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Ultrafine Particles and Freeways

Yifang Zhu , Ph.D.

Assistant Professor

Department of Environmental Engineering

Texas A&M University –Kingsville

Email: yzhu@even.tamuk.edu

yifang.zhu@tamuk.edu

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Comparison of PM10, PM2.5, and Ultrafine PM

PM10PM10(10 (10 m)m)

PM2.5PM2.5(2.5 (2.5 m)m)

Ultrafine PM Ultrafine PM (0.1 (0.1 m)m)

Human Hair(60 m diameter)

PM2.5PM2.5

(2.5 (2.5 m)m)

PM10PM10(10 (10 m)m)

Relative size of particles

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Atmospheric Aerosols: Particulate Matter (PM) Size Distribution

Number Distribution

Mass Distribution

Ultrafine Particles

PM2.5

PM10

Source: Hinds 1999

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Res

pira

tory

Dep

ositi

on, f

ract

ion

0.0

0.2

0.4

0.6

0.8

1.0

Particle Diameter (nm)

1 10 100 1000 10000

Number Weighted

Mass Weighted

Head Airways

Tracheobronchial

Alveolar

Particle Regional Deposition for Light Exercise

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Pathways of Particle Translocation Within and Outside Respiratory Tract

Translocation of UFP fromNP and TB region along sensoryneurons to CNS (neurodegeneration)

•Translocation of UFP to interstitium, capillaries, heart•Uptake by endothelium; platelets•Activation/interaction of endothelial cells, platelets and leukocytes

Alveolar inflammation

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Publications Address Ultrafine Particles

Pollution Health Toxcicity Cardiovascula Asthma

Nu

mb

er o

f P

ub

licat

ion

s

0

100

200

300

400

500

Before 19961996-2005

7

8

I-405 Freeway

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Sampling Site

Day

Night

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INSTRUMENTS

Scanning Mobility Particle Sizer (SMPS): Particle Size Distribution (6-300 nm) Condensation Particle Counter (CPC):

Total Particle Number Concentration

Q-Trak: CO, CO2, Temp, Rh

Portable Aethelometer: EC

Dust Trak: Real timePM10, PM2.5

Weather Wizard III:Wind speed and direction

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Experimental Setup: 2001 Daytime

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Traffic Effect: Total Particle Number Concentration & Traffic Density

Zhu et al., 2002a

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Normal Traffic

Traffic Slowdown

Zhu et al., 2002a

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RESULTS: Change in Ultrafine Particle Size Distribution with Increasing Distance

Day

Zhu et al., 2002a

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RESULTS: Number Concentration for Different Size Ranges Vs. Increasing Distance from Freeway 405.

Zhu et al., 2002a

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RESULTS: Relative Particle Number, Mass, Black Carbon, CO Concentration, Vs. Downwind Distance from Freeway 405.

Zhu et al., 2002a

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18

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Experimental Setup: 2004 Nighttime

20Distance from the freeway (m)

500 400 300 200 100 0 100 200 300 400 500

Tot

al P

artic

le N

umbe

r C

once

ntra

tion

(cm

-3)

0.0

2.0e+4

4.0e+4

6.0e+4

8.0e+4

1.0e+5

1.2e+5

1.4e+5

1.6e+5

1.8e+5

2.0e+5

Freeway 405 Eastern SideLA National Cemetery

Western SideVA Facility

Daytime Dominant Wind

RESULTS: Decay of Total Particle Number Concentration

Nighttime Dominant WindNighttime Dominant Wind

Daily exposure to Ultrafine Particles:3 folds of difference between the two cases

21Distance from the freeway (m)

500 400 300 200 100 0 100 200 300 400 500

Tot

al P

artic

le N

umbe

r C

once

ntra

tion

(cm

-3)

0.0

2.0e+4

4.0e+4

6.0e+4

8.0e+4

1.0e+5

1.2e+5

1.4e+5

1.6e+5

1.8e+5

2.0e+5

Freeway 405 Eastern SideLA National Cemetery

Western SideVA Facility

Daytime Dominant Wind

RESULTS: Decay of Total Particle Number Concentration

Nighttime Dominant WindNighttime Dominant Wind

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RESULTS: Temperature Effect

Temperature ( oC )

0 10 20 30 40

Par

ticle

Num

ber

Con

cent

ratio

n/ve

hicl

e (c

m-3

)

0.0

2.0e+4

4.0e+4

6.0e+4

8.0e+4

1.0e+5

1.2e+5

405 Fwy Summer

405 Fwy Winter

405 Fwy Night Time

Y=7.35e4-1.74e3XR2=0.98

Y=5.17e3+1.17e5exp(-0.071X)R2=0.99

Zhu et al, 2006

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Indoor Study Sampling Site and Dominant Wind

Zhu et al., 2005

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I-405 Freeway

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RESULTS: Effect of distance from freeways

Apartment 1

Apartment 2

Zhu et al., 2005

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RESULTS: Effect of Ventilation Conditions on Size Segregated I/O Ratios

Zhu et al., 2005

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RESULTS: Effect of Ventilation Conditions on Size Segregated I/O Ratios

Zhu et al., 2005

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RESULTS: Effect of Ventilation Conditions on Size Segregated I/O Ratios

Zhu et al., 2005

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In-Cabin Study

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Outdoor and In-Cabin Size Distribution Time Series

Zhu et al., 2007

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Average Outdoor UFP Distribution on Different Freeways

Zhu et al., 2007

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Average In-Cabin UFP Distribution on Different Freeways

Zhu et al., 2007

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Similar I/O Ratio Profiles on Different Freeways

Zhu et al., 2007

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Effect of Ventilation Conditions on I/O Profiles

Zhu et al., 2007

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TAKE HOME MESSAGES

• Because of dilution (and coagulation/condensation) ultrafine particles behave like a local source.

• Central station monitoring not useful for estimating dose

• 1 hr on freeway exceeds 23 hrs away from freeway.

• Newer vehicles with recirculation on helps to reduce in-cabin ultrafine particle exposure.

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• Most ultrafine particles formed after exhaust leaves the tailpipe

• Cooling and dilution both occurring• Cooling increases nucleation• Dilution decreases nucleation• Complex physical process• Sensitive to environmental conditions

TAKE HOME MESSAGES

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• Assessing Children’s Exposure to Ultrafine Particles from Vehicular Emissions

Objective: To identify hot spots in South Texas where school children are likely to be exposed to high levels of UFPs and develop simple models to estimate children’s exposure to UFPs from vehicular emissions.

• Using In-Situ Observations to Quantify Emissions from Prescribed Fires in two Grassland-Pine Ecosystems

Objective: To directly quantify UFP emissions from prescribed fires on DoD managed grassland and grass-shrub type ecosystems with different fuel types and fuel loadings.

FUTURE WORD

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FUTURE WORD

Master and Ph.D. Students will be Financially Supported in Part by National Science Foundation (NSF) sponsored Center for Research Excellence in Science and Technology (CREST)- Research in Environmental Sustainability for Semiarid Coastal Areas (RESSACA) at Environmental Engineering Department at Texas A&M University-Kingsville.