Agenda Date: June 11, 2015

Prepared By: Yushuo Chang, Planning and Monitoring Section Manager

Topic: Approval of the Placer County Air Pollution Control District Ozone 

Emergency Episode Plan

Action Requested:

1) Conduct a Public Hearing regarding the proposed Ozone Emergency Episode Plan.

2) Adopt Resolution #15-07 (Attachment #1), thereby approving the Ozone Emergency 

Episode Plan for Placer County (Attachment #2).

Discussion: Under the Code of Federal Regulations (CFR)1, areas that (1) do not attain the 

federal standards for ozone and (2) have hourly ozone concentrations above 0.10 parts per 

million (ppm) are classified as a Priority I area. It is required to develop a contingency plan

which must, at a minimum, provide for taking action necessary to prevent ambient ozone 

concentrations at any location in such region from reaching the significant harm level of 0.6 

ppm, averaged over two hours. As set forth in CFR, three trigger levels (stages) are 

established for the ozone pollution episodes: Alert level (0.2 ppm), Warning level (0.35 

ppm), and Emergency level (0.5 ppm)2. Corresponding actions for each specified trigger 

level should be identified and will be implemented when the ambient ozone hourly 

concentration measurements reach the specified trigger levels. These elements and actions 

should provide for rapid short-term emission reductions at each trigger level, to avoid high 

ozone concentrations from reaching significant harm levels during an episode.

Placer County is classified as non-attainment for the 2008 federal ozone eight-hour average 

standard. Between 2011 and 2012, Placer County has had more than one day with the 

maximum one-hour concentration greater than 0.10 ppm. Although the California Air 

Resources Board (CARB) requested U.S. Environmental Protection Agency (EPA) to 

reclassify Placer County from Priority I to Priority III area with no emergency episode plan 

requirement, EPA disapproved the request3. The Placer County Air Pollution Control District 

(District) is therefore required to prepare an ozone emergency episode plan.

The District’s Ozone Emergency Episode Plan provides the review of air quality and 

emission inventory within Placer County and proposes actions for each trigger level to 

prevent ambient ozone concentrations within Placer County from reaching the significant 

harmful level. Because ozone precursors emissions in Placer County have been substantially 

reduced through the implementation of existing control regulations and programs, the ozone 

concentration trend shows a decrease over time and there has not been an exceedance over 

0.15 ppm in the last thirteen years (2000-2013). In addition to the three trigger levels, the 

 

1

40 CFR 51.150 and 51.151

2

40 CFR 51 Appendix L

3

79 FR 63350-53363

Board Agenda Item 6

Public Hearing/Action
PCAPCD Ozone Emergency Episode Plan

June 11, 2015

Page 2

District proposes an additional level at 0.15ppm as the Health Advisory level, which is lower 

than the Alert level, which is lowest of three trigger levels required by the CFR, to initiate 

and fulfill the actions proposed by the Plan to abate the harmful ozone concentration should 

it occur. 

The proposed Ozone Emergency Episode Plan identifies actions for each trigger level of the 

ozone emergency episode, including public notification and emission mitigation for 

industrial and mobile sources. The purposes of these actions are 1) to provide notification to 

the public of each identical episode when atmospheric stagnation conditions would result in 

substantially high ozone concentration measurements, and 2) to reduce the ozone precursor 

emissions rapidly in order to lower the ozone concentration below the triggered emergency 

episode level.

Public Comment: The proposed Ozone Emergency Episode Plan was posted on the District’s 

website for public review. A notice of the public hearing was published in the Auburn 

Journal on April 29, 2015 and posted on the District’s website (Attachment #3). The public 

review period was ended on June 1, 2015. No comment was received during the public 

review period.

Recommendation: Staff recommends adoption of Resolution #15-07, thereby approving the 

Placer County Air Pollution Control District Ozone Emergency Episode Plan.

Attachments: #1: Resolution #15-07

#2: Placer County Air Pollution Control District Ozone Emergency 

Episode Plan

#3: Proof of Publication