# SOUTH COAST AIR QUALITY

MANAGEMENT DISTRICT



# General Aviation Airport Air Monitoring Study

FINAL REPORT

August 2010

Prepared for the U.S. Environmental Protection Agency, Region IX San Francisco, CA 94105

i

## AUTHORS AND CONTRIBUTORS

The following individuals contributed to the development, implementation, and reporting of this project.

South Coast Air Quality Management District

Executive Officer Barry R. Wallerstein, D.Env.

Deputy Executive Officer Chung Liu, D. Env. Science and Technology Advancement



## AUTHORS

Philip Fine Atmospheric Measurements Manager Andrea Polidori Air Quality Specialist Solomon Teffera Principal Air Quality Chemist



## CONTRIBUTORS

Libby Ayers Meteorological Technician Steven Barbosa Principal Air Quality Chemist Paul Chavez Senior Air Quality Instrument Specialist Kevin Durkee Senior Meteorologist Rudy Eden Senior Laboratory Services Manager Sandra Hom Senior Air Quality Chemist Dan Houghton Senior Air Quality Chemist Judy Hwa Air Quality Chemist Aaron Katzenstein Program Supervisor Michael Koch Senior Air Quality Instrument Specialist Kay Liu Air Quality Chemist Jianhang Lu Air Quality Chemist Jason Low Quality Assurance Manager Paul Mayo Air Qualit y Instrument Specialist I Richard Parent Air Qualit y Instrument Specialist II Tom Parsons Atmospheric Measurements Manager Claudius Phipps Senior Air Quality Instrument Specialist Edward Ruffino Air Quality Instrument Specialist II Yang Song Air Quality Chemist Steve Taw Laboratory Technician Na Mon Trinh Assistant Air Quality Chemist Brian Vlasich Senior Air Quality Instrument Specialist Mark Von Der Au Supervising Air Quality Inspector Sumner Wilson Principal Air Quality Instrument Specialist Robert Yi Air Quality Chemist

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## TABLE OF CONTENTS

FIGURE AND TABLE CAPTIONS ......................................................................................................... III

EXECUTIVE SUMMARY ........................................................................................................................ IX

BACKGROUND

.............................................................................................................................. .. IX
OBJECTIVE

.............................................................................................................................. ......... IX
METHODS

.............................................................................................................................. ........... IX
KEY FINDINGS

.............................................................................................................................. .... X
CONCLUSIONS AND RECOMMENDATIONS

............................................................................. XII

INTRODUCTION

.............................................................................................................................. .......... 1

REGULATORY BACKGROUND ..................................................................................................... 1

AIRCRAFT EMISSIONS .................................................................................................................... 1

RESULTS FROM PREVIOUS STUDIES ........................................................................................... 3

CURRENT STUDY ON GENERAL AVATION ................................................................................ 5 The Van Nuys Airport (VNA)

........................................................................................................ 6 The Santa Monica Municipal Airport (SMO)

............................................................................... 7

METHODS

............................................................................................................................... ..................... 7

MONITORING SITES AT THE VAN NUYS AIRPORT ................................................................... 7 Van Nuys Airport Sampling Loctions

........................................................................................... 9

MONITORING SITES AT THE SANTA MONICA AIRPORT ....................................................... 10 Santa Monica Airport Sampling Location

.................................................................................. 11

MEASURED POLLUTANTS ........................................................................................................... 13

SAMPLING SCHEDULE ................................................................................................................. 13

LABORATORY ANALYSIS ............................................................................................................ 14

RESULTS AND DISCUSSION ................................................................................................................. 16

METEOROLOGY

............................................................................................................................. 16 Van Nuys Airport

........................................................................................................................ 16 Santa Monica Airport

................................................................................................................. 17

LEAD

............................................................................................................................... .................. 18 Van Nuys Airport

........................................................................................................................ 18 Santa Monica Airport

................................................................................................................. 20

EAST TARMAC SITE (METHOD COMPARISON) ....................................................................... 22

VOLATILE ORGANIC COMPOUNDS (VOC) ............................................................................... 24 Van Nuys Airport

........................................................................................................................ 25 Santa Monica Airport

................................................................................................................. 28

EIGHT-HOUR VOC ......................................................................................................................... 31 Van Nuys Airport

........................................................................................................................ 31 Santa Monica Airport

................................................................................................................. 33

CARBONYLS

.............................................................................................................................. ..... 34 Van Nuys Airport

........................................................................................................................ 34 Santa Monica Airport

................................................................................................................. 36

PM 2.5 MASS, ELEMENTAL AND ORGANIC CARBON ............................................................... 38 Van Nuys Airport

........................................................................................................................ 38 Santa Monica Airport

................................................................................................................. 41

ULTRAFINE PARTICLES ............................................................................................................... 44 Van Nuys Airport

........................................................................................................................ 44 Phase 1(November 2005 - March 2006)

.......................................................................... 44 Phase 2 (July - September, 2006)

.................................................................................... 47

iSanta Monica Airport

........................................................................................................................ 50 Phase 1(April - July, 2006)

.............................................................................................. 50 Phase 2 (October 2006 - February 2007)

........................................................................ 55

DAILY CARBON MONOXIDE (CO) VARIATIONS ..................................................................... 58

TRACE ELEMENTS ......................................................................................................................... 61

JET SIGNATURES ........................................................................................................................... 64

CONCLUSIONS AND RECOMMENDATIONS .................................................................................... 70

ACKNOWLEDGEMENTS ....................................................................................................................... 71

REFERENCES

.............................................................................................................................. ............. 72

APPENDIX A ............................................................................................................................................ 77

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## FIGURE AND TABLE CAPTIONS

Figure 1 A current aerial view of the Van Nuys Airport

Figure 2 A current aerial view of the Santa Monica Airport

Figure 3 Map of the Van Nuys Airport sampling sites. Yellow and blue circles represent “fully” and “partially” instrumented site s, respectively (see text for details)

Figure 4 Map of the Santa Monica Airport sampling si tes. Yellow and blue circles represent “fully” and “partially” instrumented sites, respectively (see text for details)

Figure 5 Average wind speed and direction at th e Van Nuys Airport during a) Phase 1 (November 2005 - March 2006) and b) Phase 2 (July - September, 2006)

Figure 6 Average wind speed and direction at the Santa Monica Airport during a) Phase 1 (April - July, 2006) and b) Phas e 2 (October 2006 - February 2007)

Figure 7 Box plots showing the median and mean l ead concentrations in total suspended particles (black and red lines wi thin each box, respectively) (ng/m 3 ) measured at the Van Nuys Airport during Phase 1 (November 2005 - March 2006) and Phase 2 (July - September, 2006). Representative lead levels fo r the South Coast Basin are also reported for comparison. Data collected during Phase 2 have been magnified on the top right panel to facilitate a comparison among sites

Figure 8 Box plots showing the median and mean lead concentrations in total suspended particles (black and red lines wi thin each box, respectively) (ng/m 3 ) measured at the Santa Monica Airport during Phase 1 (Apr il - July, 2006) and Phase 2 (October 2006 - February 2007). The correspondent lead levels for the South Coast Basin have also been reported for comparison

Figure 9 Comparison between lead concentra tions obtained from XRF and ICP-MS analyses of selected TSP samples collected at the East Tarmac site (Santa Monica Airport) during Phase 1

Figure 10 Box plots showing the median and mean lead concentrations (ng/m 3 ) in fine particulate matter (PM 2.5 ) measured at four monitoring si tes of the Santa Monica Airport (black and red lines within each box, respec tively) during Phase 1 (April - July, 2006) and Phase 2 (October 2006 - February 2007). Lead levels for the South Coast Basin (same time periods) and at MATES III sites (from April 2005 to March 2006 only) are shown for comparisoniv Figure 11 Spatial distributions of a) 1,3-butadiene, methylene chloride, and chloroform, b) benzene, carbon tetrachloride, and toluene, and c) perchlroethyl ene at 5 monitoring sites of the Van Nuys Airport (i.e. Golf Course, Holmes School, VOR, and National Guard sites) during Phase 1 (November 2005 - March 2006) and Phase 2 (July 200 - September, 2006). Data collected concurrently at a monitoring station in Burbank are also included for comparison

Figure 12 Spatial distributions of a) 1,3-butadiene, methylene chloride, and chloroform, b) benzene, carbon tetrachloride, and toluene, and c) tr ichloroethane and perchloroethylene at selected monitoring site s of the Santa Monica Airport (i.e. Richland School, Marine Park, Ernst Residence, East Tarmac, West Tarmac sites) during Phase 1 (April - July, 2006) and Phas e 2 (October 2006 - February 2007). Data collected concurrently at a monitoring site in Central Los Angeles are also included for comparison

Figure 13 Percentage contribution of volatile organic compounds (VOCs) measured at the VOR site during three 8-hr intervals (i.e. 00:00 to 08:00, 08:00 to 16:00, and 16:00 to 00:00) to the corresponding 24-hr average conc entrations. The two panels refer to a) Phase 1 (November 2005 - March 2006) and b) Phase 2 (July - September, 2006) data

Figure 14 Percentage contribution of volatile organic compounds (VOCs) measured at the West Tarmac site during three 8-hr inte rvals (i.e. 00:00 to 08: 00, 08:00 to 16:00, and 16:00 to 00:00) to the correspond ing 24-hr average concentrations. The two panels refer to a) Phase 1 (April - Jul y, 2006) and b) Phase 2 (October 2006 - February 2007) data

Figure 15 Spatial distributions of formaldehyde, acetaldehyde, acetone, and methyl ethyl ketone (MEK) at selected monitoring sites of the Van Nuys Airpor t (i.e. Golf Course, Holmes School, VOR, and National Guard sites) during Phases 1 and 2. Data collected at an AQMD monitoring station in Burba nk are also included for comparison

Figure 16 Spatial distributions of formaldehyde, acetaldehyde, acetone, and methyl ethyl ketone (MEK) at selected monitoring site s of the Santa Monica Airport (i.e. Richland School, Marine Park, Ernst Residence, East Tarmac, and West Tarmac sites) during Phases 1 and 2. Data collected at an AQMD monitoring station in Central Los Angeles are also included for comparison

Figure 17 Spatial distributions of fine particulate matter (PM 2.5 ), organic and elemental carbon (OC and EC, respectively) at selected monitoring sites of the Van Nuys Airport (i.e. Golf Course, Holmes School, VOR, and Na tional Guard sites) during Phases 1 and 2. Data collected at an AQMD monitoring sta tion in Burbank are also included for comparison

Figure 18 Spatial distributions of fine particulate matter (PM 2.5 ), organic and elemental carbon (OC and EC, respectively) at selected monitoring sites of the Santa Monica Airport (i.e. Richland School, Marine Park, Ernst Residenc e, East Tarmac, and West Tarmac sites) during Phases 1 and 2. Data co llected at an AQMD monitoring station in Central Los Angeles are also included for comparisonv Figure 19 Representative hourly averag e ultrafine particle (UFP) number concentrations (#/cm 3 ) at the Van Nuys Airport measured from 02/10/06 to 02/28/06. Hourly data were averaged from 1-min values to facilitate comparison among sites (top panel). An example

of more resolved 1-min data is shown in the magnified portion of the graph within broken

lines

Figure 20 Average diurnal profiles of the ultraf ine particle (UFP) number concentration (#/cm 3 ) measured at three sites of the Van N uys Airport (i.e. Golf Course, VOR, and Holmes School stations) during Ph ase 1 (November 2005 - March 2006)

Figure 21 Representative hourly averag e ultrafine particle (UFP) number concentrations (#/cm 3 ) at the Van Nuys Airport measured be tween 09/01/06 and 09/18/06. Hourly data were averaged from 1-min measurements to facilitate comparison among sites (top panel). An example of more resolved 1-mi n data showing elevated UFP levels from 09/07/06 to 09/09/06 is illustrated in the magni fied portion of the graph within broken

lines

Figure 22 Average diurnal profiles of the ultraf ine particle (UFP) number concentration (#/cm 3 ) measured at three sites of the Van N uys Airport (i.e. Golf Course, VOR, and National Guard stations) during Ph ase 2 (July - September, 2006)

Figure 23 Representative hourly averag e ultrafine particle (UFP) number concentrations (#/cm 3 ) at the Santa Monica Municipal Air port measured from 05/03/06 to 05/24/06. Hourly data were averaged from 1-min m easurements to facilitate comparison among sites (top panel). An example of more resolv ed 1-min data showing elevated UFP levels

from 05/11/06 to 05/12/06 is illustrated in the magnified portion of the graph within

broken lines

Figure 24 Ultrafine particle (UFP) number concen trations data showing the impact of aircraft movements at the East Tarmac, Ernst Residence, West Tarmac, Richland Elementary School sites on 07/07/06

Figure 25 Average diurnal profiles of the ultraf ine particle (UFP) number concentration (#/cm 3 ) measured at five sites of the Santa Monica Airport (i.e. East Tarmac, West Tarmac, Ernst Residence, Richland School, a nd Marine Park) during Phase 1 (April - July, 2006)

Figure 26 Representative hourly averag e ultrafine particle (UFP) number concentrations (#/cm 3 ) at the Santa Monica Municipal Air port measured from 01/01/07 to 01/23/07. Hourly data were averaged from 1-min m easurements to facilitate comparison among sites (top panel). An example of highly resolved 1-min data showing elevated UFP levels

from 01/02/07 to 01/03/07 is illustrated in the magnified portion of the graph within

broken linesvi Figure 27 Average diurnal profiles of the ultraf ine particle (UFP) number concentration (#/cm 3 ) measured at four sites of the Santa Monica Airpor t (i.e. East Tarmac, West Tarmac, Ernst Residence, and Richland School ) during Phase 2 (October 2006 - February 2007)

Figure 28 Average diurnal variations of carbon monoxi de (CO; ppm) at four sites of the Van Nuys Airport (i.e. Golf Course, VOR, Holmes School and National Guard). Measurements were taken from a) November 2005 to March 2006 (Phase 1) and b) between July and September 2006 (Phase 2). Because of a malfunctioning of several monitors deployed at VNA and issues related to data recovery, CO concentrations for Phase 1 are only available at the VOR site

Figure 29 Average diurnal variations of carbon m onoxide (CO; ppm) at different four

sites of the Santa Monica M unicipal Airport, namely West Tarmac, Ernst Residence, Richland School, and Marine Park. Measurements were taken a) from April to July 2006 (Phase 1) and b) between October 2006 and March 2007 (Phase 2)

Figure 30 Ambient concentrations of selected metals in fine particulate matter (PM 2.5 ) at different sampling locations of the Van Nuys Airport during a) Phases 1 (from November 2005 to March 2006) and b) Phase 2 (from July to September 2006)

Figure 31 Ambient concentrations of selected me tals in fine particulate matter (PM 2.5 ) at different sampling locations of the Santa Monica Airport during a) Ph ase 1 (from April to July 2006) and b) Phase 2 (f rom October 2006 to March 2007)

Figure 32 Comparison between the emission pr ofiles of the two canister samples

collected at the East Tarmac site and those of a) jet fuel, b) diesel exhausts, and c) gasoline vehicle emissions. Data are expressed as the percentage weight contribution of each species to the total measured organic ga s concentration. The emission profiles of jet fuel exhaust (aircraft exhaust - jet fuel), typical gasoline vehicle emissions (gasoline - catalyst - stabilized exhaust - ARB summer 2003), and diesel exhaus t (farm equipment - diesel - light & heavy) were downloaded from the California Air Resource Board (CARB) speciation database for organic compounds (ORGPROF; http://www.arb.ca.gov/ei/speciate/speciate.htm )

Figure 33 Comparison between the hazardous air po llutants (HAPs) speciation profile for commercial aircraft engi nes emission profiles provided by EPA (Aircraft Engine Speciated Organic Gases: Speciation of Unbur ned Organic Gases in Aircraft Exhaust, prepared by EPA in 2009) and those of the tw o canister sample collected at the East Tarmac site when jets were either idling or taking-off (sample #1; bottom panel) and when no aircraft activity was ongoing (sample #2; top panel)

Table 1 List of the most relevant particle a nd gaseous species monitored during this study at both the Van Nuys and Santa Monica Airports

Table 2 Sampling schedule for the Van N uys and Santa Monica Airportsvii Table 3 Sampling and analysis methods

Table 4 Average and median lead concentrations in total suspended particles (ng/m 3 ) at the Van Nuys Airport during Phase 1 (Nove mber 2005 - March 2006) and Phase 2 (July - September, 2006). Minimum (Min) and maximu m (Max) values, standard deviations (SD), and the total number of valid samples (Va lid N) have also been reported along with representative lead data for the South Coast Basin (in red)

Table 5 Average and median lead concentrations in total suspended particles (ng/m 3 ) at the Santa Monica Airport during Phase 1 (Apr il - July, 2006) and Phase 2 (October 2006 - February 2007). Minimum (Min) and maxi mum (Max) values, standard deviations (SD), and the total number of valid samples (Va lid N) have also been reported along with representative lead data for the South Coast Basin (in red)

Table 6 Average and median fine particulate matter (PM 2.5 ), organic and elemental carbon (OC and EC, respectivel y) concentrations (μg/m 3 ) at the Van Nuys Airport

stations and at an urban site in Burba nk (CA) during Phase 1 (November 2005 - March 2006) and Phase 2 (July - September, 2006). Minimum (Min) and maximum (Max) values, standard deviations (SD), and the total number of va lid samples (Valid N) have

also been included

Table 7 Average and median fine particulate matter (PM 2.5 ), organic and elemental carbon (OC and EC, respectivel y) concentrations (μg/m 3 ) at the Santa Monica Airport

stations and at an urban site in Central Los Angeles (CA) during Phase 1 (April - July, 2006) and Phase 2 (October 2006 - March 2007 ). Minimum (Min) and maximum (Max) values, standard deviations (SD), and the total number of va lid samples (Valid N) have

also been included

Table 8 Average and median ultrafine particle (UFP) number concentrations (μg/m 3 ) at the Van Nuys Airport stations during Phas e 1 (November 2005 - March 2006). Minimum (Min) and maximum (Max) values, standard de viations (SD), and the total number of valid samples (Valid N) have also been included

Table 9 Average and median ultrafine particle (UFP) number concentrations (μg/m 3 ) at the Van Nuys Airport stations during Phas e 2 (July - September, 2006). Minimum (Min) and maximum (Max) values, standard deviat ions (SD), and the total number of valid samples (Valid N) have also been included

Table 10 Average and median ultrafine particle (UFP) number con centrations (#/cm 3 ) at the Santa Monica Airport sta tions during Phase 1 (April - July, 2006). Minimum (Min) and maximum (Max) values, standard deviat ions (SD), and the total number of valid samples (Valid N) have also been included

Table 11 Santa Monica Airport take-off observa tion data on 7/17/2006. Time periods associated with the particle number concentr ation peaks in Figure 24 are highlighted in

redviii Table 12 Average and median ultrafine particle (UFP) number con centrations (#/cm 3 ) at the Santa Monica Airport stations du ring Phase 2 (October 2006 - March 2007). Minimum (Min) and maximum (Max) values, st andard deviations (SD), and the total number of valid samples (Valid N) have also been included

Table 13 Ambient concentrations (p pb) of several important gaseous pollutants present in canister samples collected at the East Ta rmac site (samples #1 and #2) and behind the blast-fence (sample #3) at SMOix 

## EXECUTIVE SUMMARY

BACKGROUND The Van Nuys and Santa Monica Municipal Airports (VNA and SMO, respectively) are among the most important ge neral aviation airports (GA) in the South Coast Air Basin. In 2005, VNA was the worl d's busiest GA air port with around 450,000 takeoffs and landings annually, while SMO is the oldest operating GA airport in Los Angeles County. Both airports are surrounded by public areas and private residences, and odor and/or noise complaints by people living in nearby communities have raised concerns about possible health effects from exposure to gaseous and particle pollutants emitted from the airport areas.

OBJECTIVE Conducted as part of a Community-Scale Air Toxics Ambient Monitoring Grant from the U.S. Environmental Protection Agency (U.S. EPA), the main goal of this study

is to characterize the ambient levels of several important air toxics in communities adjacent to VNA and SMO. Since GA aircraft with piston-driven engines use leaded gasoline, lead monitoring was a major focu s of this study. Also, because jet turbine engines emit substantial am ounts of ultrafine particles (UFPs) and other combustionrelated pollutants, attenti on was given to the monitori ng of the particle number concentration (an indicator of UFPs). R ecent studies conducted at the Los Angeles International Airport (LAX) and at SMO (Fanni ng et al., 2007; Westerdahl et al., 2008; Hu et al., 2009) have shown that UFP levels are higher in areas adjacent to and downwind of the airport runways. Vola tile organic compounds (VOCs), carbonyl compounds, fine particulate matter (PM 2.5 ) and some of its organic and inorganic components (i.e. organic and elemental carbon, and trace elements) were also measuredat VNA and SMO. Although the monitoring approach was designed to focus on longterm exposures, the potential for short-te rm exposures was examined by continuous measurements of UFP and carbon monoxide (CO).

METHODS The monitoring strategy included deployment of sampling equipment near runways and at locations in the community under the flight path to detect and characterize pollution levels and exposure gradients caused by airport emissions. The sampling protocols were primarily based on pr evious AQMD air toxics studies such as the Multiple Air Toxics Exposure Study (MATES-III). Sites that were placed upwind and downwind of each airport included a full array of integrated samplers (for the collection of total suspended particles for lead analysis, selected VOCs, carbonyls, and metals) and continuous analyzers (for UFP and CO measur ements). Other locations situated to the sides of the runways were monitored using lead samplers and CO sensors only. Sampling was conducted for two different periods at each airport to assess th e seasonal variability of the measured pollutants. Each monitoring period lasted for a nominal three months. The first phase of sampling at VNA was fr om 11/22/2005 to 3/3/2006. This was followedx by a field campaign at SMO from 4/26/2006 to 7/19/2006. The second sampling campaign in Van Nuys was conducted from 7/28/2006 to 9/29/2006, followed by

measurements in Santa Monica from 10/20/2006 to 3/1/2007. Integrated and continuous data from the analysis of all collected sample s were analyzed to assess the levels of air

toxics in the communities relative to other ar eas of Southern California. The data were also examined to determine, if possible, th e contribution of airpor t-related emissions and those from other potential po llution sources (such as local traffic) on the measured ambient levels. Meteorological data at VNA and SMO were provided by the local airport

authorities.

KEY FINDINGS

• The 24-hr average total suspended particulat e (TSP) lead concentration gradient at the Van Nuys and Santa Monica Airports reflected the relati ve distance of the various monitoring sites from the runway areas. This indicates that piston-driven aircraft and the leaded fuel they use we re sources of TSP lead at the monitored stations. Daily average TSP lead con centrations at VNA and SMO sites were substantially higher (up to two and nine times higher, respectively) than the corresponding South Coast Basin levels dur ing the same time periods, and mostly

below the new national ambient air quality standard (NAAQS) of 150 ng/m 3

. However, 24-hr average concentrations cl ose to, or above the current NAAQS for

lead were recorded at SMO near the Tarmac in more than one occasion and during both phases of the study. In add ition to direct aircraft exhaust contributions, decades of aircraft exhaust emissions may have caused lead accumulation in the soil on which the samplers were located. A recent study conducted by U.S. EPA regarding lead emissions from SMO included soil analysis for lead (U.S. EPA, 2010). However, results from the analysis of samples collected at SMO using the PM 2.5 speciation samplers indicates that the majority of particulate lead is present in the fi ne fraction, suggesting that a relatively high proportion of lead at this airport was not associated with re-suspended material.

• The atmospheric levels of VOCs at VNA and SMO stations were mostly influenced by their proximity to busy surface streets surrounding the airports’ perimeters and nearby freeways. However, the contributions of these and other potential pollution sources (including airport-related em issions) to the measured VOC and carbonyl levels could not be a ssessed from the available data. The highest VOC concentrations measur ed at VNA and SMO were generally comparable to or lower than those obse rved at two companion urban monitoring sites (Burbank and Central Los Angeles, respectively), where motor-vehicles emissions dominate the atmospheric le vels of most primary pollutants.

• The mass concentrations of PM 2.5 , organic carbon (OC) and elemental carbon (EC) at all Van Nuys and Santa Moni ca stations were at or below the corresponding South Coast Basin averag es. Comparisons among sampling sites did not show any significant spatial or tem poral gradient that could be attributed to aircraft operations. It is likely that other local and regional sources (e.g. motor-xi vehicle emissions from nearby traffic and atmospheric transport of aged pollutants, respectively) were mainly responsible for the observed atmospheric

levels of PM 2.5 and its carbonaceous components.

• Aircraft idling near the runway before departure and duri ng take-off were found to generate large numbers of UFPs ov er short time periods. Continuous (1- minute) particle number levels up to 600 times higher than those measured in background air were observed both in Van Nuys and in Santa Monica, including

at a residential site located less than 100 m downwind of SMO. Emissions from major freeways and surface streets surrounding both airports are another source ofUFPs, but the largest short term increases were often not consistent with motorvehicle sources. Further work is needed to better de fine the contribution of aircraft to community UFP exposures with respect to specific ai rcraft and airport operations.

• The average diurnal profile of CO at the Van Nuys and Santa Monica stations followed a distinctively different pattern from that observed for other combustionrelated pollutants su ch as UFP count and EC, with peak values during morning

rush hour traffic and lower levels in the afternoon. This suggests that the concentration of this gaseous polluta nt was dominated by contributions from motor-vehicle emissions from nearby road ways/freeway and surface streets, and that the influence from airport-related activities was not significant.

• Our results suggest that the majority of the trace elements detected in the PM 2.5 samples collected at both airports orig inated from re-suspension of crustal materials. The atmospheric concentrations of all measured metals are comparable to those reported in previous studies conducted in the South Coast Air Basin.

• An analysis of the VOC profile of two can ister samples collected at SMO near the blast-fence when jet-propelled planes were idling close to the runway and when no airplane activity was occurring revealed that emissions fr om aircrafts idling before departure increased the concentr ation of all combustion-related VOCs substantially. The speciation pr ofile of the idling sample closely resembles that of typical jet exhaust, indicating that short- term VOC levels near the runway were influenced by aircraft emissions when jets were idling before take-off. Conversely, the emission profile of the other sample is similar to that of diesel truck emissions; when no airplane activit y was taking place, the ambient air was probably affected by diesel emissions from vehicles operating within or in close proximity of the airport’s perimeter. Lastly, the VOC profiles of both these samples differ from that of gasoline ve hicle exhaust, indicating that gasolinepowered vehicles did not influence the co mposition of the two canister samples at the time of sampling.

• Overall, the atmospheric concentrations of most of the measured air toxics were higher during the winter mont hs than in the summer period. This seasonal pattern

of air toxics levels is similar to that observed in previous studies in the Southxii Coast Air Basin. In the late fall and early winter, light winds result in reduced ventilation, and overnight inversions contribute to incr easing surface-level concentrations of those pollutants th at are emitted from ground-level sources. During the summer months, stronge r on-shore breezes and atmospheric

circulation due to increased solar in sulation results in higher wind speeds, increased vertical atmospheric disper sion and, subsequently, reduced ambient concentrations at ground level.

CONCLUSIONS AND RECOMMENDATIONS Overall, the most significant airport-rela ted impacts on air quality were observed for lead and for UFPs. Airport impacts on other pollutant levels were difficult to determine, but appeared to be minor when considering long-term averages. This study focused on longer-term exposure as it was based on MATES-III sampling protocols. Shorter term impacts may be present, such as those observed for UFPs, instantaneous VOCs, and odors. Further investigation into s hort-term impacts would require a different study design with more continuous measur ements, although continuous instruments for some air toxics are not commercially availa ble. Future work may also include more

detailed measurements of UFP levels correlate d to aircraft type and aircraft operations.1 

## INTRODUCTION

REGULATORY BACKGROUND Questions regarding the impact of airpor t related pollution on local air quality arose in the 1960s. The first comprehensiv e studies on aircraft’s emissions were conducted by the then Los Angeles County Ai r Pollution Conctrol District in 1960 and 1965 (Bastress 1973). Their results indicated th at aircraft contributed to a small but significant fraction of the pollutants emitted in the Los Angeles County. However, the integrated and centralized assessment and gath ering of data in a regulatory framework

started after the Clean Air Ac t (CAA) of 1970 was passed by the United States Congress. CAA gave the Environmental Protection Agency (EPA) the right to establish air pollution standards, including those appli cable to aircraft exhaust. Section 231(a)(2)(A) of the

CAA directs the EPA administrator to “issue proposed emission standards applicable to the emission of any air pollutant from any cla ss or classes of aircraft or aircraft engines which in his judgment causes, or contribute s to, air pollution wh ich may reasonably be anticipated to endanger public health or welfare”. Under this authority EPA has conducted several rulemakings since 1973, esta blishing emission standards and related requirements for several classes of aircrafts and aircraft engines, including commercial and general aviation engines. Although airpor ts don’t meet the definition of “area” or “major” source under section 112 of the CAA, the EPA has taken a “combinations of sources” approach to tackle the issue of airport emissions and their impact on the surrounding communities. To this end, EPA releas ed a report in April 1999 that assessed the potential impact of aircraft emissions on loca l air quality at ten se lected airports (U.S. EPA, National Emission Trends, Average A nnual Emissions, All Criteria Pollutants, 1970-2001, August 13, 2003). The International Civil Aviation Organi zation (ICAO) was created by the United Nations in 1947 to "achieve maximum compatibility between the safe and orderly development of civil aviation and the quali ty of the human environment". The United States is one of more than 150 participati ng members or "Contracting States" of this organization. To achieve its objective, ICAO established exhausts emissions standards and test procedures for three pollutants: hydr ocarbons (HCs), carbon monoxide (CO), and oxides of nitrogen (NOx), that are expected to be met by each of the Contracting States. Throughout the past few decades numerous a nd increasingly stringent standards have been set by ICAO to reduce aircraft emi ssions, and in 2005 EPA amended the existing

emission standards for NOx for new commercia l aircraft engines (EPA, 2005) to bring

the United States aircraft standards into al ignment with the international guidelines. These standards apply to new aircraft engine s utilized on small regiona l jets, single-aisle airplanes, twin-aisle aircrafts, and other larger commercial units.

AIRCRAFT EMISSIONS In addition to the carbon dioxide (CO 2 ) released by airplanes in flight through the burning of fuels [such as jet-A for turbine aircraft, or aviation gas (Avgas) for piston aircraft], other important pollutants are typi cally present in aircraft emissions. These include CO, nitrogen dioxide (NO 2 ) and nitrogen monoxide ( NO), water vapor, sulfur2 oxides (SOx), incompletely-burned HCs, tr ansition metals (e.g. lead) and particulate matter (PM) of various sizes (http://epa.gov/oms/aviation.htm) . Ultrafine pa rticles [UFP; particle diameter (Dp) ≤ 0.10 μm] are the biggest contributo r to the total pa rticle number concentration and have the highest potential to penetrate deeply into the human lungs. In a recent study conducted by Ntziachristos et al. (2007a), size-fractionated ambient PM samples [i.e. UFP, accumulation (Dp ≤ 2.5μm), and coarse (2.5 μm ≤ Dp ≤ 10 μm) mode particles] were collected at four different locations in the Los Angeles Basin, and analyzed for their redox potential (an indicator of particle t oxicity; Cho et al, 2005; Geller et al., 2006). The ultrafine fr action had the highest redox ac tivity on a per-PM mass basis. No health-based standards are currently in place for this important PM fraction. Emissions from airports are associated with both direct emission (i.e . aircraft exhaust) and different airport activities including refueling, pre-flight safety procedures, and fuel venting (Federal Aviation Administration; http://www.faa.gov/regula tions_policies/). In the Los Angeles metropolitan area the combustion of gasoline and other hydrocarbon fuels in automobile, trucks, airpla nes and marine vessels represent the main sources of PM (including UFP), transiti on metals, volatile organic compounds (VOCs), CO, NOx, and other primary emitted pollutants. In order to improve our understanding of the toxic risk associated with exposure to these particulate and ga seous species, it is important to characterize the contribution and spatial distri bution of the most important mobile, point and areas sources, and thei r relative impact on nearby communities. Although most of the air toxic studies on co mbustion-related species have focused on motor-vehicles emissions, the contribution of aircraft emissions to air toxic exposure

levels should be examined for individuals livi ng in close proximity of an airport area. The term “general aviation” (GA) refers to most of the aircraft used for recreational flying and persona l transportation. Airplanes th at support business travel, usually on an unscheduled basis, are also included in this cate gory. General aviation flights range from gliders and powered par achutes to large, non-scheduled cargo jet flights. As a result, the majority of the world's air traffic falls into this category, and most of the world's airports serve GA exclusively. One of the fastest growing areas in the GA sector is that of small pass enger aircraft and cargo for s hort distance. These airplanes, usually smaller than those opera ted by major carriers and ofte n referred to as “air taxis”, provide scheduled services by carrying passengers, freight, or both. Ai r taxis have been playing an increasingly important role in the U.S. aviation system, and by 2015 such operations are forecast to repres ent 54% of total air traffic (http://www.apo.data.faa.gov/main/taf.asp; U. S. EPA Average Annual Emissions, All

Criteria Pollutants Years Includ ing 1980, 1985, 1989–2001, February 2003). Most GA aircraft are powered by piston engines and are fueled by Avgas [one hundred octane low lead aviation gas (100LL Avgas) is the most commonly available type of aviation gasoline in the United States], which is characterized by a higher volatility and lead content than other gasoline fu els. Lead is added to the fuel as tetraethyl lead, an additive that boosts fu el octane and prevents valve seat recession, which can be a significant concern from a safety standpoint. Lead is not present in the je t fuel that is used in commercial, military, or other turbine-engine powered aircrafts.3 RESULTS FROM PREVIOUS STUDIES Unlike the present work, the vast majority of the studies that examined the impact of airport operations on local air quality focused on emissions from very large commercial aircraft. Spicer et al. (1984) first reported NOx, CO, PM, and speciated HC emission rates from jet aircraft turbine engi nes. Further studies by Spicer et al. (1992, 1994) provided additional information on the detailed organic composition of turbine engine exhausts, and revealed that during engine idle, emissions were dominated by products from fuel cracking, unburned fuel a nd products of incomplete combustion, with ethene, propene, acetylene and formaldehyde comprising 30–40% of the total HC

emissions. Between 1998 and 2001, the South Coast Ai r Quality Management District (AQMD) conducted a series of monitoring campaigns at several locations surrounding the Los Angeles International Ai rport (LAX) (AQMD 1998, 2000a, 2000b, 2001). PM 10 (Dp ≤ 10 μm), organic and elemental carbon (O C and EC, respectively), CO, and VOCs (e.g. benzene, 1,3 butadiene, and formaldehyde) c oncentrations were measured with time

resolutions between 8 and 24 hours and were found to be higher th an the corresponding ambient levels away from the airport. The re lative contribution of LA X aircraft emissions to the total measured pollutant concentrati ons could not be estimated, mainly because more resolved (e.g. hourly) data were not available, and because vehicular emissions from heavily trafficked roads nearby (e.g. Aviation Boulevard and the 405 Freeway) may have influenced the atmospheric concen tration of the targ eted compounds. In 2000, AQMD undertook a study at Felton Elementary School and Lloyde High School in response to community concerns about the impact of the pollutants emitted from the LAX and the 405 Freeway on local ai r quality (Air Monitoring Study at Felton and Lloyde Schools, September 2001, South Coas t Air Quality Management District).

The results indicated that concentrations of all monitored air contaminants (with the exception of carbonyl compounds) at these schools were at or below the average levels for the Los Angeles Basin. Increased concen trations of carbonyl sp ecies were probably

related to emissions from both LAX and th e heavily trafficked 405 Freeway. A proposed plan to conduct a more comprehensive air monitoring study with measurements within and outside the airport was delayed due to the September 11, 2001 incident. This monitoring campaign is currently planned to be conducted by Los Angeles World Airports, the operator of LAX, for 2011. A more recent field study was conducted in 2003 by Westerdahl et al. (2008) to

determine how emissions from LAX affect the ambient air of a nearby residential neighborhood located downwind of the airport. A mobile air monitoring platform was deployed to measure UFP number, black carbon (BC), NOx and particle-bound polycyclic aromatic hydrocarbons (p-PAHs) concentrations and the particle size distribution. Ultrafine partic le counts at an upwind coastal site (580-3,800 #/cm 3 ) were substantially lower than those observe d 500 m downwind of the airport (~50,000 #/cm 3 ) in a residential area. Black carbon, p-PAHs, and NOx levels were also elevated at locations further downwind, but to a lesser extent. Peaks of about 5×10 6 #/cm 3 were occasionally measured downwind of a runway used by jet aircrafts for take-off. The size distributions found at the upwind and downwi nd sites were dominated by particles with

mode diameters of ~90 a nd ~10-15nm, respectively.4 A similar study was conducted by the Califor nia Air Resource Board (CARB) and the University of California, Los Angele s (UCLA), in 2005-2006 (Fanning et al., 2007)

to monitor UFP and BC levels at and in the vicinity of the LAX. Near real-time instruments were employed to measure the number concentrations and the size

distribution of UFP from airc raft emissions, and to capture the corresponding temporal variability. Increased number concentrations of UFP with a mode diameter of around 14

nm were found downwind of an area where ai rcrafts were taking-off, and the total UFP

counts exceeded 10 7 #/cm 3 in some occasions, consistent with the findings of Westerdahl et al., 2008. Number concentratio ns of UFP were lower at a residential community 2-3 km east of the LAX, but still higher than those at a background re ference site located further away. Time averaged levels of PM 2.5 mass, formaldehyde, and acrolein were elevated at the airport site s relative to those at a background location. However, the

concentrations of most VOCs were ar ound or below the corresponding Los Angeles Basin average values. Despite the influen ce of airport emissions on the UFP count observed at this residential community, no increa se in the exposure levels to any of the other measured pollutants were found. During a monitoring study conducted in 2006 at the Teterboro Airport (TEB; one of the busiest GA airports in the United St ates located in Teterboro, New Jersey), ENVIRON Corp. measured the concentrations of selected air toxics at the airport fenceline, and evaluated the associated risks to human health (Teterboro Airport, New Jersey, Detailed Air Quality Evaluation, Final Re port Prepared by ENVIRON Corp. in 2008). Four sampling stations were set-up to monitor PM 2.5 , BC, and selected VOCs and carbonyls. The median, mean, and maximum concentrations of certain VOCs (formaldehyde and toluene in particular) were significantly higher than those measured further from TEB, where concentrations are typically dominated by mobile source emissions (such as in Elizabeth, New Jersey). The atmospheric concentrations of other VOCs detected around TEB (e.g., benzene, aceta ldehyde) were comparable to those at other “representative” New Jersey locations. A conservative risk assessment was also

conducted to estimate the health implications of these monitoring data. Between 75 and

87% of the cancer risk associated with th e concentrations of VOCs detected at the 4

monitored locations was associated with formaldehyde exposure. Although the PM 2.5 and BC levels measured around the TEB area appeared to be higher than those at other New Jersey monitoring locations, th e data were insufficient to quantify the contributions from airport activities, which ar e highly dependent on wind direction and wind speed. Another relevant study was conducted inSeptember 2004 at the HartsfieldJackson International Airport (one of the world’s busiest airports both in terms of

numbers of aircraft and numb ers of passengers conveyed) in Atlanta, Georgia, to characterize commercial aircraft engine emi ssions of in-use aircrafts (Herndon et al., 2008). A mobile laboratory wa s set-up downwind of the active runway and taxiway, inside the airport fence-line. Emissions from in-use commercial aircraft engines were analyzed continuously for selected gaseous and particle species (e.g. CO, NOx and BC) and particle characteristics (e.g. particle number concentrat ion and size distribution). The CO emission index (i.e. amount of CO emitted per Kg of fuel burnt) observed in ground idle plumes was up to 100% greater than th at predicted by engine certification data provided by ICAO at 7% thrust conditions. Significant differen ces were also observed in the emissions of BC and particle numbe r among different aircrafts and engine5 models/technologies, sugge sting that total emissions of gaseous and particle pollutants from aircraft exhausts might be misrep resented (or under estimated) in current inventories such as the ICAO databank (s ee Herndon et al. 2009 for more details). Therefore, this study concluded that there is a need to re vise the current information

about emissions of air contaminants from modern aircraft engines run under different operating conditions (e.g. idle , take-off and cruise). Similar studies on air pollutant emissions from aircrafts and airport-related

activities have also be en conducted at several European cities. For example, during the AIRPUR project Lelievre et al. (2006) characterized the physical and chemical characteristics of various gaseous and particle pollutants at the Charles de Gaulle (CDG) Airports in Paris, France, using various real-time, integrated and remote sensing techniques, and investigated the influence of these em issions on local air quality. Measurements of PM, UFP number, soot, CO, NOx, and speciated VOCs were taken three days in late 2004 and seven days in early 2005 at aprons, beside taxiways and runways, at engine test areas, along roads, and at ai rport landscape areas. Sampling performed inside engine plumes for different power settings showed a maximum in UFP

number on the order of 10 6 #/cm 3 at 7-10 nm in diameter, while the number concentration of the soot mode (20-40 nm) was a factor of 100 lower. The analysis of the collected filter samples revealed the presence of aggregated soot (20-40 nm) and aerosols containing some proportion of S, Si, Fe, Ca, Mg, and K. Volatile organic compound emissions indicated a maximum for ehtyne, propene, ethane, benzene, toluene, m/pxylenes, nonane and 1,3-butadiene. Although co ntributions of particle and gaseous pollutants from the CDG Airports were found to be substantial, the airport maximums

were lower than those observed in its vicinities and in the city of Paris during the same time period. In a recent field campaign conducted in the spring/summer of 2008, Hu et al. (2009) measured real-time air pollutant concentrations downwind of Santa Monica Airport, a GA airport operated for priv ate aircraft and corporate jets in Los Angeles County, California. Aircraft operations resulted in study average UFP levels that were elevated by factors of 10 and 2.5 at 100 and 660 m downwind of the runway, respectively, over background c oncentrations. These elevated UFP concentrations were mostly associated with jet departures, but al so with jet taxi and idle, and operations of propeller aircrafts. Conversel y, aircraft emissions did not appreciably el evate average levels of BC and p-PAHs, although spikes in the concentration of these pollutants were commonly associated with jet take-offs. Jet de partures resulted in peak 1-min average concentrations of up to 2.2 × 10 6 #/cm 3 , 440 ng/m 3 , and 30 μ g/m 3 for UFPs, p-PAH, and BC, respectively, 100 m downwind of the take-off area. These peak levels were elevated by factors of 440, 90, and 100 compared to the corresponding backgroun d concentrations.

CURRENT STUDY ON GENERAL AVATION Between November 2005 and February 2007 AQMD conducted a series of field campaigns aimed to study the air quality in the communities around the Van Nuys Airport (VNA) and Santa Monica Municipal Airport (SMO). The concentrations of several gaseous and particle pollutants (i.e. PM, BC, OC, VOCs, lead and other trace elements, VOCs and carbonyls) and some of th eir physical and chemical characteristics(e.g. number of UFPs) were measured using re al-time and time-integrated instruments at multiple monitoring stations set-up inside and at different distances from the airports perimeters. The average concentrations of th e measured chemical species were compared to the corresponding South Coast Air Basin av erages and to values obtained at two additional concurrent monitoring sites locate d in Central Los Angeles and in Burbank, CA. The resulting data were analyzed to de termine if one or both of the study areas showed ambient air toxic concentration gradie nts that can be attr ibuted to aircraft emissions/airport activities and/ or to other potential source s of air pollution such as roadway emissions. Launched as part of the U.S. EPA Commun ity Scale Air Toxics Grant, the main objectives of this study are a) to characteri ze the air toxics levels in the communities around SMO and VNA, b) to determine the potential impact of airport emissions on measured pollutant levels, c) to establish if airport-related emissions are distinguishable from those of other potential sources (e.g. nearby traffic), and d) to pr ovide baseline data for future studies. Background information about the two airports studi ed during this field campaign is reported below.

The Van Nuys Airport (VNA) Located in the San Fernando Valley area in the city of Los Angeles, California, VNA (Figure 1) is a public airport used by pr ivate, chartered, and small commercial aircraft (no commercial airlines fly into this airport). Owned and operated by Los Angeles World Airports (LAWA), VNA is one of the busiest GA air ports in the world with around 450,000 takeoffs and landings annua lly (2005). With two parallel runways, this airport handled around 1,200 and 1,100 operations per day in 2005 and 2006, respectively. By comparison, LAX (with 4 r unways and a large amount of commercial traffic) has about 1,700 operations /day. Most of the news helicopters used in the Los Angeles area are based at VNA. With 725 acr es, this airport is surrounded by more open non-residential areas compared to SMO.

Figure 1 A current aerial view of the Van Nuys Airport

6The Santa Monica Municipal Airport (SMO)

Located in the heart of the residential community of Sa nta Monica, California, the airport is around 9 miles north -west of LAX, and approximately 23 miles south-west of VNA. The Douglas Aircraft Company began to use SMO (Figure 2) to test and fly aircraft in 1922. By 1924, production was ra mped up to 24/7 with the number of employees increasing into the thousands. A large number of employees working in aircraft manufacturing needed housing and, c onsequently, the City of Santa Monica and the Los Angeles County designated areas im mediately adjacent to the airport for residential use. Santa Monica Airport handles an average of about 300 operations per day (2009 data) and annual jet air traffic has in creased from about 1,000 in 1984 to almost 14,000 in 2009, mostly due to the ease of access and the increased fees associated with fewer access slots at LAX. Total aircraft operations in 2009 numbered 111,688 with 85% propeller, 13% jet, and 2% helicopters. In order to minimize the noise and pollution impact on the residential area nearby, the city of Santa Monica has st rict ordinances that prohibit take-offs between the hours of 11p m and 7am on weekdays, and between 11pm

and 8am on weekends. The lack of a buffer z one separating the airport from residences and odor and/or noise complaints by people living in nearby community have raised concerns about possible health effects from exposure to gaseous and particle pollutants emitted from the airport areas.

Figure 2 A current aerial view of the Santa Monica Airport



## METHODS

MONITORING SITES AT THE VAN NUYS AIRPORT The airport air quality study work plan incl uded a series of “f ully” and “partially” instrumented sampling sites (Figure 3). The “f ully” instrumented stations (i.e. VOR, Golf Course and Holmes School) were set-up at both ends of the runways and in nearby communities under the flight path, and were equipped with sequential VOC samplers (Xontec ® 924 multi-canister VOC sampler), sequential carbonyl samplers (Xontec ® 924 Sampler), total suspended particle (TSP) samplers for lead, speciated PM 2.5 samplers (Met One® SASS Sampler), c ontinuous CO analyzers, and UFP counters (Condensation

7Particle Counters, or CPCs; TSI ® Model 3020 and Model 3781). The “partially” instrumented sampling sites (where only a TSP lead sampler and a CO sensor were operated) were located on both sides of the runways (i.e. Maintenance Yard and National Guard) and at a local elementary school (C ohasset School station). On July 2006, the Air National Guard station (Site 5 in Figure 3) wa s upgraded to a “fully” instrumented site. The sampling campaign was divided into two intensive pe riods to study the seasonal variations of the studied air po llutants: from November 2005 to March 2006 (Phase 1) and from July 2006 to September 2006 (Phase 2). All sampling locations were chosen upon examination of historical wind patterns collected from the Federal Aviation Administration (FAA) me teorological network.

Figure 3 Map of the Van Nuys Airport sampling sites. Yellow and blue circles represent “fully” and “partially” instrumented site s, respectively (see text for details)

4

3 5

6 2

1 Site # Location

1 Golf Course

2 VOR Site

3 Maintenance Yard

4 Holmes School

5 National Guard

6 Cohasset School

89 Van Nuys Airport Sampling Locations

Site 1: Golf Course (Executive Golf Course Service Yard site) Address: 16235 Gilmore St., Van Nuys, California

This monitoring site was located at a Golf Course main tenance facility, about 700 m south of the airport and directly under the airport’s fixed wing traffic paths. Carbon monoxi de, TSP for lead, speciated PM 2.5 , carbonyls, air toxics (in both the pa rticle and the gaseous phases) and particle number concentration were collected/measured at this site.

Site 2: VOR (VHF Omnidirec tional Range site) Address: 8300 Hayvenhurst Pl ace, Van Nuys, California

Set-up near the VHF Omnidirectional Range (VOR) navigation system, on the strip of land separating Hayvenhurst Ave. from Hayvenhurst Place, this station was situated just north of the airport, and sat directly under the airport’s fixed wing traffic path. Here sampling consisted of CO, TSP for lead, speciated PM 2.5 , carbonyls, air toxics (in both the particle and the gaseous phases) and particle number concentration.

Site 3: Maintenance Yard Address: 7701 Sophia Ave., Van Nuys, California

This site was operated east of the ru nway and within the airport facilities maintenance complex adjacent to the Tarmac. Here sampling consisted of

TSP for lead and CO.

Site 4: Holmes School (Holmes Middle School site) Address: 9351 Paso Robles Ave., Los Angeles, California

This monitoring site was set-up in the teacher’s parking lot on the southeast corner of the school complex, and near the intersection between

Prairie Street and Paso Robles Ave. The school itself is approximately 2,400 m north-west of the airport an d, although it was more than 1,000 m

from the extended centerline of the runway, airplanes were observed directly over the school on several oc casions. Here sampling consisted of CO, TSP for lead, speciated PM 2.5 , carbonyls, air toxics (in both the particle and the gaseous phases) a nd particle number concentration. The first sampling session at the school was from December 2005 to February 2006. The second monitoring period started in July 2006 and it was stopped on 8/11/2006 because of a cons truction project at the school.

Site 5: National Guard (Air National Guard Site) Address: Van Nuys Airport, Van Nuys, California10 Located next to building No. 105 at the unused Air National Guard facility, this site was set-up within the north-west perimeter of the airport complex and perpendicular to the centerline of the runway. Here sampling consisted of TSP for lead, and CO (D räger personal monitor) during Phase 1. This monitoring location was upgraded to a “fully” instrumented site upon closure of the Holmes Middle School station in August 2006, at which point sampling consisted of CO, TSP for lead, speciated PM 2.5 , carbonyl, air toxics (in both the par ticle and the gaseous phases) and particle number concentration.

Site 6 : Cohasset School (Cohasset Str eet Elementary School) Address: 15810 Saticoy Stre et, Van Nuys, California

This monitoring station was operated on the roof of classroom 26, on the south-east perimeter of the school campus, and approximately 900 m east of the airport. Sampling at this site consisted of TSP for lead and CO.

MONITORING SITES AT THE SANTA MONICA AIRPORT Similar to VNA, the airport air quality st udy work plan included a series of “fully” and “partially” instrumented sites (Fi gure 4). The stations were located close to the airport runway (West and East Tarmac sites) , in the back yard of a private residence downwind of the airport (Ernst Residence site ), at an elementary school further away from the SMO area (Richland School station) , and at a park upwind of the airport (Marine Park site). These “fully” instrument ed sites were equipped with sequential VOC samplers (Xontec ® 924 multi-canister VOC sample r), carbonyl samplers (Xontec ® 924 Sampler), TSP samplers for lead, speciated PM 2.5 samplers (Met One® SASS Sampler), continuous CO analyzers, and UFP counters (TSI ® Model 3020 and Model 3781). The “partially” instrumented sampling stations (i.e. Maintenance Faci lity and Walgrove School), were set-up on opposite sides of the airport and the center line of the runway. Only a TSP lead sampler and a CO sensor were run at these sites. The sampling campaign was divided into two intensive pe riods to study the seasonal variations of the studied air polluta nts: from April 2006 to July 2006 (Phase 1) and from October 2006 to February 2007 (Phase 2). All sampling locations were chosen upon examination of historical wind patterns collected from the FAA meteorological

network.Figure 4 Map of the Santa Monica Airport sampling si tes. Yellow and blue circles represent “fully” and “partially” instrumented sites, respectively (see text for details)

7 5

6 1 2 3 4

11 Site # Location

1 West Tarmac

2 East Tarmac

3 Ernst Residence

4 Richland School

5 Maintenance Facility

6 Walgrove School

7 Marine Park

Santa Monica Airport Sampling Locations

Site 1: West Tarmac Address: Santa Monica Airport

This monitoring site was located in a field west of the runway, at the same elevation as the runway a nd within the south-west perimeter of the airport. Here sampling consisted of CO , TSP for lead, speciated PM 2.5 , carbonyls, air toxics (both in the particle and in the gase ous phases) and particle

number concentration.

Site 2: East Tarmac Address: Santa Monica Airport

This station was set-up approximately 30 to 40 m west of the end of the runway, on the north-east perimeter of the airport and in very close proximity to the blast-fence. During Phase 1 sampling was limited due to lack of available power and consis ted of TSP for lead (using battery operated samplers) and gaseous air toxi cs (collected once every six days). During the second phase of the study , SMO personnel provided power to the site and sample collection was upgr aded to include co ntinuous particle count measurements, three 8-hr VOC samples per day (i.e. 00:00 to 08:00, 08:00 to 16:00, and 16:00 to 00:00), and speciated PM 2.5

.12 Site 3: Ernst Residence Address: 12130 Sardis Ave., Los Angeles, CA

Set-up in the back yard of a private re sidence, this site was directly under the fixed wing arrival/departure rout e. The residence (and the surrounding neighborhood) sits at a lower elev ation than the airport and is approximately 100 m northeast of the end of the runway. Sampling consisted of CO, TSP for lead, speciated PM 2.5 , carbonyls, air toxics (in both the particle and the gaseous phases) and particle count.

Site 4: Richland School (Richl and Elementary School site) Address: 11562 Richland Ave., Los Angeles, CA

This monitoring station was operated in the teacher’s parking lot, close to

the extended centerline of the runw ay. The school is less than 1,000 m northeast of the airport, a nd located at a lower elevation than SMO. At this location sampling consisted of CO, TSP for lead, speciated PM 2.5 , carbonyls, air toxics (in both the pa rticle and the gaseous phases) and particle number concentration.

Site 5: Maintenance Facility (Air port Maintenance Facility site) Address: Santa Monica Airport

Set-up next to the airport facilities maintenance building, which is located on the Tarmac, this station was less than 150 m north of the runway. Sampling consisted of TSP for lead and CO.

Site 6: Walgrove School (Wal grove Elementary School site) Address: 1630 Walgrove Ave., Los Angeles, CA

This monitoring site was located on the roof of one of the classrooms on the north perimeter of the campus and approximately 600 m south of SMO. Sampling consisted of TSP for lead and CO.

Site 7: Marine Park Address: 1406 Marine Street; Santa Monica, CA

This station was set-up 1,000 m south-we st of SMO, next to several tennis courts and directly under the fixed wi ng arrival/departure flight path. The park (and the surrounding neighborhood) is at a s lightly lower elevation than the airport. Sampling at this site consisted of CO, TSP for lead, speciated PM 2.5 , carbonyls, air toxics (in both the particle and the gaseous phases) and particle number concentration.13 MEASURED POLLUTANTS Table 1 lists the targeted air toxics meas ured at VNA and at SMO. Previous work has shown that these species are among the most significant contributo rs to health risks related to exposure to air toxi cs in the South Coast Air Basi n (MATES III report). The air toxics data have been complemented by the additional measurements of OC, EC, PM 2.5 and ultrafine particle count. Information about wind speed and wind direction for the entire duration of the study has been obtai ned from the local airport authorities.

Table 1 List of the most relevant particle a nd gaseous species monitored during this study at both the Van Nuys and Santa Monica Airports

Target Pollutants

PM 2.5 mass 1,3-Butadiene Perchloroethylene

Organic Carbon (OC) Methylene chloride Formaldehyde

Elemental Carbon (EC) Chloroform Acetaldehyde

Trace Elements (e.g. Lead) Benzene Acetone

Ultrafine Particles (UFP) Count Carbon Tetrachloride Methyl Ethyl Ketone

Carbon Monoxide (CO) Trichloroethene
Vinyl Chloride Toluene

SAMPLING SCHEDULE All 24-hr integrated PM 2.5 samples were collected on a one-in-three day basis. High volume total suspended particulate samples for lead analyses could not be collected at the East Tarmac site during Phase 1 because of a lack of electrical power, and a low volume sampler with a smaller power requirement (BGI ® Model PQ100 Sampler; Waltham, Massachusetts) was used instead. Three 8-hr VOC samples (i.e. 00:00 to 08:00, 08:00 to 16:00, and 16:00 to 00:00) were co llected every third day at the “fully” instrumented monitoring locations. This sc hedule is identical to that used by AQMD during the third Multiple Air Toxics Expos ure Study (MATES III) and the typical U.S. EPA schedule for ambient PM sampling. One minute data from all continuous instruments (i.e. CO and ultrafine particle measurements) were recorded on a data logger and averaged to hourly concentrations to faci litate comparison among sites. The data files were periodically downloaded to a laptop computer and transferred to the AQMD’s central database. A summary of the samp ling schedule for VNA and for SMO is shown below (Table 2).14 Table 2 Sampling schedule for the Van N uys and Santa Monica Airports

Van Nuys Airport Santa Monica Airport
November 2005 – Site set-up March 2006 – Site set-up December 2005 – Sampling start date ( Phase 1 ) April 2006 – Sampling start date ( Phase 1 ) March 2006 – Sampling end date July 2006 – Sampling end date July 2006 – Site set-up N ovember 2006 – Site set-up August 2006 – Sampling start date ( Phase 2 ) December 2006 – Sampling start date ( Phase 2 )

November 2006 – End of the sampling campaign March 2007 – End of the sampling campaign

LABORATORY ANALYSIS Laboratory analysis of the collected samples was conducted by the AQMD laboratory. A variety of analytic al methods were used to m easure the concentrations of the targeted chemical compounds (Table 3).

Table 3 Sampling and analysis methods

Ambient Species Sampling

Method Analysis Method

Volatile Organic Compounds Silica-Lined

Canisters Gas Chromatography-Mass Spectrometry (GCMS) with automated pre-concentration

Carbonyls DNPH Cartridge Solvent recovery and subse quent analysis via high pressure liquid chromatography (HPLC)

Carbon

Monoxide Continuous Analyzers Infrared radiation absorption using gas filter

correlation

Lead TSP Samplers Inductively Coupled Plasma Mass Spectrometry (ICP-MS)

Ultrafine

Particles CPC Particle

Counter Continuous particle counts via photo detection of light scattering from particles

PM 2.5 Mass PM 2.5 Speciation Samplers PM 2.5 Mass determined using analytical

microbalance

PM 2.5 Metals PM 2.5 Speciation Samplers Metals determined by Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF) & ICP-MS

Organic and

Elemental

Carbon PM 2.5 Speciation Samplers Sections of the PM filter were removed and analyzed using a thermal-optical carbon analyzer (IMPROVE method)15 Volatile organic compounds were measured from air samples collected in silicalined 6-liter canisters connected to Xontec ® 910/912 multi-canister samplers. In addition to integrated 24-hr canister samples, VOCs we re also collected at 8-hr intervals (i.e. 00:00 to 08:00, 08:00 to 16:00, and 16:00 to 00:00 ) to get some insight into the diurnal variation of this compound class. VOCs we re identified and measured using a Gas Chromatograph-Mass Spectrometer (GC/MS). A modified EPA TO-15 method was used to collect and analyze all VOC samples. Carbonyl compounds were sampled by drawing air through a DNPH (2, 4- Dinitrophenylhedrazine) cartr idge attached to Xontec ® 924 samplers; carbonyls undergo derivatization upon contact with DNPH. The derivatives were extracted using acetonitrile and analyzed using Waters ® High Pressure Liquid Chromatography (HPLC) in

accordance with U.S. EPA method TO-11. The HPLC system employed for the analysis of these samples c onsists of a Waters ® 2690 separation module and a Waters ® 996 Photodiode Array Detector. At all “fully” instrumented sites, CO wa s continuously monitored in accordance with U.S. EPA equivalent methods cr iteria using CO Analyzers (Dasibi ® 3008 model) that operate on the principle of infrared radiation abso rption. Personal CO monitors, consisting of a CO detector tube attached to a small air pump (Dräger ® Personal CO Monitors), were used at the “partially” in strumented stations. All sampling probes met U.S. EPA criteria for CO sampling. Data we re stored on electronic data recorders, downloaded on a laptop computer, and transf erred to AQMD’s air quality database. The concentrations of lead and beryl lium were measured on total suspended particulate (TSP) samples collected on glass fiber filters using high volume samplers (Graseby/Anderson TSP Sampler). The glass fibe r filters were extracted with acid and analyzed using Inductively Coupled Pl asma Mass Spectrometer (ICP-MS; Leco ®
Renaissance Time of Flight). The concentration of ultrafine particle s at VNA (Phases 1 and 2) and at SMO (Phase 1 only) was measured continuously by mean of butanol-based condensation particle counters (CPCs; TSI® Model 3070). The CPC uses a laser photo diode to flash light on the particles that have been supersat urated and grown to de tectable sizes with nbutyl alcohol. A photo detector is then used to count the particles in the sample stream. The sample inlet probe uses a PM 2.5 sharp cut cyclone to eliminate particles larger than 2.5 μm in diameter. Particle counts were r ecorded on the same electronic data recorders

that also stored the CO data. Because the term of the loan for the butanol-based CPCs used during the first phase of the Sant a Monica field campaign (April–July, 2006) expired at the end of September 2006, wate r-based CPCs (TSI® Model 3781) were purchased by AQMD and used instead during the second part of the campaign in Santa Monica (October 2006–February 2007). This ne wer model utilizes water instead of butanol to reach supersatur ation conditions and grow pa rticles, eliminating the characteristic strong odor asso ciated with the Model 3070. Integrated 24-hr PM 2.5 samples were collected on quartz or teflon filters using

SASS PM 2.5 speciation samplers (Met One ® SASS Speciation Sampler), and analyzed for: gravimetric mass (using an analytical micro-balance; Sartorus® MC-5), trace elemements, OC and EC. Metal analysis of particulate samples was performed using a methodology based on IO-3 (Compendium of Methods for Inorganic Air Pollutants)16 implementing a combination of energy di spersive X-ray fluorescence (PANalytical Epsilon 5® Energy Dispersive X-Ray Fl uorescence Spectrometer), and inductively coupled plasma mass spectro metry (Leco® ICP-MS). Carbon analysis for the determination of OC and EC was performed on small

circular disks taken from the loaded PM 2.5 quartz fiber filter samples. These disks were placed inside a heated furnace of a Thermal/O ptical Carbon Analyzer (Desert Research Institute, Model 2001) one at the time a nd subjected to a programmed, step-wise temperature increase while helium gas (He) with varying amounts of oxygen was passed over the sample. This method (based on the IMPROVE protocol) uses a laser beam to monitor and correct, when necessary, the degr ee of oxidation or car bonization (pyrolysis) that occurs during the analysis.



## RESULTS AND DISCUSSION

The data collected at VNA and at SMO were examined for upwind/downwind differences, concentration gradients, eval uated against measurements collected at companion AQMD sites (located in downtown Central Los Angeles and in Burbank, CA) and compared to the corresponding South Coas t Air Basin averages (when available). Ultrafine particle count meas urements were not taken else where in the Basin and, thus, UFP number concentrations at the study sites were compared to one another to assess spatial and temporal variabilities.

METEOROLOGY

Van Nuys Airport The wind patterns at the Van Nuys Airport are influenced by the orientation of the San Fernando Valley, the surrounding mount ain ranges, and the synoptic weather systems which pass over Southern Calif ornia. Wind conditions during Phase 1 (November 2005-March 2006) and Phase 2 (J uly-September 2006) of this study are typical for this location and the surroundi ng areas in the San Fernando Valley (e.g. Burbank) (Figure 5). In part icular, winds around the Van Nuys Airport are influenced by a predominant on-shore flow during the day a nd a lighter off-shore flow at night. This

land-sea breeze effect dominates the Basin for most of the year. During the winter months, north and north-northwest winds are more prevalent and stronger than at other times of the year (Figure 5a). Five to ten times a year, normally in the winter months, high pressure systems build over the desert plateaus of Nevada and Utah spreading southward into the Mojave Desert. The cloc kwise circulation around these high pressure systems can produce a warm, intense north-east wind known locally as Santa Ana winds.

Santa Ana winds can last from a few hours to several days. The wintertime is the wettest season of the year in the Basin and the heavie st precipitation typically occur in February. During Phase 2 of this study, the predomin ant wind flow at the Van Nuys Airport was from south-southeast (Figure 5b), alt hough all wind directions are represented in varying amounts throughout the year. During summer, atmospheric conditions are more

consistent when the dominant features influe ncing winds are strong temperature gradients caused by heating over the deserts and the cold waters along the co ast. The July throughSeptember wind rose has featur es that are representative of the San Fernando Valley during a transitional summer to fall climatology. At this time of year, predominant winds correspond more closely with south to sout h-east flows which dominate throughout the

year.

Figure 5 Average wind speed and direction at th e Van Nuys Airport during a) Phase 1 (November 2005 - March 2006) and b) Phase 2 (July - September, 2006)

17 0 0

270 0 90 0

180 0

0 0

270 0 90 0

180 0 0 0

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180 0

0 0

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180 0 a) b)

Wind Speed (mph)

Santa Monica Airport At this location winds were monitored from April through July 2006 (Phase 1) and between October 2006 and February 2007 (P hase 2). Wind rose charts for these time periods show the presence of a distinct da ytime sea breeze, char acteristic of beach communities in the South Coast Air Basin (Figure 6). During the spring and summer months, winds were predominantly from the west-southwest and sout hwest (Figure 6a). In addition to this strong onshore see breeze, the fall and winter periods were characterized by winds coming from all directio ns (Figure 6b). It is worth noting that strong north winds are probably indicating th at Santa Ana offshore wind conditions were present occasionally.

Figure 6 Average wind speed and direction at the Santa Monica Airport during a) Phase 1 (April - July, 2006) and b) Phas e 2 (October 2006 - February 2007)

0 0

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Wind Speed (mph)18 LEAD

Van Nuys Airport

TSP lead concentrations collected at a ll six monitoring stations and during both phases of the study were examined for spatial and seasonal patterns, and the results have been summarized in Table 4 and Figure 7. Th e highest average and median lead levels (26.1 and 24.4 ng/m 3 , respectively) during Phase 1 (November 2005-March 2006) were measured at the Maintenance Yard site, in cl ose proximity to the east side of the runway and within the airport fence-line, and were approximately 3 times higher than the lowest average lead concentration (8.45 ng/m 3 ; measured at the Holmes School site) (Figure 7a). Higher increases over typical background concen trations are likely to occur on smaller time scales (1-min to 1-hr), especially duri ng periods of intense traffic activity when piston driven aircraft are taking-off or la nding. A non-parametric one-way Analysis of Variance (ANOVA) on ranks revealed that the median lead concentration at the Maintenance Yard site is significantly hi gher (p<0.05) than the corresponding median

levels observed at all othe r airport sites and in the South Coast Basin (11.0 ng/m 3 ). The

median lead concentrations at the Cohasset School (17.3 ng/m 3 ), at the VOR site (12.0 ng/m 3 ), and at the National Guard site (12.8 ng /m3) were also higher than the typical

median value for the South Coast Basin. Overall, our data suggest that the l ead concentration gr adient at VNA during

Phase 1 reflect the distance of the six monito ring sites from the runway area, probably because of lead emissions from piston driven aircraft operations including idling, takeoff, landing and re-fueling. As explained in a previous paragraph, most aircraft operation at GA airports are powered by piston e ngines and fueled by Avgas, which is characterized by a higher volatil ity and lead content than re gular jet fuel. These results

are in line with those obtained at the Butt onville Airport near Toronto in 2000 (Airborne Particulate Matter, Lead and Manganese at Buttonville Airport; prepared by Conor Pacific Environmental Technologies Inc. in 2000), where the averag e lead concentration

in 24-hr PM 10 air samples collected at four different sites near (15 to 50 m) the runway was 30 ng/m 3 , a value four times higher than that measured at a background station. The Buttonville Airport averages about 22,000 airc raft movements per month, many of which are small aircraft using avia tion gas containing lead, and it is fairly comparable to VNA in terms of size and traffic activity (VNA averages about 33,000 per month). During the second part of the study (Phase 2; July-September 2006), the overall

lead concentrations at all sites were substa ntially smaller than dur ing Phase 1 (Figure 7b), with average values between 3.88 and 7.11 ng/m 3 (measured at the Holmes School and at the Cohasset School, respectively). A non- parametric one way ANOVA on ranks indicated that there is no statistically significant difference among the median lead concentrations across all monitored sites (p > 0.05). It is possible th at these substantially

lower concentrations observed in the warmer months are related to seasonal differences in airport practices and traffic volume or, most likely, in mete orological conditions. Generally, in the late fall a nd winter light winds result in reduced ventilation, and late night/early morning inversions contribute to increasing the surface-level concentrations of those pollutants that are emitted from ground-level sources. During the summertime months, stronger land breeze/sea breeze circulation and increa sed insulation results inhigher wind speeds, increased vertical atmos pheric dispersion and, subsequently, reduced

ambient concentrations.

Figure 7 Box plots showing the median and mean l ead concentrations in total suspended particles (black and red lines wi thin each box, respectively) (ng/m 3 ) measured at the Van Nuys Airport during Phase 1 (November 2005 - March 2006) and Phase 2 (July - September, 2006). Representative lead levels fo r the South Coast Basin are also reported for comparison. Data collected during Phase 2 have been magnified on the top right panel to facilitate a comparison among sites

Mean

Median 75 %

25 % 90 %

10 %

5 % 95 %

Mean

Median 75 %

25 % 90 %

10 %

5 % 95 %

Interestingly, a revised airport-specific l ead inventory recently released by EPA in 2008 (Lead Emissions from the Use of Leaded Aviation Gasoline in the United States, prepared by the U.S. EPA) showed that in 2002 lead emissions from landing and take-off activities of piston-engine aircraft at the Van Nuys Airport amounted to 1,256 Kg (the highest recorded value in the U.S. for that y ear). It should be noted that the sum of lead emissions at the 3,413 airport fa cilities listed in this EPA document was estimated to be 282 tons, or about 45% of the total lead emitte d nationwide from the use of leaded Avgas. The sources that are most likely to account for the remaining 55% include a) over 16,000 airport facilities where leaded Avgas is used but emissions are not accounted for in the national emission inventory, and b) lead em itted outside the landing and take-off cycle (airport-specific lead emissions estimates account only for the lead emitted during taxi/idle-out, takeoff, climb-out, approach, a nd taxi/idle-in and do not account for lead emitted during cruise).

1920 Finally, as of October 2008 the U.S. Environmental Protection Agency strengthened the National Ambient Air Qual ity Standard (NAAQS) for lead, lowering it from 1500 ng/m 3 (quarterly average) to a more stringent 150 ng/m 3 (rolling 3-month average). In this respect, none of the concen trations measured at the Van Nuys Airport between November 2005 and September 2006 were close to or above the current NAAQS.

Table 4 Average and median lead concentrations in total suspended particles (ng/m 3 ) at the Van Nuys Airport during Phase 1 (Nove mber 2005 - March 2006) and Phase 2 (July - September, 2006). Minimum (Min) and maximu m (Max) values, standard deviations (SD), and the total number of valid samples (Va lid N) have also been reported along with representative lead data for the South Coast Basin (in red)

Golf

Course VOR Holmes

School National

Guard Cohasset

School Maintenance

Yard South

Coast

Phase 1 Average 10.2 15.1 8.45 14.5 18.6 26.1 12.3

Median 10.1 12.0 6.52 12.8 17.3 24.4 11.0

SD 5.06 11.5 6.1 9.26 13.3 16.7 7.12

Min 1.45 1.51 1.55 1.68 0.95 0.10 0.93

Max 20.7 40.5 21.9 30.5 64.7 83.7 45.9

Valid N 30 31 33 33 29 33 180

Phase 2 Average 4.51 7.85 3.88 6.31 7.11 5.61 5.92

Median 4.13 7.06 4.19 5.96 7.64 5.49 4.02

SD 1.84 2.60 1.54 2.59 2.40 2.49 9.24

Min 1.81 4.66 2.09 2.49 4.07 2.51 0.75

Max 10.3 15.7 6.10 13.2 9.07 11.1 89.5

Valid N 22 19 5 21 4 18 131

Santa Monica Airport Figure 8 illustrates the spatial and seasonal variations in lead concentration (TSP) at all monitored SMO locations. As reported in Table 5, the highest average and median

lead levels were measured at the East Ta rmac and at the Ernst Re sidence sites, both located north (downwind) of the runway and under the fixed wing arrival route. The average and median lead concentrations at all other monitoring sites were always slightly lower than the correspondent values for the South Coast Basin. The results of a one-way

ANOVA on ranks revealed that the median l ead levels at the East Tarmac and Ernst Residence sites were significantly (p<0.05) higher than those at the other monitored locations throughout the entire duration of the study. It is worth noting that the average lead c oncentrations at the East Tarmac station (85.2 and 77.0 ng/m 3 , for Phases 1 and 2, respectively) were 14 to 26 times higher than the corresponding average background levels at the Marine Park si te, and around one halfthe current, more stringent, NAAQS for lead (150 ng/m 3 ; rolling 3-month average) (Table 5). Twenty four hour average values close t o, or above the current NAAQS for lead were

recorded at the East Tarmac site in more th an one occasion and during both phases of the study. The highest recorded 24-hr le ad concentration value was 299 ng/m 3 and refers to a TSP sample collected at the East Tarmac in Phase 2. These increased values are probably related to the close proximity ( 30-40 m) of this last site to the blast-fence, where planes sometimes idle before clearance for take-off, and to the fact that the predominant winds (from southwest) are aligned to the runways of the airport and blowing towards the East

Tarmac station.

Located around 100 m northeast of the runw ay and directly under the fixed wing arrival route, the Ernst Resi dence site (where average l ead levels were 28.6 and 22.2 ng/m 3 during Phases 1 and 2, respectively) was also characterized by increased lead concentrations with respect to background conditions (average lead values at the Marine Park station were 4 to 9 times lower). Un like what was observed at VNA, the magnitude

of the lead concentrations measured in Santa Monica was not s ubstantially different between Phase 1 and Phase 2 (Figures 8).

Figure 8 Box plots showing the median and mean lead concentrations in total suspended particles (black and red lines wi thin each box, respectively) (ng/m 3 ) measured at the Santa Monica Airport during Phase 1 (Apr il - July, 2006) and Phase 2 (October 2006 - February 2007). The correspondent lead levels for the South Coast Basin have also been reported for comparison

It is worth mentioning that a revised ai rport-specific lead inventory released by EPA in 2008 (Lead Emissions from the Use of Leaded Aviation Gasoline in the United States, prepared by the U.S. EPA) showed that in 2002 lead emissions from landing and take-off activities of piston-e ngine aircraft at SMO were 369 Kg, a value 3.4 times lower than that recorded at VNA during the same year, but within the top 2% among the 3,413 airport facilities considered in this EPA document.

21Overall, our results show that the meas ured lead concentration at the Santa Monica sites increased with decreasing distan ce from areas where airplanes were idling, taking-off and landing. These outcomes are in li ne with those obtained at the Buttonville Airport near Toronto in 2000 (discussed in th e previous chapter) and with those from a study conducted at the O’Hare Internationa l Airport (Chicago, Illinois) in 2000, where airport emissions were found to have an impact in the areas adjacent to the airport for several key target compounds including lead (Chicago O’Hare Airport Air Toxic Monitoring Program; prepared by the Illinois Environmental Protection Agency, Bureau of Air, in 2002).

Table 5 Average and median lead concentrations in total suspended particles (ng/m 3 ) at the Santa Monica Airport during Phase 1 (Apr il - July, 2006) and Phase 2 (October 2006 - February 2007). Minimum (Min) and maxi mum (Max) values, standard deviations (SD), and the total number of valid samples (Va lid N) have also been reported along with representative lead data for the South Coast Basin (in red)

ND = non detected Walgrove

School Richland

School Marine

Park Maintenance Facility Ernst

Residence East

Tarmac West

Tarmac South

Coast

Phase 1 Average 3.38 4.50 3.30 3.66 28.6 85.2 4.58 9.47

Median 2.66 4.00 2.76 2.69 25.3 83.5 4.07 8.86
SD 2.35 3.57 2.17 3.20 14.1 33.0 4.18 3.55
Min 0.10 0.10 0.10 0.10 1.59 27.0 0.10 5.19
Max 9.58 14.7 8.72 13.5 60.1 135.0 17.7 15.0
Valid N 29 37 30 32 20 12 31 13

Phase 2 Average 5.79 7.59 5.50 7.68 22.2 77.0 9.05 13.1
Median 5.97 6.92 5.95 6.52 17.1 67.0 7.14 12.7
SD 2.66 5.32 2.48 4.92 16.6 68.6 6.84 4.05
Min ND ND 0.10 1.78 3.99 0.10 2.01 4.88
Max 9.22 30.1 9.86 21.3 70.1 299 37.7 19.3

Valid N 25 32 35 25 38 33 32 16

EAST TARMAC SITE (METHOD COMPARISON) During Phase 1 electrical power was not available at the East Tarmac site to operate the hi-volume TSP samplers. Theref ore, a smaller battery powered low volume sampler (BGI ® Model PQ100 Sampler; Waltham, Mass achusetts) configur ed to collect TSP was deployed instead. In this case, all filter samples were collected on teflon substrates at 12 lpm and analyzed for lead using X-Ray Fluorescen ce (XRF) rather than Inductively Coupled Plasma Mass Spectrometry (ICP-MS). PM 2.5 speciated samples were

also collected at the Ernst Re sidence, Marine Park and Ri chland School stations during the entire duration of the study and analyzed for lead using XRF. Small quantities of all

22loaded teflon filters were also digested with acid, and the extracts analyzed by ICP-MS to compare the two methods. Although the lead concentrations obtained by XRF may be biased about 25 ng/m 3 high compared to those from IC P-MS analyses, an excellent agreement (R 2 = 0.97) was found between the results of these two analytical methods (Figure 9). It is possible that the teflon filte r matrix may require a more rigorous digestion step than the glass fiber filter typically used for ICP-MS, since teflon is well known for its resistance to aqueous wetting.

Figure 9 Comparison between lead concentra tions obtained from XRF and ICP-MS analyses of selected TSP samples collected at the East Tarmac site (Santa Monica Airport) during Phase 1

Lead data from the analysis of samples collected using the PM 2.5 speciation samplers show a spatial pattern across the f our monitored locations (i.e. East Tarmac, Ernst Residence, Marine Park and Richland Sc hool stations) (Figure 10) similar to that observed from the TSP lead data (Figure 8). The average and median lead concentrations in fine particles were elevated above the typical South Coast Basi n levels at both the Ernst Residence site (during both phases) and at the East Tarmac station (during Phase 2 only; PM 2.5 samples for lead analysis were not colle cted at this location during Phase 1). This suggests that a relatively high proporti on of lead at these two stations was not associated with re-suspended material (which would consist of coarse r particles primarily above 2-5μm in diameter), and may have orig inated from fresh emissions from aircraft idling, landing, or taking-offs, or from other ai rport-related activities such as re-fueling. At all sites Pb(PM 2.5 ) / Pb(TSP) ratios were between 0.83 and 1.48. Values higher than one may be due to differences in measurem ent methods. The average and median lead

levels measured in PM 2.5 particles during the second y ear of the MATES III study (from April 2005 to March 2006) were comparable to the corresponding aver age concentrations observed at the Marine Park station (backgr ound site) during both Phas es 1 and 2 of this

23study. Overall, our results suggest that avia tion gas combustion leads to the formation and emission of small primary PM 2.5 particles containing lead.

Figure 10 Box plots showing the median and mean lead concentrations (ng/m 3 ) in fine particulate matter (PM 2.5 ) measured at four monitoring si tes of the Santa Monica Airport (black and red lines within each box, respec tively) during Phase 1 (April - July, 2006) and Phase 2 (October 2006 - February 2007). Lead levels for the South Coast Basin (same time periods) and at MATES III sites (from April 2005 to March 2006 only) are shown for comparison

VOLATILE ORGANIC COMPOUNDS (VOC) The following volatile organic compounds ( VOCs) were selected for discussion because of their potential importance relative to toxic cancer risk in the South Coast Air Basin: 1,3-butadiene, methylene chloride, chloroform, benzene, carbon tetrachloride, toluene, and perchloroethylene. Nearly all samples collected at all sites showed vinyl chloride and trichloroethene levels at or below their corresponding detection limits. Thus,

the concentrations of these two volatile species are not discussed in the following paragraphs. Averaged 24-hr VOC concentr ations were then compared to the corresponding daily-averaged le vels at two AQMD companion monitoring stations, one in Burbank, CA (about 14 mi south-east of VNA) and the other in Central Los Angeles (around 14 mi east of SMO). In an effort to ge t some insight into th e daily variations of the measured VOCs three 8-hr samples (i.e. 00:00 to 08:00, 08:00 to 16:00, and 16:00 to 00:00) were collected daily at four sites for VNA [i.e. Golf Course, Holmes School, National Guard (Phase 2 only) and VOR] and at five sites for SMO (i.e. Richland School, Marine Park, Ernst Residence, East Tarmac a nd West Tarmac). A detailed discussion of important VOC results follows.

2425 Van Nuys Airport With the exception of chloroform, the av erage and median concentrations of 1,3- butadiene, methylene chloride, benzene, carbon tetrachlori de, toluene, and perchloroethylene were generally higher dur ing the first phase of the study (November 2005 – March 2006) (Figures 11a, 11b, and 11c ) as compared to the second phase. Typically, in the fall/winter months light wi nds result in reduced ventilation, and late night/early morning inversions contribute to increased surf ace-level concentrations of pollutants emitted from ground-level sources . During the summer months, stronger

land/sea breeze circulation and increased in sulation results in higher wind, increased vertical atmospheric dispersi on and, subsequently, reduced ambient concentrations. A similar seasonal variability in the concentration of ben zene, 1,3 butadiene, methylene chloride and perchloroethylene, with wi ntertime maximums and summertime minimums,

was also observed in the South Coast Basi n during the MATES II and MATES III studies (prepared by AQMD in 2000 and 2008, respectively). The spatial distribution of most VOCs did not vary substantially across the two sampling periods and, in most cases, the hi ghest concentrations across all Van Nuys

stations were observed at site s that were closer to busy su rface streets an d, to a lesser extent, to the airport area. For example, the Golf Course station, characterized by relatively high VOC levels, was less than 100 m north of Victor y Blvd. (a major eastwest arterial road traversing the entire le ngth of the San Fernando Valley) and about 700 m from the south perimeter of the airport, directly under the airpor t’s fixed wing traffic path. Because the concentration of vehicle-related pollutants decreases exponentially with distance from roadways and returns to background levels after only 300 to 2,500 m (depending on the type of the pollutant, tra ffic conditions, time of the day, and local meteorology) (Zhu et al., 2002a and 2002b; Hu et al., 2009), it is possible that motorvehicle emissions played a significant role in increasing the measured atmospheric

concentrations of most VOCs at the Golf Course site. Conversely, the Holmes School station, where lower gaseous concentrati ons were generally observed, was around 2,400 m north-west of the Van Nuys Airport and at least 300 m away from any major surface street. The levels of most volatile species at the VOR and National Guard sites (set-up in close proximity and within the airport fence-line, respectively) were mostly between those recorded at the Golf Course and at Holmes School monitoring stations. The highest VOC concentrations measur ed at VNA were comparable to those observed at an urban site in Burbank (espec ially during Phase 1; Figure 11), located in close proximity to the Ventura Freeway (Rout e 134), the Golden State Freeway (I-5), and several other major and local roads. Overall, our results seem to suggest the concentration gradient of most VOCs measured in the VNA ar ea is mostly influenced by proximity to mobile sources surrounding the airport’s perimete r. The extent of the contributions of this and other pollution sources including aircraft em issions and other air port activities to the

measured VOC levels cannot be a ssessed from the available data.

These outcomes are in line with those obtai ned from similar studies in other parts of the United States. For example, the resu lts from a recent field campaign conducted by ENVIRON Corp. at the Teterbor o Airport in New Jersey (one of the busiest GA airports in the United States) revealed that the con centrations of most VOCs were comparable to

or lower than those measured in the urban area of Elizabeth (NJ), where the atmospheric levels of these volatile pollutants are typi cally dominated by mob ile source emissions(Teterboro Airport, New Jerse y, Detailed Air Quality Eval uation, Final Report Prepared by ENVIRON Corp. in 2008). A comparison betw een ambient VOC data at the O’Hare International Airport (one of the world’s bus iest airports) and those representing “typical urban” concentrations in the Chicago, Atlanta, Detroit, H ouston and Milwaukee metropolitan areas led to similar conclusi ons (Chicago O’Hare Airport Air Toxic Monitoring Program; prepared by the Illinois Environmental Protection Agency, Bureau of Air, in 2002). A summary of all 1,3-but adiene, methylene chloride, chloroform, benzene, carbon tetrachloride, toluene, a nd perchloroethylene da ta collected at VNA can be found in Appendix A.

Figure 11 Spatial distributions of a) 1,3-butadiene, methylene chloride, and chloroform, b) benzene, carbon tetrachloride, and toluene, and c) percholoethy lene at 5 monitoring sites of the Van Nuys Airport (i.e. Golf Course, Holmes School, VOR, and National Guard sites) during Phase 1 (November 2005 - March 2006) and Phase 2 (July - September, 2006). Data collected concurrently at a monitoring station in Burbank are also included for comparison

26 

### a)

### b)

c)

2728 Santa Monica Airport
With the exception of carbon tetrach loride, the average and median concentrations of all VOCs present in s ubstantial amounts in the canister samples collected at SMO (namely, 1,3-butadiene, me thylene chloride, chloroform, benzene, carbon tetrachloride, toluene, perchloroethyl ene and trichloroethene) were generally higher during the fall/winter months (from October 2006 to February 2007; Phase 2) than in the spring/summer period (between April 2006 and July 2006; Phase 1). This is consistent with typical seasonal changes in local meteorological conditions, and with

what was observed at th e Van Nuys Airport. Although the spatial distribution of mo st volatile species did not vary substantially across the 2 sampling periods, it is difficult to discern a consistent concentration gradient across the sampling site s (Figures 12a, 12b, and 12c). However, in most occasions slightly higher VOC levels were observed at the Richland School, East Tarmac, Ernst Residence, and West Tarmac stations, probably because of their relative proximity to the Santa Monica freeway (I-10), to several congested surfaces streets and, possibly, to the airport area. In particular, the Richland Schoo l site (the furthest from SMO) was less than 300 m south of the I-10 (a major east-west interstate highway that runs east from Santa Monica through Los Ange les), about 600 m west of interstate 405 (I-405; a heavily traveled nor th-south thoroughfare known to be one of the busiest freeways in the United States), and close to several trafficked surface streets. The East Tarmac and Ernst Residence sampling locations were within 100 m from the inner and outer edge of the airport fence-line, respect ively, in very close proximity to Bundy Dr. and National Blvd (two highly tr afficked streets adjacent to the north-east side of the airport), and about 600-800 m south of the I-10. The West Tarmac site was within the southwest perimeter of the airport, less than 100 m from the southern end of the runway, but approximately 1,700 m away from the I-10. Lastly, the Marine Park station, where the lowest VOC levels were generally meas ured, was the farthest from the I-10 (more than 2,100 m) and possibly too far from the ai rport perimeter to be influenced by VOCs emitted from aircraft operations and other related-activities. As observed at VNA, the VOC levels in Santa Monica were generally comparable to or lower than those at the companion ur ban monitoring station (Central Los Angeles, in this case) where motor-vehicles emissions dominate the atmospheric levels of most primary pollutants. Overall, our results seem to suggest that the VOC levels measured at the Santa Monica stations were mostly influe nced by their proximity to nearby freeways (e.g. the I-10) or local surface streets and, possi bly to a lesser degr ee by their relative distance to the airport. However, the contribu tions of these and othe r pollution sources to

the measured VOC levels cannot be assessed from the available data. A summary of all 1,3-butadiene, methylene chloride, chloroform, benzene, carbon tetrachloride, toluene, perchloroethylene and trichloroethene data collected at SMO can be found in Appendix

A.Figure 12 Spatial distributions of a) 1,3-butadiene, methylene chloride, and chloroform, b) benzene, carbon tetrachloride, and toluene, and c) tr ichloroethane and perchloroethylene at selected monitoring site s of the Santa Monica Airport (i.e. Richland School, Marine Park, Ernst Residence, East Tarmac, West Tarmac sites) during Phase 1 (April - July, 2006) and Phas e 2 (October 2006 - February 2007). Data collected concurrently at a monitoring site in Central Los Angeles are also included for comparison



### a)

2930 

### b)

c)31 EIGHT-HOUR VOC

Van Nuys Airport In addition to integrated 24-hr canister samples, VOCs were also collected daily at 8-hr intervals (i.e. 00:00 to 08:00, 08:00 to 16:00, and 16:00 to 00:00) to examine the diurnal variability of this important com pound class. Typically, the concentrations of most VOCs were higher between 00:00 and 08:00 and, to a lesser extent, from 16:00 and 00:00, probably because of a decreased mixing he ight and increased atmospheric stability early in the morning and late at night. Inte restingly, the percentage contribution of most

VOCs collected between 00:00 and 08:00 to their correspondi ng 24-hr average concentrations was higher during the summer mo nths (the average for all VOCs and at all sites during Phase 2 is 45%) than in the fa ll/winter period (the corresponding average contribution during Phase 1 is 37%). This s ituation (shown for the VOR site in Figures 13a and 13b and representative of all othe r stations at VNA) may be due to more persisting inversions throughout the winter days and, perhaps, to seasonal variations in airport activities such as increased air traffic in the early mornings of most summer months (July – September, 2006). All avai lable 8-hr VOC concentrations and the corresponding percentage contributions to thei r total daily levels have been summarized in Appendix A.Figure 13 Percentage contribution of volatile organic compounds (VOCs) measured at the VOR site during three 8-hr intervals (i.e. 00:00 to 08:00, 08:00 to 16:00, and 16:00 to 00:00) to the corresponding 24-hr average conc entrations. The two panels refer to a) Phase 1 (November 2005 - March 2006) and b) Phase 2 (July - September, 2006) data

0% 20% 40% 60% 80% 100%1,3-ButadieneBenzeneCarbonTetrachlorideChloroformMethylene ChloridePerchloroethyleneTolueneTrichloroethene% of VOCper time period Van Nuys Airport - VOR Site - Phase 1

00:00 - 08:00

08:00 - 16:00

16:00 - 00:00

0% 20% 40% 60% 80% 100%1,3-ButadieneBenzeneCarbonTetrachlorideChloroformMethylene ChloridePerchloroethyleneTolueneTrichloroethene% of VOCper time period Van Nuys Airport - VOR Site - Phase 2

00:00 - 08:00

08:00 - 16:00

16:00 - 00:00 

### b) a)

32Santa Monica Airport
As at VNA, three integrated 8-hr canister samples (i.e. 00:00 to 08:00, 08:00 to 16:00, and 16:00 to 00:00) were collected daily at all Santa Monica sites and analyzed for VOCs. Also in this case, the concentrations of most volatile species were higher between 00:00 and 08:00, and the percentage contributio n of most VOCs collected in this time frame to their corresponding 24-hr averag e concentrations was higher during the spring/summer months (the average for all VOCs and at all sites during Phase 1 is 49%) than in the fall/winter peri od (the corresponding average c ontribution during Phase 2 is 42%). This situation is illustrated for the West Tarmac site in Figures 14a and 14b, and it is representative of all other Santa Monica stations. All available 8-hr VOC levels and the corresponding percentage contri butions to their total daily concentrations have been summarized in Appendix A.

Figure 14 Percentage contribution of volatile organic compounds (VOCs) measured at the West Tarmac site during three 8-hr inte rvals (i.e. 00:00 to 08: 00, 08:00 to 16:00, and 16:00 to 00:00) to the correspond ing 24-hr average concentrations. The two panels refer to a) Phase 1 (April - Jul y, 2006) and b) Phase 2 (October 2006 - February 2007) data

0% 20% 40% 60% 80% 100%1,3-ButadieneBenzeneCarbonTetrachlorideChloroformMethyleneChloridePerchloroethyleneTolueneTrichloroethene% of VOCper time period Santa Monica Airport - West Tarmac Site - Phase 1

00:00 - 08:00

08:00 - 16:00

16:00 - 00:00

0% 20% 40% 60% 80% 100%1,3-ButadieneBenzeneCarbonTetrachlorideChloroformMethyleneChloridePerchloroethyleneTolueneTrichloroethene% of VOCper time period Santa Monica Airport - West Tarmac Site - Phase 2

00:00 - 08:00

80:00 - 16:00

16:00 - 00:00 

### a )

b)

3334 CARBONYLS

Van Nuys Airport The most abundant carbonyl species presen t in all canister sa mples collected at VNA were formaldehyde, acetaldehyde, aceton e and methyl ethyl ketone (MEK).

Previous studies conducted on commercial ai rcraft engines have found formaldehyde and acetaldehyde to be the dominant carbonyls in aircraft exhaust emissions (Agrawal et al., 2008). As for most VOCs, our results seem to suggest that the concen tration gradient of the majority of carbonyl compounds measured acr oss all Van Nuys sites is influenced by proximity to local streets and, to a lesser extent, to the airport area (Figure 15). In particular, while the lowest carbonyl levels were observed at the Holmes School station (~ 2,400 m from the north-west perimeter of th e airport and more than 300 m away from any major surface street), hi gher concentrations of MEK, acetone, acetaldehyde and formaldehyde were always detected at the Golf Course, VOR, and National Guard sites (closer to more heavily traveled roads a nd near or within the airport fence-line). However, unlike what was observed for most volatile species, the concentrations of all carbonyl compounds measured at the urban site in Burbank were generally lower than those recorded at the Van Nuys Airport st ations (Figure 15). The difference was more evident in Phase 2 during the warmer months . More specifically, a non-parametric oneway ANOVA on ranks showed that the median ambient levels of acetone (during Phases 1 and 2) and those of MEK (during Phase 1 only) in Burbank were significantly lower (p< 0.05) than the corresponding co ncentrations at all other monitoring sites. Although it is possible that emissions of certain carbonyls from aircraft and airport operations might

have increased the ambient concen trations of these air toxics with respect to typical urban levels, the extent of the contribution of th is and other airport-related sources to the carbonyl levels measured at the Van Nuys Ai rport cannot be assessed from the available data. A summary of all formaldehyde, acetaldehyde, acetone and MEK data collected at VNA during this study can be found in Appendix A.Figure 15 Spatial distributions of formaldehyde, acetaldehyde, acetone, and methyl ethyl ketone (MEK) at selected monitoring sites of the Van Nuys Airpor t (i.e. Golf Course, Holmes School, VOR, and National Guard sites) during Phases 1 and 2. Data collected at an AQMD monitoring station in Burba nk are also included for comparison

3536 Santa Monica Airport
The average and median concentrations of the most abundant carbonyl compounds measured at SMO (formaldehyde , acetaldehyde, acetone and MEK) were higher during the fall/winter period (from October 2006 to Fe bruary 2007; Phase 2) than during the spring/summer months (from April 2 006 to July 2006; Phase 1) (Figure 16), which is consistent with the expected s easonal variations in local meteorological

conditions. The ambient concentrations of th e carbonyls measured at an urban site in Central Los Angeles were generally comparable to those recorded at the Santa Monica stations. The exception is lower MEK and acetone at the Central Los Angeles site during Phase 1, but there is no obvious explanati on for this observed difference. Although the spatial distribution of most carbonyl species did not vary substantially across the two sampling periods, it is difficult to discern a definite concentrati on gradient across the monitoring sites. However, it is worth mentioning that the average and median formaldehyde concentration at the Marine Pa rk site (away from the I-10 freeway and relatively far from the airport perimeter) were the lowest across all stations monitored during Phase 1, and the highest during Phase 2. The reasons for this unexpected seasonal difference are not clear, but might be relate d to one or more localized sources of carbonyls around the park area. We cannot excl ude that emissions of formaldehyde and other carbonyl compounds from aircraft and ai rport activiti es might have also contributed to increase the concentrations of these pollutant s at SMO sites. However, the extent of the contribution of this and other potential impor tant sources (e.g. motor-vehicle emissions from the I-10 freeway and from other local roadways) to the carbonyl levels measured

around SMO cannot be assessed from the availa ble data. A summary of all formaldehyde, acetaldehyde, acetone and MEK data collected at SMO throughout this study can be found in Appendix A.Figure 16 Spatial distributions of formaldehyde, acetaldehyde, acetone, and methyl ethyl ketone (MEK) at selected monitoring site s of the Santa Monica Airport (i.e. Richland School, Marine Park, Ernst Residence, East Tarmac, and West Tarmac sites) during Phases 1 and 2. Data collected at an AQMD monitoring station in Central Los Angeles are also included for comparison

37PM 2.5 MASS, ELEMENTAL AND ORGANIC CARBON

Van Nuys Airport
Although the average and median levels of PM 2.5 , OC and EC measured at VNA sites were not substantially different across the two phases of the study, a higher variability in the atmospheric concentrations of these three particulate pollutants was observed during Phase 1 (November 2005 – Ma rch 2006), as shown in Figure 17 and in Table 6. The spatial distribution of PM 2.5 and that of its carbona ceous components did not vary substantially across the two sampling periods and, in most cases, it was similar to that observed for most VOCs and carbonyl co mpounds. In particular, the highest average

concentrations of PM 2.5 , OC and EC across all Van Nuys stations were measured at locations that were closer to the airport (i.e. VOR and National Guard stations) and to heavily trafficked surface stre ets (i.e. Golf Course site), while the lowest levels were recorded at the Holmes School site (bac kground), further away from these pollution

sources.

Figure 17 Spatial distributions of fine particulate matter (PM 2.5 ), organic and elemental carbon (OC and EC, respectively) at selected monitoring sites of the Van Nuys Airport (i.e. Golf Course, Holmes School, VOR, and Na tional Guard sites) during Phases 1 and 2. Data collected at an AQMD monitoring sta tion in Burbank are also included for comparison

3839 The average and median concentrations of PM 2.5 , OC and EC at the Golf Course,

VOR and National Guard stations were elevated by a factor of less than two with respect to “background levels”. At Holmes School this is probably due to the fact that these measurements refer to integrated 24-hr average samples. More substantial increases in the concentrations of EC may o ccur on shorter time-scales (e.g. minutes to hours) and closer to the runway area, especially while airp lanes are taking-off. A previous study that focused on the chemical and physical analysis of the exhaust from various in-use

commercial aircraft at two different air ports indicated that take-off plumes are characterized by substantial increases in black carbon (BC; another indicator, along with EC, of combustion particles similar to t hose emitted from diesel engines) content (Herndon et al., 2005). A non-parametric one way ANOVA on ranks indicated that during Phase 1 the

median concentrations of PM 2.5 and EC at an urban site in Burbank (20.2 and 3.05 μg/m 3

, respectively) were significantly higher (p <0.05) than the corresponding levels measured at all Van Nuys stations. Similarly, a stat istically significant difference (p<0.05) in

median OC levels was also observed between the Burbank station and the Holmes School and VOR sites. Overall, our da ta do not point to airport opera tions as the main source of the particulate pollutants measured at VNA sites. It is more likely that other local and regional sources (e.g. motor-vehicle emissi ons from nearby traffic and atmospheric transport of aged pollutants, respectively) co ntributed to the observe d atmospheric levels

of fine PM and those of its carbonaceous co mponents. This is consistent with the previous observations of the concentration gr adients of the gaseous pollutants measured at the same locations. None of the seasonal average (or median) PM 2.5 values measured at VNA sites were higher than the corresponding 2006 annual average in the South Coast Basin (20.6 μg/m 3 ), or the U.S. EPA NAAQS for fine PM (35 μg/m 3 , expressed as the 3- year average of the 98 th percentile of 24-hr c oncentrations).Table 6 Average and median fine particulate matter (PM 2.5 ), organic and elemental carbon (OC and EC, respectivel y) concentrations (μg/m 3 ) at the Van Nuys Airport

stations and at an urban site in Burba nk (CA) during Phase 1 (November 2005 - March 2006) and Phase 2 (July - September, 2006). Minimum (Min) and maximum (Max) values, standard deviations (SD), and the total number of va lid samples (Valid N) have

also been included

Golf

Course Holmes

School VOR National

Guard Burbank

PM 2. 5 - Phase 1

Average 13.9 12.0 14.2 N/A 22.8

Median 10.6 7.84 12.2 N/A 20.2

SD 9.87 8.69 9.75 N/A 13.0

Min 3.51 2.89 2.99 N/A 4.03

Max 37.4 31.7 34.8 N/A 58.7

Valid N 32 33 33 N/A 39

PM 2. 5 - Phase 2

Average 14.7 10.8 17.7 16.7 N/A

Median 13.6 10.9 16.8 17.3 N/A

SD 4.69 2.70 8.45 4.23 N/A

Min 7.72 6.48 7.13 10.1 N/A

Max 24.8 13.6 48.2 26.3 N/A

Valid N 22 5 22 14 N/A

OC - Phase 1

Average 9.35 6.03 7.28 N/A 10.4

Median 9.79 5.00 7.89 N/A 11.0

SD 4.74 3.38 3.88 N/A 3.75

Min 1.97 1.72 1.60 N/A 2.89

Max 19.4 13.4 13.8 N/A 19.6

Valid N 31 33 33 N/A 39

OC - Phase 2

Average 7.63 6.49 8.76 8.74 N/A

Median 7.32 5.30 7.69 7.49 N/A

SD 3.75 4.72 5.19 4.12 N/A

Min 2.18 2.11 1.94 4.98 N/A

Max 19.1 14.4 27.0 17.8 N/A

Valid N 22 5 22 14 N/A

EC - Phase 1

Average 1.85 1.51 1.86 N/A 3.07

Median 1.62 1.33 1.56 N/A 3.05

SD 1.36 1.18 1.33 N/A 1.48

Min 0.25 0.03 0.11 N/A 0.43

Max 5.51 3.93 4.67 N/A 6.18

Valid N 31 33 33 N/A 39
EC - Phase 2

Average 1.65 1.21 1.99 1.89 N/A

Median 1.52 1.20 1.86 1.57 N/A

SD 0.72 0.88 0.94 0.81 N/A

Min 0.33 0.44 0.10 0.77 N/A

Max 3.75 2.62 4.08 4.02 N/A

Valid N 22 5 22 14 N/A

40Santa Monica Airport
The average and median PM 2.5 mass concentrations at SMO stations showed rather low spatial and seasonal variability (from 14.9 to 17.4 μg/m 3 during Phase 1, and from 14.7 to 17.3 μg/m 3 during Phase 2), and were comparable (or lower) to those

measured at an urban station in Central Los Angeles (Figure 18 and Table 7). As observed in the previous section, this is probably related to th e fact that regional transport was driving the PM 2.5 levels in this area at the time of sampling. None of the 24-hr seasonal average (or median) PM 2.5 values measured at SMO sites were higher than the corresponding 2006 annual average in the South Coast Basin (20.6 μg/m 3 ).

Figure 18 Spatial distributions of fine particulate matter (PM 2.5 ), organic and elemental carbon (OC and EC, respectively) at selected monitoring sites of the Santa Monica Airport (i.e. Richland School, Marine Park, Ernst Residenc e, East Tarmac, and West Tarmac sites) during Phases 1 and 2. Data co llected at an AQMD monitoring station in Central Los Angeles are also included for comparison

4142 The spatial distribution of OC and EC di d not vary substant ially across the two sampling periods and, for the most part, it was similar to that observed for VOC and carbonyl compounds. In particular, the atmos pheric levels of these two carbonaceous components seemed to be more variable at si tes that were closer to the airport area of operation (e.g. East Tarmac and Ernst Residence), and slightly lower average and median OC and EC values were generally measured at the Marine Park site (background), away from the influence of airport emissions. A non-parametric ANOVA on ranks revealed that, with the exception of the median OC le vel at the Ernst Residence site during Phase 1, the median ambient levels of OC and EC at the Santa Monica stations were significantly lower (p<0.05) than those in Central Los Angeles, both during Phase 1 and Phase 2. This might be due to a relatively higher contribution of carbonaceous material

from motor-vehicles at this urban site in Central Los Angeles. Higher average and

median concentrations were measured in the colder months (October 2006–February 2007), which is consistent with more persistent inversions during the fall/winter period. As noted in previous sections, the eff ect of airport activities on EC may be observed on a shorter time-scale (e.g. minutes to hours), and previous studies have shown sharp increases in EC (or BC) levels dur ing take-off and landing (Herndon et al., 2008; Westerdahl et al., 2008; Dods on et al., 2009; Hu et al., 2009 ). In particular, in the summer/spring of 2008 Hu et al. (2009) conduc ted a four-day field campaign using an electric vehicle equipped with fast response in struments to measure real time air pollutant concentrations downwind of SMO. They found that aircraft did not appreciably elevate the average levels of BC (which supports th is study’s results), although spikes in the

concentration of this and other combustion-re lated pollutants (i.e. polycyclic aromatic hydrocarbons and UFP) were generally obs erved during jet take-offs and, possibly, aircraft arrivals. Specifically, jet departures resulted in 1-min average BC concentrations of up to 30 μg/m 3 at a site located 100 m downwind of the takeoff area (in a similar geographical location as our Ernst Reside nce station), a value 100 higher than the corresponding summer background level.43 Table 7 Average and median fine particulate matter (PM 2.5 ), organic and elemental carbon (OC and EC, respectivel y) concentrations (μg/m 3 ) at the Santa Monica Airport

stations and at an urban site in Central Los Angeles (CA) during Phase 1 (April - July, 2006) and Phase 2 (October 2006 - March 2007 ). Minimum (Min) and maximum (Max) values, standard deviations (SD), and the total number of va lid samples (Valid N) have

also been included

Richland

School Marine

Park Ernst

Residence East

Tarmac West

Tarmac Central Los Angeles

PM 2. 5 - Phase 1

Average 14.9 15.2 17.4 N/A 15.8 16.9

Median 15.2 14.4 16.7 N/A 15.8 15.3

SD 6.76 6.70 5.75 N/A 6.28 9.14

Min 4.13 4.64 9.18 N/A 4.74 4.71

Max 35.8 34.8 34.6 N/A 32.5 40.7

Valid N 35 30 25 N/A 34 28

PM 2. 5 - Phase 2

Average 16.2 18.5 17.3 14.7 16.6 16.8

Median 13.6 17.1 14.3 12.5 14.8 16.6

SD 9.20 8.90 9.36 8.81 9.28 6.79

Min 4.95 9.81 5.07 1.86 3.10 5.63

Max 49.8 45.4 51.2 41.4 49.6 33.5

Valid N 43 13 40 29 39 27
OC - Phase 1

Average 4.78 3.96 5.69 N/A 4.05 6.26

Median 4.32 3.70 4.48 N/A 3.52 6.07

SD 2.13 1.60 2.65 N/A 2.49 1.92

Min 2.09 1.92 2.83 N/A 1.78 2.38

Max 11.9 11.3 12.3 N/A 16.7 9.52

Valid N 37 31 26 N/A 35 34
OC - Phase 2

Average 8.43 8.49 8.49 7.84 7.60 10.5

Median 8.28 6.63 8.24 7.77 7.22 9.62

SD 2.97 4.90 3.16 3.30 2.44 4.15

Min 2.88 5.32 3.66 2.58 2.30 4.31

Max 15.7 22.7 17.2 14.9 13.2 22.3

Valid N 43 13 40 29 39 30
EC - Phase 1

Average 0.89 0.70 1.17 N/A 0.64 1.54

Median 0.66 0.60 0.98 N/A 0.54 1.31

SD 0.52 0.43 0.59 N/A 0.44 0.87

Min 0.07 0.09 0.54 N/A 0.02 0.25

Max 1.99 1.94 2.90 N/A 1.65 3.70

Valid N 69 60 50 N/A 66 66

EC - Phase 2

Average 2.78 2.52 2.70 2.69 2.43 3.79

Median 2.67 2.28 2.66 2.74 2.27 3.50

SD 1.53 0.57 1.20 1.53 1.34 1.35

Min 0.48 1.74 0.63 0.53 0.21 0.57

Max 5.92 3.74 5.02 5.32 5.79 6.64

Valid N 43 13 40 29 39 30ULTRAFINE PARTICLES

Van Nuys Airport Ultrafine particle (UFP) number concentration measurements (#/cm 3 ) were taken between November 2005 and March 2006 (Phase 1) and again from July to September of 2006 (Phase 2) at four select ed sites of the Van Nuys Ai rport: the Golf Course, VOR, Holmes School (only during Phase 1), and National Guard (only during Phase 2) stations. Butanol-based condensation particle counters (CPC) were used at all sites throughout the two monitoring campaigns. The highly resolved (1-min) data were averaged over 1-hr periods to facilitate comparison among these sites, and average di urnal variation plots were obtained to gain some insight into how UFP levels changed throughout the day. Overall, the data collected at the Van Nuys stations were found to be dynamic in range, with significant variability ove r very short temporal and spatial scales. A more in-depth analysis of these data is described belo w for each of the two monitoring periods.

Phase 1(November 2005 - March 2006) Figure 19 (main panel) illustrates the representative time evolution of the 1-hr UFP count measured at all monitored locations between 02/10/06 and 02/28/06, and shows that during the winter months the highest particle number concentrations were observed at the VOR site, close (about 150 m) to the north side of the airport and under the fixed wing arrival/departure route. On 2/ 13/06 at 17:00 the 1-hr UFP count level at this station peaked at a ma ximum value of about 203,000 #/cm 3 , a concentration 19 and six times higher than that measured at the Golf Course and at the Holmes School sites, respectively, during the same time frame and further away from the airport fence-line. The latter station was set-up about 2,400 m north-west of the airport and, although airplanes were observed dire ctly over the school on se veral occasions, it can be considered to be typical of bac kground conditions in the study area.

44Figure 19 Representative hourly averag e ultrafine particle (UFP) number concentrations (#/cm 3 ) at the Van Nuys Airport measured from 02/10/06 to 02/28/06. Hourly data were averaged from 1-min values to facilitate comparison among sites (top panel). An example

of more resolved 1-min data is shown in the magnified portion of the graph within broken

lines

4546 When averaged across the entire duration of Phase 1, the particle count at the VOR site (~32,100 #/cm 3 ) was 1.4 times higher than that at the Golf Course station (~23,400 #/cm 3 ), and 3.6 times more elevated than that at the Holmes School site (8,900 #/cm3) (Table 8). These results are in lin e with those obtained at the Santa Monica Airport during this and previous studies (e.g. Hu et al., 2009), where measured UFP

concentrations decreased with incr easing distance from the runway.

Table 8 Average and median ultrafine particle (UFP) number concentrations (μg/m 3 ) at the Van Nuys Airport stations during Phas e 1 (November 2005 - March 2006). Minimum (Min) and maximum (Max) values, standard de viations (SD), and the total number of valid samples (Valid N) have also been included



## Van Nuys Airport

Golf

Course Holmes

School VOR National

Guard
UFP number (#/cm 3 ) - Phase 1

Average 23365 8892 32084 N/A

Median 18914 7124 26265 N/A

SD 19600 6423 23307 N/A

Min 1691 1389 1949 N/A

Max 182581 136558 202621 N/A

Valid N 2065 1634 2157 N/A

A closer look at the more resolved 1-min data revealed the presence of sharp particle count peaks at both the VOR and, le ss frequently, the Golf Course sites (see magnified portion of Figure 19), probably caused by aircraft takeoffs/landings. A few occasional spikes in UFP count were also obs erved at the Holmes School station (not shown), and were likely attr ibutable to landing aircraft passing overhead, or nearby vehicular traffic. Between peak events the coun ts generally returned to levels closer to those in background air. Because of limitations with the data-logging system connected to the butanol-based CPCs, partic le counts higher than 260,000 #/cm 3 could not be measured at VNA sites during Phase 1. It is likely that the actual maximum UFP peaks corresponding to periods of aircraft operations were higher than the instrument threshold, but less than 0.45, 0.15 and 0.05% of all 1-min measurements at the VOR, Golf Course, and Holmes School sites, respectively, we re equal to and likely higher than 260,000

#/cm 3 . The effect of underestimating these extreme data-points on comparisons of 1-hr average particle levels across sites is minimal. This limitati on of the data-logging systems was corrected before the beginning of Phase 2. Unfortunately, detailed information a bout the aircraft operating at VNA (e.g. model and engine type) and th eir takeoff/landing schedule wa s not available at the time of the study, and the effect of aircraft movements on the magnitude of the measured UFP peaks could not be assessed at VNA sites. However, while working at the VOR station AQMD staff members reported that observati ons of particle count peaks corresponded with visual sightings of airc rafts preparing from departure, taking off, or landing, with a short delay between the sighting and the peak count recorded on the instrument. It isinteresting to note that a few recent field campaigns conducted both in the United States and in Europe (i.e. APEX, EXCAVATE and AI RPUR) have indicated that while the PM mass in the exhaust of turbine engines is es sentially a conserved quantity as the plume dilutes downwind, the particle number is probably a consequence of post emission condensation (Wey et al., 2006; Lelievre et al ., 2006; Herndon et al., 2008). In particular, formation of UFPs by nucleation seems to occu r up to a distance of 25 m from the exit of the engine (Lelie vre et al., 2006). Figure 20 shows the average diurnal pr ofile of hourly particle number concentrations at VNA monitoring sites. Wh ether the “bimodal” appearance of the particle count distribution (with peaks between 7:00 and 10:00 am, and from 3:00 to 8:00pm) can be attributed to airport activitie s or to rush hour tra ffic from the highly trafficked surface streets surrounding the ai rport (e.g. Roscoe Blvd. and Balboa Blvd.)

cannot be assessed from the ava ilable data. Ultrafine particle levels at night and early in the morning (i.e. from 22:00 to 03:00) suggest a substantial decrease in particle count as the airport activities and th e vehicular traffic subsided in the evening hours.

Figure 20 Average diurnal profiles of the ultraf ine particle (UFP) number concentration (#/cm 3 ) measured at three sites of the Van N uys Airport (i.e. Golf Course, VOR, and Holmes School stations) during Ph ase 1 (November 2005 - March 2006)

0 10000 20000 30000 40000 50000 60000 700000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00# ptcl/cm3 Van Nuys Airport - Phase 1

Golf Course

VOR Site

Holmes School

Phase 2 (July - September, 2006)

47 The UFP levels measured at VNA in the summer/fall period were significantly lower than those observed during Phase 1, but followed a similar concentration gradient across all available sampling locations (see the main panel of Figure 21 for a representative time series from 09/01/06 to 09/ 18/06). Particle count data at the Holmes School (background) station were not available during this part of the study since the site was no longer available. Ultrafine particle measurements were carried out at the National Guard station instead, within the north-west perimeter of the airport complex and away from the fixed wing arrival/departure routes or traffic paths. Also in this case, the highest 1-hr particle count peaks (between 70,000 and 115,000 #/cm 3 ) were measured at the VOR site, and were about half of the highest number concentrations observed at the same location during Phase 1. On 9/15/06 at 15:00 th e particle number concentration at theVOR station increased to a maximum value of about 115,000 #/cm 3 , about ten and 13 times the corresponding count levels measured at National Guard and at the Golf Course sites, respectively.

Figure 21 Representative hourly averag e ultrafine particle (UFP) number concentrations (#/cm 3 ) at the Van Nuys Airport measured be tween 09/01/06 and 09/18/06. Hourly data were averaged from 1-min measurements to facilitate comparison among sites (top panel). An example of more resolved 1-mi n data showing elevated UFP levels from 09/07/06 to 09/09/06 is illustrated in the magni fied portion of the graph within broken

lines

When averaged across the entire duration of Phase 2, the UFP concentration at the VOR site (~19,200 #/cm 3 ) was only slightly more elevated than that measured at the National Guard (16,400 #/cm 3 ) and at the Golf Course (11,700 #/cm 3 ) stations (Table 9) Lower concentrations during th e summertime period are expected for most air pollutants, mostly because of a decreased atmospheric st ability and less freque nt inversions, which favor atmospheric dispersion.

4849 Table 9 Average and median ultrafine particle (UFP) number concentrations (μg/m 3 ) at the Van Nuys Airport stations during Phas e 2 (July - September, 2006). Minimum (Min) and maximum (Max) values, standard deviat ions (SD), and the total number of valid samples (Valid N) have also been included



## Van Nuys Airport

Golf

Course Holmes

School VOR National

Guard

UFP number (#/cm 3 ) - Phase 2

Average 11740 9115 19154 16404

Median 11116 8340 17181 15197

SD 4093 3868 10878 7719

Min 3171 1327 3652 3519

Max 42494 34182 114296 62955

Valid N 1055 290 1005 726

A more in depth analysis of the highly resolved 1-min data confirmed that, although sharp peaks as high as 300,000-400,000 #/cm 3 (probably associated with aircraft takeoffs or landings) were observed on differe nt occasions at the VOR site, the overall UFP levels measured during the second part of the sampling campai gn were significantly lower than those seen during Phase 1 (ma gnified portion of Figure 21). However, on 09/08/06 at 16:09 the 1-min ultrafine particle concentration at the VOR station reached a maximum of 427,000 #/cm 3 , a value 32 and 36 times more elev ated than those at the Golf Course and National Guard sites during the sa me time period. No information about the operations schedule at VNA or lo cal roadway traffic is availa ble to specifically identify the cause of that high partic ulate count value. Figure 22 shows the average diurnal pr ofile of hourly particle number concentrations observed at VNA sites during Phase 2. As during the fall/winter period, the highest particle number counts throughout the warmer months occurred from late morning to late afternoon. Ultrafine particle concentrations at ni ght and early in the morning (i.e. from 22:00 to 03:00) were typically comparable at all stations, suggesting a substantial decrease in UFPs in and around the VNA area as the airport activities and the vehicular traffic subsided in the evening hours.Figure 22 Average diurnal profiles of the ultraf ine particle (UFP) number concentration (#/cm 3 ) measured at three sites of the Van N uys Airport (i.e. Golf Course, VOR, and National Guard stations) during Ph ase 2 (July - September, 2006)

0 10000 20000 30000 40000 50000 60000 700000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00 Van Nuys Airport - Phase 2

Golf Course

VOR Site

National Guard#ptcl/cm3

Santa Monica Airport Ultrafine particle number concentrations (#/cm 3 ) were measured between April and July 2006 (Phase 1) and from October 2006 to February 2007 (P hase 2) at five selected sites of the Santa Monica Airport, namely East Tarmac, Ernst Residence, West Tarmac, Richland School, and Marine Park ( only during Phase 2). The highly resolved (1-min) data were averaged over 1-hr periods to facilitate compar ison among these sites. Average diurnal variation plots were also obtained for all stations to gain some insight into how UFP levels changed throughout the da y. As at VNA, the data collected at SMO were found to be very dynamic in range, with even higher spatial and temporal

variabilities. Because the terms of the loan for the butanol-based CPCs used during the first phase of the Santa Monica field campa ign expired at the end of September 2006, water-based CPCs were purchased by AQMD and used during Phase 2.

Phase 1(April - July, 2006) The time series plot in Figure 23 (main panel) summarizes observations made

from 05/03/06 to 05/24/06 and illustrates how during the first phase of the study the UFP number concentration gradient was affect ed primarily by proximity to the take-off location on the airport’s runway. The highest 1-hr average particle count peaks were measured at the East Tarmac site, approximate ly 35 m west from the end of the runway

and near the blast-fence. In particular, on 05/11/06 at 14:00 the 1-hr ultrafine particle

count level at this station increased to about 510,000 #/cm 3 , a concentration five times higher than that recorded at the Ernst Re sidence site (about 10 0 m downwind of the runway but outside the air port’s fence-line) during the same time period. The corresponding ultrafine levels measured at the West Tarmac (around 100 m west from the southern end of the runway), Richland School (the furthest site from SMO), and Marine Park (background) stations were 7,500, 7,000, and 6,500 #/cm 3 , respectively, or 70 to 80 times lower than those at East Tarmac. These findings are consistent with an aircraft

50source given the stations relative proximity to the area where aircraft were idling and taking off, and the predominant wind flow (from the south-sout heast direction).

Figure 23 Representative hourly averag e ultrafine particle (UFP) number concentrations (#/cm 3 ) at the Santa Monica Municipal Air port measured from 05/03/06 to 05/24/06. Hourly data were averaged from 1-min m easurements to facilitate comparison among sites (top panel). An example of more resolv ed 1-min data showing elevated UFP levels

from 05/11/06 to 05/12/06 is illustrated in the magnified portion of the graph within

broken lines

When averaged across the entire duration of Phase 1, the UFP level at the East Tarmac site (~52,200 #/cm 3 ) was two times higher than th at at the Ernst Residence station (~26,300 #/cm 3 ), and seven times more elevated than that at the background site (Marine Park; 8,000 #/cm 3 ) (Table 10). Our results are lo wer than those obtained by Hu et al. (2009) during a four day campaign conducted in the spring/summer of 2008, when the study-average UFP concentrations at tw o sites 80 and 100 m downw ind of the airport were 106,000 and 97,000 #/cm 3 , respectively, or about 10 times the corresponding background levels for all measurement days combined. One explanation for this

5152 discrepancy is that while our CPCs were operated 24-hours, Hu et al. measured only daytime UFP number concentrations and with in a much shorter time frame (i.e. 4 to 6 hours for four sampling days) when the airport was in operation.

Table 10 Average and median ultrafine particle (UFP) number con centrations (#/cm 3 ) at the Santa Monica Airport sta tions during Phase 1 (April - July, 2006). Minimum (Min) and maximum (Max) values, standard deviat ions (SD), and the total number of valid samples (Valid N) have also been included



## Santa Monica Municipal Airport

Richland

School Marine

Park Ernst

Residence East

Tarmac West

Tarmac

UFP number (#/cm 3 ) - Phase 1

Average 13273 8037 26284 52240 8406

Median 10011 7216 14963 31097 7316

SD 9135 4505 28147 67741 5310

Min ND 1684 1221 1345 1444

Max 80548 53010 312524 513135 96942

Valid N 2804 1753 1846 930 2469

An analysis of the more resolved 1-min data revealed the presence of spikes in particle number concentrations as high as 9,000,000 #/cm 3 , as measured on 05/11/06 at 18:45 at the East Tarmac (magnified portion of Figure 23). These ex ceptionally elevated levels were rare, but 1-min maxima between 4,000,000 and 4,500,000 #/cm 3 were relatively more common at the East Tarm ac and, occasionally, at the Ernst Residence

site. The 1-min concentration measured at the Marine Park (background) site was as much as 2,100 times lower than the corresponding value at the East Tarmac. However, a relative decrease in 1-min background part icle counts between 100 and 600 times was more common during Phase 1. For comparison, Hu et al. (2009) observed that the

maximum 1-min UFP measured in Clarkson R d. (100 m north from the runway of SMO) was 2,200,000 #/cm 3 , or about 440 times the corresponding summer background level (~5,000 #/cm 3 ), which is consistent with our observa tions at the Ernst Re sidence site (setup in close proximity to Clarkson Rd.) during the same season. Increased peak

concentrations in UFP counts were also m easured near the Los Angeles International Airport (LAX) during a study carried out between September 2005 and March 2006 by Fanning et al. (2007). Here, the highest peak s in UFP number le vels were clearly correlated with aircraft take-off events, and 2% of the measured data points (recorded at 1-sec intervals) exceeded 10,000,000 #/cm 3 , the upper limit of the CPCs used for that study. In earlier work conducted by Westerdahl et al. (2008) at the same international airport (LAX), data collect ed about 100 m downwind of one of the south runways revealed that particle counts (measured at 10-sec intervals) reached approximately 4,800,000 #/cm 3 during some of the observed take-offs.The effect of aircraft movements on the magnitude of the UFP number peaks

measured at SMO sites is illustrated in Figure 24, which shows the particle number concentration time series at the East Tarmac, West Tarmac, Ernst Residence and Richland School stations on 07/07/06. As exp ected, measurements at the East Tarmac and Ernst Residence sites peaked when aircraft where either taxing or taking-off.

Figure 24 Ultrafine particle (UFP) number concen trations data showing the impact of aircraft movements at the East Tarmac, Ernst Residence, West Tarmac, Richland Elementary School sites on 07/07/06

These time periods (corresponding to the br oken lines in Figure 24) have been highlighted in red in Table 11, which also includes detailed inform ation about the model

and identification number of the aircraft asso ciated with these in creases in particle number concentration. AQMD staff members ope rating at the East Tarmac site reported that observations of partic le count peaks during takeoffs corresponded with visual sightings of aircraft preparing from departur e, with a short delay between the sighting and the peak count recorded on the instrument (o ften accompanied by an odor of jet-fuel).

5354 Jets and piston driven planes taxi a few hundred meters from the take-off area to the north of the runway near the East Tarm ac site. As summarized in Table 11, the taxi

time for most aircraft is between two and fi ve minutes (for comp arison, the acceleration time on the runway during takeoff is only of 20-30 seconds). Also, because the jet flight path from SMO intersects LAX flight path s less than 20 Km after takeoff, aircraft departing from SMO must wait for permission from LAX, resulting in an additional waiting time of up to 5 minutes or more. Ther efore, the typical total taxi-waiting time observed for an average airplane (“Grand To tal” in Table 11) during our field campaign was between 4 and 10 minutes. It is likely that these relatively long standby periods

contribute to increased the concentrations of UFPs and other co mbustion products (e.g. BC) in the vicinity of the takeoff area.

Table 11 Santa Monica Airport take-off observa tion data on 7/17/2006. Time periods associated with the particle number concentr ation peaks in Figure 24 are highlighted in

red

Observation

No. Aircraft

No. Aircraft Type Taxi Begins (a) Hold Begins (b) Departure

Time

(c) Total

Taxi (b-a) Total

Hold (c-b) Grand

Total (c-a)

1 480DG Cessna 560 7:34:19 7:37:22 7:39:01 03:03 01:39 04:42

2 374QS Cessna 560 7:39:57 7:43:25 7:46:41 03:28 03:16 06:44

3 25FS Cessna 550 8:13:27 8:16:16 8:17:27 02:49 01:11 04:00

4 555LG CL-600-2B16 8:47:50 8: 53:06 8:57:25 05:16 04:19 09:35

5 834QS Cessna 560 9:12:26 9:16:14 9:22:16 03:48 06:02 09:50

6 238SM Cessna 560XL 9:31:11 9:35:09 9:37:40 03:58 02:31 06:29

7 268QS Falcon 2000 9:38:00 9: 41:23 9:45:51 03:23 04:28 07:51

8 647QS Cessna 560XL 9:58:00 10: 01:16 10:03:12 03:16 01:56 05:12

9 827RM Beech B100 10:04:04 10:06:17 10:12:40 02:13 06:23 08:36

10 25LZ Cessna 525A 10:22:20 10:26:50 10:29:26 04:30 02:36 07:06

11 884QS Hawker 800XP 10:48:00 10:50:28 10:53:40 02:28 03:12 05:40

12 426CH Cessna 560XL 10:55:24 10:57:41 10:59:40 02:17 01:59 04:16

13 324MM Beech 400 10:58:41 11:01:14 11:09:15 02:33 08:01 10:34

14 169TA CL-600-2A12 12:35:11 12:38: 20 12:39:12 03:09 00:52 04:01

15 281QS Falcon 2000 13:31:41 13:33:45 13:37:51 02:04 04:06 06:10

16 268QS Falcon 2000 14:18:03 14:20:45 14:24:22 02:42 03:37 06:19

17 227WS Cessna 560 14:18:03 14:21: 42 14:25:30 03:39 03:48 07:27

18 105AX Beech 400A 15:20:21 15:23:38 15:27:07 03:17 03:29 06:46

19 51HF Cessna 525A 15:48:11 15:50:20 15:53:37 02:09 03:17 05:26

20 777DY Cessna 525A 15:50:08 15:53:47 15:54:48 03:39 01:01 04:40

21 411QS G-IV 15:51:52 15:54:29 15:56:20 02:37 01:51 04:28

22 931QS Cessna 750 16:38:21 16:41:19 16:43:45 02:58 02:26 05:24As suggested by the average diurnal profile of hourly particle number concentrations measured at SMO sites (Fi gure 25), the highest traffic activity during

Phase 1 occurred between 09:00 and 17:00. Ultrafin e particle levels at night and early in the morning (i.e. from 22:00 to 03:00) were typically comparable at all stations, suggesting a substantial decrea se in particle count as th e numbers of take-offs and landings subsided in the evening hours and ce ased overnight. Hu et al. (2009) analyzed airport count information from traffic logs provided by SMO, and reported that in the spring/summer of 2008 the great majority of aircraft operations (diurnal hourly arrivals and departures) took place from 09:00 and 20:00, consistent with our results. The Santa Monica Airport allows operations of noneme rgency aircraft only from 07:00-23:00 on weekdays and 08:00-23:00 on weeke nds due to noise ordinances.

Figure 25 Average diurnal profiles of the ultraf ine particle (UFP) number concentration (#/cm 3 ) measured at five sites of the Santa Monica Airport (i.e. East Tarmac, West Tarmac, Ernst Residence, Richland School, a nd Marine Park) during Phase 1 (April - July, 2006)

0 20000 40000 60000 80000 100000 120000 1400000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00# ptcl/cm3 Santa Monica Airport - Phase 1

West Tarmac

East Tarmac

Ernst Residence

Richland School

Marine Park

Phase 2 (October 2006 - February 2007) During the second field campaign at SMO, the UFP concentrations (measured using water-based CPCs) were substantially lower than those observed during Phase 1, and more homogeneous across sampling sites (main portion of Figure 26). The magnitude of the highest 1-hr peaks at th e East Tarmac and Ernst Residence stations (124,000 and 155,000 #/cm 3 , respectively) were comparable to the maximum 1-hr ultrafine levels measured at the West Tarmac site (122,000 #/cm 3 ) and 2-2.5 times higher

than that the Richland School station (64,000 #/cm 3 ; 900 m north-east of SMO). Because

of an instrument malfunction no particle count data were ob tained at the Marine Park (background) station, which make s it difficult to estimate the relative increase in UFP concentration downwind of the runway with respect to background conditions.

55Figure 26 Representative hourly averag e ultrafine particle (UFP) number concentrations (#/cm 3 ) at the Santa Monica Municipal Air port measured from 01/01/07 to 01/23/07. Hourly data were averaged from 1-min m easurements to facilitate comparison among sites (top panel). An example of highly resolved 1-min data showing elevated UFP levels

from 01/02/07 to 01/03/07 is illustrated in the magnified portion of the graph within

broken lines

5657 When averaged across the entire duration of Phase 2, the UFP level at the East Tarmac and Ernst Residence sites (~27,900 and 25,000 #/cm 3 , respectively) were still about 2.5 times higher than those at the other two sites (Table 12).

Table 12 Average and median ultrafine particle (UFP) number con centrations (#/cm 3 ) at the Santa Monica Airport stations du ring Phase 2 (October 2006 - March 2007). Minimum (Min) and maximum (Max) values, st andard deviations (SD), and the total number of valid samples (Valid N) have also been included



## Santa Monica Municipal Airport

Richland

School Marine

Park Ernst

Residence East

Tarmac West

Tarmac
UFP number (#/cm 3 ) - Phase 2

Average 11503 N/A 24987 27907 11404

Median 9454 N/A 18468 22002 9053

SD 9398 N/A 20650 21023 9724

Min 167 N/A 1135 1200 1167

Max 63722 N/A 155498 124213 121802

Valid N 1048 N/A 1956 1312 1908

The fact that most of the 1-min peak con centrations measured at the East Tarmac and Ernst Residence sites (see the magnified portion of Figure 26 for data collected between 01/02/07 and 01/03/07) were never above 500,000 #/cm 3 (more than one order of magnitude less than the highest levels re corded during the spring/summer campaign) is likely related to limitations of the water-based CPCs (i.e. their detectable particle range is between 0 and ~500,000 #/cm 3 ). Also, it is possible that th e counting efficiency of waterbased CPCs for particles smaller than 20 nm in diameter (which comprise a substantial

fraction of the total number of particles in aircraft emissions) is significantly lower than that of their butanol-based counterparts (Herman et al., 2007; Mordas et al., 2008). Although these measurement uncertainties limit our ability to provide a more quantitative

assessment of the effect of aircraft takeo ffs/landings at sites upwi nd and downwind of the SMO runway during Phase 2, 1-min particle counts at the East Tarmac and Ernst Residence sites were still up to 70 times hi gher than those observed at the other two stations further away from the airport (i.e. Richland School and West Tarmac).

Recent studies conducted at the Santa M onica Airport (Hu et al., 2009) and at LAX (Fanning et al., 2007; West erdahl et al., 2008) have sh own that UFPs downwind of these two airports were dominated by fres hly generated particles with peak modes between 10 and 15 nm, while the upwind aerosol was comprised by larger aged particles

with a diameter of about 90 nm. There is now a growing body of work concerning the potential for adverse health effects from exposure to UFPs emitted from different combustion processes (Xia et al., 2004; Delf ino et al., 2005; Sioutas et al. 2005; Nel et al., 2006; Pope and Dockery, 2006), and the presen ce of highly elevated ultrafine particlelevels downwind of general avia tion and international airports may have potential health implications for persons living in adjacent areas. Figure 27 shows the average diurnal pr ofile of hourly particle number concentrations observed at SMO sites during Phase 2. As during the first phase of the study, the highest traffic activity occurred between 09:00 and 18:00. Average UFP levels at night and early in the morning (i.e. fr om 22:00 to 03:00) were comparable at all stations, suggesting a substantial decrease in pa rticle count as airpor t activities subsided at night.

Figure 27 Average diurnal profiles of the ultraf ine particle (UFP) number concentration (#/cm 3 ) measured at four sites of the Santa Monica Airpor t (i.e. East Tarmac, West Tarmac, Ernst Residence, and Richland School ) during Phase 2 (October 2006 - February 2007)

0 20000 40000 60000 80000 100000 120000 1400000:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00# ptcl/cm3 Santa Monica Airport - Phase 2

West Tarmac

East Tarmac

Ernst Residence

Richland School

DAILY CARBON MONOXIDE (CO) VARIATIONS Carbon monoxide (CO) was measured at all “fully” instrumented sites by mean of

Dasibi ® 3008 CO Analyzers. Attempts were ma de to use personal monitors at the “partially” instrumented stations, but the re sulting data are not reliable and will not be discussed in the following paragraphs. Because of the malfunctioning of several monitors deployed at VNA and some data recovery probl ems, CO concentrations for Phase 1 are only available at the VOR site. None of the 1- hr average CO concentrations measured at both VNA and SMO was above the current U.S. EPA NAAQS for CO (35 ppm, not to be exceeded more than once per year). The average diurnal profile of CO at VNA during Phases 1 and 2 (Figures 28a and 28b, respectively) followed a distinctively different pattern from that observed for other combustion-related pollutants such as UFP count and BC, with peak values during morning rush hour traffic (average peak con centrations were between 1 and 1.4 ppm) and lower levels (typically below 0.2 ppm) in the afternoon. This indicates that the concentration of this gaseous pollutant wa s probably dominated by contributions from motor-vehicle emissions from nearby roadways and freeways, and su rface streets, and that the influence from airport-related activities was not significant. This seems to be

58particularly true at the VOR and Golf Course sites (outside the airport fence-line and where the highest CO levels were generally measured) and at the National Guard station. Similar results were obtained from previ ous work conducted in close proximity to international airports. For example, using nonparametric regression of hourly pollutant concentrations on wind speed and direction, Yu et al. (2004) studied the impact of two major urban airports, LAX and the Hong Kong International Airport (HKG), on local air quality. At both locations CO was dominate d by emissions from ground vehicles going in and out of the airport. Howe ver, near HKG Airport operations were occasionally found to be a significant contri butor to CO and respirable suspended particles. Emissions from the parking lots surrounding an airport area have also been associated with increased CO concentrations (Schurmann et al. 2006).

Figure 28 Average diurnal variations of carbon monoxi de (CO; ppm) at four sites of the Van Nuys Airport (i.e. Golf Course, VOR, Holmes School and National Guard). Measurements were taken from a) November 2005 to March 2006 (Phase 1) and b) between July and September 2006 (Phase 2). Because of a malfunctioning of several monitors deployed at VNA and issues related to data recovery, CO concentrations for Phase 1 are only available at the VOR site

0 0.2 0.4 0.6 0.8

1 1.2 1.4 1.60:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00CO (ppm) Van Nuys Airport - Phase 1

VOR SIte

0 0.2 0.4 0.6 0.8

1 1.2 1.4 1.60:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00 Van Nuys Airport - Phase 2

Golf Course

VOR Site

Holmes School

National GuardCO (ppm) 

### a)

b)

5960 As observed at VNA, the average diurna l profile of CO at SMO followed a distinctively different pattern from that observed for UFP count and BC (Figures 29). Also in this case, increased CO values during morning rush hour (not higher, on average, than 1.4 ppm) and minimum values in the af ternoon (generally below 0.2 ppm) suggest that the concentration of this gaseous pollu tant was mostly influenced by motor-vehicle emissions from roadways or freeways in the SMO area. The slightly higher CO levels measured at the Ernst Residence site during Phase 1 (Figure 29a) are probably due to the close proximity of this station to Bundy Dr. and National Blvd, two highly trafficked streets adjacent to the north-ea st side of the airport. The sa me relative increase in CO at

the Ernst Residence station was not observed during the second part of the study (Figure 29b), when the average CO levels at all mon itored sites were almost three times higher than during Phase 1. It is important to note that short term increases in CO c oncentrations from aircraft emissions have been typically observed when measurements are taken within a short distance from the plume of an engine. During a sampling campaign conducted at the Zurich Airport (Switzerland) Schurmann et al. (2007) collected real-time CO data in an area where four aircraft were generally pa rked and simultaneously handled. Here each aircraft movement on the taxiway led to s hort-term (3-min) CO peaks as high as 3,900 ppm at a distance between 50 and 100 m behind the aircraft, a concentration about 40 times higher than the corresponding background level. At low power setting such as when idling or taxiing, jet a nd piston engines emit high amounts of CO (and incompletely oxidized hydrocarbons), due to incomplete combustion. A summary of all CO concentration data collected at VNA and SMO during this study can be found in Appendix A.Figure 29 Average diurnal variations of carbon m onoxide (CO; ppm) at different four

sites of the Santa Monica M unicipal Airport, namely West Tarmac, Ernst Residence, Richland School, and Marine Park. Measurements were taken a) from April to July 2006 (Phase 1) and b) between October 2006 and March 2007 (Phase 2)

0 0.2 0.4 0.60:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00CO (ppm) Santa Monica Airport - Phase 1

West Tarmac

Ernst Residence

Richland School

Marine Park

0 0.2 0.4 0.6 0.8

1 1.2 1.4 1.60:001:002:003:004:005:006:007:008:009:0010:0011:0012:0013:0014:0015:0016:0017:0018:0019:0020:0021:0022:0023:00CO (ppm) Santa Monica Airport - Phase 2

West Tarmac

Ernst Residence

Richland School 

### a)

b)

TRACE ELEMENTS As discussed in the previous sections, particle and gaseous pollutants in and around an airport area can be emitted from a mu ltitude of airport-related sources such as re-fueling, ground support vehicles , passenger cars coming in and out the airport, but also from nearby traffic. Therefore, estimating th e relative contributions of these and other point and area sources to the measured atmos pheric concentrations of the targeted air pollutants can be challenging. The elemental co mposition of the collected aerosols can be used to provide an important fingerprint to help distinguish among emission sources from different environments including, roadways (Ntziachristos et al ., 2007b), harbor/ports (Arhami et al., 2009), and airports (Groma et al., 2008). Although more than 40 trace elements were analyzed on the PM 2.5 samples collected at the Van Nuys and Santa Monica Airports, only the concentrations of thos e species that were present in significant amounts (i.e. Mg, Al, Si, S, K, Ca, Fe, and Ba) will be discussed in the following

6162 paragraphs. The temporal and spatial distribut ion of lead has alrea dy been characterized in a previous section. The spatial distribution of each tra ce element measured at VNA was quite uniform across all sampling stations (i.e . Golf Course, VOR, Holmes School, and National Guard, all set-up outsi de the airport fence-line), regardless of their relative distance from the airport and runway (Figur e 30). Typically, S was the most abundant element in the collected PM samples, followed by Mg, Ca, K, Fe, Si, Ba and Al. Sulfur is typically generated from combustion sources su ch as gasoline and diesel-powered motorvehicles and aircraft, and it is a component of both Avgas and jet fuel. Previous studies conducted in the Los Angeles area (Ntziacris tos et al., 2007b; Arhami et al., 2009) have indicated that S is present in all three fractions of the atmospheric PM (ultra-fine, accumulation and coarse), with high values found in both ultra-fine and accumulation mode particles. During a recent campaign conducted between February and April 2006 and in close proximity to and downwind of the I-710 freeway (the primary route for heavy-duty diesel truck traffi c between the ports complex of Long Beach/San Pedro and the shipping yards in East Los Angeles) Nt ziachristos et al. (2007b) reported that the study average S concentration in PM 2.5 particles was about 300 ng/m 3 . This level is comparable to that observed at the Van Nuys sites during Phase 1 (240 to 280 ng/m 3 ) (Figure 30a), but is more than five times lo wer than the range of values measured during Phase 2 (1,520 to 1,580 ng/m 3 ) (Figure 30b). This substantia l difference can probably be attributed to increased presence of sec ondary sulfate particles during the summer campaign (Phase 2). The remaining trace elements detected in VNA samples mainly originate from mechanical processes such as vehicle brake abrasi on (Ba and Fe; Sanders et al., 2003) or from re-suspension of crustal materials (i.e. Mg, Ca, K, Fe, Si, and Al),

and their concentrations are well within thos e reported in previous road-side, tunnel, and port studies conducted in the Los Angeles Basi n (Singh et al., 2002; Ntziachristos et al., 2007b; Arhami et al., 2009) and other urban ar eas (Birmili et al., 2006). Calcium (used as anti-wear, detergent, and stabilizing additive in oils) has also been proposed as marker for

lube-oil combustion.Figure 30 Ambient concentrations of selected metals in fine particulate matter (PM 2.5 ) at different sampling locations of the Van Nuys Airport during a) Phases 1 (from November 2005 to March 2006) and b) Phase 2 (from July to September 2006)

Similarly, the concentrations of most trace elements measured at SMO were comparable at all stations (i.e. Richland Sc hool, Marine Park, East Tarmac, West Tarmac, and Ernst Residence), regardless of their re lative distance from the airport area (Figure 31). Average S concentrations were substantia lly lower throughout th e second part of the study (October 2006–February 2007), with values ranging from 175 ng/m 3 at the East Tarmac site (in very close proximity to an ar ea where aircraft were idling and taking-off) to 200 ng/m 3 at the Richland School site (background station) (Figure 31b). Overall, the temporal profile of the trace elements meas ured at SMO throughout the entire duration of this study is variable, with hi gher Al and S levels in the wa rmer months and increased P, K, Ca and Fe concentrations during the cold er period. This is al so consistent with increased amounts of of secondary sulf ate in late spring and early summer. Overall, the majority of the tr ace elements detected in the PM 2.5 samples collected in Santa Monica probably origin ated from re-suspension of crustal materials, and their concentrations are comparable to those reporte d in previous studies conducted in the Los Angeles Basin (Singh et al., 2002; Ntziachristos et al., 2007b ; Arhami et al., 2009) and other urban areas (Birmili et al., 2006). A summ ary of all trace element data collected at VNA and SMO during this study can be found in Appendix A.

63Figure 31 Ambient concentrations of selected me tals in fine particulate matter (PM 2.5 ) at different sampling locations of the Santa Monica Airport during a) Ph ase 1 (from April to July 2006) and b) Phase 2 (f rom October 2006 to March 2007)

JET SIGNATURES

To better characterize the influence of aircraft emissions on the air pollution levels at SMO, two canister samples were collected on 05/12/06 at the East Tarmac site, one when jet-propelled planes were idling ne ar the runway (sample #1) and one when no airplane activity was ongoing (sample #2). On the same day, a third canister sample was taken behind the blast-fence when jets we re taking-off (sample #3). These air samples were then analyzed to determine the con centrations of several relevant VOCs and gaseous air toxics. The results of this analys is are reported below in Table 13 and suggest that emissions from aircraft idling n ear the Tarmac (sample #1) increased the concentration of many measur ed pollutants substantiall y. Of the overall speciated mixture, some compounds such as 1,3-butadie ne, benzene and toluene are considered to be hazardous air pollutants (HAPs), while others (e.g. acetone) may be significant

contributors to the overall le vel of VOC emissions but da ta indicating toxicity are lacking. It is worth noting that at cruise speed, most aircraft engines convert significantly

more than 99% of the fuel th rough complete combustion to CO 2 and H 2 O. However, at idle conditions (those most commonly found n ear the East Tarmac station) less fuel is consumed and, in order to maintain a stable combustion at lower power settings, a small loss in combustion efficiency occurs. This leads to higher emissions of incompletely

6465 burned hydrocarbons (Aircraft Engine Speciated Organic Gases: Spec iation of Unburned Organic Gases in Aircraft Exhaust, prepared by EPA in 2009). Interestingly, the concentrations of al l gaseous species observed at the East Tarmac site while no aircraft activity was ongoi ng (sample #2) were comparable to those measured from the analysis of the canister sample collected behind the blast-fence when jets were taking-off (sample #3; see Table 13 for details). This agrees well with the results from a previous study conducted at the Logan Airport in Boston, where the aircraft exhaust from engine idle and taxiway acceleration was found to contain substantially greater con centrations of hydrocarbons (including formaldehyde, acetaldehyde, benzene, and toluene) than the exhaust during landing and takeoff (Herndon et al., 2005). This observation is also qualitatively consistent with the ICAO databank values for hydrocarbon emissions at id le relative to takeoff (ICAO, 2006)

Table 13 Ambient concentrations (p pb) of several important gaseous pollutants present in canister samples collected at the East Ta rmac site (samples #1 and #2) and behind the blast-fence (sample #3) at SMO

Sample #1

East Tarmac (Airplanes idling) (ppb) Sample #2

East Tarmac (No airplane activity) (ppb) Sample #3

Blast-Fence (Airplanes take-off)

(m+p)-Xylenes 1.32 0.20 0.33

1,2-Dibromoethane ND ND ND

1,2-Dichloroethane ND ND ND
1,2-Dichloropropane ND ND ND

1,3-Butadiene 7.39 ND 0.38

Acetone 6.13 4.20 4.01

Benzene 4.83 0.34 0.44

Carbon Tetrachloride 0.09 0.09 0.09

Chloroethene ND ND ND

Chloroform ND 0.03 0.04
Ethylbenzene 0.45 0.08 0.12

MEK ND ND 0.45
Methylene chloride 0.22 0.20 0.25

MTBE 0.03 ND ND

o-Dichlorobenzene ND 0.02 0.03
o-Xylene 0.39 0.26 0.21

p-Dichlorobenzene ND 0.02 0.05

Perchloroethylene 0.04 0.03 0.06

Styrene 0.67 0.08 0.15

Toluene 2.37 1.08 0.74

Trichloroethene ND ND ND

ND = non detected66 The emission profiles of th e two canister samples coll ected at the East Tarmac station were then compared to those of jet fu el exhaust (aircraft exha ust-jet fuel), typical gasoline vehicle emissions (g asoline - catalyst - stabili zed exhaust - ARB summer 2003), and diesel exhaust (farm equipment - diesel - light & heavy), all downloaded from the California Air Resource Board (CARB) sp eciation database for organic compounds (ORGPROF; http://www.arb.ca .gov/ei/speciate/speciate.htm) . This database provides estimates of the chemical composition of emissions for a variety of emission source categories, and data are reported as the fracti on of the total organic gases (TOG) that are reactive organic gases (ROGs). Hence, the concentrations of each species detected in the two canister samples collected at the East Tarmac (samples #1 and #2) were converted to the corresponding percentage contribution to the total measured gaseous levels to facilitate a comparison with the ARB data. Formaldehyde and ethylene were not qua ntified in samples #1, #2, and #3 since GC/MS analysis of canister samples is not accurate for formaldehyde detection, and ethylene is not considered an air toxic. However, data obtained from the chemical analysis of emissions from a commercial aircraft gas turbine engine (a CFM56 high bypass turbofan) indicate that the sum of these two com pounds alone represent about 55% of the total speciated non-methane hydrocarbon (NMHC) emissions on a concentration basis (Spicer, 1994). The same wo rk also reported th at around 40% of the organic gas mass was accounted for by th e compounds, ethene, formaldehyde, propene, ethyne and methane. While different data sets provide detailed information on the emission indexes of several air pollutants fr om various jet-engines types, the exact amount of individual organic gases emitted from jet propelled aircraft is difficult to quantify because it depends on the type of th e engine/airframe being tested, the sampling conditions (e.g. engine tests vs ambient sa mpling near airports), which species are included in the total mix, and which measurem ent technique has been employed for their analysis. Recent studies conducted both in th e United States and in Europe (Herndon et al., 2006; Schürmann et al., 2007) have shown that refueling activities can also alter the profile of most hydrocarbons considerably. These factors should be kept in mind while comparing the results of the various emission profiles presented below. As shown in Figure 32a, sample #1 clos ely resembles the emission profile of typical jet exhaust, which s uggests that the ambient air at the East Tarmac site was influenced by jet aircraft emissions when idling before take-off. Conversely, the emission profile of sample #2 is similar to that of diesel emission (Figure 32b), probably because when no airplane activity was taking place near the East Tarmac site the ambient air was affected by diesel emissions from vehicles ope rating within or in close proximity of the airport’s perimeter. Lastly, the emission pr ofiles of samples #1 and #2 seem to differ from that of gasoline exhaust (Figure 32c), indicating that gasoline-powered vehicles did not influence the composition of the two caniste r samples at the time of sampling. A more extensive study and data analysis is need ed to confirm these re sults and to better evaluate the contributions of jet exhaust and diesel emissions to the composition of

ambient air at the East Tarmac site a nd, in general, in the SMO area.Figure 32Comparison between the emission profiles ofthe two canister samples collected at the East Tarmac site and those of a) jetfuel, b) diesel exhausts, and c)gasoline vehicle emissions. Data are expressed asthe percentage weight contribution of each species tothe total measured organic gas concentration. The emission profiles of jet fuel exhaust (aircraft exhaust -jet fuel), typicalgasolinevehicle emissions (gasoline - catalyst - stabilized exhaust - ARB summer 2003), and diesel exhaust (farm equipment - diesel - light &heavy) were downloaded from the California Air Resource Board (CARB) speciation database for organic compounds (ORGPROF;http://www.arb.ca.gov/ei/speciate/speciate.htm)a)b)c)(Sample #1: idle)(Sample #1: idle)(Sample #1: idle)6768 It is worth noting that the benzene/toluene ratio of sample #1 (canister sample affected by emissions from airplanes idling at the East Tarmac) was equal to 2, while the corresponding ratio for sample #2 (character istic of “airport bac kground” conditions) was about 0.3. After complete ignition, when the engine temperature of an aircraft is constant and relatively high (during taxiing, for exampl e), aromatics tend to crack leading to the production of increasing amounts of ben zene. Thus for idling conditions, a

benzene/toluene ratio of a bout 1.6 is expected (Schurma nn et al., 2007). Conversely, the

characteristic benzene/toluene ratio for kerosene fuel evaporation is about 0.27. Therefore, sample #2 might be indicative of fuel evaporation (Schur mann et al., 2007). In an attempt to better ch aracterize the hazardous air po llutants (HAPs) speciation profile for commercial aircraft engines, the Federal Avia tion Administration (FAA) and the U.S. EPA have recently reviewed the av ailable HAPs emission data from commercial aircrafts (Aircraft Engine Sp eciated Organic Gases: Spec iation of Unburned Organic Gases in Aircraft Exhaust, prepared by EPA in 2009). Consolidated HAPs information from measurements conducted during the pa st 35 year using various sampling and analysis methods were investig ated and combined to provide a single, accurate, and more reliable profile. The resulting FAA/EPA docum ent includes results from the work of Spicer et al. (1994) on military engines, a nd from the more recent Aircraft Particle Emissions eXperiment (APEX) campai gn on commercial aircrafts (see Wey, 2004; Onasch et al., 2006; Wey et al., 2006; Lobo et al., 2007, for details). In addition to dedicated engine tests, sampling from air ports during routing operation (most noticeably from the works of Herndon et al., 2006 and Schürmann et al., 2007) have also provided

useful data for HAPs emissions that have been included in the above mentioned

FAA/EPA work. The speciated data included in this FAA/EPA document were also compared to the emission profile of sample #1 at th e East Tarmac. No correlation was observed between the HAPs emission profile from th e EPA/FAA document and that from the analysis of sample #2 (top panel in Figure 33) . Overall, although our data are based on limited measurements, they seem to confirm that emissions from jets idling near the East Tarmac before take-off may increase the short term concentrations of several HAPs at

this location.Figure 33 Comparison between the hazardous air po llutants (HAPs) speciation profile for commercial aircraft engi nes emission profiles provided by EPA (Aircraft Engine Speciated Organic Gases: Speciation of Unbur ned Organic Gases in Aircraft Exhaust, prepared by EPA in 2009) and those of the tw o canister sample collected at the East Tarmac site when jets were either idling or taking-off (sample #1; bottom panel) and when no aircraft activity was ongoing (sample #2; top panel)

6970 

## CONCLUSIONS AND RECOMMENDATIONS

Long-term average concentrations of CO, PM 2.5 , OC, EC, VOCs, carbonyls and

trace elements in communities near VNA and SMO were generally similar to, and often lower than, those measured elsewhere in the South Coast Air Basin. For these pollutants, there were generally no disti nguishable concentrations gr adients within the studied communities which would suggest the airport as a major source. Therefore, emissions from aircraft and other airport-related sources are not likely to signi ficantly increase the long-term risk associated with exposure to these pollutants. The exception to this general finding is TSP lead. Study-average concentr ations near VNA and SMO were found to be significantly higher than the co rresponding levels present in background air or elsewhere in the Basin, and the concentration gradient pointed to the runway take-off area as a source. Lead is likely emitted from piston-dr iven engines using leaded general aviation fuel. However, the highest lead levels f ound in this study, which occurred on airport property, are still below the recently tighten ed U.S. EPA National Ambient Air Quality

Standard for lead.

Near-continuous measurements obtained dur ing this and other field campaigns have shown that sharp and rapid increases (e .g. 1-min) in the concentrations of UFPs occur when jet aircraft are idling, taking o ff, and sometimes landing. At VNA the highest particle counts were generally measured about 150 m from the north side of the airport, at a site located under the fixed wing arrival/depar ture route. Here, the average UFP number

concentration measured in the colder m onths (fall 2005 - winter 2006) were 3.6 times higher than those observed at a background site set-up about 2,400 m northwest of the airport. At SMO the spring/summer 2005 averag e UFP levels recorded 35 m west from the end of the runway and n ear the blast-fence were two times higher than those 100 m north (and downwind) of the runway and se ven times higher than those in background air. Overall, our results are in line with t hose obtained by Hu et al . (2009) during a four day campaign conducted at SMO during the spring/summer of 2008, when the studyaverage UFP concentrations at two sites 80 and 100 m downwind of the airport were about 10 times the corresponding background leve ls for all measurement days combined. Our analysis of aircraft activ ity data at SMO confirmed that peaks in UFP concentration

at the downwind sites were associated with jet aircraft take-off operations. These shortlived spikes in UFP levels were up to 2,000 times higher than background levels, and

often extended into residential areas. Furthe r work is needed to better understand the emission rates, atmospheric behavior, physic al and chemical properties, and health consequences of both short-term and long-term exposure to UFP emitted from jet aircraft. The majority of previous studies focu sing on the characterization of engine

exhaust and the effect of emissions on local air quality have been conducted on large commercial jets. Although there are likely di fferences in the chemical and physical characteristics of emissions from piston-driven airplanes, small private jets, and larger commercial aircraft, the result s of our study are consistent with previous works at LAX and other large internat ional airports in the US and in Europe. The monitoring plan developed for this study was based largely on the Multiple Air Toxics Exposure Study III (MATES III), a monitoring and evaluation study conducted by AQMD between April 2004 and Ma rch 2006 to characteri ze the long-term carcinogenic risk from exposure to air toxi cs in the South Coast Air Basin. Timeintegrated (24-hr) measurements were take n for most of the pollutants measured, and71 therefore a limitation of this study was that short-term exposur es could not be assessed. The only near-continuous measur ements available were UFP and CO, as well as some limited instantaneous VOC samples. The short-term VOC samples collected near the blast-fence area did show evidence of jet exhaust. Community members as well as AQMD staff have experienced short-term odors during nearby aircraft operations. As

more advanced continuous instrumentation fo r measuring air toxics becomes available,

future work could include an assessment of these short-term impact s and acute exposures. Future work may also include measurements of UFP levels and partic le size distributions correlated to aircraft type and aircraft operations.



## ACKNOWLEDGEMENTS
This study was conducted as part of a Community-Scale Air Toxics Ambient Monitoring Grant from the U.S. EPA. AQMD wo uld like to thank Virginia Ernst and the Santa Monica Airport for their help and suppor t in carrying out this study. We would also like to acknowledge the important contri butions of the following individuals and organizations who provided valuab le input to this effort:

Airports Air Quality Study Advisory Committee

The Office of California State A ssembly Member Fran Pavley The Office of Congressman Henry Waxman The Office of Congresswoman Jane Harman The Office of Congresswoman Maxine Waters Los Angeles City Councilman Bill Rosendahl Todd Campbell Coalition for Clean Air Gretchen Hardison Los Angeles City Department of Environmental Affairs Mike McDaniel Million Air Van Nuys Susan L. Mearns, Ph.D. Santa Monica Task Force on Environment Rod Merl Santa Monica Airport

Martin Rubin Concerned Resi dents Against Airport Pollution

Other Contributors Los Angeles City Councilwoman Jan Perry California State Assembly Member Ted Lieu Brandon Eaton Los Angeles World Airports Ping Ho Friends of Sunset Park Brett Horner City of Santa Monica Christopher Patton Los Angeles City De partment of Environmental Affairs Bill Piazza Los Angeles Unified School District Dennis Quilliam Los Angeles World Airports Cyrus Rangan, M.D. Los Angeles County Public Health Department Marty Tachiki City of Santa Monica Attorney Robert Trimborn Santa Monica Airport Lin Wang Los Angeles World Airports72 

## REFERENCES

Agrawal, H., Sawant, A.A., Jansen, K., M iller, J.W., and D.R. Cocker III (2008)

Characterization of chemical and particulate emissions from aircraft engines, Atmospheric Environment 42: 4380–4392

Aircraft Engine Speciated Organic Gases: Speciation of Unburned Organic Gases in Aircraft Exhaust, prepared by EPA in 2009

Airborne Particulate Matter, Lead and Ma nganese at Buttonville Airport; prepared by

Conor Pacific Environmental Technologies Inc. in 2000

Arhami, M., Sillanpää, M., Hu, S., Geller, M.D. , Schauer, J.J. and Sioutas, C. (2009) Sizesegregated Inorganic and Organic Components of PM In the Communities of the Long Angeles Harbor Across Southern Los Angeles Basin, California, Aerosol Science and Technology, 43(2), 145-160

Bastress, E.K. (1973) Impact of aircraft e xhaust emissions at ai rports. Environmental Science & Technology, 7(9): 811-816

Birmili, W., Allen, A.G., Bary, F., Harrison, R. M. (2006) Trace metal concentrations and water solubility in size-fractionated atmos pheric particles and influence of road traffic, Environmental Scie nce & Technology 40(4): 1144–1153

Chicago O’Hare Airport Air Toxic Monitori ng Program (2002) Prepared by the Illinois Environmental Protection Agency, Bureau of Air

Cho A.K., Sioutas C., Schmitz, D.A., Kumagai Y., Singh M., Miguel A.H and Froines, J.R. (2005) Redox activity of ai rborne particulate matter (P M) at different sites in the Los Angeles Basin, Environm ental Research, 99 (1): 40 - 47

Delfino, R.J., Sioutas, C., Malik, S. (2005) Potential role of ultr afine particles in associations between airborne par ticle mass and cardiovascular health,

Environmental Health Pers pectives, 113(8): 934-946

Dodson, R.E., Houseman, E.A., Morin, B., and Levy, J.I. (2009) An analysis of

continuous black carbon concentrations in proximity to an airport and major roadways, Atmospheric Environment 43: 3764–3773

ENVIRON Corp. (2008) Teterbor o Airport, New Jersey, Deta iled Air Quality Evaluation, Final Report Prepared for the New Je rsey Department of Environmental

Protection.

Fanning, E., Yu, R.H., Lu, R., and Froines, J. (2007) Monitoring and Modeling of

Ultrafine Particles and Black Carbon at the Los Angeles International Airport, Final Report Prepared for the California Air Resources Board and the California Environmental Protection Agency

Federal Aviation Administration; http://www.faa.gov/regulations_policies/

Geller M.D., Ntziachristos L., Mamakos A., Sa maras Z., Schmitz D.A., Froines J.R. and Sioutas, C. (2006) Physicochemical and Redox Characteristics of Particulate73 Meter (PM) Emitted From Light Duty Gasoline and Diesel Passenger Cars, Atmospheric Environment, 40:6988–7004

Groma, V., Osan, J., Torok, S., Meirer, F., Streli, C., Wobrauscbe k, P., and Falkenberg, G. (2008) Trace element analysis of ai rport related aerosols using SR-TXRF, IDOJARAS, 112(2): 83-97

Hermann, M., Wehner, B., Bischof, O., Han, H. S., Krinke, T., Liu, W., Zerrath, A. and Wiedensohler, A. (2007) Particle counti ng efficiencies of new TSI condensation particle counters, Aerosol Science 38: 674–682

Herndon, S.C., Onasch, T.B., Frank, B.P., Marr, L.C., Jayne, J.T., Canagaratna, M.R., Grygas, J., Lanni, T., Anderson, B.E., Worsnop, D., and Miake-Lye, R.C. (2005)

Particulate Emissions from in-use Comm ercial Aircraft, Aerosol Science and Technology, (39):799–809

Herndon, S.C., Rogers, T., Dunlea, E.J., Jayne , J.T., Miake-Lye, R., and Knighton, B. (2006) hydrocarbon emissions from in-use commercial aircraft during airport operations, Environmental Scie nce & Technology, 40(14): 4406-4413

Herndon, S.C., Jayne, J.T., Lobo, P., Onasch, T.B., Fleming, G., Hagen, D.E., Whitefield, P.D. and Miake-Lye, R.C. (2008) Comm ercial aircraft engine emissions

characterization of in-use aircraft at Hartsfield-Jackson Atlanta International Airport, Environmental Scien ce and Technology, 42(6):1877-1883

Herndon, S.C., Wood, E.C., Northway, M.J., Mi ake-Lye, R., Thornhill, L., Beyersdorf, A., Anderson, B.E., Dowlin, R., Dodds, W ., and Knighton, W.B. (2009) Aircraft Hydrocarbon Emissions at Oakland Intern ational Airport, Environmental Science and Technology, 43: 1730-1736

http://epa.gov/oms/aviation.htm

http://www.apo.data.faa.gov/main/taf.asp

Hu, S., Fruin, S., Kozawa, K., Mara, S., Winer, A.M., and Paulson (2009) S.E. Aircraft Emission Impacts in a Neighborhood Adjacen t to a General Aviation Airport in

Southern California. Environm ental Science & Technology, 43: 8039–8045

International Civil Aviation Organization (I CAO) Aircraft Engine Emissions DataBank (2006), http://www.caa.co.uk/docs/702/introduction-05102004.pdf

Lelievre, C.P., Magnani, G.,Ramaroson, R., Gouriou, F., Talbaut, M., Frejafon, E., Schuermann, G., Schaefer, K., Cornier, I., Emeis, S., Vannier, F., Paux, E., Copalle, A., and Perros, P. (2006) Air qua lity and engine emission at Paris CDG airport during AIRPUR field campai gns, Air Pollution XIV, 86: 261-276

Lobo, P., Hagen, D.E., Whitefield, P.D., and Alof s, D.J. (2007) Physical characterization

of aerosol emissions from a Commerc ial Gas Turbine Engine, Journal of Propulsion and Power, 23: 919-929

Mordas, G., Manninen H.E., Petäjä, T., Aalt o, P.P., Hämeri, K., and Kulmala M. (2008) On Operation of the Ultra-Fine Water-Based CPC TSI 3786 and Comparison with Other TSI Models (TSI 3776, TSI 3772, TSI 3025, TSI 3010, TSI 3007), Aerosol Science and Technology, 42:152–158, 200874 Nel, A., Xia, T., Madler, L., and Li, N. (2006) Toxic potential of materials at the nanolevel. Science, 311 (5761): 622–627

Ntziachristos, L., Froines, J.R., Cho, A.K., and Sioutas, C. (2007a) Relationship between redox activity and chemical speciation of size-fractionated particulate matter,

Particle and Fibre T oxicology, DOI:10.1186/1743-8977-4-5

Ntziachristos L., Ning Z., Geller M.D., Sheesle y R.J., Schauer J.J., Sioutas C., Fine P. (2007b) Ultrafine and nanopa rticle trace element compositions near a major freeway with a high heavy-duty diesel fraction, Atmospheric Environment, 41 (27), 5684-5696

Onasch, T.B., Jayne, J.T., Herndon, S.C., Mortimer, P., Worsnop, D.R., and Miake-Lye, R.C. (2006) Chemical Properties of Airc raft Engine Exhaust Aerosols Sampled During APEX, NASA/TM-2006-214 382 ARL_TR_3903: Appendix J

ORGPROF; http://www.arb.ca .gov/ei/speciate/speciate.htm

Petzold, A., Fiebig, M., Fritz sche, L., Stein, C., Schuma nn, U., Wilson, C.W., Hurley, C.D., Arnold, F., Katragkou, E., Baltensperger, U., Gysela, M., Nyeki, S., Hitzenberger, R., Giebel, H., Hughes, K.J., Kurtenbach, R., Wisen, P., Madden, P., Puxbaum, H., Vrchotickt, S. and WAHL , C. (2005) Particle emissions from aircraft engines – a survey of the Eur opean project PartEmis, Meteorologische Zeitschrift, Vol. 14, No. 4, 465-476

Pope, A., Dockery, D.W. (2006) Health Effects of Fine Particulate Air Pollution: Lines that Connect, Journal of the Air & Waste Management Association, 56:709–742

Rogers, F., Arnott, P., Zielinska, B., Sagebi el, J., Kelly, K.E., Wa gner, D., Lighty, J.S., and Sarofim, A.F. (2005) Real-Time Measur ement of Jet Aircraft Engine Exhaust, Journal of the Air & Waste Management Association, 55 583-593

Sanders, P.G., Xu, N., Dalka, T.M., and Ma ricq, M.M. (2003) Airborne Brake Wear Debris: Size Distributions, Composition, and a Comparison of Dynamometer and Vehicle Tests, Environmental Science & Technology, 37:4060–4069

Schurmann, G., Schäfer, K., Jahn, C., Hoffmann, H., Groma, V., Török, S., and Emeis, S. (2006) Airport air quality and emission st udies by remote sensing and inverse dispersion modeling, Remote Sensing of Clouds and the Atmosphere XI, 6362:

U370-U381

Schurmann, G., Schafer, K., Jahn, C., Hoffmann, H., Bauerfeind, M., Fleuti, E., and Rappengluck, B. (2007) The impact of NOx, CO and VOC emissions on the air quality of Zurich airport, Atmospheric Environment, 41(1): 103-118

Singh, M., Jaques, P.A., and Sioutas, C. (2002) Size distribution and diurnal characteristics of particle-bound metals in source and receptor sites of the Los Angeles Basin. Atmospheric Environment 36: 1675–1689

Sioutas, C., Delfino, R.J., Singh, M. (2005) Exposure assessment for atmospheric ultrafine particles (UFPs) and implications in epidemiologic research,

Environmental Health Pers pectives, 113(8): 947-95575 South Air Quality Management District (1998) Air Monitoring Study at Los Angeles International Airport

South Coast Air Quality Manage ment District (2000a) Air Monitoring Study in the Area of Los Angeles Inte rnational Airport

South Coast Air Quality Mana gement District (2000b) I nglewood Particulate fallout Study Under and Near the Flight Path to Los Angeles International Airport

South Coast Air Quality Mana gement District (2000c) Mu ltiple Air Toxics Exposure Study (MATES II)

South Coast Air Quality Manage ment District (2001) Air Mo nitoring Study at Felton and Lloyde Schools

South Coast Air Quality Mana gement District (2008) Mu ltiple Air Toxics Exposure Study (MATES III)

Spicer, C.W., Holdren, M.W., Lyon, T.F ., and Riggin, R.M. (1984) Composition and Photochemical Reactivity of Turbine Engine Exhaust, USAF (Report No. ESL-TR84-28)

Spicer, C.W., Holdren, M.W., Smith, D.L., Hughes, D.P., and Smith, M.D. (1992) Chemical Composition of Exhaust Airc raft Turbine Engines, Journal of Engineering for Gas Turbines and Power, 114(1): 111-117

Spicer, C.W., Holdren, M.W., Riggin, R. M., and Lyon, T.F. (1994) Chemical Composition and Photochemical Reactivity of Exhaust from Aircraft Turbine Engines, Annales Geophysicae-Atmosphe res Hydrospheres and Space Science, 12(10-11): 944-955

U.S. EPA (2003) National Emission Trends, Average Annual Emissions, All Criteria Pollutants, 1970-2001; www.epa.gov /ttn/chief/trends/index.html

U.S. EPA (2003) Average Annual Emissions, All Criteria Pollutants Years Including 1980, 1985, 1989–2001

U.S. EPA (2005) Documentati on for Aircraft, Commercial Ma rine Vessel, Locomotive, and other Non-Road Compnents of th e National Emission Inventroy, Vol. I

U.S. EPA (2008) Lead Emissions from the Use of Leaded Aviation Gasoline in the

United States

U.S. EPA (2009) Aircraft E ngine Speciated Organic Gase s: Speciation of Unburned Organic Gases in Aircraft Exhaust

U.S. EPA, (2010) Development and Evaluation of an Air Quality Modeling Approach for Lead Emissions from Piston-Engine Ai rcraft Operating on Leaded Aviation

Gasoline

Westerdahl, D., Fruin, S.A., Fine, P.M., a nd Sioutas, C. (2008) The Los Angeles International Airport as a source of ultr afine particles and other pollutants to nearby communities, Atmospheric Environment (42), 3143–3155

Wey, C.C. (2004) Overview of the Aircraft Particle Emissions eXperiment (APEX) Program, Aircraft Particle Em issions Workshop, Cleveland, OH76 Wey, C.C., Anderson, B.E. et al. (2006) Aircra ft Particle Emissions eXperiment (APEX), NASA/TM-2006-214382; ARL-TR-3903; NASA: Washington, DC.

Xia, T., Korge, P., Weiss, J.N., Li, N., Ve nkatesen, M.I., Sioutas, C., Nel, A. (2004) Quinones and aromatic chemical compounds in particulate matter (PM) induce mitochondrial dysfunction: implications for ultrafine particle toxicity,

Environmental Health Pe rspectives 112 (14), 1347–1358

Yu, K.N., Cheung, Y.P., Cheung, T., and Henr y, R.C (2004) Identifying the impact of large urban airports on local air quality by nonparametric regression, Atmospheric Environment, 38: 4501–4507

Zhu, Y.F., Hinds, W.C., Kim, S., Shen, S., Si outas, C. (2002a) Study of ultrafine particles near a major highway with heavy-duty diesel traffic Author, Atmospheric Environment, 36(27): 4323-4335

Zhu, Y.F., Hinds, W.C., Kim, S., and Si outas, C. (2002b) Concentration and size distribution of ultrafine pa rticles near a major highw ay, Journal of the Air & Waste Management Association, 52(9): 1032-104277 

## APPENDIX ATable A1 Average and median 1,3-butadiene, me thylene chloride, and chloroform concentrations (ppb) at the Van Nuys Ai rport during Phase 1 (November 2005 - March 2006) and Phase 2 (July - September, 2006). Minimum (Min) and maximum (Max) values, standard deviations (SD), and the total number of va lid samples (Valid N) have also been reported for each species al ong with the corresponding values from a companion monitoring station in Burbank (i n red). Concentrations reported as 0.00 ppb represent non detected (ND) values.



### Van Nuys Airport

Golf

Course Holmes

School VOR National

Guard Burbank

1,3-Butadiene (ppb) - Phase 1

Average 0.16 0.09 0.16 N/A 0.23

Median 0.09 0.05 0.10 N/A 0.19

SD 0.14 0.10 0.15 N/A 0.17

Min 0.00 0.00 0.00 N/A 0.00

Max 0.44 0.41 0.52 N/A 0.62

Valid N 29 25 30 N/A 30 1,3-Butadiene (ppb) - Phase 2

Average 0.05 0.01 0.05 0.06 0.06

Median 0.05 0.01 0.04 0.05 0.05

SD 0.03 0.01 0.04 0.04 0.05

Min 0.01 0.00 0.01 0.01 0.01

Max 0.13 0.02 0.15 0.18 0.23

Valid N 20 4 20 14 20 Methylene Chloride (ppb) - Phase 1

Average 0.25 0.21 0.25 N/A 0.42

Median 0.17 0.16 0.24 N/A 0.35

SD 0.18 0.20 0.20 N/A 0.49

Min 0.04 0.00 0.00 N/A 0.03

Max 0.67 0.87 0.70 N/A 2.81

Valid N 29 25 30 N/A 30 Methylene Chloride (ppb) - Phase 2

e 0.19 0.13 0.21 0.25 0.26 Avera g

Median 0.20 0.11 0.21 0.25 0.28

SD 0.09 0.07 0.09 0.09 0.13

Min 0.06 0.08 0.08 0.12 0.08

Max 0.43 0.24 0.39 0.46 0.67

Valid N 20 4 20 14 20 Chloroform (ppb) - Phase 1

Average 0.07 0.05 0.05 N/A 0.06

Median 0.06 0.05 0.05 N/A 0.06

SD 0.04 0.03 0.04 N/A 0.03

Min 0.00 0.01 0.00 N/A 0.01

Max 0.14 0.12 0.13 N/A 0.11

Valid N 29 25 30 N/A 30 Chloroform (ppb) - Phase 2

Average 0.13 0.06 0.09 0.11 0.06

Median 0.13 0.04 0.10 0.10 0.06

SD 0.07 0.04 0.05 0.06 0.03

Min 0.03 0.04 0.02 0.03 0.02

Max 0.23 0.13 0.18 0.22 0.15

Valid N 20 4 20 14 20

78Table A2 Average and median benzene, carbon tetr achloride, and toluene concentrations (ppb) at the Van Nuys Airport during Phas e 1 (November 2005 - March 2006) and Phase 2 (July - September, 2006). Minimum (Min ) and maximum (Max) values, standard deviations (SD), and the total number of valid samples (Valid N) have also been reported for each species along with the correspondi ng values from a companion monitoring station in Burbank (in red). Concentrations reported as 0.00 ppb represent non detected (ND) values.



### Van Nuys Airport

Golf

Course Holmes

School VOR National

Guard Burbank

Benzene (ppb) - Phase 1

79 Avera g e 1.05 0.57 0.80 N/A 1.08

Median 0.95 0.46 0.63 N/A 1.21

SD 0.69 0.53 0.86 N/A 0.52

Min 0.15 0.10 0.11 N/A 0.11

Max 3.03 2.71 4.66 N/A 1.85

Valid N 29 25 30 N/A 30 Benzene (ppb) - Phase 2

Average 0.39 0.20 0.38 0.45 0.43

Median 0.40 0.16 0.39 0.43 0.46

SD 0.19 0.09 0.18 0.20 0.20

Min 0.15 0.13 0.16 0.20 0.17

Max 0.90 0.34 0.93 1.07 0.98

Valid N 20 4 20 14 20 Carbon Tetrachloride (ppb) - Phase 1

Average 0.09 0.08 0.08 N/A 0.09

Median 0.09 0.09 0.09 N/A 0.09

SD 0.02 0.02 0.02 N/A 0.01

Min 0.03 0.00 0.00 N/A 0.06

Max 0.13 0.11 0.11 N/A 0.10

Valid N 29 25 30 N/A 30 Carbon Tetrachloride (ppb) - Phase 2

Average 0.08 0.08 0.08 0.09 0.08

Median 0.08 0.08 0.08 0.09 0.08

SD 0.01 0.01 0.01 0.01 0.01

Min 0.05 0.07 0.06 0.06 0.07

Max 0.10 0.09 0.10 0.10 0.10

Valid N 20 4 20 14 20 Toluene (ppb) - Phase 1

Average 3.85 1.28 1.98 N/A 3.76

Median 3.88 1.26 1.67 N/A 4.20

SD 2.58 0.98 1.60 N/A 2.10

Min 0.31 0.12 0.14 N/A 0.17

Max 10.2 3.27 4.85 N/A 6.83

Valid N 29 25 30 N/A 30 Toluene (ppb) - Phase 2

Average 1.22 0.56 1.15 1.43 1.87

Median 1.28 0.38 1.04 1.43 1.43

SD 0.61 0.40 0.66 0.72 1.50

Min 0.31 0.30 0.34 0.43 0.48

Max 3.03 1.15 2.89 3.36 6.46

Valid N 20 4 20 14 20Table A3 Average and median perchloroethylene concentrations (ppb) at the Van Nuys Airport during Phase 1 (November 2005 - Marc h 2006) and Phase 2 (July - September, 2006). Minimum (Min) and maximum (Max) valu es, standard deviations (SD), and the total number of valid samples (Valid N) have also been reported for each species along with the corresponding values from a compani on monitoring station in Burbank (in red). Concentrations reported as 0.00 ppb repr esent non detected (ND) values.



## Van Nuys Airport

Golf

Course Holmes

School VOR National

Guard Burbank

Perchloroethylene (ppb) - Phase 1

Average 0.10 0.04 0.05 N/A 0.15

Median 0.07 0.03 0.04 N/A 0.13

SD 0.09 0.04 0.05 N/A 0.15

Min 0.00 0.00 0.00 N/A 0.00

Max 0.32 0.12 0.15 N/A 0.79

Valid N 29 25 30 N/A 30 Perchloroethylene (ppb) - Phase 2

Average 0.05 0.03 0.05 0.08 0.07

Median 0.06 0.03 0.05 0.07 0.07

SD 0.03 0.02 0.03 0.05 0.03

Min 0.01 0.01 0.01 0.01 0.02

Max 0.11 0.06 0.13 0.21 0.16

Valid N 20 4 20 14 20

80Table A4 Average and median 1,3-butadiene, me thylene chloride, and chloroform concentrations (ppb) at the Santa Monica Ai rport during Phase 1 (April - July, 2006) and Phase 2 (October 2006 - February 2007). Mi nimum (Min) and maximum (Max) values, standard deviations (SD), and the total number of valid samples (Valid N) have also been reported for each species along with the corresponding values from a companion monitoring station in Central Los Angeles (in red). Concentrations reported as 0.00 ppb represent non detected (ND) values.



## Santa Monica Municipal Airport

Richland

School Marine

Park Ernst

Residence East

Tarmac West

Tarmac Central Los Angeles 1,3-Butadiene (ppb) - Phase 1

Average 0.01 0.01 0.02 0.02 0.01 0.02

Median 0.00 0.00 0.00 0.00 0.00 0.00

SD 0.03 0.02 0.02 0.03 0.02 0.03

Min 0.00 0.00 0.00 0.00 0.00 0.00

Max 0.09 0.08 0.06 0.07 0.10 0.11

Valid N 24 19 16 9 24 20 1,3-Butadiene (ppb) - Phase 2

Average 0.13 0.08 0.14 0.12 0.09 0.14

Median 0.12 0.07 0.13 0.11 0.08 0.13

SD 0.09 0.06 0.08 0.08 0.06 0.08

Min 0.00 0.00 0.00 0.02 0.00 0.00

Max 0.42 0.24 0.35 0.32 0.31 0.31

Valid N 41 21 43 24 44 39 Methylene Chloride (ppb) – Phase 1

Average 0.18 0.13 0.18 0.25 0.18 0.33

Median 0.18 0.12 0.18 0.15 0.14 0.33

SD 0.11 0.08 0.09 0.29 0.12 0.11

Min 0.00 0.00 0.05 0.01 0.00 0.15

Max 0.39 0.36 0.37 0.97 0.55 0.53

Valid N 24 19 16 9 24 20 Methylene Chloride (ppb) - Phase 2

Average 0.28 0.22 0.27 0.20 0.25 0.41

Median 0.25 0.16 0.24 0.16 0.24 0.38

SD 0.16 0.12 0.15 0.11 0.15 0.19

Min 0.07 0.07 0.07 0.06 0.07 0.10

Max 0.85 0.44 0.84 0.44 0.82 0.84

Valid N 41 21 43 24 44 39 Chloroform (ppb) - Phase 1

Average 0.03 0.04 0.05 0.05 0.03 0.03

Median 0.03 0.05 0.05 0.05 0.03 0.04

SD 0.02 0.02 0.02 0.03 0.02 0.03

Min 0.00 0.00 0.02 0.02 0.00 0.00

Max 0.07 0.10 0.09 0.10 0.06 0.08

Valid N 24 19 16 9 24 20 Chloroform (ppb) - Phase 2

Average 0.07 0.06 0.07 0.05 0.05 0.05

Median 0.07 0.06 0.07 0.04 0.05 0.05

SD 0.03 0.02 0.03 0.02 0.02 0.02

Min 0.01 0.03 0.03 0.01 0.01 0.03

Max 0.14 0.12 0.13 0.10 0.10 0.12

Valid N 41 21 43 24 44 39

81Table A5 Average and median benzene, carbon tetr achloride, and toluene concentrations (ppb) at the Santa Monica Airport during Phase 1 (April - July, 2006) and Phase 2 (October 2006 - February 2007). Minimum (Min) and maximum (Max) values, standard deviations (SD), and the total number of valid samples (Valid N) have also been reported for each species along with the correspondi ng values from a companion monitoring station in Central Los Angeles (in red).



## Santa Monica Municipal Airport

Richland

School Marine

Park Ernst

Residence East

Tarmac West

Tarmac Central Los Angeles Benzene (ppb) - Phase 1

Average 0.27 0.21 0.30 0.29 0.23 0.46

Median 0.23 0.15 0.22 0.30 0.19 0.47

SD 0.21 0.17 0.25 0.18 0.15 0.18

Min 0.10 0.06 0.10 0.09 0.10 0.19

Max 1.15 0.78 1.17 0.59 0.82 0.82

Valid N 24 19 16 9 24 20 Benzene (ppb) - Phase 2

Average 0.62 0.46 0.64 0.52 0.50 0.66

Median 0.60 0.43 0.60 0.41 0.49 0.65

SD 0.31 0.21 0.31 0.28 0.25 0.28

Min 0.16 0.17 0.19 0.17 0.14 0.20

Max 1.52 0.93 1.58 1.16 1.38 1.31

Valid N 41 21 43 24 44 39 Carbon Tetrachloride (ppb) - Phase 1

Average 0.09 0.09 0.09 0.11 0.09 0.09

Median 0.09 0.09 0.09 0.10 0.09 0.09

SD 0.01 0.03 0.01 0.03 0.01 0.02

Min 0.08 0.06 0.07 0.09 0.07 0.06

Max 0.11 0.18 0.12 0.17 0.11 0.12

Valid N 24 19 16 9 24 20 Carbon Tetrachloride (ppb) - Phase 2

Average 0.09 0.09 0.09 0.09 0.09 0.09

Median 0.09 0.09 0.08 0.09 0.09 0.09

SD 0.02 0.02 0.01 0.01 0.01 0.01

Min 0.06 0.07 0.06 0.06 0.06 0.06

Max 0.16 0.14 0.14 0.12 0.15 0.11

Valid N 41 21 43 24 44 39 Toluene (ppb) - Phase 1

Average 0.71 0.55 0.81 0.80 0.66 1.33

Median 0.67 0.45 0.82 0.62 0.60 1.31

SD 0.30 0.30 0.24 0.42 0.35 0.52

Min 0.25 0.19 0.43 0.33 0.26 0.62

Max 1.59 1.53 1.36 1.48 1.75 2.64

Valid N 24 19 16 9 24 20 Toluene (ppb) - Phase 2

Average 1.82 1.31 1.96 1.63 1.53 2.05

Median 1.80 1.06 1.94 1.23 1.46 2.09

SD 1.07 0.81 1.07 1.24 0.90 0.95

Min 0.26 0.36 0.36 0.29 0.21 0.49

Max 4.82 3.19 4.67 4.70 3.88 4.33

Valid N 41 21 43 24 44 39

82Table A6 Average and median trichloroethene and perchloroethylene concentrations (ppb) at the Santa Monica Airport during Phase 1 (April - July, 2006) and Phase 2 (October 2006 - February 2007). Minimum (Min) and maximum (Max) values, standard deviations (SD), and the total number of valid samples (Valid N) have also been reported for each species along with the correspondi ng values from a companion monitoring station in Central Los Angeles (in red). Concentrations reporte d as 0.00 ppb represent non detected (ND) values.



## Santa Monica Municipal Airport

Richland

School Marine

Park Ernst

Residence East

Tarmac West

Tarmac Central Los Angeles Trichloroethene (ppb) - Phase 1

Average 0.00 0.00 0.01 0.01 0.00 0.02

Median 0.00 0.00 0.00 0.00 0.00 0.01

SD 0.00 0.01 0.01 0.02 0.00 0.03

Min 0.00 0.00 0.00 0.00 0.00 0.00

Max 0.01 0.03 0.02 0.05 0.01 0.10

Valid N 24 19 16 9 24 20 Trichloroethene (ppb) - Phase 2

Average 0.01 0.01 0.03 0.02 0.01 0.02

Median 0.01 0.00 0.02 0.02 0.00 0.02

SD 0.02 0.01 0.02 0.02 0.01 0.02

Min 0.00 0.00 0.00 0.00 0.00 0.00

Max 0.07 0.05 0.08 0.06 0.06 0.09

Valid N 40 21 43 24 43 39 Perchloroethylene (ppb) - Phase 1

Average 0.03 0.02 0.02 0.05 0.02 0.05

Median 0.03 0.02 0.02 0.03 0.02 0.06

SD 0.03 0.02 0.02 0.04 0.02 0.03

Min 0.00 0.00 0.00 0.00 0.00 0.00

Max 0.09 0.07 0.05 0.12 0.07 0.13

Valid N 24 19 16 9 24 20 Perchloroethylene (ppb) - Phase 2

Average 0.13 0.07 0.10 0.08 0.08 0.09

Median 0.10 0.06 0.09 0.08 0.07 0.08

SD 0.13 0.06 0.08 0.08 0.06 0.09

Min 0.00 0.00 0.00 0.00 0.00 0.00

Max 0.72 0.25 0.34 0.36 0.32 0.53

Valid N 41 21 43 24 44 39

8384 Table A7 Average 8-hr VOC concentr ations (ppb) at the Van Nuys Airport during Phase 1 (November 2005 - March 2006). The correspondi ng percentage contributions to their total daily levels have also been included



## Van Nuys Airport

- Phase 1

Concentration (ppb) P ercentage Contribution

00:00

08:00 08:00

16:00 16:00

00:00 00:00

08:00 08:00

16:00 16:00

00:00

1,3-ButadieneGOLF COURSE 0.22 0.11 0.15 45.4% 23.0% 31.6%

Benzene 1.28 0.86 1.03 40.3% 27.2% 32.5%

Carbon Tetrachloride 0.09 0.09 0.09 34.2% 32.6% 33.2%

Chloroform 0.11 0.05 0.06 48.7% 22.0% 29.3% Methylene Chloride 0.34 0.20 0.20 46.3% 26.7% 27.1% Perchloroethylene 0.12 0.07 0.10 41.8% 24.4% 33.8%

Toluene 5.11 2.82 3.72 43.8% 24.2% 32.0%

Trichloroethene 0.02 0.06 0.07 15.1% 39.0% 45.8%

1,3-ButadieneHOLMESSCHOOL 0.10 0.06 0.12 37.1% 20.5% 42.3%

Benzene 0.63 0.49 0.60 36.7% 28.4% 34.9%

Carbon Tetrachloride 0.08 0.08 0.09 32.7% 33.0% 34.4%

Chloroform 0.07 0.03 0.06 45.7% 19.0% 35.3% Methylene Chloride 0.20 0.21 0.22 30.8% 33.7% 35.5% Perchloroethylene 0.04 0.04 0.04 33.7% 34.7% 31.6%

Toluene 1.37 1.04 1.45 35.4% 27.0% 37.6%

Trichloroethene 0.00 0.04 0.04 4.5% 51.1% 44.4%

1,3-ButadieneVOR 0.19 0.10 0.19 38.8% 21.7% 39.5%

Benzene 0.92 0.63 0.88 38.1% 25.8% 36.1%

Carbon Tetrachloride 0.08 0.09 0.08 33.3% 33.9% 32.7%

Chloroform 0.07 0.03 0.05 45.8% 20.4% 33.8% Methylene Chloride 0.31 0.21 0.24 41.2% 27.5% 31.2% Perchloroethylene 0.06 0.05 0.05 38.6% 31.8% 29.6%

Toluene 2.28 1.49 2.25 37.9% 24.7% 37.4%

Trichloroethene 0.10 0.05 0.06 47.2% 24.0% 28.8%Table A8 Average 8-hr VOC concentr ations (ppb) at the Van Nuys Airport during Phase 2 (July - September 2006). The corresponding percen tage contributions to their total daily

levels have also been included



## Van Nuys Airport

- Phase 2

Concentration (ppb) P ercentage Contribution

00:00

08:00 08:00

16:00 16:00

00:00 00:00

08:00 08:00

16:00 16:00

00:00

1,3-ButadieneGOLF COURSE 0.08 0.02 0.04 56.3% 16.2% 27.5%

Benzene 0.54 0.33 0.28 46.9% 29.0% 24.2%

Carbon Tetrachloride 0.09 0.09 0.07 34.7% 35.1% 30.1%

Chloroform 0.24 0.06 0.07 65.3% 15.1% 19.6% Methylene Chloride 0.24 0.18 0.13 44.3% 32.3% 23.4% Perchloroethylene 0.06 0.06 0.04 39.4% 37.9% 22.7%

Toluene 1.89 0.97 0.71 52.9% 27.2% 19.9%

Trichloroethene 0.00 0.01 0.00 32.0% 48.0% 20.0%

1,3-ButadieneHOLMESSCHOOL 0.01 0.01 0.01 37.5% 37.5% 25.0%

Benzene 0.24 0.16 0.16 42.4% 28.4% 29.1%

Carbon Tetrachloride 0.08 0.08 0.08 33.1% 34.7% 32.2%

Chloroform 0.10 0.03 0.04 56.3% 19.5% 24.1% Methylene Chloride 0.15 0.12 0.10 40.4% 32.2% 27.3% Perchloroethylene 0.03 0.03 0.02 40.0% 37.5% 22.5%

Toluene 0.74 0.39 0.40 48.4% 25.6% 26.0%

Trichloroethene 0.00 0.01 0.00 25.0% 75.0% 0.0%

1,3-ButadieneNATIONALGUARD 0.09 0.04 0.04 49.8% 25.7% 24.5%

Benzene 0.58 0.39 0.30 45.4% 30.8% 23.7%

Carbon Tetrachloride 0.09 0.08 0.09 33.9% 32.3% 33.8%

Chloroform 0.19 0.08 0.04 60.9% 24.7% 14.4% Methylene Chloride 0.33 0.22 0.18 45.4% 30.3% 24.3% Perchloroethylene 0.09 0.09 0.06 36.4% 38.1% 25.5%

Toluene 2.11 1.11 0.86 51.8% 27.2% 21.0%

Trichloroethene 0.01 0.01 0.01 48.5% 29.0% 22.5%

1,3-ButadieneVOR 0.08 0.03 0.05 51.7% 16.1% 32.2%

Benzene 0.52 0.27 0.32 47.0% 24.4% 28.6%

Carbon Tetrachloride 0.08 0.08 0.08 34.9% 33.0% 32.1%

Chloroform 0.17 0.04 0.05 63.9% 16.5% 19.6% Methylene Chloride 0.25 0.19 0.16 42.0% 31.6% 26.4% Perchloroethylene 0.07 0.06 0.03 43.4% 36.6% 20.0%

Toluene 1.74 0.72 0.82 52.9% 21.9% 25.1%

Trichloroethene 0.01 0.00 0.00 50.8% 25.4% 23.7%

85Table A9 Average 8-hr VOC concentrations (p pb) at the Santa Monica Airport during Phase 1 (April - July, 2006). The corresponding percentage contributi ons to their total daily levels have also been included



## Santa Monica Municipal Airport

- Phase 1

Concentration (ppb) P ercentage Contribution

00:00

08:00 08:00

16:00 16:00

00:00 00:00

08:00 08:00

16:00 16:00

00:00

1,3-ButadieneEAST TARMAC 0.01 0.02 0.04 21.1% 26.3% 52.6%

Benzene 0.39 0.27 0.16 47.7% 32.8% 19.4%

Carbon Tetrachloride 0.11 0.10 0.10 37.1% 31.2% 31.7%

Chloroform 0.09 0.04 0.03 58.9% 23.9% 17.3% Methylene Chloride 0.26 0.25 0.06 45.6% 43.6% 10.9% Perchloroethylene 0.06 0.03 0.01 57.2% 30.7% 12.1%

Toluene 0.96 0.81 0.44 43.2% 36.8% 20.0%

Trichloroethene 0.02 0.01 0.01 56.0% 23.3% 20.7%

1,3-ButadieneWEST TARMAC 0.02 0.00 0.00 73.8% 12.3% 13.8%

Benzene 0.36 0.17 0.18 51.0% 23.6% 25.4%

Carbon Tetrachloride 0.09 0.09 0.09 32.6% 33.7% 33.7%

Chloroform 0.04 0.02 0.02 52.5% 19.4% 28.1% Methylene Chloride 0.20 0.19 0.14 37.2% 35.7% 27.0% Perchloroethylene 0.05 0.01 0.01 68.0% 21.6% 10.4%

Toluene 1.18 0.39 0.46 58.0% 19.4% 22.5%

Trichloroethene 0.00 0.00 0.00 30.9% 49.4% 19.7%

1,3-ButadieneERNSTRESIDENCE 0.01 0.02 0.02 22.8% 40.6% 36.5%

Benzene 0.42 0.28 0.19 46.9% 31.3% 21.9%

Carbon Tetrachloride 0.09 0.09 0.09 33.3% 32.5% 34.2%

Chloroform 0.07 0.04 0.05 45.5% 23.6% 30.9% Methylene Chloride 0.20 0.27 0.08 36.1% 49.9% 14.0% Perchloroethylene 0.02 0.02 0.01 38.0% 40.6% 21.4%

Toluene 1.04 0.80 0.59 42.8% 32.8% 24.4%

Trichloroethene 0.01 0.00 0.00 78.1% 17.5% 4.4%

1,3-ButadieneMARINE PARK 0.03 0.01 0.00 72.7% 15.3% 12.0%

Benzene 0.34 0.15 0.12 55.3% 24.5% 20.1%

Carbon Tetrachloride 0.09 0.11 0.08 32.5% 38.7% 28.8%

Chloroform 0.07 0.03 0.03 52.4% 21.7% 26.0% Methylene Chloride 0.21 0.12 0.07 52.8% 29.6% 17.6% Perchloroethylene 0.05 0.02 0.01 62.4% 22.0% 15.6%

Toluene 0.98 0.36 0.30 59.8% 22.0% 18.2%

Trichloroethene 0.00 0.01 0.00 25.0% 70.0% 5.0%

1,3-ButadieneRICHLANDSCHOOL 0.03 0.01 0.01 63.4% 16.4% 20.2%

Benzene 0.44 0.21 0.18 53.2% 25.1% 21.7%

Carbon Tetrachloride 0.09 0.09 0.09 34.4% 32.4% 33.2%

Chloroform 0.06 0.02 0.02 59.1% 19.2% 21.7% Methylene Chloride 0.21 0.22 0.10 39.0% 41.5% 19.5% Perchloroethylene 0.06 0.03 0.02 54.7% 28.2% 17.1%

Toluene 1.13 0.55 0.47 52.8% 25.5% 21.7%

Trichloroethene 0.00 0.00 0.00 58.2% 41.8% 0.0%

86Table A10 Average 8-hr VOC concentrations (p pb) at the Santa M onica Airport during Phase 2 (October 2006 - February 2007). The corresponding percentage contributions to their total daily levels have also been included



## Santa Monica Municipal Airport

- Phase 2

Concentration (ppb) P ercentage Contribution

00:00

08:00 08:00

16:00 16:00

00:00 00:00

08:00 08:00

16:00 16:00

00:00

1,3-ButadieneEAST TARMAC 0.12 0.11 0.14 33.5% 29.2% 37.3%

Benzene 0.56 0.46 0.52 36.5% 29.9% 33.6%

Carbon Tetrachloride 0.09 0.09 0.08 34.0% 33.7% 32.2%

Chloroform 0.07 0.04 0.04 44.3% 27.4% 28.3% Methylene Chloride 0.24 0.22 0.15 39.2% 35.8% 25.0% Perchloroethylene 0.11 0.09 0.05 44.7% 35.5% 19.8%

Toluene 1.66 1.40 1.68 35.0% 29.5% 35.5%

Trichloroethene 0.04 0.01 0.01 57.9% 20.8% 21.3%

1,3-ButadieneWEST TARMAC 0.12 0.05 0.12 40.4% 18.7% 40.9%

Benzene 0.52 0.40 0.57 34.8% 26.9% 38.3%

Carbon Tetrachloride 0.09 0.09 0.09 33.8% 33.6% 32.6%

Chloroform 0.06 0.04 0.04 42.5% 26.6% 30.9% Methylene Chloride 0.28 0.26 0.22 37.1% 34.1% 28.8% Perchloroethylene 0.10 0.07 0.06 42.9% 30.5% 26.6%

Toluene 1.73 1.09 1.80 37.5% 23.6% 38.9%

Trichloroethene 0.01 0.01 0.01 46.0% 24.1% 29.9%

1,3-ButadieneERNSTRESIDENCE 0.18 0.10 0.16 40.5% 22.3% 37.2%

Benzene 0.77 0.49 0.70 39.3% 24.9% 35.8%

Carbon Tetrachloride 0.09 0.09 0.09 33.4% 33.3% 33.3%

Chloroform 0.10 0.04 0.06 48.3% 21.3% 30.4% Methylene Chloride 0.34 0.26 0.23 41.0% 31.6% 27.4% Perchloroethylene 0.15 0.10 0.07 46.7% 30.2% 23.1%

Toluene 2.41 1.47 2.14 40.1% 24.4% 35.5%

Trichloroethene 0.05 0.01 0.02 58.8% 14.4% 26.8%

1,3-ButadieneMARINE PARK 0.11 0.05 0.12 40.2% 17.5% 42.3%

Benzene 0.55 0.38 0.55 37.1% 25.5% 37.4%

Carbon Tetrachloride 0.09 0.09 0.09 34.0% 33.4% 32.6%

Chloroform 0.09 0.05 0.06 44.8% 23.0% 32.1% Methylene Chloride 0.28 0.19 0.22 40.3% 27.0% 32.7% Perchloroethylene 0.11 0.06 0.05 49.1% 26.9% 23.9%

Toluene 1.69 0.97 1.57 39.9% 23.0% 37.2%

Trichloroethene 0.01 0.01 0.01 50.1% 20.6% 29.3%

1,3-ButadieneRICHLANDSCHOOL 0.19 0.06 0.14 48.0% 16.1% 36.0%

Benzene 0.80 0.43 0.65 42.8% 22.7% 34.5%

Carbon Tetrachloride 0.09 0.09 0.09 33.7% 33.4% 32.9%

Chloroform 0.10 0.04 0.06 49.3% 20.1% 30.6% Methylene Chloride 0.36 0.23 0.24 43.1% 27.7% 29.2% Perchloroethylene 0.22 0.10 0.07 56.6% 25.0% 18.4%

Toluene 2.46 1.17 1.84 45.0% 21.4% 33.6%

Trichloroethene 0.02 0.01 0.01 56.9% 19.4% 23.6%

8788 Table A11 Average and median formaldehyde and acet aldehyde concentrations (ppb) at the Van Nuys Airport during Phase 1 (Nove mber 2005 - March 2006) and Phase 2 (July - September, 2006). Minimum (Min) and maximu m (Max) values, standard deviations (SD), and the total number of valid samples (Valid N) have also been reported for each species along with the corre sponding values from a comp anion monitoring station in Burbank (in red).



## Van Nuys Airport

Golf

Course Holmes

School VOR National

Guard Burbank

Formaldehyde (ppb) - Phase 1

Average 3.30 2.85 3.70 N/A 4.04

Median 3.40 2.96 3.72 N/A 4.52

SD 1.12 1.46 1.67 N/A 1.67

Min 1.19 0.77 1.15 N/A 0.54

Max 5.23 5.23 6.89 N/A 6.87

Valid N 27 26 27 N/A 28 Formaldehyde (ppb) - Phase 2

Average 6.05 3.66 6.52 5.64 4.80

Median 6.18 3.23 6.77 5.98 4.76

SD 2.10 1.60 2.22 1.68 1.72

Min 2.54 2.24 2.87 2.54 2.44

Max 10.2 5.95 10.3 7.56 8.41

Valid N 22 4 22 15 19 Acetaldehyde (ppb) - Phase 1

Average 2.55 1.96 2.31 N/A 2.17

Median 2.37 1.96 2.39 N/A 2.48

SD 1.07 1.05 1.22 N/A 0.97

Min 0.97 0.53 0.72 N/A 0.31

Max 4.56 3.80 4.53 N/A 3.81

Valid N 27 26 27 N/A 28 Acetaldehyde (ppb) - Phase 2

Average 3.72 2.05 3.25 3.04 1.88

Median 3.57 1.65 3.58 3.24 2.14

SD 1.22 1.23 1.23 0.89 0.80

Min 1.75 1.06 1.11 1.26 0.79

Max 5.49 3.85 5.36 4.22 3.43

Valid N 22 4 22 15 1989 Table A12 Average and median acetone and methyl ethyl ketone (MEK) concentrations (ppb) at the Van Nuys Airport during Phas e 1 (November 2005 - March 2006) and Phase 2 (July - September, 2006). Minimum (Min ) and maximum (Max) values, standard deviations (SD), and the total number of valid samples (Valid N) have also been reported for each species along with the correspondi ng values from a companion monitoring station in Burbank (in red).



## Van Nuys Airport

Golf

Course Holmes

School VOR National

Guard Burbank

Acetone (ppb) - Phase 1

Average 5.28 4.47 6.66 N/A 3.15

Median 4.81 4.35 5.43 N/A 2.00

SD 2.72 2.96 4.91 N/A 2.71

Min 1.03 0.66 0.93 N/A 0.35

Max 10.6 11.1 17.7 N/A 11.22

Valid N 27 26 27 N/A 28 Acetone (ppb) - Phase 2

Average 4.42 2.56 5.09 5.51 0.66

Median 4.06 1.81 4.81 5.42 0.60

SD 2.57 1.89 3.69 2.38 0.49

Min 1.19 1.28 1.10 2.00 0.20

Max 12.7 5.3 18.5 11.4 2.49

Valid N 22 4 22 15 19 MEK (ppb) - Phase 1

Average 0.67 0.43 0.58 N/A 0.41

Median 0.61 0.46 0.59 N/A 0.37

SD 0.31 0.26 0.39 N/A 0.26

Min 0.23 0.10 0.13 N/A 0.05

Max 1.40 0.94 1.51 N/A 1.05

Valid N 27 26 27 N/A 28 MEK (ppb) - Phase 2

Average 0.90 0.55 0.82 0.85 0.21

Median 0.97 0.48 0.76 0.93 0.16

SD 0.41 0.32 0.44 0.36 0.17

Min 0.21 0.27 0.20 0.15 0.02

Max 1.87 0.98 1.93 1.53 0.83

Valid N 22 4 22 15 1990 Table A13 Average and median formaldehyde and acet aldehyde concentrations (ppb) at the Santa Monica Airport during Phase 1 (Apr il - July, 2006) and Phase 2 (October 2006 - February 2007). Minimum (Min) and maxi mum (Max) values, standard deviations (SD), and the total number of valid samples (Valid N) have also been reported for each species along with the corre sponding values from a comp anion monitoring station in Central Los Angeles (in red). Concentrations reported as 0.00 ppb represent non detected (ND) values.



## Santa Monica Municipal Airport

Richland

School Marine

Park Ernst

Residence East

Tarmac West

Tarmac Central Los Angeles Formaldehyde (ppb) - Phase 1

Average 3.16 1.91 3.14 0.00 3.32 3.14

Median 3.14 1.92 3.11 0.00 3.32 2.84

SD 0.59 0.40 0.44 0.00 0.71 1.61

Min 2.13 1.19 2.28 0.00 2.12 0.97

Max 4.41 2.74 4.26 0.00 4.92 7.41

Valid N 37 32 25 4 34 34 Formaldehyde (ppb) - Phase 2

Average 4.20 6.18 3.89 3.93 3.75 5.50

Median 4.22 6.61 3.72 3.46 3.77 5.45

SD 1.67 2.59 2.21 1.72 1.06 2.38

Min 1.25 2.08 1.66 1.56 1.84 1.17

Max 8.30 11.4 16.4 8.50 6.08 9.91

Valid N 44 12 42 29 41 44 Acetaldehyde (ppb) - Phase 1

Average 1.53 1.31 1.36 0.00 1.39 1.18

Median 1.51 1.29 1.39 0.00 1.38 1.10

SD 0.50 0.32 0.30 0.00 0.43 0.62

Min 0.77 0.78 0.84 0.00 0.71 0.36

Max 2.65 1.97 1.97 0.00 2.31 2.76

Valid N 37 32 25 5 34 34 Acetaldehyde (ppb) - Phase 2

Average 2.17 2.18 2.17 1.82 2.03 2.37

Median 2.13 2.25 2.11 1.62 2.01 2.35

SD 0.92 0.76 1.19 0.89 0.81 1.15

Min 0.80 0.81 0.91 0.74 0.75 0.38

Max 4.11 3.81 8.16 4.23 3.89 4.90

Valid N 44 12 42 29 41 4491 Table A14 Average and median acetone and methyl ethyl ketone (MEK) concentrations (ppb) at the Santa Monica Airport during Phase 1 (April - July, 2006) and Phase 2 (October 2006 - February 2007). Minimum (Min) and maximum (Max) values, standard deviations (SD), and the total number of valid samples (Valid N) have also been reported for each species along with the correspondi ng values from a companion monitoring station in Central Los Angeles (in red). Concentrations reporte d as 0.00 ppb represent non detected (ND) values.



## Santa Monica Municipal Airport

Richland

School Marine

Park Ernst

Residence East

Tarmac West

Tarmac Central Los Angeles Acetone (ppb) - Phase 1

Average 1.95 1.97 2.04 0.00 1.90 0.88

Median 1.94 1.90 1.97 0.00 1.78 0.79

SD 0.55 0.46 0.57 0.00 0.52 0.53

Min 0.77 0.97 1.20 0.00 1.09 0.25

Max 3.63 3.42 3.56 0.00 3.55 2.50

Valid N 37 32 25 3 34 34 Acetone (ppb) - Phase 2

Average 4.68 4.45 5.07 4.09 4.14 3.89

Median 4.15 4.21 4.65 3.67 4.00 3.30

SD 2.35 1.35 2.48 2.24 2.00 2.84

Min 1.23 1.99 1.39 1.30 1.08 0.12

Max 11.7 7.00 11.3 10.6 9.51 10.72

Valid N 44 12 42 29 41 44 MEK (ppb) - Phase 1

Average 0.30 0.29 0.29 0.00 0.26 0.15

Median 0.27 0.29 0.28 0.00 0.23 0.13

SD 0.13 0.10 0.07 0.00 0.11 0.09

Min 0.12 0.15 0.20 0.00 0.12 0.05

Max 0.57 0.49 0.41 0.00 0.60 0.38

Valid N 37 32 25 5 34 34 MEK (ppb) - Phase 2

Average 0.61 0.52 0.52 0.50 0.50 0.47

Median 0.56 0.53 0.46 0.39 0.51 0.46

SD 0.26 0.17 0.29 0.27 0.23 0.27

Min 0.20 0.16 0.18 0.18 0.17 0.07

Max 1.26 0.75 1.87 1.30 1.18 1.21

Valid N 44 12 42 29 41 44Table A15 Average and median carbon monoxide (CO) concentrations (ppm) at the Van Nuys Airport during Phase 1 (November 2005 - March 2006) and Phase 2 (July - September, 2006). Minimum (Min) and maximu m (Max) values, standard deviations (SD), and the total number of valid data (Valid N) have al so been reported. Concentrations reported as 0.0 ppm re present non detected (ND) values.



## Van Nuys Airport

Golf

Course Holmes

School VOR National

Guard
CO (ppm) - Phase 1

Average 2.3 0.6 1.1 N/A

Median 0.7 0.2 0.7 N/A

SD 7.7 1.0 1.1 N/A

Min 0.0 0.0 0.0 N/A

Max 13.6 11.8 4.0 N/A

Valid N 1530 1973 2099 N/A CO (ppm) - Phase 2

Average 0.4 0.1 0.5 0.3

Median 0.3 0.1 0.3 0.2

SD 0.4 0.2 0.5 0.4

Min 0.0 0.0 0.0 0.0

Max 2.3 1.6 2.7 3.6

Valid N 1328 377 1331 1044

9293 Table A16 Average and median carbon monoxide (C O) concentrations (ppm) at the Santa Monica Airport during Phase 1 (Apr il - July, 2006) and Phase 2 (October 2006 - February 2007). Minimum (Min) and maximum (Max) values, standard deviations (SD),

and the total number of valid data (Valid N) have also been reported. Concentrations reported as 0.0 ppm represent non detected (ND) values.



## Santa Monica Municipal Airport

Richland

School Marine

Park Ernst

Residence East

Tarmac West

Tarmac CO (ppm) - Phase 1

Average 0.1 0.1 0.3 N/A 0.1

Median 0.0 0.0 0.3 N/A 0.1

SD 0.3 0.2 0.2 N/A 0.2

Min 0.0 0.0 0.0 N/A 0.0

Max 7.2 2.2 2.4 N/A 3.1

Valid N 2804 1734 1848 N/A 2671 CO (ppm) - Phase 2

Average 0.6 N/A 0.5 N/A 0.4

Median 0.3 N/A 0.2 N/A 0.2

SD 0.7 N/A 0.7 N/A 0.5

Min 0.0 N/A 0.0 N/A 0.0

Max 4.2 N/A 3.7 N/A 3.1

Valid N 3061 N/A 1805 N/A 1317