UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX

75 Hawthorne Street

San Francisco, CA 94105

November 1, 2010

Dr. Chung S. Liu, Deputy Executive Officer

Science and Technology Advancement

South Coast Air Quality Management District

21865 Copley Drive

Diamond Bar, CA 91765-4178

Dear Dr. Liu:

Thank you for your submission of the South Coast Air Quality Management District’s 

(SCAQMD) 2009 Annual Air Quality Monitoring Network Plan. We have reviewed the 

submitted document and have found that it meets the minimum requirements set forth under 40 

CFR Part 58.10. While this letter serves as official approval of the annual network plan, it does 

not constitute approval of the system modifications that are proposed in the plan for the future. 

We will continue to work with your district to review system changes as they proceed.

We also want to thank you for your timely submission of the SCAQMD’s 2010 

Monitoring Network Assessment Report, as required under 40 CFR Part 58.10. We recognize 

that preparing the network assessment was a significant project and we appreciate your effort. 

We plan on providing feedback to all agencies on network assessments during the winter 2011.

Enclosed, please find our comments on the plan. If you have any questions regarding 

this letter or the enclosed comments, please feel free to contact me at (415) 972-3851 or Kate 

Hoag at (415) 972-3970.

Sincerely,

/s/

Matthew Lakin, Manager

Air Quality Analysis Office

Air Division

Enclosure

cc: Dr. Phil Fine, SCAQMD

Dr. Jason Low, SCAQMD
Comments on 2009 Data Year Network Plan for South Coast AQMD 

Please update next year’s annual network plan to reflect the following comments:

1. The general process for soliciting public comments on the Annual Monitoring Network 

Plan is described very well on page one, including the dates that the documents were 

available. For future plans, please indicate whether or not public comments were 

received during this time

2. For all proposed changes, when the District has completed its evaluation, please submit 

any request with the appropriate documentation to EPA Region 9 for our approval.

3. Page ten outlines the requirements for PM2.5 samplers. The table lists all the required 

monitors together. For future plans, please list separately the various requirements 

(FRM, continuous, collocated) and how they are met. 

4. Please specifically state which sites are meeting the collocation requirements for PM2.5 

and PM10.

5. Table 1 on page 12 does not list a NO2 monitor at the Riverside site, but one is included 

in the detailed site information on page B-236. Please change the table or the site 

description to reflect the monitors currently at the site.

6. While Appendix B provides a good overview of the monitoring stations in SCAQMD, 

some of the detailed site information is incomplete. The following list provides 

examples of information that was not included or consistent for all monitors. Please 

ensure that these tables are complete for your future network plans:

i. Site type (SLAMS/SPM etc.)

ii. List FRM/FEM/non-FEM and method code for particulate monitors. 

iii. List POC for each monitor 

iv. Date of the last Annual Performance Evaluation, App. A, 3.2.2 (gaseous 

instruments)

v. Dates of the last two semi-annual flow rate audits for PM monitors, App A 

3.2.4 and 3.3.3 (automated and manual)

vi. Date of the past year’s PM2.5-PEP and Pb-PEP audits, App A 3.2.7 and 

4.3.2.