UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

REGION IX 

75 Hawthorne Street 

San Francisco, CA 94105

November 1, 2010 

Michael Villegas, Air Pollution Control Officer 

Ventura County Air Pollution Control District 

669 County Square Drive 

Ventura, CA 93003-5417 

Dear Mr. Villegas: 

Thank you for submitting the 2010 Annual Monitoring Network Plan for the 

Ventura County Air Pollution Control District. We have reviewed the submitted 

document and have found that it is complete, informative, very detailed and meets all of 

the requirements for annual network plans as required by our regulations set forth under 

40 CFR Part 58.10. We have included suggestions for next year’s network plan. 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 2010 Network 

Assessment of the Ventura County Air Pollution Control District, 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. 

If you have any questions regarding this letter, please feel free to contact me at 

(415) 972-3851 or Meredith Kurpius at (415) 947-4534. 

 Sincerely, 

 /s/ 

Matthew Lakin, Manager 

 Air Quality Analysis Office 

 Air Division 

Enclosures 

cc: Keith Duval, VCAPCD 

Karen Magliano, ARB 
Comments on 2010 Network Plan for Ventura County APCD 

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

• Providing for Review of Changes to PM2.5 Network: 40 CFR 58.10(c) says: 

(c) The annual monitoring network plan must document how States and local 

agencies provide for the review of changes to a PM2.5 monitoring network that 

impact the location of a violating PM2.5 monitor or the creation/change to a 

community monitoring zone, including a description of the proposed use of 

spatial averaging for purposes of making comparisons to the annual PM2.5 

NAAQS as set forth in appendix N to part 50 of this chapter. The affected State or 

local agency must document the process for obtaining public comment and 

include any comments received through the public notification process within 

their submitted plan. 

The network plan did not address this requirement. As an example of the type of 

language that would suffice, Santa Barbara’s network plan includes the following 

statement: 

“The PM2.5 network of FRM monitors in California was largely established in 

1999 and completed in 2000. There are two monitors located in Santa Barbara and 

Santa Maria as part of this larger network in California. CARB located and 

operates these two monitors. SBCAPCD and CARB would discuss any proposed 

changes to the network of PM2.5 monitors in Santa Barbara County prior to any 

formal changes being made.” 

• Monitoring Objectives and Spatial Scales (Tables 2 and 3): In Table 2 the monitoring 

objective of “Highest Concentration” has the spatial scales of “Micro, Middle, 

Neighborhood” listed. In Table 3 sites at Piru and Simi Valley are listed as HC/US but 

Urban Scale is not listed as one of the appropriate spatial scales for HC sites. Other plans 

(e.g., Santa Barbara and San Luis Obispo) have the following kind of statement for 

spatial scales associated with highest concentration sites: “Micro, middle, neighborhood 

(sometimes urban or regional for secondarily formed pollutants).” It is recommended 

that Table 2 be modified to include urban scale for highest concentration sites with the 

appropriate caveat and then leave Table 3 unchanged. 

• Identification of FEM PM2.5 Instruments: It would be helpful to explicitly identify if 

continuous PM2.5 instruments are FEM or non-FEM versions, especially in the detailed 

site information. 

• Distance from trees was omitted for FRM PM2.5, NO2, and VOCs at the El Rio site 

(page A-5). 

• Siting Issue for Ventura – Emma Wood State Beach Site: 40 CFR 58, Appendix E, Table 

E-1 provides the minimum separation distance between roadways and probes for 

neighborhood and urban scale ozone. The minimum distance for roadways with a traffic 
count of ≥110,000 is 250 m. The distance to the road at the Emma Wood site is 90 m, 

which does not meet the siting distance of 250 m required. This site was proposed for 

possible closure, which would be supported by the siting issue mentioned above. Please 

continue to work with EPA to resolve this issue. 

• 40 CFR 58.10 requires that the network plan provide evidence that siting/operation of 

each monitor meets Appendices A, C, D, and E requirements (see section (a)(1)). The 

following requirements in Appendix A were not addressed in your network plan: 

- Frequency of flow rate verification for manual PM samplers audit, App A, 3.3.2: 

e.g. weekly, bi-weekly, monthly? (can be quarterly for high volume samplers) 

- Frequency of flow rate verification for automated PM analyzers audit, App A, 

3.2.3: e.g. weekly, bi-weekly, monthly? 

- Frequency of one-point QC check, App. A, 3.2.1 (gaseous instruments): e.g. 

daily, weekly, bi-weekly? 

- Last Annual Performance Evaluation, App. A, 3.2.2 (gaseous instruments): date 

We have included an example from Santa Barbara County APCD’s network plan that 

includes these fields (at the bottom of the table).