TRANSPORTATION-RELATED AIR POLLUTANT EXPOSURE:

Implications for Regional Policies and Public Health

Arthur M. Winer, Ph.D.

Professor of Environmental Health SciencesSchool of Public Health

University of California, Los Angeles

Transportation/Land-Use/Environment SymposiumOctober 16-18, 2005

Lake Arrowhead

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INTRODUCTION• The contribution of transportation-related pollutant

emissions to regional photochemical smog has been recognized for many decades

• In contrast, only more recently have the exposures and health impacts due to localized transportation-related emissions been characterized

• This new characterization resulted from– A paradigm shift in air pollutant exposure assessment– New physical measurements and health studies in close

proximity to roadways and other transportation facilities

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PARADIGM SHIFT IN EXPOSURE ASSESSMENT

“The Place Makes The Poison”

Kirk SmithUC Berkeley School of Public Health

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EXPOSURE ASSESSMENT PRINCIPLE

Measure air pollutants in the “microenvironments” where people spend their time (rather than where air monitoring stations long distances away are measuring outdoor air).

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EXAMPLES OF TRANSPORTATION-RELATED MICROENVIRONMENTS

• Near-roadway environments

• Passenger vehicle compartments

• School buses

• Near-roadway structures (schools pre-schools, homes)

• Proximity to ports, airports, rail, etc.

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HEALTH IMPACTS OF VEHICLE EXHAUST

• Over the past decade, dozens of studies from all over the world have shown that spending time in close proximity to heavy traffic, especially diesel truck traffic, is associated with a wide range of morbidity effects, as well as increased mortality

• Diesel exhaust particulate (DEP) declared a toxic air contaminant by ARB in 1998

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RELATIVE POLLUTANT CONCENTRATIONS vs DISTANCE FROM I-405 FREEWAY

(Zhu et al., 2002a)

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710 Freeway

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Relative Particle Number, Particle Mass, Black Carbon, and CO Concentrations vs.

Downwind Distance from I-710 (Zhu et al., 2002b)

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ULTRA-FINE PARTICLES (UFP)

• Because of dilution (and coagulation) UFPs behave like a “local” source

• Central station monitoring is not useful for estimating UFP exposure and dose

• A 1-hr exposure on a freeway exceeds 23 hrs of exposure away from freeways

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Influence of Vehicle Type and Exhaust Location on Exposure in Following Vehicle

(Sources: Rodes et al., 1997; Fruin et al., 2004)

Vehicle Followed Black Carbon Concentration

Inside Vehicle (g/m3)

Gasoline Passenger Car ~5

Diesel Truck with High Exhaust 13

Diesel Truck with Low Exhaust 21

Transit Bus with Low Exhaust 90

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IN-VEHICLE EXPOSURE• Highly elevated roadway pollutant

concentrations have profound implications for in-vehicle exposures:– In-vehicle concentrations of black carbon can be

many times those in “background” ambient air

– Ultra-fine particles are up to ten times higher on roadways compared to “background” air

– The 6% of the day spent in a vehicle can account for ~1/3 to >half of daily exposure to DEP and greater than 90% of daily exposure to UFP

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Children’s Pollutant Exposure During School Bus Commutes

UCLA: Eduardo Behrentz, Lisa Sabin, Seong Lee, Kathleen Kozawa, Steve Colome and Arthur Winer

UC Riverside: Dennis Fitz and David Pankratz

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• Children are a vulnerable population

• 70% of school buses in California are powered by diesel engines and DEP is a TAC

• Children may be exposed to high concentrations of diesel particles and gases during bus commutes, at school bus stops, or at loading/unloading zones

• Some children in southern California spend up to three hours a day on school buses

BACKGROUND

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Mean Pollutant Concentrations in Bus Commute Related Microenvironments & Background Air (Sabin et al. 2005)

Mean Concentrations

Back-grounda

Loading/

Unloading Zone

Bus StopsBus

Commutesb,c

BC (mg m-3)

2 ± 0.1 2 ± 0.3 4 ± 0.4 3 - 19 (8)

PB-PAH (ng m-3)

27 ± 1.5 15 ± 0.3 44 ± 4.5 64 - 400 (134)

NO2

(ppb)49 ± 1.0 35 ± 0.2 54 ± 1.9 34 - 110 (73)

PC count cm-3)d 83 ± 3.1 N/C 62 ± 1.8 77 - 236 (130)

PM2.5

(mg m-3)20 ± 2.4e N/C 25f 21 - 62 (43)

N/C = Concentration data were not collected; aThese values were measured around Los Angeles with the bus parked, engine off, and with the windows fully open and represent urban ambient air background concentrations during the study; bThe ranges are associated with the different bus types and window position (open and closed); cThe values within parentheses are the means for all runs; dIn 0.3–0.5 um size range; eFrom published data for Los Angeles basin. fNot enough data to establish a confidence interval.

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15:10 15:15 15:21 15:27 15:33 15:38 15:44 15:50 15:56 16:02 16:07

Time

Bla

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arb

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Black Carbon

20 Second Moving Average

Traveling behind a diesel school bus - intermixed with periods of idling in traffic on surface streets

Traveling behind a medium duty diesel truck on freeway

Traveling behind a diesel school bus on freeway

Diesel school bus emitted large cloud of black smoke while accelerating past our bus (see picture)

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KEY FINDINGS

• In terms of exposure, bus commutes are much more important than bus stops or loading-unloading zones.

• Peak pollutant concentrations occurred for close proximity to other diesel vehicles and when idling (due to bus’s own exhaust).

• Impact of a bus’s own exhaust is most important when windows are closed due to self-pollution.

• Cleaner fuels (e.g. CNG) and particle traps reduce pollutant concentrations inside bus.

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Recommendations for Reducing Children’s Exposure During School Bus Commutes

• Minimize time spent on sidewalks in front of schools when diesel school buses are arriving or departing.

• Assign the cleanest buses to the longest routes.

• Instruct school bus drivers to avoid other diesel school buses.

• Develop strategies to shorten commute times.

• Instruct school bus drivers to turn off engines immediately on arrival at a school; do not turn engines on until ready to depart.

• Properly maintain in-use diesel school bus engines to eliminate visible exhaust.

• Phase out conventional diesel school buses and replace with cleaner buses, such as CNG or trap-outfitted diesel.

GOODS MOVEMENTFROM THE PORTS

Exposure Impacts Along Transportation Corridors

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Where is this cargo going and how will it get there?

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HOW CARGO CONTAINERS LEAVE THE PORTS

According to Alameda Corridor Transportation Authority (ACTA):– 50% by big-rig diesel trucks directly to

businesses or to distribution warehouses• Warehouses in Riverside & San Bernardino Counties

where cargo is sorted and sent to other cities/states

– 25% by truck on I-710 to intermodal facilities where containers transfer to trains

• Downtown L.A., East L.A., Commerce

– 25% onto Alameda Corridor, a 20-mile express railroad to downtown Los Angeles

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Trucks on the Terminal Island Freeway

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1975 1985 1995 2001 2003

47 Trucks

103 Trucks (#1)

103 Trucks (#2)

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Community Park

Hudson School

Terminal Island Fwy

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“Protecting” residents and students: a chain link fence!

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POLICY IMPLICATIONS

• .

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REDUCING VEHICLE EMISSIONS: A TRIPLE WIN

• Phase out dirtiest school buses• Maintain buses to eliminate visible exhaust• Encourage more rapid turn-over or retrofit

the dirtiest diesel trucks• Eliminate “super emitter” passenger cars• Adopt remote sensing and buy/crush plans• Electrify diesel transfer stations and cargo

ship docks (ie. reduce diesel idling)• Adopt more stringent fuel economy

standards

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LIMITS OF TECHNICAL FIXES• > 50% of reductions in 2003 AQMP are in

a “black box” of undefined measures• SCAQMD says they are out of viable

options for cleaning up stationary sources • ARB’s ZEV program failed• Hybrids do not provide dramatic benefits• The “Hydrogen Highway” is pure hype• Major regulatory barriers exist to reducing

marine and air traffic emissions• CONCLUSION: We must reduce VMT as

well as emissions!

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SMART GROWTH IMPLICATIONS• Reduce VMT and “cold starts” through “Smart

Growth” strategies:– Create housing next to jobs and services– Use mass transit hubs as foci for housing– Promote mixed use and infill

• But must avoid:– High density housing in close proximity to

major roadways– Impacting residents with toxic air emissions

from close-by industrial or retail sources

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ENVIRONMENTAL JUSTICE• New EJ issues raised by our understanding

of localized impacts of vehicle emissions:– Health disparity concerns may be overlooked by

typical regional AQ “conformity” process– Non-white children 3-4 times more likely to live in

areas with high traffic densities– UCLA research shows minority and high-poverty

neighborhoods in LA bear over two times the traffic density of rest of So. Cal.

– These findings add to traditional concerns about disproportionate impacts of toxic release facilities and other stationary air pollutant sources in minority communities

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CONCLUSIONS• AQ problems occur at two distinct scales:

– Regional smog vs localized vehicle/facility impacts

• Addressing both poses new challenges for government, the private sector and the public:– Growth in region may prevent us from reaching AQ

goals absent new approaches– We need a new paradigm:

• Reduce diesel emissions from all sources• Develop effective strategies to reduce VMT• Eliminate gasoline “super emitters”• Create real and/or virtual “Buffers” along major roadways• Pay attention to EJ issues posed by direct vehicle emissions

– Will require greater cooperation and integrated policy approaches across “disciplinary” agencies