Chapter 1Chapter 1Chapter 1IntroductionFile 02 Chap 1 Alm2013 p1-24.indd 112/16/2013 10:24:02 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-2The California Almanac of Emissions and Air Quality containsinformation about current and historical air quality and emissionsin California. In addition, forecasted emissions are presented. Thisalmanac represents our best current understanding of emissions andbest estimate of emission forecasts. This document is a reference foranyone interested in air quality and emissions for criteria pollutants(ozone, particulate matter, ammonia, nitrogen dioxide, and sulfurdioxide) and diesel particulate matter. When using this information,please note that the air quality and emission values are a snapshotof data at a particular point in time. This edition of the almanac is ayear 2013 snapshot of the air quality and emission inventory databases. It is important to keep in mind that emission and air qualitydata can change over time. For example, emission data may be revisedto reflect improved estimation methods, and air quality data may bechanged because of corrections or additions of data.The information in this document is based on data maintained inthe ARB’s emission and air quality databases. The emission estimatesare presented at five-year intervals from 2000 to 2035. The vehiclemiles traveled (VMT) and human population estimates are providedat five-year intervals from 1990 to 2035. The air quality statisticsin this almanac are for the period 1992 to 2011 for ozone, carbonmonoxide (CO), nitrogen dioxide (NO2), and sulfur dioxide (SO2).In addition, available 2012 statistics for ozone data are included forthe five major air basins. Particulate Matter (PM) monitoring did notbegin until 1999 for PM2.5. Therefore, PM2.5data cover the period1999 through 2011.OverviewThis almanac focuses on air emissions and air quality.The CalEPA has developed a set of indicators to measureCalifornia’s overall environmental health. The indicatorscover all media, not just air, and help us understand thecauses of environmental problems, the status of the environment, and the effectiveness of our environmental strategies.The data in this almanac are more detailed indicators of theState’s air quality health, and in conjunction with CalEPA’sindicators, provide a continuum of information from detailedair quality trends to California’s overall environmentalhealth. The most recent set of CalEPA indicators are available at www.oehha.ca.gov/multimedia/epic/.File 02 Chap 1 Alm2013 p1-24.indd 212/16/2013 10:24:08 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-3This document is divided into four chapters and five appendices thatinclude information, maps, graphs, and tabular data. Chapter 1 contains introductory material. Chapters 2 through 4 and Appendices Aand B provide information on the most important criteria pollutantsfor which health-based ambient air quality standards have been established. Appendix C includes information on population and VMT,and Appendix D contains information on natural emissions. In addition to this information, Appendix E provides lists of the figures andtables included in Chapters 1 through 4 along with a glossary of AirQuality and Emissions terminology.To help the reader navigate the document, a short summary of eachchapter and appendix is provided below:Chapter 1contains introductory material designed to help thereader better understand the remaining chapters. Included isinformation about data interpretation, emission estimation, airquality monitoring, the State and national standards, web resources, and area designations for the national standards.Chapter 2includes current emissions for oxides of nitrogen(NOx), volatile organic compounds (VOC), particulate matter(PM10, PM2.5), diesel particulate matter (DPM), oxides of sulfur (SOx), and ammonia (NH3) and air quality data for ozone,PM2.5, CO, NO2, and SO2. Also included is California’s movement towards attaining air quality in regards to ozone and PMstandards.Chapter 3provides historical emission trends from a statewideperspective. Statewide emission trends for NOx, SOx, VOC, PM10,PM2.5, DPM, and NH3and air quality trends for ozone andPM2.5.Chapter 4provides historical emission and air quality trends forthe State’s five most populated regions. The pollutants coveredare ozone, NOx, SOx, VOC, PM10, PM2.5, DPM, NH3, and NO2.Appendix Aprovides air quality data for the criteria pollutants:ozone, PM2.5, CO, NO2, and SO2. Data are provided for all airbasins arranged by pollutant.Appendix Bincludes more detailed emission data for NOx, SOx,VOC, PM10, PM2.5, DPM, NH3, and CO organized alphabetically,by county. Air quality data are provided similar to that provided inAppendix A and include PM10as well. These data are arranged byair basin and county (or county portion) within these air basins.Appendix Cprovides tabulated information on surface area,population, and VMT for the entire State and each county.Appendix Dprovides emission estimates for natural sources,including wildfires, vegetation (biogenic sources), and oil seeps(geogenic sources) statewide and for each county.Appendix Eprovides lists of the figures and tables included inChapters 1 through 4. A glossary of terms used in the Almanac isprovided at the end of this appendix.OrganizationFile 02 Chap 1 Alm2013 p1-24.indd 312/16/2013 10:24:08 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-4California is fortunate to have a wide range of scenic features encompassing mountains, valleys, oceans, and deserts. The Pacific Oceanforms the State’s western boundary, stretching more than 1,200 milesfrom southern California’s sunny beaches to northern California’sfog-shrouded redwood forests. The inland valleys, with their hot summers and cool winters, boast millions of acres of cropland. The SierraNevada Mountain range to the east runs nearly two-thirds the lengthof the State. Most of the southeastern portion of California is desert,varying from sun-baked Death Valley to the scenic mountain rangesof the Mojave Desert. To a large extent, California’s pleasant climateand varied landscape are the major features that draw people to theState.In terms of size, California is larger than many nations, comprisingmore than 150,000 square miles of land and almost 8,000 squaremiles of water.• California is the nation’s most populous state and the thirdlargest in terms of land area.• There are 58 counties and close to 500 incorporated cities andtowns, most of which are located in the large metropolitanareas where the majority of the population lives: South Coast,San Francisco Bay Area, San Diego, San Joaquin Valley, andthe greater Sacramento area.• Thirty five air districts, in conjunction with ARB, manage airquality programs in California.• California’s growing population, along with weather conditionsand terrain that favor a build up of pollutants, contribute tothe State’s air quality challenges.California Facts and FiguresFile 02 Chap 1 Alm2013 p1-24.indd 412/16/2013 10:24:08 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-5The federal Clean Air Act requires U.S. EPA to setnational ambient air quality standards for six pollutants: ozone, PM, CO, NO2, SO2, and lead. Althoughthe federal standards for these pollutants have beenin place for many years, U.S. EPA recently loweredthe standards for all pollutants but carbon monoxide, based on the newest scientific evidence of healtheffects. Over time, California has made dramaticprogress in reducing public exposure to these pollutants.• Over the last 20 years, California’s population increased 22 percent and the numberof vehicle miles traveled each year increasedmore than 45 percent.• At the same time statewide emissions of VOCand NOx, key contributors to ozone and particulate matter, decreased 50 and 60 percent,respectively, since 1990.• Today’s car is 98 percent cleaner than a similar mid-1970smodel, and new diesel engines are 95 percent cleaner thanthose manufactured during the 1980s.• As a result, more areas in California continue to come intocompliance with the ozone and PM standards.Ozone and PM2.5ProgressAlthough California has made great strides in improving air quality,ozone and PM2.5still present significant challenges. Nonetheless,nearly 63 percent of Californians now live in areas that meet thePercentagecurrent federal standard for ozone, compared with only 24 percentin 1990. Progress toward attainment continues to occur throughoutthe State.• Compared with 1990, ozone concentrations are about 10 to50 percent lower throughout California, with some of the largest decreases occurring in areas with the worst ozone air quality.• As a result, ozone air quality in 23 counties and 10 additionalpartial county areas now meet the current 8-hour ozone standard of 0.075 ppm.Quick FactsOverviewFigure 1-1People living in areas meeting or exceeding the 8-Hour Ozone Standard



# MEET EXCEEDFile 02 Chap 1 Alm2013 p1-24.indd 52/4/2014 11:25:13 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-6• Seven areas, originally designated as nonattainment, nowattain the previous 8-hour ozone standard of 0.08 parts permillion (ppm). In addition, although U.S. EPA revoked thefederal 1-hour ozone standard, Sacramento recently attainedthis milestone.• Seven areas were originally designated as nonattainment forthe 24-hour PM2.5standard. Today, only 3 areas remain nonattainment for this standard.• The number of days exceeding the 24-hour PM2.5standardstatewide has declined dramatically since 2001, from 299days to 128 days, and the annual average concentrationshave declined approximately 35 percent in most California airbasins.The South Coast and San Joaquin Valley pose the most significantremaining challenges for ozone and PM2.5attainment. Additionalinformation on progress in these areas is provided below.South CoastCalifornia’s largest urban area includes most of Los Angeles County,all of Orange County, and the western urbanized portions of Riversideand San Bernardino counties. More than 16 million people, representing 42 percent of the State’s population, live in the South Coastand generate 24 percent of the State’s NOxemissions and 16 percentof the State’s PM2.5emissions.Although South Coast ozone and PM2.5levels are still among thehighest in the nation, the region’s long history of emission controlprograms has resulted in continued progress over the years. Since1990, air quality has improved throughout the South Coast, despitesignificant economic growth and increases in population.• VMT increased 42 percent from 1990 to 2010, and populationincreased 20 percent, yet on-road NOxemissions decreased62 percent and PM2.5emissions decreased 53 percent.• Today, approximately 55 percent of the South Coast population lives in areas that meet the current federal 8-hour ozonestandard. Contrast this with 1990, when air quality throughout the South Coast region violated the standard.• In 1990, ozone concentrations exceeded the 8-hour standardon 181 days with concentrations as high as 0.186 ppm. The2011 design value was 0.107 ppm, with 106 days exceedingthe standard.• The South Coast has experienced dramatic improvements inPM2.5. Both annual and 24-hour concentrations decreasedalmost 50 percent since 2001, and concentrations are nearingthe levels of the federal standards with compliance of bothstandards expected by 2014.San Joaquin ValleyThe San Joaquin Valley (Valley) also faces significant challenges interms of ozone and PM2.5air quality. The Valley encompasses a largearea that includes eight counties, bordered by the San FranciscoBay and Sacramento Valley areas of northern California and theSouth Coast region of southern California. Although the Valley isthe State’s largest agricultural area, urban and industrial development has increased substantially over the last several decades. About10 percent of the State’s population now lives in the Valley, generating about 15 percent of the State’s NOxemissions and 20 percent ofthe State’s PM2.5emissions.Over the next decade, population and VMT are expected to growmore rapidly in the Valley than in other parts of the State. The widedistribution of emission sources, along with weather and terrain thatFile 02 Chap 1 Alm2013 p1-24.indd 612/16/2013 10:24:12 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-7provide optimum conditions for the formation of high ozone andPM2.5concentrations, further complicates the challenge of improvingair quality. However, despite these challenges and as a result of ongoing emission control programs, ozone and PM2.5air quality in the SanJoaquin Valley has improved since the 1990s.• Between 1990 and 2010, VMT increased 87 percent andpopulation increased 45 percent, yet on-road NOxemissionsdecreased 33 percent and PM2.5emissions decreased 56 percent.• Today, about 17 percent of San Joaquin Valley residents live inareas that meet the current federal 8-hour ozone standard. In1992, ozone concentrations exceeded the standard throughoutthe Valley.• While progress toward attainment has been more gradual inthe Valley than in other parts of the State, the federal 8-hourozone design value has decreased 12 percent since 1990, andthe number of days exceeding the standard has decreased29 percent (from 153 to 109).• Annual and 24-hour PM2.5design values decreased 26 and40 percent, respectively, during the last decade. Compliancewith the annual standard of 15μg/m3is expected in 2014, andwith the 24-hour standard in 2019.File 02 Chap 1 Alm2013 p1-24.indd 712/16/2013 10:24:12 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-8Understanding Emission Data.Emission inventory trends makeuse of historical emission inventory data and projections based onexpectations of future economic and population growth and emissioncontrols. As mentioned earlier, our best understanding of emissionsand best estimate of emission forecasts are reflected here. The historical emission inventory data in this almanac were updated to reflectimprovements in emission inventory methodologies. Included are thelatest point source estimates provided by districts as well as inventory improvements from recent State Implementation Plans (SIPs).The future year projections for stationary and area-wide sourceswere developed using the California Emissions Projection AnalysisModel (CEPAM) assuming a 2012 base year and California-specificeconomic projections. These economic projections were prepared byTranSystems (formerly E.H. Pechan and Associates) and reflect information provided by local air districts. The stationary source emissionforecasts reflect control measure information received from local airdistricts as of June 2013. Future year emission projections for on- andoff-road vehicles were developed using the ARB EMFAC2011 andvarious off-road models, respectively. For more information on theseforecasts, please see the ARB State Implementation Plan (SIP) webpage atwww.arb.ca.gov/planning/sip/sip.htm.Understanding Air Quality Statistics.California has a network ofmore than 200 air quality monitoring sites located throughout theState. Each year, more than 10 million measurements are collectedat these sites and stored in a comprehensive air quality database. Itwould be difficult, if not impossible, to analyze each individual measurement. So, we use air quality indicators to summarize the data.An air quality indicator is a summary statistic that reflects a certainaspect of air quality in a particular region. No single indicator provides a complete picture of air quality, because each one tells a different story. Therefore, it is important to evaluate multiple indicators tobetter understand the degree of progress made and the nature of theair quality challenge an area faces.A number of factors can influence the value of an air quality indicator. Two of the most important factors are changes in emissionsand year-to-year variations in weather. Long term changes (over thecourse of five to ten years or more) generally reflect emissions reductions achieved by emissions control programs. In contrast, changesover a shorter timeframe (one or two years) often reflect year-to-yearvariations in weather. For example, ozone concentrations are generally lower than normal during summers with relatively cool temperatures and good dispersion and higher than normal during summerswith hot temperatures and poor dispersion. Weather can also havea noticeable impact on PM2.5, with higher concentrations duringwinters with cold, stable conditions and lower concentrations duringwinters with frequent storms and unstable concentrations. Weatherrelated fluctuations in air quality are independent of changes in emissions.Additionally, measurements may be affected by exceptional events.Exceptional events are unusual or naturally occurring events that canaffect air quality but are not reasonably preventable or controllable.Example of exceptional events include high winds and wildfires. Allof these factors should be kept in mind when using and interpretingthe trends.This document presents long term trends to assess the improvementsin air quality resulting from emissions reductions. Several indicatorsare used to provide a more complete picture of the overall changes.These include indicators that are directly comparable with the federalstandards, as well as indicators that characterize the high concentrations, the frequency with which high concentrations occur, and thedifference in concentrations from one location to another. The followInterpreting the Emissionand Air Quality StatisticsFile 02 Chap 1 Alm2013 p1-24.indd 812/16/2013 10:24:12 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-9ing paragraphs provide brief descriptions of the indicators, how theyare calculated, their limitations, and their value to understandingoverall air quality.High Concentration:The high concentration indicator is easy todetermine and provides information about the level, or severity ofan air quality problem. The high concentration indicator for ozoneis the fourth high 8-hour average concentration. Very simply, all8-hour average concentrations for each site during a particular yearare ranked from high to low. The fourth highest concentration is theozone high concentration indicator. This value is then averaged withthe fourth high from the two previous years to get the Design Value.In contrast to ozone, there are two high concentration indicators forPM2.5: the 98th percentile concentration and the annual average concentration. Similar to ozone, 24-hour PM2.5concentrations measuredat a site during a particular year are ranked from high to low; the 98thpercentile concentration is the value below which 98 percent of allthe daily values fall. Generally, the 98th percentile concentration isthe second high for sites that sample every six days, the third high forsites that sample every three days, and the eighth high for sites thatsample every day. The annual average PM2.5concentration is mucheasier to calculate — it is simply an average of the quarterly averagesduring a given year.The high concentration indicators for both ozone and PM2.5arebased on data for a single year and are generally calculated for eachindividual site.Design Value:The design value is based on the high concentrationindicator and is the only indicator that can be directly compared witha national ambient air quality standard (federal standard, standard,or NAAQS). The design value is used for determining attainment ornonattainment, thus providing an indication of how far an area hasto go before it meets the standard. The design value calculations forozone and PM2.5are different, but both are based on data collectedduring a three year period, with the design value assigned to the endyear. For example, a 2011 design value is based on data from 2009,2010, and 2011. Using three years of data helps make the indicatormore stable and less likely to be influenced by year-to-year changesin weather.A design value is calculated for each individual federal standard.Currently, there is one federal standard for ozone: an 8-hour standardof 0.075 ppm. The ozone design value is calculated as a three yearaverage of the fourth highest 8-hour concentration.There are two federal standards for PM2.5: a 24-hour standard of35μg/m3and an annual standard of 15.0μg/m3. The 24-hour PM2.5design value is calculated as a three year average of the 98th percentile concentration. Similarly, the annual PM2.5design value is a threeyear average of the annual average concentrations.Design values for both ozone and PM2.5are calculated for each individual monitoring site in an area. The site with the highest designvalue becomes the design site for the entire area. As a result, largeportions of a nonattainment area may actually attain the standardbefore the area is deemed attainment.Ozone Exceedance Days:The exceedance days indicator provides ameasure of the frequency of an air quality problem. Ozone concentrations are measured daily, and the number of ozone exceedance days isa simple count of the number of days during a year that at least onesite in the area had a measured concentration that was higher thanthe federal standard (note that because PM2.5is not measured daily,no PM2.5exceedance day statistics are provided).Although the ozone exceedance days indicator gives a good indication of the frequency of exposure to concentrations above the federalstandard, it has several limitations. First, the indicator gives no information about how widespread the exceedances are, because it countsonly one exceedance day, even though exceedances may be measuredat multiple sites. Second, the indicator gives no information aboutthe level of exposure – was the concentration that exceeded just abovethe federal standard or far above the standard. Finally, the exceedancedays indicator can be highly influenced by weather because it is basedFile 02 Chap 1 Alm2013 p1-24.indd 912/16/2013 10:24:12 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-10on data for only one year.Ozone Contour Maps:Contour maps present a simplified pictureof how ozone air quality differs across an area. The maps are basedon measured data that is mapped across a grid. An indicator value isestimated for each grid point, giving greater weight to measurementsthat are located close by and lesser weight to those located furtheraway. As a result, the denser the monitoring network, the more representative the resulting contours. Contour maps work well for urbanareas, where the population is distributed fairly uniformly and thereis a relatively dense network of monitoring sites. Conversely, they donot work well in rural areas which are sparsely populated and havevery few monitoring sites.Almost any indicator value can be mapped, but the most commonlymapped are the design value indicator and the exceedance days indicator. Ozone contour maps are useful for comparing relative changesin the indicator over time or relative differences within an area orbetween areas. However, because of the nature of the estimationprocedure, contour maps are not well suited for evaluating absolutechanges or differences.SUMMARY:In summary, air quality indicators provide a means forsummarizing data to simplify the evaluation of air quality trends.Some indicators are simple to calculate and easy to understand, whileothers are more complex. Because each indicator relates to a specificaspect of air quality, no single indicator provides a complete pictureof air quality. Each indicator has strengths and weaknesses. Therefore,it is important to evaluate multiple indicators to facilitate the bestunderstanding of historical progress and future challenges.File 02 Chap 1 Alm2013 p1-24.indd 1012/16/2013 10:24:12 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-11This almanac presents air quality trends for a 20-year period. Thesetrends reflect the progress achieved through a long history of emissioncontrol programs. Besides emissions, the trends are affected by meteorology (weather) and terrain. Meteorology causes year-to-year changesin air quality trends that can mask the benefits of emission reductions.Therefore, this almanac focuses on long-term rather than short-termtrends.Meteorology does not affect all pollutants in all places the same way.Ozone is formed in the atmosphere as sunlight initiates a complex setof chemical reactions. On hot sunny days, the abundant sunlight startsthe ozone-forming processes and high temperatures promote fast chemical reactions. If the air is stagnant, the ozone formed is not dispersedor diluted by cleaner air. So, the highest ozone concentrations usuallyoccur on hot and sunny days with light breezes or calm air. In someareas, high ozone levels may represent transport from upwind regions;local weather conditions associated with transport may differ from placeto place. Since hot and sunny summer days typically lead to high ozone,it is not surprising that cold and cloudy winter days have much lowerconcentrations.California’s terrain also plays a role in promoting high levels of pollutants. The mountains that surround the San Joaquin Valley and thosethat form a barrier to the east of the Los Angeles area tend to retain airwithin these basins, which limits the dispersion of all pollutants, including ozone.Meteorology affects PM, though some of its effects differ from its effectson ozone. Ambient PM is comprised of primary PM that is directlyemitted and secondary PM that forms in the atmosphere through chemical and physical processes. Primary PM includes dust and soot, whilesecondary PM includes particulate nitrates and sulfates. Some areas aresubject to strong winds that lift dust into the air resulting in high concentrations of primary PM. In other situations, cold, calm, and humid aircan promote the buildup of secondary PM. Relatively high PM levels inthe South Coast and San Joaquin Valley often occur in the winter underthese meteorological conditions. The lowest PM concentrations oftenoccur on rainy winter days when winds disperse PM and rain washes PMout of the air.Year-to-year variations in meteorology can affect year-to-year changes inambient air quality trends. As a result, meteorological variations add tothe difficulty of interpreting long term air quality trends. However, datafor meteorological parameters such as temperature, wind speed, andwind direction can help characterize a year with respect to the weatherconditions influencing air pollution. Similar to ozone, annual averagePM concentrations are also affected by meteorology – in particular, rainfall. These year-to-year variations in the average meteorological conditions are reflected in the long term pollutant trends.The Web Resources Section provides information on how to accesssources of meteorological data. Sources such as ARB’s real-time AirQuality and Meteorological Information System (AQMIS2) allow accessto various parameters including wind speed/direction, temperature,humidity, and visibility.Meteorology’s Role in Air QualityFile 02 Chap 1 Alm2013 p1-24.indd 1112/16/2013 10:24:12 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-12California is a large state with many diverse sources of air pollution.To estimate the sources and quantities of pollution, the ARB, in cooperation with local air districts and industry, maintains an inventory ofCalifornia emission sources. Sources are divided into four major emission categories: stationary sources, area-wide sources, mobile sources,and natural sources.Stationary source emissions are based on estimates made by facility operators and local air districts. Emissions from specific facilitiescan be identified by name and location. Area-wide emissions areestimated by ARB and local air district staffs. Emissions from areawide sources may be either from small individual sources, such asresidential fireplaces, or from widely distributed sources that cannotbe tied to a single location, such as consumer products and dust fromunpaved roads. Mobile source emissions are estimated by ARB staffwith assistance from districts and other government agencies. Mobilesources include on-road cars, trucks, and buses and other sources suchas boats, off-road recreational vehicles, aircraft, and trains. Naturalsources are also estimated by the ARB staff and the air districts. Thesesources include biogenic hydrocarbons, geogenic hydrocarbons, natural wind-blown dust, and wildfires.For the inventoried emission sources, the ARB compiles emission estimates for criteria pollutants. Chapters 2 through 4 and AppendicesA and B focus on four criteria pollutants: ozone, PM, NO2, and SO2.Emissions related to these criteria pollutants include volatile organiccompounds (VOC), oxides of nitrogen (NOx), oxides of sulfur (SOx),ammonia (NH3), directly emitted PM10and PM2.5, and diesel PM(DPM).While some pollutants are directly emitted, others are formed in theatmosphere by chemical reactions ofprecursor emissions. Such is thecase with ozone, which is formed in the atmosphere when NOxandVOC react in the presence of sunlight. PM which includes PM10andPM2.5, is a complex pollutant that can either be directly emitted orformed in the atmosphere from precursor emissions. PM precursorsinclude NOx, VOC, SOx, and NH3. Examples of directly emitted PMinclude dust and soot.Hydrocarbons are classified as to how photochemically reactive theyare: relatively reactive or relatively non-reactive. Emissions ofTotalOrganic Gases(TOG) andVolatile Organic Compounds(VOC) are twoclasses of hydrocarbons measured for California’s emissions inventory. TOG includes all hydrocarbons, both reactive and non-reactive.In contrast, VOC includes only the reactive hydrocarbons.Sources of Emissions in CaliforniaFile 02 Chap 1 Alm2013 p1-24.indd 1212/16/2013 10:24:13 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-13Figure 1-2Air Quality MonitoringThe ARB, local air districts, National Park Service, and other publicagencies operate a comprehensive statewide network of monitors. Airdistricts generate comprehensive network plans containing detailedinformation on their networks and work to ensure the adequacy ofthe monitoring network in characterizing the air quality in the area.As shown in Figure 1-2, there are more than 200 monitoring sites inCalifornia. In addition to the California sites, a few monitoring sitesare located in Mexico. These sites were established in cooperationwith the U.S. EPA and the Mexican government to monitor the crossborder transport of pollutants and pollutant precursors.Each year, more than 10 million air quality measurements from all ofthese sites are collected and stored in a comprehensive air quality database maintained by the ARB. To ensure the integrity of the data, theARB routinely conducts audits and reviews of the monitoring instruments and the resulting data.CaliforniaAir QualityMonitoring SitesCriteria SitesFile 02 Chap 1 Alm2013 p1-24.indd 1312/16/2013 10:24:13 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-14California Air BasinsCalifornia contains a wide variety of climates, physical features, andemission sources. This variety makes the task of improving air quality complex, because what works in one area may not be effectivein another area. To better manage common air quality problems,California is divided into 15 air basins, as shown in Figure 1-3 andTable 1-1. The ARB established the initial air basin boundaries during 1968.An air basin generally has similar meteorological and geographicalconditions throughout the region. To the extent possible, the air basinboundaries follow political boundary lines and are defined to includeboth the source area and the receptor area. However, air masses canmove freely from basin to basin. As a result, pollutants such as ozoneand PM, as well as their precursors, can be transported across airbasin boundaries, and interbasin transport is dealt with in air quality programs. Although established in 1968, the air basin boundarieshave been changed several times over the years, to provide for betterair quality management.California Air BasinsFigure 1-3File 02 Chap 1 Alm2013 p1-24.indd 1412/16/2013 10:24:13 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-15Table 1-1Great Basin Valleys Air Basin Alpine Inyo MonoLake County Air Basin LakeLake Tahoe Air Basin El Dorado (portion) Placer (portion)Mojave Desert Air Basin Kern (portion) Los Angeles (portion) Riverside (portion) San Bernardino (portion)Mountain Counties Air Basin Amador Calaveras El Dorado (portion) Mariposa Nevada Placer (portion) Plumas SierraTuolumneNorth Central Coast Air Basin Monterey San Benito Santa CruzNorth Coast Air Basin Del Norte Humboldt Mendocino Sonoma (portion) TrinityNortheast Plateau Air Basin Lassen Modoc SiskiyouSacramento Valley Air Basin Butte Colusa Glenn Placer (portion) Sacramento Shasta Solano (portion) Sutter Tehama Yolo YubaList of Counties in Each Air BasinFile 02 Chap 1 Alm2013 p1-24.indd 1512/16/2013 10:24:15 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-16Table 1-1 (continued)List of Counties in Each Air BasinSalton Sea Air Basin Imperial Riverside (portion)San Diego Air Basin San DiegoSan Francisco Bay Area Air Basin Alameda Contra Costa Marin Napa San Francisco San Mateo Santa Clara Solano (portion) Sonoma (portion)San Joaquin Valley Air Basin Fresno Kern (portion) Kings Madera Merced San Joaquin Stanislaus TulareSouth Central Coast Air Basin San Luis Obispo Santa Barbara VenturaSouth Coast Air Basin Los Angeles (portion) Orange Riverside (portion) San Bernardino (portion)File 02 Chap 1 Alm2013 p1-24.indd 1612/16/2013 10:24:16 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-17Very simply, an ambient air quality standard is the definition of“clean air.” More specifically, a standard establishes the concentrationabove which the pollutant is known to cause adverse health effectsto sensitive groups within the population, such as children and theelderly. Both California and the federal government have adoptedhealth-based standards for thecriteria pollutants, which include butare not limited to ozone, PM10, PM2.5, CO, and lead. U.S. EPArecently revised the national PM, ozone, lead, NO2, and SO2standards. Information on all of the new standards can be found on theU.S. EPA’s website atwww.epa.gov/airquality/urbanair/, click on the pollutant of interest and select “Regulatory Actions”.An abbreviated list of the national ambient air quality standards canbe found on page 1-23, while a complete list can be found on theARB website atwww.arb.ca.gov/research/aaqs/aaqs.htm. In general, theair quality standards are expressed as a measure of the amount of pollutant per unit of air. For example, the PM standards are expressed asmicrograms of particulate matter per cubic meter of air (μg/m3) andthe ozone standards are expressed in parts per million (ppm).DesignationsBoth the California and federal governments use monitoring data todesignate areas according to their attainment status for most of thepollutants with ambient air quality standards. The purpose of thedesignations is to identify those areas exceeding air quality standardsand thereby initiate planning efforts to achieve air quality levels protective of public health. There are three basic designation categories:nonattainment, attainment, and unclassified. Historically, Californiastandards have been more stringent than federal standards. However,U.S. EPA has recently tightened federal standards for a number ofCriteria Air PollutantsNational Ambient Air Quality Standards and Designationspollutants. This has resulted in both state and federal standards beingsimilar in their ability to protect human health.Anonattainment designationindicates that the air quality violates anambient air quality standard. Although a number of areas may bedesignated as nonattainment for a particular pollutant, the severity ofthe problem can vary greatly. To identify the severity of the problemand the extent of planning required, ozone and PM nonattainmentareas are assigned a classification that is commensurate with theseverity of their air quality problem (e.g., moderate, serious, severe).In contrast to nonattainment, anattainment designationindicates thatthe air quality does not violate the established standard. Under thefederal Clean Air Act, nonattainment areas that are redesignated asattainment must develop and implement maintenance plans designedto assure continued compliance with the standard.Finally, anunclassified designationindicates that there are insufficient data for determining attainment or nonattainment.TheU.S. EPA combines unclassified and attainment into one designationfor ozone, PM10, PM2.5and CO. More detailed information on thearea designation categories can be found on the ARB’swebsite atwww.arb.ca.gov/desig/desig.htm.File 02 Chap 1 Alm2013 p1-24.indd 1712/16/2013 10:24:16 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-18OzoneOzone, a colorless gas which is odorless at ambient levels, is the chiefcomponent of urban smog. Ozone is not directly emitted as a pollutant, but is formed in the atmosphere when hydrocarbon and NOxprecursor emissions react in the presence of sunlight. Meteorologyplays a major role in ozone formation. Generally, low wind speedsor stagnant air, coupled with warm temperatures and cloudless skiesprovide the optimum conditions for ozone formation. As a result,summer is generally the peak ozone season. Because of the reactiontime involved, peak ozone concentrations often occur far downwindof the precursor emissions. Therefore, ozone is a regional pollutantthat often impacts a large area.The ARB and U.S. EPA are required to periodically review its airquality standards and the most recent health studies to ensure thatthe standards are adequately protective of human health. Air qualitystandards have become more stringent over time as new studies haveshown adverse impacts at lower concentration levels.In 1997, U.S. EPA made a fundamental change to the ozone standard, moving from a 1-hour averaging time to an 8-hour averagingtime. The 8-hour standard is designed to protect against the chronichealth effects of day-long exposures to unhealthy concentrations.On March 12, 2008, U.S. EPA completed their review of the most current health studies and concluded that the level of the national ozonestandard at 0.08 ppm was not sufficiently protective of human health.They subsequently adopted a new standard of 0.075 ppm. It has triggered a new set of planning requirements which build upon previousSIP efforts. For more information on the new national ozone standard,please refer to the U.S. EPA’s webpage atwww.epa.gov/air/ozonepollution/actions.html.Establishing a more stringent (health-protective) standard means thatmore areas are identified as having unhealthy air, there are a greaternumber of days when concentrations exceed the standard, and concentrations have to be reduced by a greater percentage in order tomeet the more stringent standard. Although air quality standardschange over time, changing the level of a standard does not negatethe progress already made. It does, however, change the target used tojudge compliance.Table 1-2PollutantYear Averaging TimeStandardOzone19791-Hour0.12 ppm19978-Hour0.08 ppm20088-Hour0.075 ppmChange in Federal Ozone Standards over timeNational Ozone Standard:0.075 ppm for 8 hours,not to be exceeded,based on the fourth highestconcentration averagedover three years.File 02 Chap 1 Alm2013 p1-24.indd 1812/16/2013 10:24:16 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-19Figure 1-4Ozone - National 8-Hour Area DesignationsNational 8-HourOzone DesignationsThere are two designation categories for ozone — attainment/unclassified and nonattainment. Figure 1-4 shows the designations for thenational 8-hour standard, which were effective as of April 30, 2012.An area violates the national 8-hour ozone standard if the fourthhighest 8-hour concentration averaged over a three-year periodexceeds the level of the standard at any monitoring site in the region.There are 15 nonattainment areas in California, including the State’sfive largest urban areas. In addition, a number of smaller counties andrural areas exceed the standard.The following areas were designated as nonattainment for the revisednational 8-hour ozone standard by the U.S. EPA.• Calaveras County• Chico (Butte County)• Imperial County• Kern County (Eastern Kern)• Los Angeles-San Bernardino Counties (West Mojave Desert)• Los Angeles-South Coast Air Basin• Mariposa County• Nevada County (Western part)• Riverside County (Coachella Valley)• Sacramento Metropolitan (includes portions of El Dorado,Placer, and Yolo-Solano Counties)• San Diego County• San Francisco Bay Area• San Joaquin Valley• San Luis Obispo County (Eastern San Luis Obispo)• Tuscan Buttes• Ventura CountyFile 02 Chap 1 Alm2013 p1-24.indd 1912/16/2013 10:24:16 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-20Particulate Matter (PM2.5)Exposure to PM aggravates a number of respiratory illnesses andmay even cause early death in people with existing heart and lungdisease. Both long-term and short-term exposure can have adversehealth impacts. All particles with a diameter of 10 microns orsmaller (PM10) are harmful. PM10includes the subgroup of finerparticles with a diameter of 2.5 microns or smaller (PM2.5). Thesefiner particles pose an increased health risk because they can depositdeep in the lungs and contain substances that are particularly harmful to human health.PM is a mixture of substances that includes elements such as carbonand metals; compounds such as nitrates, sulfates, and organic compounds; and complex mixtures such as diesel exhaust and soil. Thesesubstances may occur as solid particles or liquid droplets. Some particles are emitted directly into the atmosphere. Others, referred toas secondary particles, result from gases that are transformed intoparticles through physical and chemical processes in the atmosphere.Sources of fine particles include all types of combustion activities(motor vehicles, power plants, wood burning, cooking, etc.) and certain industrial processes. Particles with diameters between 2.5 and10 micrometers are referred to as “coarse.” Sources of coarse particles include crushing or grinding operations, and dust from pavedor unpaved roads. Other particles may be formed in the air from thechemical reactions of gases. They are indirectly formed when gasesfrom burning fuels react with sunlight and water vapor. These canresult from fuel combustion in motor vehicles, at power plants, andin other industrial processes.EPA issued the fine particle standards in 1997 after evaluating hundreds of health studies and conducting an extensive peer review process. The 1997 annual standard was established at a level of 15μg/m3,based on the 3-year average of annual mean PM2.5concentrations.The 1997 24-hour standard was established at a level of 65μg/m3,determined by the 3-year average of the annual 98th percentile concentrations.The agency modified the standards in 2006, when they reaffirmedthe 15μg/m3annual standard and lowered the 24-hour standard from65μg/m3to 35μg/m3. On December 14, 2012, EPA strengthenedthe annual standard for fine particles to 12.0μg/m3and retained the24-hour fine particle standard of 35μg/m3.Table 1-3Change in Federal PM2.5Standards over timePollutantYear Averaging TimeStandardPM2.51997Annual15.0μg/m324-Hour65μg/m3200624-Hour35μg/m32012Annual12μg/m3National PM2.5Standards:35μg/m3for 24 hours based on the98thpercentile concentration averagedover three years, not to be exceededand12μg/m3annual arithmetic meanaveraged over 3 years, not to be exceeded.File 02 Chap 1 Alm2013 p1-24.indd 2012/16/2013 10:24:17 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-21Figure 1-5PM2.5- National Area DesignationsThe U.S. EPA promulgated first time area designations for the 1997annual PM2.5standard in early 2005. The San Joaquin Valley andSouth Coast air basins were the only two areas designated as nonattainment. An area violates the annual PM2.5standard when the3-year annual average exceeds 15.0μg/m3at any one site.U.S. EPA promulgated area designations for the recently tightened24-hour PM2.5standard which was effective in Spring 2009. An areaviolates the 24-hour standard when the 3-year average of the 98thpercentile concentrations exceeds 35μg/m3at any one site. Figure 1-5shows the areas that are designated nonattinment for the 24-hour andannual PM2.5standard. However, all areas except South Coast, SanJoaquin Valley, and Imperial now record design values meeting thestandard.The following areas were designated as nonattainment for the revisedNational 24-hour PM2.5standard by the U.S. EPA.• Butte County AQMD (partial)• Imperial County APCD (partial)• South Coast AQMD• Sacramento Metropolitan nonattainment area (includes portions of El Dorado, Placer, and Yolo-Solano Counties)• Bay Area AQMD• San Joaquin Valley APCD• Feather River AQMD (partial)The designation process for the revised annual PM2.5standard will befinalized in early 2015.NationalPM2.5DesignationsFile 02 Chap 1 Alm2013 p1-24.indd 2112/16/2013 10:24:18 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-22National CO Standards:35 ppm for 1 hourand9 ppm for 8 hours,neither to be exceededmore than once per year.National NO2Standards:100 ppb for 1 hourand53 ppb annually,not to be exceededmore than once per year.National SO2Standards:75 ppb for 1 hourand50 ppb for 3 hours,not to be exceededmore than once per year.Carbon MonoxideCO is a colorless and odorless gas that is directly emitted as a byproduct of combustion. The highest concentrations are generallyassociated with cold stagnant weather conditions that occur duringwinter. In contrast to ozone, which tends to be a regional pollutant,CO problems tend to be localized. All of California complies withState and federal CO standards.Nitrogen DioxideNO2is one of a group of highly reactive gases known as “oxides ofnitrogen (NOx).” NO2is the component of greatest interest and theindicator for the larger group of nitrogen oxides. It forms quicklyfrom emissions from cars, trucks and buses, powerplants, and off-roadequipment. It is also linked to the formation of ground-level ozone,fine particle pollution, and a number of adverse affects on the respiratory system. On January 22, 2010 the U.S. EPA finalized revisionsto the 1-hour NO2standard, lowering the level to 100 ppb. This leveldefines the maximum allowable concentration anywhere in an area. Itwill protect against adverse health effects associated with short-termexposure to NO2, including respiratory effects that can result in hospitalization. All of California complies with federal NO2standards.Sulfur DioxideSO2is one of a group of highly reactive gases known as “oxides ofsulfur (SOx).” The largest sources are from fossil fuel combustion atpower plants and other industrial facilities. SO2is linked with a number of adverse affects on the respiratory system. On June 2, 2010 theU.S. EPA finalized revisions to the 1-hour SO2standard, lowering thelevel to 75 ppb. U.S. EPA’s evaluation of the scientific informationand the risks posed by breathing SO2indicate that this new 1-hourstandard will protect public health by reducing people’s exposure tohigh short-term (5-minutes to 24-hours) concentrations of SO2. Allof California complies with federal SO2standards.File 02 Chap 1 Alm2013 p1-24.indd 2212/16/2013 10:24:19 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-23National Ambient Air Quality StandardsPollutantAveraging TimeNational Standards1Primary2Secondary3Ozone (O3)1 Hour——8 Hour0.075 ppmSame as Primary StandardParticulate Matter (PM10)24 Hour150μg/m3Same as Primary StandardFine Particulate Matter(PM2.5)24 Hour35μg/m3Same as Primary StandardAnnual Arithmetic Mean 12μg/m315μg/m3Carbon Monoxide (CO)8 Hour9 ppm—1 Hour35 ppmNitrogen Dioxide (NO2)Annual Arithmetic Mean53 ppbSame as Primary Standard1 Hour100 ppb—Sulfur Dioxide (SO2)3 Hour—0.5 ppm1 Hour75 ppb—LeadRolling 3 Month Average.15μg/m3Same as Primary Standard1. National standards (other than ozone, particulate matter, and those based on annual averages or annual arithmetic mean) are not to be exceeded more than once a year. The ozone standard is attained when the fourth highest eight hour concentration in a year, averaged over three years, is equal to or lessthan the standard. For PM10, the 24 hour standard is attained when the expected number of days per calendar year with a 24-hour average concentration above 150μg/m3is equal to or less than one. For PM2.5, the 24 hour standard is attained when 98 percent of the daily concentrations, averaged overthree years, are equal to or less than the standard. Contact U.S. EPA for further clarification and current federal policies.2. National Primary Standards: The levels of air quality necessary, with an adequate margin of safety to protect the public health.3. National Secondary Standards: The levels of air quality necessary to protect the public welfare from any known or anticipated adverse effects of a pollutant.Table 1-4File 02 Chap 1 Alm2013 p1-24.indd 2312/16/2013 10:24:19 AMChapter 1Chapter 1ARB Almanac 2013 – Chapter 1: Introduction1-24DataReal-time Air Quality Data- Air Quality and MeteorologicalInformation System (AQMIS2) - Allows access to near real-time airquality and meteorological data. These data are available in tabularsummary reports.Historical Air Quality Data- Aerometric Data Analysis andManagement System (iADAM) - Allows access to historical data (datafor record) in tabular summary reports or displayed as graphs.Emission Inventory Data- Allows access to historical and projectedemissions, vehicle activity, and human population. Data are availablefor 2012, as well as for the years 2000-2035 at five year intervals.Facility Search Engine- Allows users to locate criteria or toxics emissions data for a specific facility.Top 25 Source Categories- Provides users with emissions for thetop 25 highest emitting source categories by geographic area.EMFAC -EMFAC2011 is ARB’s official model for estimating emissions from on-road cars, trucks, and buses in California. The webbased EMFAC emission database provides annual and seasonal estimates for VMT, vehicle population, trips and emissions by vehicletype for years 1990-2035.InformationArea Designations- Provides information regarding the designationof areas in California with respect to the State ambient air qualitystandards.Air Quality Standards- Provides information on State and nationalair quality standards.Central California Air Quality Studies (CCAQS)- Comprises twostudies with the goal of providing an improved understanding of PMand visibility in central California.Climate Change- Information regarding ARB’s Climate ChangeProgram.Goods Movement Plan (GMP)- Presentation materials and policyinformation on California’s Goods Movement Plan.Community Health -Provides information on Community Healthprogams in place.Air Quality Data Monitoring Sites- Air monitoring web site withaccess to the most recent quality assurance information on any particular air monitoring site. This information consists of pollutantsmonitored, location, operation information, and photos of the site,if available.Web Resources(www.arb.ca.gov/californiaalmanac)Much of the information used to develop the Almanac is accessible through a variety of databases and tools available on the ARB website atwww.arb.ca.gov/californiaalmanac.File 02 Chap 1 Alm2013 p1-24.indd 2412/16/2013 10:24:19 AM