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Technical Support Document for 2008 Ozone NAAQS Designation for Puerto Rico

Puerto Rico

Area Designations for the 

2008 Ozone National Ambient Air Quality Standards

No areas of Puerto Rico violate the 2008 National Ambient Air Quality Standards for ozone (2008 

NAAQS). Two monitors constitute the EPA-approved ozone network in Puerto Rico and both have 

design values well under the 0.075ppm NAAQS. 

Technical Analysis for Puerto Rico

Since the air quality from the EPA-approved network is attainment at all the sites in Puerto Rico, the 

only factors to review are 1) the air quality data and 2) whether Puerto Rico impacts any nonattainment 

areas.

In a February 4, 2009 letter to the USEPA, Puerto Rico recommended that all of Puerto Rico be 

designated as attainment for the 2008 ozone NAAQS based on air quality data from 2006-2008. These 

data are from Federal Reference Method (FRM) monitors sited and operated in accordance with 40 CFR 

Part 58. . 

After considering Puerto Rico’s recommendation and based on EPA's technical analysis described 

below, EPA intends to designate all of Puerto Rico as attainment/unclassified for the 2008 ozone 

NAAQS. 

Factor Assessment

Factor A: Air Quality Data 

For this factor, we considered 8-hour ozone design values (in ppm) for air quality monitors in Puerto 

Rico based on data for the 2008-2010 period (i.e., the 2010 design value, or DV), which are the most 

recent years with fully-certified air quality data. A monitor’s DV is the metric or statistic that indicates 

whether that monitor attains a specified air quality standard. The 2008 ozone NAAQS are met when the 

annual fourth-highest daily maximum 8-hour average concentration, averaged over 3 years is 0.075 ppm 

or less. A DV is only valid if minimum data completeness criteria are met. See 40 CFR part 50 

Appendix P. Where several monitors are located in a county (or a designated nonattainment area or 

maintenance area), the DV for the county or area is determined by the monitor with the highest level.

The 2010 DVs for the ozone NAAQS for counties in Puerto Rico are shown in Table 2. 

Table 2. Air Quality Data.

Location 2008-2010 Design Value (ppb)

Catano 40

Juncos 40
2

Data for these two sites meet EPA’s completeness requirements and are well under the 75ppb ozone 

NAAQS. See the attached report from EPA’s Air Quality System for the data used for this table. 

PR-VI O3.pdf

Factor B: Impact on other areas

As part of EPA’s evaluation of Section 110 ozone transport State Implementation Plans, EPA 

determined that Puerto Rico is too far from any other nonattainment areas to cause to contribute to 

violations of the ozone NAAQS in these areas. The nearest nonattainment areas are in the eastern 

portion of the continental United States, over a thousand miles from San Juan, Puerto Rico.

PR_110(a)(2)(D)(i) 

letter_Nov 29.pdf

Conclusion

Based on the assessment of factors described above, EPA has preliminarily concluded that Puerto Rico 

has met the CAA criteria attainment of the 2008 ozone NAAQS, all monitors in its EPA-approved ozone 

network show attainment of the ozone standard. In addition, Puerto Rico is far enough from other ozone 

nonattainment areas that is does not cause or contribute to any nonattainment for the 2008 ozone 

NAAQS.