Background
A clean air plan (also called the State Implementation Plan, or SIP), was adopted in 1994 in compliance with the 1990 Amendments to the Federal Clean Air Act. At that time, our region could not show that we would meet the federal 1-hour standard by 1999. In exchange for moving the deadline to 2005, the region accepted a designation of “severe nonattainment”, with additional emission requirements on stationary sources.
In July 1997, EPA promulgated a new 8-hour standard for ozone. This change would lower the standard for ambient ozone from 0.12 parts per million of ozone averaged over one hour to 0.08 parts per million of ozone averaged over eight hours. In general, the 8-hour standard is more protective of public health and more stringent than the federal 1-hour standard. EPA's 8-hour ozone rule established designations and nonattainment classifications in June 2004, and revoked the 1-hour ozone standard in June 2005. However, the rule addresses anti-backsliding provisions in the Clean Air Act, so 8-hour ozone nonattainment areas remain subject to control measure commitments that applied under the 1-hour ozone standard.
The Sacramento Region was designated as a “serious” nonattainment area for the 1997 federal 8-hour ozone standard with an original attainment deadline of June 2013. Updated photochemical modeling information indicated that the region could not meet the attainment deadline. The Boards of Directors for each of the five air districts which compose the Sacramento Federal Nonattainment Area (SFNA) requested that the California Air Resources Board (CARB) submit a formal request for voluntary reclassification from a “serious” to a “severe” for the 8-hour ozone nonattainment area with an associated attainment deadline of June 15, 2019. CARB submitted that request on February 14, 2008. See the reclassification page.
In addition, the EPA released the new 8-hour ozone standard in March 2008. The new standard is 0.075 parts per million and reflects new scientific evidence of health problems including cardiac events, school absences, and mortality.
The control strategies included in the 8-hour SIP will continue our progress in improving air quality. After completing the current planning effort, we will begin the process of identifying the additional reductions needed to meet the new standards. The region will have additional time to meet the new standards.
Transportation Conformity
Transportation conformity is the federal regulatory procedure for linking and coordinating the transportation and air quality planning processes. Conformity provisions require that federal funding and approvals are only given to those transportation plans and projects that are consistent with air quality goals specified in state implementation plans (SIPs). Conformity with the SIP means that emissions from transportation activities are at or below the motor vehicle emission budgets established in the SIPs.
Transportation conformity budgets were included in the Sacramento region's 8-hour ozone reasonable further progress plan[1] for 2008. These motor vehicle emissions were based on ARB’s improved emission factors (EMFAC2002 version2.2, Apr 03) and the travel activity projections prepared by the Sacramento Area Council of Governments (SACOG).
In the March 14, 2006 Federal Register, EPA found that the motor vehicle emissions budgets for 2008 were determined to be adequate for transportation conformity purposes by the United States Environmental Protection Agency. SACOG was able to demonstrate that the 2006 Metropolitan Transportation Plan and the 2006/08 Metropolitan Transportation Improvement Program for the Sacramento region were below the 2008 budgets.
On April 15, 2008, the AQMD submitted to CARB the 2011 Reasonable Further Progress (RFP) plan demonstrating that the Sacramento region will meet minimum emission reduction requirements specified in the Clean Air Act. The RFP plan documented a 27% reduction in volatile organic compounds (VOC) and/or nitrogen oxides (NOx) emissions from 2002 to 2011 and included required motor vehicle emissions budgets for 2011. The 2011 RFP demonstration relies on revised motor vehicle emissions using EMFAC2007 and updated transportation activity data. However, the motor vehicle emissions budgets for 2011 are being maintained at the 2008 budget levels (previously established based on EMFAC2002.) See the RFP page for more information.
The Sacramento Regional Nonattainment Area 8-Hour Attainment Demonstration Plan currently being developed will update the allowable motor vehicle emissions budgets for ROG and NOx for 2011 using the new EMFAC model (EMFAC2007) and population and travel activity figures. In addition, it will establish new budgets for several other years up to and including the attainment deadline year. After EPA finds these new budgets adequate, then SACOG must demonstrate that emissions from subsequent transportation plans will be below the emission budget levels established in this new air quality plan.
[1] Sacramento Regional Nonattainment Area 8-Hour Ozone Rate-of-Progress Plan (Final Report, February 2006).
Where does our pollution come from?
The emission inventory charts represent the 2005 summer planning emissions for the SFNA. Stationary and area-wide emissions are generated by CARB's emission forecasting model, California Emission Forecast System (CEFS), Version 1.06 (Rf#980), February 28, 2007, using the 2002 base year inventory. On-road emissions are modeled using EMFAC2007, version 2.3, and travel activity from SACOG’s transportation modeling (SACSIM, February 2008) of the Sacramento Region’s recent Metropolitan Transportation Plan (MTP2035) with Blueprint. Off-road and farm equipment under Other Mobile are based on the OFFROAD2007 model. The inventory contains external adjustments reflecting new emissions and recently implemented district, state and federal control measures adopted as of December 31, 2006. Aircraft emissions are based on activities from Draft Final Sacramento International Airport Master Plan, February 19, 2004, and Mather Airport Master Plan Revised Draft, February 2004.
Additional 2005 inventory information is available on the 2005 Emission Inventory page.
What's happening in our region?
Our ozone trends are good, the overall rate of population exposure to ozone is down, and the number of days and hours over the standard are also trending down. The annual peak number of days exceeding the federal 8-hour ozone standard at any individual monitoring site in the region has averaged about 26 per year over the last 10 years. In 2004, there were 10 exceedance days at the peak site. The air monitoring stations located at downwind foothill sites (such as, Cool, Folsom, Placerville, and Auburn) generally measure the majority of the 8-hour ozone exceedances. Note that the federal 8-hour ozone standard requirements could allow for an average of 3 exceedance days per year at any monitoring site.
The air districts of the region have adopted more than 25 rules to reduce emissions from stationary sources. Fleet turnover with new cleaner motor vehicles has also resulted in less air pollutants from mobile sources despite increasing population and vehicle travel in the region. Overall, the emissions of ozone-forming pollutants (reactive organic gases and nitrogen oxides) from human-caused sources have declined about 30% over the last 10 years. However, to attain the 8-hour ozone standard, significant additional emission reductions will be needed.
What are our planning responsibilities?
The Clean Air Act established two key air quality improvement requirements:
- Reasonable Further Progress (RFP) must demonstrate how the air districts’ efforts will meet minimum annual emission reduction targets during the years prior to attaining the 8-hour standard. The ROP Plan must show a 3% per year emission reduction in volatile organic compounds (or the NOx equivalent) at three year increments through the attainment year.
- An 8-hour attainment plan will contain sufficient control measures to demonstrate that the region will attain the 8-hour standard as expeditiously as practical but not later than 2018. The plan will result in a new Motor Vehicle Emissions Budget (MVEB).
