© 2007, TSI Incorporated Inter-comparison of Long-Term Ambient Ultrafine Particle Size Distribution...

© 2007, TSI Incorporated

Inter-comparison of Long-Term Ambient Ultrafine Particle Size Distribution Measurements at a Near-Roadway and a

Representative Urban Site in New York City

Brian P. Frank1, Jacqueline Perry1, H.D. Felton1,

Robert C. Anderson2, Oliver Rattigan1,

Kevin Civerolo1, and Olga Hogrefe3

1Division of Air Resources, New York State Department of Environmental Conservation, Albany, NY, 2TSI, Inc., Shoreview , MN,3Department of Chemistry and Biochemistry, Siena College, Loudonville, NY

http://www.facebook.com/pages/AIRNow/170565504768


Outline– 1. Definitions: What is a Nanoparticle? Ultrafine?

Fine?– 2. Near Road Monitoring, Mass, Number– 3. What criteria should be used for selecting a

monitoring location?– 4. What tools are available to monitor these

particles?– 5. How do initial monitoring results look?

A) -Queens College / Ike Park 1 year Study

Urban Pollution

Industrial Pollution


Examples of Particle Sizes in Workplace

Nuclei Mode Accumulation Mode Coarse Mode

Fine Mode Coarse Mode

0.001 0.01 0.1 1 10 100

Particle Size Range (micrometers)

Typ

es

of

Par

tic

les

Welding Fumes

BacteriaVirus

Paint Pigments

Diesel Soot(Dieselized Coal Mines)

Boilers/Furnaces

VirusCarbon Black(Photocopiers)

Coal Dust (Coal Mines)

Construction Activities

Vacuuming/Dusting

Tobacco Smoke

Inhalable PM

(Total dust)

Respirable PM

Thoracic PM


Nanoparticle and Ultrafine Monitoring

Definitions: What is a Nanoparticle?

Coarse particle – ≤10 µm

Fine particle – ≤2.5 µm

Ultrafine particle – ≤0.1 µm (100nm)

Nanoparticle • Dimensions between 1 and 100 nm in at least

one dimension• Nanoparticle size may go up to 200 – 300 nm

for occupational exposure(Note: terminology from ASTM Committee E56, definitions are only considerations)


What are Ultra-Fine Particles?1. US EPA definition: Particles with a diameter <100nm

2. UFPs occur in massive numbers in urban air but essentially have no measurable mass

3. Most common source in urban environment is vehicle exhaust

Human Hair ~70 m>700x UFP

Fine Beach Sand ~90 m>900x UFP

PM10 <10 m>100x UFP

PM2.5 <2.5 m>25x UFP

EPA, Office of Research and Development

UFP: 100nm


Aerosol Particle Nucleation

6Kulmala M Science 302 Nov 2003


Near Road Monitoring= PM Mass Confusion

7

2.3.1.6 Particulate Matter (PM). Motor vehicles emit significant amounts of PM through combustion, brake wear, and tire wear. Motor vehicles may also

contribute to elevated near-road PM concentrations by re-suspending dust present on the road surface. In the United States, the NAAQS regulates

ambient concentrations of PM less than 10 μm in diameter (PM10) and PM less than 2.5 μm in diameter (PM2.5). Both of these PM size fractions are

emitted from motor vehicles. In general, PM emitted by combustion will be in the PM2.5 size fraction. Since combustion-emitted particles typically

occur at less than 0.1 μm in diameter, these emissions tend to contribute little to ambient PM2.5 mass concentrations, but do contribute

significantly to PM number concentrations, and may impact the chemical composition of the PM2.5 mass collected near the road relative

to urban background conditions

Near-Road Air Quality Monitoring: Factors Affecting Network Design and Interpretation of Data

R. Baldauf1,2,*, N. Watkins3, D. Heist4, C. Bailey1, P. Rowley1, R. Shores2


Near Road Monitoring= PM Mass Confusion

8

2.3.3.1 PM number concentration. As previously discussed, PM emitted through the combustion

process occurs primarily in the ultrafine size range (i.e. less than 0.1 μm in diameter); thus, the impact

on PM mass may be negligible. However, emissions of these small particles occur in extremely large quantities; therefore, PM number concentration

measurements often provide a good indication of primary PM exhaust emissions from motor vehicles. In addition, several health studies suggest that ultrafine particles may lead to adverse health effects identified in

the near-road literature

Near-Road Air Quality Monitoring: Factors Affecting Network Design and Interpretation of Data

R. Baldauf1,2,*, N. Watkins3, D. Heist4, C. Bailey1, P. Rowley1, R. Shores2


Need For Field-Robust, Affordable, Count Based Measurements

µg

/m3

Mass Concentration

Par

ticl

es/c

m3 Number

Concentration

Virtually No Mass Contribution < 100 nm

– Growing interest in ultrafine particles (UFP)

• UFP health affect research• Evidence that perhaps UFP are

the most variable component of urban atmosphere

• UFP recognized as primarily component of vehicle exhaust

– Traditional mass based measurements like PM10 & PM2.5 underestimate contribution of UFPs

– CPCs good choice for UFP concentration measurement

– WCPCs convenient field choice

Ultrafine Particles (UFP) <100nm

Seinfield et al, 1998


How Do You Quantify UFP?Particle Counting Less Than 0.1 m (100nm)

Problem: Detection of light scattering “peters out” for particles less than 0.1 µm

Solution: Make the particles BIGGER → Condensation Particle Counters

Aerosol Inlet w/screen assembly

Transport Flow

Saturator 20oC

Growth Tube 60oC

Optical Detection

Water Separator

External Vacuum

Excess Water Drain

Continuous Flow Water-base Condensation Particle Counter


EPC Flow Schematic

Particle Size RangeD50 7 nm - ~ 3 µmParticle Concentration Range 0.001 to 106 particles/cm3

Single Particle Counting; w/live-time correctionParticle Concentration Accuracy10% at 106 particles/cm3

Flow

High-flow Inlet 3 0.3 Liters/minuteLow-flow Inlet 0.60.06 Liters/minuteAerosol Flow Rate 120 12 cm3/minuteWorking Fluid WaterEnvironmental Operating ConditionsAmbient Temperature Range 10 to 40 oC


The operating principle of the UFP Monitor is based on diffusion charging of particles, followed by size segregation within a Differential Mobility Analyzer (DMA) and detection of the aerosol via a sensitive electrometer. The charging device in the UFP Monitor is a "Corona-Jet"

charger. Within the charger, the total flow of 5.0 L/min is split into 1.0 L/min passing through two filters (a carbon and a HEPA) and an ionizer and 4.0 L/min of aerosol remaining as sample flow. The flow streams are merged in a mixing chamber where particles in the aerosol

flow mix with the ions carried by the filtered clean air. The charged aerosol then moves on to the DMA for size segregation. After leaving DMA, the aerosol enters a faraday cage where the particles, and their charge, are collected on a particle filter. The filter is conductive, and

is electrically connected to the input of a sensitive electrometer amplifier. One measurement cycle takes approximately 10 minutes with one minute zeroing time between cycles.

3031 Ultrafine Particle Monitor

How Do You Quantify UFP?Particle Sizing & Counting Less Than 0.1 m (100nm)

I 20nm-30nm I 30nm-50nm I 50nm-70nm I 70nm-100nm I 100nm-200nm I >200nm I


Filter

11.7 L/min

Roof

16.7 L/min

5 L/min

5 L/min

UFP Monitor

PM10 Inlet

PM1 Cyclone

Exhaust

Valve

Nafion Dryer

Flow Splitter

Dry Aerosol

Filtered Air

Filtered Air

Pump

Filter

11.7 L/min

Roof

16.7 L/min

5 L/min

5 L/min

UFP Monitor

PM10 Inlet

PM1 Cyclone

Exhaust

Valve

Nafion Dryer

Flow Splitter

Dry Aerosol

Filtered Air

Filtered Air

Pump

The UFP Monitor was deployed in concert with the TSI Model 3031200 Environmental Sampling System. A representative sample of ambient air is continuously drawn through a size selective PM10 inlet at a standard flow rate of 16.7 L/min. Next, the sample passes through a PM1

cyclone which removes larger particles. The main sample stream is subsampled into the UFP Monitor at a flow rate of 5 L/min. A Nafion dryer upstream of the UFP Monitor ensures proper conditioning of the aerosol to minimize effects due to relative humidity. The remaining

11.7 L/min of make-up air is routed through the Nafion dryer as purge air and drawn through a vacuum pump and exhausted.

Environmental Sampling System

How Do You Quantify UFP?


Distance, Noise and Vegetation Barrierseffect PN monitoring measurements

14

Figure 2. Mobile monitoring measurements of the number of 20 nm size particles present at varying distances from a 125,000 AADT highway for an at-grade road with no obstructions (open field), behind only a noise barrier (noise barrier only), and behind a noise barrier with mature vegetation stands (noise barrier & vegetation). Bars represent 95 percent confidence

intervals for each distance (Baldauf et al., 2008b).


Case Study A

QUEENS COLLEGE

& IKE PARK

Long Island, NY

June 2009 – June 2010


Monitoring Locations

16

27 KM


The Queens College monitoring site is a well instrumented monitoring site representative of the New York City metropolitan area located on the campus of Queens College in New York City. The site is bordered by

a mix of sources, including mobile sources from the Long Island and Horace Harding Expressways, as well as local campus parking. It is located 27 kilometers NW of the Eisenhower Park monitoring site.

Hourly wind rose for Queens College averaged over the analysis period.

*Courtesy of Brian Frank & NYSDEC – 2010 AAAR POSTER Intercomparison of Long-Term Ambient Ultrafine Particle Size Distribution

Measurements at a Near-Roadway and a Representative Urban Site in New York City

Queens College


How do initial monitoring results look?Queens College, NY

0:07

1:07

2:07

3:07

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711

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0

5000

10000

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NY StateTuesday, January 19, 2010

20-30nm

30-50nm

50-70nm

70-100nm

100-200nm

200-500nm

Total

Par

ticl

es /

cc

Typical Commuter Traffic Patterns


The Eisenhower Park monitoring site is located at a near-roadway site on Long Island, 27 kilometers SE of the Queens College Site. The site is backed by unoccupied parkland and is adjacent to a 4

lane roadway that runs parallel to the site in a NNW direction. The site is within 22 meters of the roadway in a W-WSW direction, and within 53 meters of the roadway in a S direction. A waste-to-

energy conversion plant and several restaurants are also proximate to the site.

Hourly wind rose for Eisenhower Park averaged over the analysis period.

*Courtesy of Brian Frank & NYSDEC – AAAR POSTER Intercomparison of Long-Term Ambient Ultrafine Particle Size Distribution


Eisenhower Park Monitoring Site


How do initial monitoring results look Eisenhower Park

Commuter TrafficIncineratorOperating

0:10 4:10 8:10 12:1016:1020:10 0:13 4:13 8:13 12:1316:1320:13 0:13 4:13 8:13 12:1316:1320:13 0:13 4:13 8:13 12:1316:130

10000

20000

30000

40000

50000

60000

NY StateJanuary 15, 16, 17& 18 2010

20-30nm

30-50nm

50-70nm

70-100nm

100-200nm

200-500nm

Total

Par

ticl

es /

cc

Friday Saturday Sunday Monday(Holiday)


Commuter TrafficIncineratorOperating

0:10 4:10 8:10 12:1016:1020:10 0:13 4:13 8:13 12:1316:1320:13 0:13 4:13 8:13 12:1316:1320:13 0:13 4:13 8:13 12:1316:130

10000

20000

30000

40000

50000

60000

NY StateJanuary 15, 16, 17& 18 2010

20-30nm

30-50nm

50-70nm

70-100nm

100-200nm

200-500nm

Total

Par

ticl

es /

cc

Note: Differences in Particle Size

Distributions from different sources of

aerosols.

Friday Saturday Sunday Monday(Holiday)

How do initial monitoring results look Eisenhower Park


22

For events of this type, the behavior of ultrafine particles < 100 nm was closely correlated with the behavior of larger ultrafine particles and with PM 2.5.



Regionally Correlated Atmospheric Formation Events





For events of this type, the behavior of ultrafine particles < 100 nm was closely correlated with the behavior of larger ultrafine particles and with PM 2.5.


For events of this type, the behavior of ultrafine particles < 100 nm was not closely correlated with the behavior of larger ultrafine particles or with PM 2.5, suggesting that PM2.5 is not

necessarily a good indicator of the near-road behavior of ultrafine particles < 100 nm.







Regionally Correlated Diurnal Events


Ike ParkNOx vs Channel 1 (20-30nm)


Ike ParkNO2 vs Channel 4 (70-100nm)


Ike ParkNOx vs Channel 4 (70-100nm)


Queens College NO2Channel 4 (70-100nm)


SO2 Channel 1 (20-30nm) & 6 (200-500nm)


SO2 Channel 5 (200-500nm)


PSO4 Channel 5 (200-500nm)


Conclusions NOX vs UFP

• Does not correlate well with the largest (200-500nm) or smallest (20-50nm) channels. This supports a significant general conclusion that we found, which was that none of the non-UFP data we gathered ever correlated with the smallest (20-50 nm) bin, i.e., there are no surrogates for UFPs below 50 nm; they have to be directly measured.

• The middle channels (50-200 nm) correlate well with NOx in Fall, Winter and Spring, but not in Summer.

• We speculate that this is due to the high temperatures in summer, which cause particle-phase nitrate to evaporate even if it forms. This is supported by the finding that we see the same seasonal behavior for NO2, which is an intermediate for nitrate

formation Less pronounced at IP than at QC.


Conclusions SO2 vs UFP• Again, consistently low correlations (R2 always < 0.5) for the smallest (20-

50 nm) size bin. [• The middle channels (50-200nm) correlate well with SO2 in Winter, but not

in Spring, Summer, and Fall. Winter has the highest correlations and Summer has no correlations (ie R2 < 0.5).]

• For QC only (we don’t have IP data on this); particle phase SO4 also correlates with UFPs according to the same trend.

• Our measurements also indicate that SO2 is higher in the winter, and we speculate that greater amounts are therefore available for particle formation. This higher SO2 may be potentially due to local heating; the lower amount of transport SO2 available in the summer may be insufficient for particle formation.

• Side note: since the correlation with PMSO4 was so low in the summertime we wouldn’t expect to learn anything useful from looking at the AMS data from the QC09 summer intensive.


The authors wish to thank Michael Christopherson, Robert Murway, Aaron Pulaski, Sergio Fleishaker, and Enrique Lopez of the New York State Department of Environmental Conservation

for their assistance.

Acknowledgements


Thank You For

Your Attention

Any Questions?

Robert C. Anderson ([email protected])


Forrest Fire in Quebec – Smoke Blowing into Boston


Boston Quebec Fire Event -- Hourly PM2.5, Aeth DC, and # concPM2.5 is average of N.End and Roxbury MA-DEP sites

Courtesy of NESCAUMGeorge Allen

Courtesy of George Allen - NESCAUM

© 2007, TSI Incorporated Inter-comparison of Long-Term Ambient Ultrafine Particle Size Distribution...

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