Particulate Matter Strategy Meeting
What is the Nature of California’s PM Problems?
October 13, 2004
Air Resources Board
California Environmental Protection Agency
Outline of Presentation
• How far have we come?
– Progress on attaining federal PM10 standards
• Where are we now?
– Characterization of the PM2.5 problem
• What are the future challenges?
– State standards, changes to federal standards
How Far Have We Come?
What Areas Have Recently Attained the Federal PM10 Standard?
4 areas now meet federal PM10 standards
• Sacramento County • Mammoth Lakes • 2 Areas in Searles Valley • Portion of San Bernardino County
What are the Remaining Federal PM10 Nonattainment Areas?
• Owens Lake and Coso Junction, Mono Lakes and Coachella Valley
– Fugitive dust measures underway
• Imperial County
– Fugitive dust and transport from Mexico need to be addressed
• South Coast, San Joaquin Valley
– Complex particulate matter problems – SIPs updated in 2003 with variety of control measures
What Progress Has Been Made Toward Attaining the Federal Annual PM10 Standard?
Concentrations (ug/m3)
100 80 60 40 20 0 Annual Standard
1991
1998
1992
1993
1999
2000
1990
1994
1995
1996
1997
2001
2002
South Coast
San Joaquin Valley
2003
Where Are We Now?
Federal PM2.5 Nonattainment Areas
Annual Average PM2.5 Concentrations
Concentrations (ug/m3)
30 25 20 15 10 5 0 South Coast San Joaquin Valley San Diego
California accounts for majority of national PM exposure
Annual PM2.5 (3-year mean)
Rest of Nation 37%
24-Hour PM2.5 (3-year mean 98th percentile)
Rest of Nation 2%
California 63% California 98%
Population-weighted and minus NAAQS, based on 2000-02 AIRS data
What do we Need to Know to Design Effective Strategies?
• What level of control is needed at different sites?
• How do controls for the 24-hour standard help attain the annual standard? • What are the contributing sources? • Which precursor species reductions are the most effective?
Spatial Variations in PM2.5 Annual Concentrations
South Coast
Spatial Variations in PM2.5 Annual Concentrations
San Joaquin
Spatial Variations Summary
• San Joaquin Valley:
– Concentrations increase from north to south – Highest site is Bakersfield
Level of Control at Different Sites
• South Coast:
– Concentrations increase from west to east – Highest site is Riverside-Rubidoux
24-Hour Versus Annual Standard Controls
PM2.5 Monthly Peaks
2001
180
PM2.5 Annual Average
35 30 25 20 15 10 5 0
2001
Concentrations (ug/m3)
160 140 120 100 80 60 40 20 0 1 2 3 4 5 6 7 8 9 10 11 12
SC SJV
Riverside
Bakersfield
With Exceedances W/O Exceedances
Seasonal Variations Summary
• Need to reduce both 24-hour exceedances and mid-level concentrations to attain annual standard
24-Hour Versus Annual Standard Controls
• San Joaquin Valley - need to reduce fall and winter concentrations
• South Coast - need to reduce concentrations throughout the year
Source Apportionment
Secondary components: ammonium nitrate, Primary components: • Mobile sources
on- and off-road (gasoline vs diesel based on emissions inventory split) wood combustion, ag and prescribed burning, cooking other combustion sources dust, water, etc… ammonium sulfate, organic carbon
• Burning/cooking • Other carbon • Other
Contributing Sources
PM2.5 Annual Average
Other Carbon 3% Burning/ Cooking 17% Other 7%
Burning/ Cooking 4%
Other Carbon 4% Other 6%
Diesel 11% Gasoline 4%
Secondary OC 11%
Amm Nitrate 47%
Amm Nitrate 39%
Diesel 9% Gasoline 7%
Amm Sulfate 13%
Secondary OC 8%
Amm Sulfate 10%
Riverside
27 ug/m3
Bakersfield
21 ug/m3
PM2.5 24-Hour Concentration
Other Carbon 4%
Contributing Sources
Other Carbon Other 2% 3% Burning/ Cooking 15% Diesel 4%
Amm Nitrate 62%
Burning/ Cooking 2% Diesel 8% Gasoline 3%
Secondary OC 8%
Other 4%
Gasoline 3%
Secondary OC 5%
Amm Sulfate 9%
Amm Nitrate 62%
Amm Sulfate 6%
Riverside
72 ug/m3
Bakersfield
76 ug/m3
24-Hour PM2.5 Spatial Variation
Other Carbon Other 2% 3% Burning/ Cooking 15% Diesel 4% Gasoline 3%
Secondary OC 5%
Contributing Sources
Other Carbon 2%
Other 3% Amm Nitrate 32%
Burning/ Cooking 33%
Amm Nitrate 62%
Amm Sulfate 4% Diesel 11% Gasoline 8%
Secondary OC 7%
Amm Sulfate 6%
Bakersfield
76 ug/m3
Fresno
69 ug/m3
Seasonal and Spatial Variations Summary
• Secondary ammonium nitrate is a key contributor at all sites and all times of year • Contributions from burning are significant in the San Joaquin Valley, especially in the winter in Fresno
Contributing Sources
• Different sites within an air basin can have significantly different source contributions
Control of Precursors
Key Concepts
• Secondary PM2.5 precursors include NOx, SOx, VOC, and NH3 • NOx and VOC form ozone in the process of forming secondary ammonium nitrate • The precursor available in the least amount provides the greatest impact for control • The response to precursor reductions is not necessarily linear
Control of Precursors
Current Knowledge
• San Joaquin Valley
– NOx control most effective for reducing ammonium nitrate
• South Coast
– 2003 AQMP included NOx/VOC/NH3 strategy. Current modeling suggests importance of VOC reductions for PM
• Both Areas
– SOx reduces secondary ammonium sulfate – VOC reduces secondary organic carbon
What Are The Future Challenges?
Severity of State PM10 Problem
Severity of State PM2.5 Problem
Potential Changes to Federal Standards
• Revisions to federal PM2.5 standards • Replacement of PM10 standard with PM coarse standard
Regional Haze and Climate Change Considerations
• Regional and global scale PM is caused by fossil fuel use, biomass burning, and land disturbance • Research is ongoing to determine the relative impact of individual pollutant species/sources
• Controls on combustion sources can have significant benefits for PM, regional haze, and global climate change
Summary of Key Points
• PM2.5 composition varies by region and time of year • Both peak and mid-level concentrations must be reduced to attain both the 24-hour and annual standards • Key contributors include ammonium nitrate/sulfate, burning, mobile sources, and secondary organic carbon