Measurement techniques, advances and limitations

Workplace and Indoor Aerosols Conference 2012 Lund University

Measurement techniques, advancesand limitations

Joakim Pagels and Aneta Wierzbicka

Ergonomics and Aerosol TechnologyLund University

Workplace and Indoor Aerosols 2012

http://www.eat.lth.se/aerosols2012


Aerosol Group

C. Isaxon, E. Nordin, P. Nilsson, C. Svensson, L. Ludvigsson, A. Wierzbicka, J. Löndahl, J. Rissler, J. Pagels, A. Gudmundsson, M. Sanati, M. Bohgard,

Ergonomics & Aerosol Technology, Lund University

A. Eriksson, C. Wittbom, M. Sporre, E. Fors, M. Frosch Mogensbæk Foverskov, N. Perron, G. Frank, S. Sjögren, B. Svenningsson, E. Swietlicki

Nuclear Physics, Lund University

M. Messing, K. DeppertSolid State Physics, Lund Universit

M. Hedmer, H. TinnerbergOccupational and Environmental Medicine, Lund University







Outline

• Which particle properties should be measured?

• Different types of measurements depending on purpose of

measurements

• Small portable instruments

• Detail characteristics with in situ techniques




Which particle properties should be measured

• mass concentration• number concentration• particle size • surface area • geometric form • chemical composition • bioavailable transition metals • solubility • acidity • particle surface chemistry • core chemistry




Measurements

• Personal exposure

• Monitoring in microenvironments

• Detail characterisation for specific purpose




Personal exposureCollection of particles on filters for:

• Gravimetric analysis• Chemical speciation (ion chromatography, OC/EC

analysis, PIXE, X-ray fluorescense)• Morphology assessment (TEM, SEM)




Monitoring in microenvironmentsWorkplace and Indoor Aerosols 2012









Number concentration - Hand-heldCondensation Particle Counter (CPC)

- 10 - 20 nm to about 1 m

- Conc. limit 100 000 cm-3 - 500 000 cm-3

- Battery operation about 5-6 hours

- Requires liquid refill every 6-8 hours

- Has to be kept in horisontal orientation




Approximation of mass concentration -Photometers

- Robust, cheap instruments

- Fast response to detect sudden changes (1s)

- But ….. cannot be used as an absolute

mass concentration measuring instrument

- Based on light scattering dependant on

refractive index (material) and size distribution

- Overestimate the mass concentrations

- ~ 0.1 to 10 m




Photometer with simultaneous collection ofthe particles on the filter

Schematics DUSTTRAK™ II – courtesy of Thomas Krinke, TSI




- Pocket sized

- Battery operated

- Measures the change in absorption of

transmitted light due to continuous collection of

aerosol deposit on filter.

- Precision ±0.1 μg BC/m3,

microAethalometer - Black Carbon measurement




NanoCheck/ NanoDiff, GrimmDISCMini, Matter Aerosol Nanotracer, Aerasense

Number concentration and particle size – small handheld instruments

• Small, portable, handheld, battery operated

• Easy to use

• Suitable for personal exposure assessment

• Open up new possibilities




Small handheld instruments – principle of operation

Unipolarcharging

- Unipolar diffusion charging of the particles

- Measurement of the particle induced current

Schematics – courtesy of Martin Fierz Two stages with different size dependantdeposition efficiency




Fierz et al., 2007, Field measurement of particle size and number concentrationwith the Diffusion Size Classifier (DiSC), SEA interantional

Components of the diffusion size classifier

Small handheld instruments – principle of operationWorkplace and Indoor Aerosols 2012


Number concentration of mobile on the road measurements

Testing presale instruments

Number concentration and particle diameter of candle smoke

Dahl et al., 2009Workplace and Indoor Aerosols 2012



Two persons having a party;playing music, smoking several cigarettes

All windows inthe appartment open

Working by the computer,using the printer

Cooking food

Example of measurements in homes – PINDA project Isaxon et al, 2010.Workplace and Indoor Aerosols 2012



Photos – courtesy of Maria Hedmer, OEM, Lund University




Asbach et al., 2012 Comparability of portable nanoparticle exposure monitors. Annals of Occupational Hygiene , in press

Compared instruments

- 6 handheld CPCs (model 3007, TSI)

- 2 DISCmini (Matter Aerosol)

- 3 Nanotracer (Aerasense)

- 2 NanoCheck (model 1.320, Grimm Aerosoltechnik)

- Aerotrak 9000 (TSI)

- Fast Mobility Particle Sizer (FMPS, TSI model 3091)

Aerosols used for intercomparison

- Sodium chloride (NaCl)

- Di-Ethyl-Hexyl-Sebacate (DEHS, C26H50O4)

- soot particles



Asbach et al., 2012 Comparability of portable nanoparticle exposure monitors. Annals of Occupational Hygiene , in press

CPCs DISCmini Nanotracer NanocheckSize range (nm) 10 ‐ 1000 10 ‐ 300 10 ‐ 300 25 ‐300

Pre‐classifier ‐particles above 700 nm are removed

‐ ‐

Manufacturer specified accuracy

± 20% ± 30% ± 1500 1/cm3 ± 5%

Number concentration accuracy in the intercomparison study

± 20% ± 30% ± 30% ± 30%

Deviations

overestimation of number conc in case of DEHS between 250 and 594%

underestimation of soot particles ‐58%

Sizing accuracy specified by manufacturer

± 30% ± 10 nm ± 5%

Sizing accuracy in the intercomparison study

± 30% ± 30%

in good agreement with FMPS for NaCl and DEHS within ± 6% , deviation for soot sizing

Lung deposited surface area

in good agreement with FMPS within ± 30%




Based on: VCI position paper „Tiered approach to an exposure measure‐ment …“ (2011); https://www.vci.de/Downloads/ Tiered‐Approach.pdf

Tiered approach for exposure assessment – presented byGerman Chemical Industry Association

Tier 2:Screening of only total concentrations, e.g. with(handheld) CPC, diffusionchargers, etc.

Tier 3:Expanded analysis of workplaceaerosol:• Chemical analysis• Size distribution (micron und

submicron)• Number, surface area, and mass

concentration• Determination of particle

background

no

Tier 1 – Data Gathering

?Can the release of nanoscale particles into theworkplace air be reasonably excluded duringproduction, handling or prcessing?

Tier 2 – Screening(e.g. with CPC)

? Significant increase ofconcentration over background?

yes

Tier 3 – ExpandedMeasurement

(e.g. with SMPS, CPC, chem. analysis, etc.)

?

Clear evidence of chemcialidentity of the ENM?

Take additional riskmanagementmeasures tomitigate exposure

yes

?

Documentand archive

Are riskmanagement measuresefficient?

yes

Check after 2 years or in case of changes

no

yes

no

no11 no ENM from activity; chemical identityof ENM known; their origin is elsewhere

Slide: Courtesty of Christof Asbach



• Particle Size

• Mass, Number, Surface Area Concentration

• Size-Resolved Composition

• Volatility

• Hygroscopic Growth / Water Solubility

• Agglomerate structure

What can be measured on-line? Workplace and Indoor Aerosols 2012


Measurement Technique Posters – Aerosols 2012

Järvinen A. et al. Calibration of diffusion charger based electrical aerosol sensors

Nilsson P.T. et al. Laser Vaporizer Aerosol Mass Spectrometry to detect metal NPs

Asbach C. et al. Portable monitor for the assessment of exposure to nanoparticles

Fierz, M. et al Nanoparticle Dosimeter for Easy Workplace Exposure Monitoring Gnewuch H. et al. Scanning-Flow Diffusion-based Particle Size Spectrometer (SFDiPS) Neubauer N. et al. Specific detection of palladium nanoparticles

Huotari J. et al. Impedance Spectroscopy of Particles from a Steel Plant Krinke T. et al. Development of a Portable, Battery-Operated Nanoparticle Sizer Steer B. et al. Comparison Studies of a Portable SMPS System

• Portable instruments: downscaling in size and cost • On-line instruments to selectively detect metals etc



Background

• Unaltered particles sized by major transport and deposition mechanisms

• Time Resolved, Size Resolved

• Avoid particle – gas-phase interactions

• Evaporation, Adsorption of gas phase, Degradation

• Avoid changes in morphology



SMPS/FMPS APS Size Distributions – In Situ Techniques

SMPS FMPS / DMS APS ELPI

Size range (nm) 10-500 5-500 500-20000 10-10000

Time Resolution ~ min ~ s ~ s ~ s

Size Resolution High Medium High Medium

Sensitivity High Medium High Medium

Eq. diameter Mobility Mobility Aerodynamic Aerodynamic



Emissions in Production of Multi-walled CNTs – Aerodynamic Particle Sizer

Hedmer et al. Senn 2012



Multi-walled CNTs – SEM analysis

Poster: Ludvigsson et al.



Highly Time Resolved

Mobility Analysis – Welding Fumes

• Quickly changing concentrations

• Need high time resolution



Surface Area Measurements

• SAdep(dp)~dp2*DF(dp)

Fissan et al. 2007, Asbach et al. 2009

13:01:02 13:08:36 13:16:00 13:23:24 13:32:16

0

1x109

2x109

3x109

4x109

5x109

6x109

7x109

Alv

eola

r S

urf

ace A

rea

Concentr

ation [

nm

²/cm

³]

Time

NSAM

FMPS



Aerosol Mass Spectrometry

• ddd

Jayne et al. 2000 DeCarlo et al. 2007



Time-Resolved PAH Analysis in Transient Wood Combustion

Erikson et al. AAAR 2012

Add fuel Flaming Phase Burnout Phase



Laser Vaporiser Aerosol Mass Spectrometer

Onasch et al. AS&T 2012

Nd:YAG laser λ=1064 nm



Selective Emissions of Metal NPs

Opened up the spark discharge generator

Nilsson et al., SENN 2012



In-Situ Measurements of Agglomerates Aerosol Particle Mass Analyzer (APM))

12

222 /ln rrr

qV

r

qEm APM

Particles are pass APM if:

2mrqEFel

Presentation at the IAC 2010 2010-09-02 Jenny Rissler

Aerosol out

Aerosol in

Rotating inner electrode

Rotating outer electrode

Air gap V APM

qE

Axis of rotation

r 1 r 2

Aerosol out

Aerosol in



Air gap V APM

Axis of rotation

r 1 r 2

Fc

Ehara et al. 1997 McMurry et al 2002



In-Situ Measurements of Agglomerates - Aerosol Particle Mass Analyzer (APM))

Particles are pass APM if:

Presentation at the IAC 2010 2010-09-02 Jenny Rissler

Aerosol out

Aerosol in



Air gap V APM

qE

Axis of rotation

r 1 r 2

Aerosol out

Aerosol in



Air gap V APM

Axis of rotation

r 1 r 2

Fc

Ehara et al. 1997 McMurry et al 2002

DMA APM

CPC

Aerosol in

6

3

meeff

dm



Particle Types at a Busy Street

Rissler et al EAC 2012

eff =0.4 g/cm3

eff =1.5 g/cm3

6

3

meeff

dm



Surface Area of Metal NPs

• Aggregates and sintered particles of the same mass (TDMA-APM) • Aggregates with primary particle size of 5 nm • Mobility diameter is 60 nm for aggregates and 31 nm for the sintered

particle • Surface Area decreases a factor of ~ 5 upon sintering (Messing et al. 2012, Nanotoxicology)



Mixing status – Tandem DMA

Tandem-DMA set-up

CPCMonodisperse Aerosol

Ambient Aerosol

DMA1 DMA2

•Humidifier•Thermo-desorber,•Chemical Reactor

etc.

Bip

ola

rC

ha

rge

r

CPC

Dri

er

•With a TDMA the properties of single particles can be studied

Combustion Aerosol

Humidifier or

Heater

Candle Aerosol

from Chamber

Figure 3. Schematic figure of the TDMA Technique

Tandem-DMA set-up


Ambient Aerosol

DMA1 DMA2


etc.

Bip

ola

rC

ha

rge

r

CPC

Dri

er


Combustion Aerosol

Tandem-DMA set-up


Ambient Aerosol

DMA1 DMA2


etc.

Bip

ola

rC

ha

rge

r

CPC

Dri

er


Combustion Aerosol

Tandem-DMA set-up


Ambient Aerosol

DMA1 DMA2


etc.

Bip

ola

rC

ha

rge

r

CPC

Dri

er


Combustion Aerosol

Humidifier or

Heater

Candle Aerosol

from Chamber

Figure 3. Schematic figure of the TDMA Technique



Particle Types from Indoor Sources



Summary – In-Situ Techniques • Size distributions can be measured with high accuracy and time

resolution. Downscaling in dimensions and price on-going

• Volatile coatings (Organics etc) can be removed in thermodenuder to sample ” d particles” only.

• Lung deposited surface area determined using NSAM, needs to be confirmed for agglomerates.

• The morphology of coated or core particle can be determined using DMA-APM and UNPA techniques

• Particle hygroscopicity/water solubility estimated using T-DMA techniques.

• Highly time- and size resolved composition can be measured using Aerosol MS techniques. Still expensive and bulky…….

• Separation into particle types (external mixture) according to volatility, hygroscopicity and morphology using tandem techniques



Measurement techniques, advances and limitations

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