This presentation will be available to view as a discussion poster at the 7th International Conference on the Science of Exposure Assessment - X2012. It will be presented on 03 July 2012 from 09.30 - 11.45 am followed by a chaired discussion of all posters in this session on modelling Exposure. Appointments with the authors are available to book at https://x2012discussionposters.acuityscheduling.com

1. Validation of the deterministic
indoor air model SprayExpo
Stefan Hahn*, Annette Bitsch, Katrin Schröder, Edith Berger-Preiss, Heiko Kock,
Wolfgang Behnke, Wolfgang Koch
Fraunhofer Institute for Toxicology and Experimental Medicine, Hannover, Germany
* contact: stefan.hahn@item.fraunhofer.de
Abstract
Sensitivity analysis as well as comparison of modeled values with measured values
(Antifouling treatment and stored-product protection)
Most influencing parameters: substance release rate and the droplet spectrum of
the spraying device, size of room (room spraying)
Minor impact: size of room (for surface spraying), diffusion constant and the air
exchange rate
SprayExpo sufficiently appropriate (max factor 4-5)
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2. Measurements
The exposure concentrations of the active
substances used were determined by time-resolved
and particle size-segregated personal sampling
(Respicon) and subsequent chemical analysis.
Model description (www.tsi.com)
Model features
Deterministic droplet transport model
Turbulent mixing
Gravitational settling
Droplet evaporation
Required input
Spray path
Spray technology (droplet spectrum)
Release rate and time
Substance data
Room geometry and ventilation
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3. Sensitivity analysis (exemplarily VP)
V a p o r p re s s u re [h P a ]
Vapour pressure of solvent (usually higher than
10 Pa) has only minor impact on the exposure
concentration
With decrease of mean droplet diameter the
exposure concentration will increase
D 5 0 [µ m ]
Model room
For SprayExpo deviations are found only at low
concentrations below 0.5 mg/m3
Strong impact of the “room size” when dealing
with large particles
For small particles the differences between the
two models/tools are only small
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4. © Fraunhofer ITEM

5. Conclusion
SprayExpo is sufficiently appropriate
to predict exposure values to
aerosols of non-evaporable
substances in indoor environments.
Validation of SprayExpo is of
relevance for regulatory acceptance
of this tool to assess the exposure to
hazardous substances during indoor
spray application.
Acknowledgement:
The results presented were part of a research project (F2137) on behalf of
the German Federal Institute for Occupational Safety and Health
(Bundesanstalt für Arbeitsschutz und Arbeitsmedizin).
The authors would like to thank Martin Tischer (presentation Thursday
9:30h, Session 11b) and Dagmar Holthenrich for general scientific support.
For more information on our work please visit
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www.item.fraunhofer.de