modelings Joonas Koivisto, National Research centre for the Working - - PowerPoint PPT Presentation
Indoor aerosol modelings Joonas Koivisto, National Research centre for the Working Environment; jok@nrcwe.dk NanoSafety Cluster WG4, 11.4.2017 Outline Exposure modelings 1. Dispersion models 2. Source characterization 3. Engineered
Joonas Koivisto, National Research centre for the Working Environment; jok@nrcwe.dk
NanoSafety Cluster WG4, 11.4.2017
Exposure modelings
Modeling Examples
ππ·(π’) ππ’ = πππ·0(π’) + ππ·(π’) π β π + πΏ + π π·(π’)
Terms and parameters: C(t) m-3 Indoor aerosol concentration Co(t) m-3 Outdoor aerosol concentration Ξ» s-1 Ventilation rate P - Particle penetration factor S(t) # s-1 Indoor particle source V m3 Compartment volume Ξ³ s-1 Particle deposition rate Ο s-1 Particle coagulation rate Q m3 s-1 Ventilation flow Background particles from ventilation air Particle removal by ventilation, deposition, and coagulation
Usually Co = 0, and Ξ³ Β« Ξ» and Ο Β« Ξ»: ππ·(π’) ππ’ = ππ·(π’) π β ππ·(π’)
Emission source Compartment concentration
Assumptions:
times
Assumptions:
times in the NF and FF
NF and FF volumes (3 m3 min-1 < Ξ² < 30 m3 min-1; Cherrie, 1999)
and deposition Zhang et al., (2009) describes the NF/FF model in detail.
A Near Field/Far Field (NF/FF) model:
ππΊπΊ ππ·πΊπΊ(π’) ππ’ = πΎπ·πΊπΊ π’ β πΎ + π π·πΊπΊ π’ β ππ,ππΊπ·πΊπΊ π’ + πΎππππ,πΊπΊ πππΊ ππ·ππΊ(π’) ππ’ = πΉππ(π’) + πΎπ·πΊπΊ π’ β πΎπ·ππΊ π’ β ππ,ππΊπ·ππΊ π’ + πΎππππ,ππΊ
Particle emission source (# s-1) characterization
Chamber measurements
1.
In steady-state (
ππ·(π’) ππ’
= 0; Co = 0, and Ξ³ Β« Ξ» and Ο Β« Ξ»):
ππ·(π’) ππ’
=
ππ·(π’) π
β ππ· π’ = 0 ο ππ·(π’) = πππ·(π’)
mathematical difference between measured and simulated concentration (Hussein et al. 2006)
Powder dustiness measurements
Dim, [mg kg-1] ππ = πΈπ½π β πΌ β ππ ππ’
Terms and parameters:
# kg-1 Dustiness index
ππ’
kg s-1 The powder use rate
Schneider and Jensen (2008)
manufactured nanomaterials (Koivisto et al. 2017)
part of the EU FP7 SUN project
100 1000 10000 100000 10 20 30 40 50 60 70 Ranked Sample Order DI(Inh) [mg/Kg] Very Low Low Moderate High Need for Very High? 2 of 66 "NM" above 25000 mg/Kg
Dustiness indices from small rotating drum method
Study information Process information: e.g. sanding and details, Materials: matrix, NM con- centration,β¦ Fragments information: density, description of released fragments Material Removal Rate or use rate, Size-resolved release rates: Sm (Β΅g/sec), SSA (Β΅m2/sec), SN (1/sec) Traceability, transparency Usability, link to reality, grouping Tier 1 information for EHS assessment (fraction of bioavailable NM, shape, elemental compositions,β¦) Quantitative release rate for dispersion models. MRR is used to estimate surface contamination and environmental release. Statistical analysis ο grouping and read-across rules Dynamic tranformation Tier 2 information for EHS assessment Dose-response Hazard library
Study Gomez et al. (2014) Reference/contact information N Process Sanding Process details Metabo FSR200 hand-held sanding machine where the dust collector cartridge was removed (user modified) and equipped with a sanding paper with a grit size of 120. Sn include sanding machine electric engine emissions. Matrix Acryl binder Matrix details Paint matrix: water, propylene glycol, Uradil AZ XP 601Z44, and others NM TiO2 NM vendor N/A NM product name Nano Amor and NaBond TiO2 rutile NM concentration (wt.%) 36 NM state Embedded MN PP size (nm) NaBond 80 nm and Nano Amor 50 nm Other information for materials and methods NaBond specific surface area of 28.2 m2/g and Nano Amor specific surface area of 139.1 m2/g Process rate (mg/sec) N/A Released fragments Sanding of the paints produced airborne particles mainly > 1Β΅m in size. Free TiO2 particles were not observed. Fragments density (g/cm3) 2.1628 Notes Density calculated as 36 % (TiO2 rutile) of 4.23 g/cm3 and 64 % density of 1 g/cm3 Mass emission Sm (ug/sec) 6800 GMDm (um) 3.6 GSDm 2 Notes Sanding machine electric engine emissions are neglected from the emission rate. Sm is for particles <10 um in diameter. Surface area emission Ssa (ug/sec) NaN GMDsa (um) NaN GSDsa NaN Notes N Number emission Sn (1/sec) 2.50E+09 GMD (um) 0.56 GSD 1.9 Notes Sanding machine electric engine emissions are excluded Dp1 (um) 9.89E-03 Dp2 2.13E-02 Dp3 3.95E-02 Dp4 7.29E-02
ππ·(π’) ππ’ = ππ
ππ·π π’ + ππ· π’
π β ππΉπ· β π + πΏ + π π· π’ + π(π
π β 1)π· π’
where 0<P<1 (0 = perfect filtration, 1 = no filtration)
π·ππβ(π’) = π·(π’) β ππππΉ
Respirator study (Koivisto et al. 2015) Air cleaner study (MΓΈlgaard et al. 2014)
Study Control measure Activity/process NM PSD (device/range) N AvEffect % SD Median 5th perc Min Max 1,2 Containment Loading in compounding process, harvesting Nanoalumina, nanoclay, graphene platelets all data (5β560 nm) 15 96,1 12,8 99,9919 80,9 50,3 99,9992 Containment (high level) 5β560 nm 8 99,890 0,26 99,48 99,3 99,9992 Containment (medium level) 200nm 7 91,7 18,4 63,4 50,3 99,9989 3,4 Fixed capturing hood Reactor clean-out, welding Mostly metals/oxides all data (<20Β΅m) 26 94,1 7,1 95,8 79,5 74,6 100,000 45-216 nm 1 87,5 300-500 nm 3 97,85 3,7 <1Β΅m 11 95,1 6,7 85,0 85,0 100,00 1Β΅m-10Β΅m 12 94,3 6,7 83,9 74,6 100,00 >10Β΅m 3 90,3 11,2 3,4 Movable capturing hood Synthesis/handling; welding Mostly metals/oxides all data (<10Β΅m) 5 88,2 8,5 90,4 77,5 75,9 97,3 Welding fume 45-216 nm 1 97,3 1 Enclosing hood (process blower) Reactor, tank cleaning Graphene platelets 5.6β560 nm 1 74,6 5,6 Fume cupboard (without glove bags) Reactor set-up & handling; sanding TiO2, CNT all data (<1Β΅m) 3 81,1 20,8 91,0 60,5 57,1 95,0 TiO2 30-50 nm 1 95,0 7 Wetting at point of release Cutting band saw Base carbon all data (0.5-20Β΅m) 3 87,9 17,3 96,4 70,8 67,9 99,3 5.6 to 560 nm 1 67,9 10 Unidirectional room airflow systems (spray rooms) Sanding (hand) CNT 20-10000nm 2 91,7 7,5 89,0 88,7 94,8 20-300nm 1 88,7 8 Unidirectional room airflow systems (not specified) Solution spraying CNT 14-630 nm (52*1473nm β 56- 1760nm) 1 84,0 12 Glove boxes Handling powders, polishing, scratching, drying CNT 20-1000nm 2 97,2
β¦ β¦
β¦ β¦ β¦ β¦ β¦ β¦ β¦ β¦ β¦ β¦
See Fransman et al. (2008) ECEL for dusts
FF NF; Sc πΊ, Pf Po Co
X X
ππΊπΊ ππ·πΊπΊ(π’) ππ’ = πΎπ·πΊπΊ π’ β πΎ + π π·πΊπΊ π’ β ππ,ππΊπ·πΊπΊ π’ + πΎππππ,πΊπΊ + π(π
π β 1)π· π’
πππΊ ππ·ππΊ(π’) ππ’ = πΉππ(π’) + πΎπ·πΊπΊ π’ β πΎπ·ππΊ π’ β ππ,ππΊπ·ππΊ π’ + πΎππππ,ππΊ
Laser printer emission rates B. Indoor air cleaner cleaning efficiency
handling
Particle concentrations during pre-operation and printing phases Lai and Nazaroff (2000) Measured Korhonen et al., (2004) πππ(π’) ππ’ = π»πΆπ(π) π β π + πΏπ + ππ ππ(π’) Solve
ο
πππ(π’) ππ’
β β π + πΏπ ππ(π’) (π is known)
ππΆπ(π) ππ’ = πππ·0 π’ + πππ(π’) π β π + πΏπ + ππ πΆπ(π)
(MΓΈlgaard et al. 2014)
Blue parameters are known
Air exchange ratio [h-1] N, [cm-3] Ncleaner , [cm-3] Cleaning efficiency, P* 0.5 3800 1250 66 % 2 2180 1370 38 % *π = 1 β
ππππππππ π
Γ 100 % ππ·(π’) ππ’ = ππ
ππ·π π’ + ππ· π’
π β π + πΏ + π π· π’ + π(π
π β 1)π· π’
NF measurements
ππ = πΈπ½π β ππ ππ’
Pouring process n DM, (mg m-3) NF/FF, (mg m-3) 500 kg RD3 4 0.08 0.37 500 kg TR92 5 0.36 0.2 500 kg Microdol 2 0.77 1.1 25 kg RD3 10 0.17 0.1 25 kg Micro Mica 17 0.31 0.78 25 kg SatinTone 16 0.98 0.41 25 kg Microdol 11 0.25 0.55
ο (PLC=1 and H = 1)
(Koivisto et al. 2014)
Ξ» 2 h-1 Ventilation rate (Known) VFF 245 m3 Compartment volume (Known) VNF 8 m3 NF volume (Guessed, same as Cherrie 1999) Ξ² 22.5 h-1 Corresponding to QNF,FF = 3 m3 min-1 (Guessed)
Sieving in a fume hood Sieving in a room Cleaning Emission rates, [ΞΌg min-1] Sm 1.9 15.2 4.0 Mass concentrations, [ΞΌg m-3] Measured 0.24 4.96 1.54 Modeled NF 0.78 6.27 2.7 Modeled FF 0.16 1.19 1.17 Modeled Single box 0.17 0.78 0.16 }
measurements with high quality conceptual information for model testing!!!
Cherrie JW. (1999) The Effect of Room Size and General Ventilation on the Relationship Between Near and Far-Field Concentrations. Appl Occup Environ Hyg; 14: 539-546. Fransman W, Schinkel J, Meijster T, Van Hemmen J, Tielemans E, Goede H. (2008) Development and Evaluation of an Exposure Control Efficacy Library (ECEL). Ann Occup Hyg; 52: 567-575. Hussein, T., Glytsos, T., OndrΓ‘cek, J., ZdΓmal, V., HΓ€meri, K., Lazaridis, M., Smolik, J., Kulmala, M.,
Environment 40, 4285-4307. Koivisto A.J., Hussein T., NiemelΓ€ R., Tuomi T., and HΓ€meri K. (2010). Impact of particle emissions of new laser printers on modeled office room. Atmospheric Environment 44, 2140-2146. Koivisto A.J., PalomΓ€ki J.E., Viitanen A.-K., Siivola K.M., Koponen I.K., Mingzhou Y., Kanerva T., Norppa H., Alenius H.T., Hussein T., Savolainen K.M., HΓ€meri K. (2014) Range-Finding Risk Assessment of Inhalation Exposure to Nanodiamonds in a Laboratory Environment. International Journal of Environmental Research and Public Health 11:5382-5402. Koivisto AJ, Jensen ACΓ, Levin M, Kling KI, Dal Maso M, Nielsen SH, Jensen KA and Koponen IK (2015) Testing a Near Field/Far Field model performance for prediction of particulate matter emissions in a paint factory Environ Sci Process Impacts 17, 62.
Koivisto AJ , Aromaa M, Koponen IKK Fransman W, Jensen KA, MΓ€kelΓ€ JM, HΓ€meri KJ. (2015) Workplace performance of a loose-fitting powered air purifying respirator during nanoparticle synthesis. J Nanopart Res 17:177. Koivisto AJ, Jensen ACΓ, Kling KI, NΓΈrgaard A, Brinch A, Christensen F, Jensen KA. (2016) Quantitative material releases from products and articles containing manufactured nanomaterials: A critical review. 5 (2017) 119β132. Korhonen, H., Lehtinen, K. E. J., Kulmala, M., 2004. Multicomponent aerosol dynamics model UHMA: model development and validation. Atmospheric Chemistry and Physics, 4, 757-771. Lai, A. C. K., Nazaroff, W. W., 2000. Modeling Indoor Particle Deposition from Turbulent Flow Onto Smooth Surfaces. Journal of Aerosol Science, 31, 463-476.
MΓΈlgaard B., Koivisto A.J., Hussein T., HΓ€meri K. (2014) Performance of portable indoor air cleaners. Aerosol Science and Technology 48:409-417. Nazaroff, W. W. (1989) Mathematical modeling and control of pollutant dynamics in indoor air. Dissertation (Ph.D.), California Institute of Technology. (http://thesis.library.caltech.edu/576/) Zhang Y, Banerjee S, Yang R, Lungu C, Ramachandran G. (2009) Bayesian Modeling of Exposure and Airflow Using Two-Zone Models. Ann Occup Hyg; 53: 409β424 Schripp, T., Wensing, M., Uhde, E., Salthammer, T., He, C., Morawska, L., 2008. Evaluation of ultrafine particle emissions from laser printers using emission test chambers. Environmental Science and Technology 42, 4338-4343.