UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX 

75 Hawthorne Street 

San Francisco, CA 94105 

March 1, 2013

Mr. Mahmood Hossain, 

Chief, Monitoring and Technical Services

San Diego County Air Pollution Control District

10124 Old Grove Road

San Diego, CA 92131-1640

Dear Mr. Hossain:

Thank you for your submission of the San Diego Air Pollution Control District’s “2011 Ambient

Air Quality Network Plan” in June 2012. Based on the information provided in the plan, EPA

approves all portions of the network plan except those specifically identified below. 

Annual network plans are important documents for regulatory purposes (e.g., State 

Implementation Plans, designations and redesignations) and public information, in addition to 

the myriad uses by the air districts. EPA is revising the review process for annual network plans 

to specifically check and document the comprehensive set of items that are required to be 

included in the annual network plans per 40 CFR 58.10 in a consistent manner. We have created 

a checklist that lists all these items and have included it as Attachment A. While the items in the 

checklist are required by EPA regulations, we acknowledge that we have not specifically 

requested some of this information in previous annual network plan reviews. We recognize that 

your plan may not have all the items that we have currently identified and hope to work with you 

on the inclusion of these items in future plans. To facilitate these changes, EPA has provided 

detailed feedback in the checklist where information should be included or revised in next year’s 

plan.

Please note that we cannot approve portions of the annual network plan for which the 

information in the plan is insufficient to judge whether the requirement has been met, or for 

which the information, as described, does not meet the requirements as specified in 40 CFR 

58.10 and the associated appendices. EPA Region 9 also cannot approve portions of the plan for 

which the EPA Administrator has approval authority. Accordingly, we are not acting on the 

specific portions of your agency’s annual network plan listed in Attachment B.

In addition to the checklist and list of specific plan elements where EPA Region 9 is not taking 

action, enclosed are additional detailed comments on the plan (Attachment C). Since the plan’s 

public comment period occurred after submission to EPA (July 1 – 31st, 2012), also enclosed is 
confirmation that the San Diego Air Pollution Control District did not receive public comments 

as of November 14th, 2012 (Attachment D). All of the comments in Attachments A, B, and C

should be addressed in next year’s network plan. If you have any questions regarding this letter 

or the enclosed comments, please feel free to contact me at (415) 972-3851 or Dena Vallano at 

(415) 972-3134.

Sincerely,

/s/

Matthew Lakin, Manager

Air Quality Analysis Office

Enclosures:

A. Annual Air Monitoring Network Plan Checklist

B. Elements where EPA is Not Taking Action

C. Additional Detailed Comments

D. Public Comments Confirmation E-mail

cc: Robert Kard, San Diego County APCD

David Shina, San Diego County APCD

Karen Magliano, CARB
Attachment B: Annual Air Monitoring Network Plan Items where EPA is Not Taking 

Action

We are not acting on the portions of annual network plans where either EPA Region 9 lacks the 

authority to approve specific items of the plan, or EPA has determined that a requirement is 

either not met or information in the plan is insufficient to judge whether the requirement has 

been met.

 NCore, PAMS, STN, and the plan for NO2 monitoring require EPA Administrator 

approval. Per 40 CFR 58.11(c), NCore, PAMS, and STN network design and changes are 

subject to approval of the EPA Administrator and per 40 CFR 58.10(a)(5) plans for 

establishing NO2 monitoring sites are submitted to the EPA Administrator for action. 

Therefore, we are not acting on these items.

 EPA identified items in you agency’s annual network plan where a requirement was not 

being met or information in the plan was insufficient to judge whether the requirement 

was being met based on 40 CFR 58.10 and the associated appendices. Therefore, we are 

not acting on of the following items:

Item Checklist Row 

(Attachment A)

Issue

Dates of last two semi-annual 

flow rate audits for Pb 

monitors

31 Insufficient information to judge 

Probe height 65 Not meeting requirement

Distance between co-located 

PM2.5 and PM10 monitors 

33 Insufficient information to judge 

Designation of any Pb 

monitors

19 Not meeting requirement 

Distance from obstructions not 

on roof

68 Insufficient information to judge 

Additional information for each of these items is in included in Attachment A.
Attachment C: Additional Detailed Comments

 [Item 6] No documentation or approval letter was included in the Plan related to previous 

system modifications. When providing future plans for public comment, please include 

information (your agency’s submittal and EPA’s approval) pertaining to any 

modifications that were approved in the data year covered by the plan (e.g. 2012 changes 

for the plan submitted in 2012). 

 [Items 9-10] Although EPA Region 9 is not taking action on the NO2 portions of the 

plans this year, for next year, please identify sites fulfilling the NO2 area-wide and RA40 

requirements.

 [Item 16] According to Appendix E, section 6.3 (b), Camp Pendleton may need to be 

changed to urban/regional scale site for PM2.5 based on site type (general/background), 

distance to nearest traffic lane (15m), traffic count for “B” St. E (n/a), and proximity to I5 AADT (100K).

 [Item 19] The El Cajon Pb monitor station is listed as “Population Exposure” (for NCore) 

in the detailed site descriptions, however, it is described as “population oriented; 

neighborhood” (App 7, p. 5), and not as either source-oriented or non-source-oriented. 

Please include the source-oriented or non-source-oriented designation for all Pb sites in 

next year’s plan.

 [Item 52] The minimum monitoring requirements are met for Pb, but the plan notes that 

official Pb sampling at airports started late (2012).

 [Item 62] The El Cajon monitor station is listed as <10m (7.8 m) from Redwood Ave.

 [Item 68] For future plans, as necessary, report any obstructions (on and off the roof) by 

providing a distance from the probe/inlet, as well as height of the obstruction.

 [Item 69] Chula Vista (9.35 m for O3), Del Mar (7.6m for O3), and Otay Mesa (5.2m for 

PM10) monitors are listed as <10m from trees. The plan notes that the vegetation at Del 

Mar is trimmed regularly to maintain a height 2m below the inlet. Please note in future 

plans whether the trees at these sites may be impacting data quality.