Aerosol Exposures Due to Re-suspension from Building Reservoir Surfaces (M3.4)

Size: px

Start display at page:

Download "Aerosol Exposures Due to Re-suspension from Building Reservoir Surfaces (M3.4)"

Theodore Brandon Pitts
5 years ago
Views:

1 Aerosol Exposures Due to Re-suspension from Building Reservoir Surfaces (M3.4) J. Freihaut,W. Bahnfleth, C. Gomes, Bin Hu, J. Firrantello, P. Aumpansub Indoor Environment Center Dept. of Architectural Engineering Pennsylvania State University B. Thran U.S. Army Center for Health Promotion and Preventive Medicine Society for Risk Analysis Annual Meeting 2004: Session M3 Microbial Dose-Response Assessment for Inhalation Exposures Slide 1

2 Objectives: Coupled Literature & Experimental Investigation of Particle Re-suspension in Indoor Air Systems 1.) Extract Bio-particle Re-suspension Factors, Re-suspension Rates and Deposition Velocities from Literature Reported Investigations 2.) Use Controlled Re-suspension Experiments to Refine and Quantify Selection 3.) Establish Methodology to Relate Particle Re-Suspension and Deposition Rates to Generation and Sink Terms of Contaminant Source Terms in Building Air Flow Simulation Program (CONTAMW) Slide 2

3 Aerosol Occupant Risk Assessment Scope Biological Agents Urban Air Quality Diesel exhausts Natural Biocontaminants Protein Allergens Endotoxins Adsorbed Mycotoxins Occupant Risk Assessment Primary Release Aersolization Secondary Aerosolization Transport & Dispersion Occupant Exposure Occupant Dosages Epidemiological Effects Slide 3

4 Allergens Can be Natural Bio-contaminants Asthma related statistics 18 million Americans (6% of US population) affected 5,000+ death per year in the US 13 billion USD per year Continues to increase Slide 4

5 Primary vs Secondary (Re-Suspension) Aerosolization Exposure Concentration PPM CFU/M 3 Primary Aerosolization /Transient Pulse Release: BWA Attack - Near Air Handle Intake or Interior Release Spores - Air Handler Start-up Smoke & Fire Aerosols Chemical Spills Aerosols Secondary Aerosolization (Occupant Activity or Equipment Cycling): Residue of Primary Aerosolization BWA Attack Conventional Allergens, Toxins, Pathogens, Spores Time Seconds/Minutes Hours Slide 5

Inhalation Exposure Paths for Re-suspension Not Known "At present the question of how allergen particles enter the lungs is not resolved, and this issue is of considerable importance since it may

6 Inhalation Exposure Paths for Re-suspension Not Known "At present the question of how allergen particles enter the lungs is not resolved, and this issue is of considerable importance since it may well define the distribution of "inflammation" and airway obstruction." Clearing the Air: Asthma and Indoor Air Exposures, National Academy of Sciences, National Academy Press, p.139, Genetically Predisposed Individual Individual LD 50 Population Distribution Need to elucidate air re-suspension mechanisms : 1.)Bioaerosol deposited during primary aersolization event; 2.)common allergens Bioaerosol 0.05 to 10 microns Aerosols 1.) BWA Deposited during primary Aersolization Event 2.) Allergen - containing particles Respiratory Disease Development Debilitation from BWA Time Slide 6

7 Aerobiology of Re-suspended Indoor Air Biocontaminants Inhalation Exposure Paths and Risk Assessment Require Aerobiological Pathway Quantification Primary Sources Reservoir Formation Aerosolization: Primary Secondary (Resuspension) Exposure Parameters Dose Disease Development (Individual risk Factors) Residue from Primary BWA Event BWA* Insects,Pets,,Pests Fungi,Molds Endotoxins Mycotoxins Protein Allergens Building Reservoirs Dust Surfaces HVAC Air Handling or Occupant Reservoir Disturbance: K i d =f K i d [Bio] i indoor air = ( ) Floor/Duct Vibration Walking Impact Electrostatics Turbulence * BWA = chemical, biological warfare agents [Bio] i indoor air K i d * [Bio] d i reservoir dust Occupant Exposure Mass EPM i d S EPM i d = d Occ(t)*[Bio] di (t) d(t) EPM i = Σ d S t Occ(t)*N i d ( t)*md *f i d* f i d d(t) Occ(t) = occupant present (=1) or not (= 0) during time t in space containing contaminant i M d = mass of aerosol carrier d = (π/6)ρd 3 N i d (t) = # aerosol d/air volume f i d = i mass fraction of d partilce mass f d i = fraction of d particles carryiing i Dose inhalation Epidemiology Statistics inhalation D Occ i = Σ d R R * η d- capture * η d- release EPM d i R R = Respiration rate occupant η d-capture = lung capture efficiency Slide 7

8 Bioaerosols from Surface Reservoirs : Steady State and Transient Components t out EPM i d = t in S 1*[Bio] i d (t) d(t) [Bio] i d t out S EPM i d = 1* N d i d ( t)*m d *f i d d(t) t in Occupant Activity Based Steady State Partitioning t in t out Time Occupant Present Occ = 1 Slide 8

Protein Allergen Aerosolization (Resuspension) via Carrier Particles Allergen d p 0.

9 Protein Allergen Aerosolization (Resuspension) via Carrier Particles Allergen d p µm 5-10nm Allergen Type Animal/Plant Carrier size range Der p 1 Der f 1 Time to settle in a room House Dust Mite 10-25µm 30 minutes Bla g 1 & g 2; Per a 1 Cockroaches >10µm 30 minutes Fel d 1 Cats 50% >9µm 50% <9µm 24 to 48 hours Carrier particle Particle size Surface Properties Chemical functional groups Charge distribution Morphology Environmental Conditions %RH Reservoir Perturbation Can f 1 Dogs Same as cat Same as cat Amb a I, Bet v I Pollen 15-25µm 30 minutes Slide 9

Particle Resuspension Reservoir-air aerosolization pathways Human walking = Aero-electro-mechanical perturbation of reservoir Mechanical Shoe Friction Air Currents Floor Vibration Aerodynamic

10 Particle Resuspension Reservoir-air aerosolization pathways Human walking = Aero-electro-mechanical perturbation of reservoir Mechanical Shoe Friction Air Currents Floor Vibration Aerodynamic Velocity Turbulence Electrostatic Human built up to 10,000 V Vibration + + Friction + Electrostatic Field Adhesion + Gravitational Van der Waals Relationship among Force components and Resuspension - Not Understood Slide 10

11 Estimating Field Strengths Required for Air Partitioning of Allergen Carrier Particles Free-ing Allergen Aerosols from Reservoir Surface Boundary Layer into Bulk Phase Flows of Room Air Aerosolization from Reservoir Aerodynamic, F A Reservoir Binding = 3πηV a d a boundary layer velocity profile limited in most conditions need directed jet impingement to disrupt Gravitational, F g = m a g = ρπd a3 /6 Mechanical Surface Vibration, F ν = m a Aω 2 sin(ωt) ω limited in most building surfaces (5 50 Hz) Electrostatic Field Over Reservoir, F E Electrostatic Adhesion, F adh = k H d a + K E q surface q a r 2 d a >0.1 µm = q a E above reservoir = q a [dv/dy)] where dv/dy = electrostatic voltage gradient human activity, tribology, determined, dv/dy can be large Electrostatic Fields Important Component for Allergen Aerosolization from Surfaces In Normal Activity Patterns Slide 11

Partitioning of Biocontaminant - Containing Aerosols Pseudo Steady State Description { [Bio] d i indoo r air = K i d * [Bio] i reservoir dust K i d (m-1 ) = [Bio] d iindoor air [Bio] i reservoir dust

12 Partitioning of Biocontaminant - Containing Aerosols Pseudo Steady State Description { [Bio] d i indoo r air = K i d * [Bio] i reservoir dust K i d (m-1 ) = [Bio] d iindoor air [Bio] i reservoir dust Standard Vapor-Solid Partitioning Gas i Contaminant Containing Aerosol Partitioning N Ai (d) K i (T) Thermal Equilibrium Gas-Solid System = [A i ] vapor / [A i ] Adsorbed Aerosol Reservoir System Aero-Electromechanical Equilibrium ( ) Floor/Duct Vibration Walking Impact Electrostatics Air Turbulence K i = Σ d K i d = Σ d ([Bio ] i d / [Bio] i R ) N RSi (d) Reservoir: Surface adsorbed Gas i Contaminant (allergen, virus, spore) i Reservoir of Carrier Particles Slide 12

13 Framework for Understanding Secondary Aersolization Aerosol Pathways of Inhalation Exposure Σ d [Bio] i aerosol K units RR, k A k D mass/l 3 1/time l/time l -1 Reservoir Perturbation ( Floor/Duct ) Walking Impact K i Vibration = Σ d K i d = Σ d [Bio] i d aerosol Electrostatics Air Turbulence [Bio] d i reservoir = k A k D Biocontaminant containing dust K i d is analogous to gas-solid chemical partitioning constants, i.e. is an equilibrium characterization whose value: - is a function of energy distribution in vapor and solid phases in system - varies with the interaction strength between the aerosol carrier particles and the reservoir surface Slide 13

14 Re-suspension Literature Summary Sehmel, G.A. Particle Re-suspension: A Review, Environment Int. 4, (1980a) Nicholoson, K.W. A Review of Particle Re-suspension, Atmospheric Environment, 22, No. 12, (1988) Aero-Electro-Mechanical Drive Re-suspension Aerodynamic Driven Re-suspension Resuspension Factor, Constant, (m -1 ) Slide 14

15 Resuspension due to human activity Nuclear Facilities (1960 s) Freshly deposited contamination: m -1 Clean or aged contamination: m -1 Residential buildings Resuspension Factors (m -1 ) 4.E-03 3.E-03 Particle size: 3-6µm 2.E-03 1.E-03 0.E+00 Blowing - 1 person Mopping - 1 person Walking - 4 person Hambraeus et al Slide 15

16 Resuspension due to human activity Residential buildings Ratio [occupant activity/inactivity] airborne concentration Cleaning: vigorous vacuuming and housecleaning Walking: done by 4 people Cleaning Walking 5 min Walking 30 min Particle Diameter (µm) Thatcher et al Slide 16

17 Resuspension due to human activity Residential buildings Resuspension Rate (min -1 ) 1.E E-06 1.E E E E-07 1.E-07 1.E E E-09 1.E >25 Particle size (µm) Thatcher et al Slide 17

18 Resuspension of an Indoor Aerosol Grass Pollen Particles Karlsson, E., Fangmark, I., Berglund, T., Resuspension of an indoor aerosol, J. Aerosol Science, Vol. 27, Suppl. 1, S441-S442, N 6.2 µm = 1.0 x10 4 /m 3 = 1.4 x 10-6 g/m 3 = 1.4 µg/m 3 N 6.2 µm = 1.0 x10 5 /m 3 = 1.4 x 10-5 g/m 3 = 14µg/m 3 1 person working at a table 4hrs 4 persons walking around 4hrs K 6.2 µm (m -1 )=4.0 x10-4 K 6.2 µm (m -1 )= 3.95 x10-3 Reservoir Containing 6x4 µm Ellipsoidal Pollen Particles N 6.2 µm = 2.6 x10 7 /m 2 M 6.2µm = 3.4 x 10-3 g/m 2 Slide 18

19 Resuspension due to human activity Residential buildings Concentration (#/m 3 ) 8.E+04 6.E+04 4.E+04 2.E+04 0.E+00 RR=2.45E-5 min -1 RR=1.8E-5 min person 4 persons Time (minutes) Karlsson et al Slide 19

20 Resuspension due to human activity Residential buildings 1.E+05 1.E+04 Spores: 1-8>-3.5 mm cfu/m 3 1.E+03 1.E+02 1.E+01 1E6 cfu/m2 1E7 cfu/m2 Vinyl Commer. Carpet Residt carpet Buttner et al Slide 20

21 Indoor Resuspension Aerosol- Penicillium Chrysogenum Spores Buttner, M.P., Cruz-Perez, P., Stetzenback., L.D., Garrett, P.J., Luedtke, A.E., Measurement of airborne fungal spore dispersal from three types of flooring materials, Aerobiologia, 18:1-11, K(m -1 ) 10 6 CFU/m 2 Reservoir Vinyl Ccarpet Rcarpet Air Sampler Anderson Buckcard K(m -1 ) 10 7 CFU/m 2 Reservoir One person walking 1 minute Vinyl Ccarpet Rcarpet Air Sampler Anderson Buckcard Floor substrates investigated Vinyl tile Commercial carpet (cut pile) Residential carpet (loop pile) K µm 1 x 10-5 < K Anderson < 9 x 10-3 Reservoir (tile/carpet) Containing 1.8 x 3.5 µm P. chrysogenum spores N 1.8x3.5 µm = >10 7 CFU/m 2 M 1.8 x 3.5 µm = 4.5 x 10-5 g/m 2 -> 4.5x10-4 g/m 2 Slide 21

22 Quiescent, Steady State Partitioning of Indoor Allergens Allergen i Aero. Conc. [ng/m 3 air] Can f 1 10 Fel d 1 10 Der p 1 < Rat n 1 * 1 20 Mus m 1* Mus m 1 NR Guinea Pig 3 20 Bla g 1 NR Note: Allergen investigations do not typically give reservoir surface coverage (gms/m 2, Particles/m 2 ) data for allergen containing dusts Quiescent Conditions Perturbation strength = 0 Primary sources present K d Allergen i * = Animal Laboratory facilities NR = not reported Allergen i Reservoir Conc. [µ gm/gm dust] Can f Fel d Der p Rat n 1 * Mus m 1* NR Mus m Guinea Pig NR Bla g Units ( ND 400 µg/gm dust) Slide 22

23 Reservoir Perturbation Induced Partitioning of Allergens Allergen i Aero. Conc. [ng/m 3 air] Can f 1 NR Can f 1** 300** Fel d ** Der p Rat n 1 * 10 80* Mus m 1* NR* Mus m 1 NR Guinea Pig Bla g 1 NR Reservoir Perturbation K d Allergen i ** I Cat or Dog Housing Facility * = Animal Laboratory facilities NR = not reported Allergen i Reservoir Conc. [µ gm/gm dust] Can f Fel d Der p Rat n 1 * Mus m 1* NR Mus m Guinea Pig NR Bla g Units ( ND 400 µg/gm dust) Slide 23

24 Re-suspension Literature Summary Aero-Electro-Mechanical Re-suspension Thatcher, et. al. (1995) 1-25 µm Nuclear storage studies (1960 s) Karlsson, et.al.(1996) 6.0 x 4.0 µm spores Hambraeus, et. al. (1978) Residential Buttner, et. al (2002) 1.8 x 3.5 µm fungal spores Aerodynamic Driven Re-suspension Resuspension Factor, Constant, (m -1 ) Slide 24

25 Resuspension due to human activity Literature review findings: Different types of activities => Different Resuspension Factors Higher intensity perturbation=> Higher Resuspension Rates, Factors Reservoir Loading => Resuspension rates proportional Resuspension rates higher for super-micron particles Different allergens => Different particle size distributions Lower the Relative Humidity => Higher the Resuspension rates?? Slide 25

26 Implications Literature Review Summary Limitations of previous studies: Experiments run under wide range of conditions and particle types Wide variation in re-suspension rates & constants appears due to wide variation in, but often uncharacterized, reservoir characteristics, reservoir perturbations, environmental conditions Particle size relationships among airborne and reservoir sources frequently not given Allergen carrier particle resuspension data normalized differently than nuclear, agricultural data Consequences Not possible to use literature data to make inhalation dose-risk analysis in buildling simulations and achieve acceptable certainty in trends Need controlled condition investigations with well characterized perturbations, reservoirs, and time-resolved airborne measurements Slide 26

27 Research Research Process Experimental Chamber Sampling Controlled Temperature & Relative Humidity Particle Free Air Perturbance: Vibration Air Puffs Transient Electrostatic Fields Particle Counters Cascade Impactor ELISA Analysis Physical and aerodynamic analysis of: Known Particle Size Known Particle Contaminant (allergen) Content Known Surface Properties Allergen Content Slide 27

Controlled Re-suspension Experimental Chamber Overall dimensions: 400x200x200 mm Test plate dimension: 100x100 mm Controlled Ambient Conditions Controlled particulate

28 Controlled Re-suspension Experimental Chamber Overall dimensions: 400x200x200 mm Test plate dimension: 100x100 mm Controlled Ambient Conditions Controlled particulate matter Inlet & outlet flow: 32.4 lpm (laminar) uniformily distributed Incorporates mechanical and aerodynamic perturbances Applied pressurization and no infiltration Slide 28

29 Controlled Particle Size and Compositional Properties Calibrated dust Quartz, aluminum oxide, polymer, silica, etc Allergen dust Roach body parts Cat hair Dog hair Dust mite Known properties Density Particle size distribution Contaminant (allergen) concentration Slide 29

impactor stages Cascade Impactor Aerodynamic Cut-offs: 0.4-0.7 µm 0.

30 Preparing Allergen Containing Reservoir Dusts Steps Initial grinding Sieving 38<d p <355 µm Secondary grinding Separation in cascade impactor stages Cascade Impactor Aerodynamic Cut-offs: µm µm µm µm µm µm µm +9.0 µm Slide 30

31 Known Allergen Concentration In Dusts: ELISA technique Standard curve Standard curve Measured O.D Concentrations (U/ml) Allergen curve Allergen curve Measured O.D Concentrations (mg/ml) Slide 31

Establishing Uniform Reservoir Dust Samples

conditions Uniform dust distribution ( 10%)

32 Establishing Uniform Reservoir Dust Samples Distribution of dust on floor samples Overall dimensions: 760x760x420 mm 25 floor samples (90x90 mm each) Dust dispersed in mixing conditions Uniform dust distribution ( 10%) Floor sample covered by protection lids before removal Slide 32

Floor vibration due to human walking Measured and digitally recorded in

33 Use Field Recorded Waveforms for Vibration Energy Input Floor vibration Simple functions: Sinusoidal, square, triangular, etc. Floor vibration due to human walking Measured and digitally recorded in the field Amplitude Vibration Signal Time (sec) Slide 33

34 Air-puff Use Smoke Test Visualization for Near Floor Air Current Distubance Velocity Approximation Air motion due to human walking Published information inexistent Performance of walking experiment Visible horizontal air velocity m/s 1.5 m/s m/s m/s Slide 34

3 2+µm, 8 bins Determination of resuspended particle size distribution Particle size

35 Optical and Impactor Train Sampling of Re-suspended Particles Sampling Equipment Optical Particle Counter µm, 8 bins Determination of resuspended particle size distribution Particle size resolved allergen concentration Condenser Particle Counter µm Cascade Impactor µm, 8 stages Particle shape Allergen concentration Slide 35

Re-suspension Experimental Results Carpet Linoleum 1.E+00 1.E+00 1.E-01 1.E-01 Quartz 1.E-02 1.E-03 1.E-02 1.E-03 1.E-04 1.E+00 1.E-01 Vibr Air Vibr+Air 1.E-04 1.E+00 1.E-01 Vibr Air Vibr+Air Maximum: RR=2.

36 Re-suspension Experimental Results Carpet Linoleum 1.E+00 1.E+00 1.E-01 1.E-01 Quartz 1.E-02 1.E-03 1.E-02 1.E-03 1.E-04 1.E+00 1.E-01 Vibr Air Vibr+Air 1.E-04 1.E+00 1.E-01 Vibr Air Vibr+Air Maximum: RR=2.73E-4 min -1 RF=6.81E-5 m -1 No E(t) field Roach dust 1.E-02 1.E-03 1.E-04 Vibr Air Vibr+Air 1.E-02 1.E-03 1.E-04 Vibr Air Vibr+Air Literature: RR=1E-8 ->7.8E-2 min -1 RF=1E-7 -> 8E-2 m -1 Experimental observations: Resuspension greatest in first two minutes perturbation Air had greater impact than vibration; but vibration important contributing component Higher resuspension rates on linoleum than carpet 0 15 µm roach allergen particles easier to resuspend than quartz Current resuspension factors and rates indicte E field likely significant contributing component Slide 36

37 Conclusions and Recommendations Conclusions: Methodology is able to determine particle resuspension for different types of dust, flooring, ambient conditions and floor disturbance type and intensity. Methodology is able to use reference allergen dusts, spores in well defined perturbation conditions.. Valuable tool to create a database of RF for particle resuspension, e.g. allergens, responsible for risk of disease development Contribute to development of activitybased human exposure risk models imbedded in building air flow simulations Recommendations: Improve floor disturbance characterization methodology Expand floor disturbance to include an electrostatic field Large chamber and field studies to validate the surface disturbance resuspension data, models Development of broader range of dust preparation protocols In Process: Implementation of results in building air flow simulation models and human respiratory models (e.g. CONTAMW) Slide 37

38 Re-suspension Literature Summary Sehmel, G.A. Particle Re-suspension: A Review, Environment Int. 4, (1980a) Nicholoson, K.W. A Review of Particle Re-suspension, Atmospheric Environment, 22, No. 12, (1988) Aero-Electro-Mechanical Re-suspension Karlsson, et.al.(1996) 6.0 x 4.0 µm spores Hambraeus, et. al. (1978) Residential Buttner, et. al (2002) 1.8 x 3.5 µm fungal spores Thatcher, et. al. (1995) 1-25 µm Aerodynamic Driven Re-suspension Nuclear storage facility studies (1960 s) Gomes, Freihaut, et. al. (2004) µm quartz calibration particles µm+ roach allergen carrier particles Controlled: Particle size Reservoir surface material %RH environment Reservoir ω and g-vibration Aero-dynamic swirl NO ELECTROSTATIC FIELD TRANSIENT Resuspension Factor, Constant, (m -1 ) Slide 38

39 Modeling Occupant Exposure Mass, EPM di (t) Occupant Interacts with Local Environments to Create Aerosol Fields Causing Exposure t out j EPM i d =Σ j S 1*[Bio] i d (t) d(t) [Bio] i d Occupant Induced Occ = 0 Occ = 1 Occ = 0 j = Reservoir t in j [Bio] i d Quiescent Background t in j =1 t out Time Time j =1 j = 2 j = 3 Time Slide 39

40 Using CONTAM to Assess Re-suspension Occupant Exposure CONTAMW Vapor Contaminant Source Term: S = G- D*C (mass/time) G i = airborne contaminant i generation rate via particle re-suspension rate D i *C i = contaminant i deposition (sink) rate on surfaces where Ci = mass fraction of vapor in air Di = k(time-1)*ρ air *V zone e.g. Fraction of reservoir particles containing i G i = R Ai (t) = A A (π/6)ρ d S [k A i(d ) * d 3 * f di (d) * f id (d) *N RS (d)] d(d) Mass fraction of i in particles containing i Particle distribution function on Reservoir surface/area Reservoir Perturbation (CONTAMW) : Linked to occupancy schedules of A A specified by mulitiplier factor K i = Σ d K i d = Σ d [Bio] i d aerosol [Bio] d i reservoir = k A k D k A, k D from Literature, Experimental, Estimated (e.g. deposition velocities) Slide 40

41 Expected Research Impact Development of Database Dust Properties Floor Properties Human Activity Ambient Conditions Resuspension Factors Allergen Concentration of Airborne Particles CFD Analysis ContamW Particle and Allergen Exposure Simulation Building Remediation Building Construction New Technology: Biocontaminant sensors Ventilation Systems Filtration Allergen Deactivation Healthier Indoor Environment Decrease of Allergen Response Syndrome including Asthma Better Quality of Life Increase of Work Productivity Slide 41

42 Acknowledgements Pennsylvania State University Institutes of the Environment U.S. Army Center for Health Promotion and Preventive Medicine Indoor Biotechnologies Corporation, Dr. Martin Chapman Slide 42

Carlos A. S. Gomes, Bin Hu, James D. Freihaut

RESUSPENSION OF ALLERGEN-CONTAINING PARTICLES UNDER MECHANICAL AND AERODYNAMIC FORCES FROM HUMAN WALKING - INTRODUCTION TO AN EXPERIMENTAL CONTROLLED METHODOLOGY Carlos A. S. Gomes, Bin Hu, James D. Freihaut