQS. New Mexico has 

developed a similar public awareness program for dust storms caused by high wind events under 

the Doña Ana County Natural Events Action Plan. A public awareness program developed for 

ozone in the Sunland Park maintenance area in the event there is a violation of the 8-hour ozone 

NAAQS would include the use of public outreach materials and health advisories to educate the 

public on the health risks associated with prolonged exposure to ozone. The program would 

utilize the following tools: 

• Outreach materials such as brochures and pamphlets specific to air quality in the Sunland 

Park maintenance area; 

• Open houses to be held at the beginning of the ozone season and mid-way through; and 

• Ozone Action Days. 

The outreach materials include an informational and health-related brochure titled “Ozone 

and Health” is published in English and Spanish. This brochure would be distributed primarily 

during the ozone season in Sunland Park, but will be available at the City Planning office in 

Sunland Park year around. Other outreach materials will include public service announcements, 

press releases, and informational pamphlets. 

The NMED will hold open houses in partnership with the New Mexico Department of 

Health, Border Health Office (DOH). The open houses will be designed to provide information 

and give the public the opportunity to speak to the NMED and/or the DOH one on one. The open 

houses would be held in May and August in Sunland Park. 

Ozone Action Days will be announced during weather forecasts on the radio and television. 

An Ozone Action Day will be called when the State weather forecasters predict that weather 

conditions will be conducive for the formation of ozone. Advisories will also be placed on the 

NMED/AQB web site. Real time monitoring data is also available on the NMED/AQB web site. 

Information on Ozone Action Days will be included in the outreach material for the Maintenance 

area. The public will be encouraged to take actions to reduce their emissions and exposure on 

ozone action days. In this way New Mexico will be taking actions to get back into attainment. 

If a violation of the 8-hour ozone standard is recorded in the Sunland Park Maintenance area, 

New Mexico has committed to implement the contingency measures listed above as 

expeditiously as practicable, but no later than 24 months after the violation. 

III. EPA Conclusion and Recommendation

Based on the above discussion, I recommend approval of the submitted SIP revision 

incorporating the Sunland Park Section 110(a)(1) 1-hr Ozone Maintenance Plan into the New 

Mexico SIP.