Ozone Initiated Chemistry in Enclosed Environment

1. Ozone Initiated Chemistry in Enclosed Environment presented by AakashChandRai Adviser: Dr. Qingyan (Yan) Chen

2. Outline • Introduction • Research tasks: • Measurements of ozone removal and its initiated VOCs • Measurements of ozone initiated particles • CFD modeling of ozone removal in an aircraft cabin mockup • Conclusions

3. Introduction • Good ozone vs. bad ozone • Ground-level ozone (bad) is a health hazard for humans (www.epa.gov/apti/ozonehealth/population.html)

4. Background and significance • Ozone ground-level limit = 80 ppb (EPA 1997) • During 2000-2002: 36-56% of ozone monitors failed to meet the standard (Hubbell et al., 2005) • 800 premature deaths • 4,500 hospital admissions • 900,000 school absences • New ozone ground-level limit = 75 ppb (EPA 2008) • between $2 billion and $17 billion health related benefits annually (EPA, 2008)

5. Background and significance • Ozone exposure in buildings • Ozone concentration ~10 ppb in buildings • People spend 90% time indoors • Indoor inhalation is about 25-60% (Weschler, 2006) • Ozone exposure in airliners • Ozone concentration ~50 ppb in airliner cabins • Cabin crew especially vulnerable • High risk environment

6. Important to study the exposure of humans to ozone and its initiated byproducts in the indoor air Background and significance • Ozone reaction byproducts • Volatile Organic Compounds (VOCs) • Formaldehyde (carcinogen) • 4-OPA (irritant) • Many others… • Particles (or aerosols) • Potentially harmful • Humans are important sites for ozone reactions!

7. Research objective and methods • Objective • To develop a modeling tool for assessing the exposure of occupants to ozone and its reaction byproducts • Research methods • Experimental measurements • Computer simulations

8. Outline • Introduction • Research tasks: • Measurements of ozone removal and its initiated VOCs • Measurements of ozone initiated particles • CFD modeling of ozone removal in an aircraft cabin mockup • Conclusions

9. Section objectives • To study the ozone initiated volatile organic compounds (VOCs) emissions from its reactions with human clothing • Quantifying the ozone removal and formation of VOCs under typical indoor conditions • Study the influence of various factors on those reactions

10. Experimental setup Exhaust Inlet • Mid-scale chamber (5.1 m3) • Ozone reactions with the T-shirt produced VOCs • Ozone was measured at inlet and exhaust • VOCs were measured before and after ozone injection T-shirt on human simulator Experimental setup

11. Ozone and VOC measurement equipments High Performance Liquid Chromatography (HPLC) Ozone monitor Gas Chromatography – Mass Spectrometry (GC-MS)

12. Effect of different surfaces • The ozone removal and its initiated VOC emissions were highest with the soiled T-shirt

13. Typical building conditions • The ozone initiated VOC emissions were high under typical building conditions

14. Section summary The ozone reactions with human clothing (cotton T-shirt) consumed ozone and produced VOCs Those reaction were enhanced by the soiling of T-shirt with human skin oils Significant ozone initiated VOCs were produced under typical building conditions

15. Outline • Introduction • Research tasks: • Measurements of ozone removal and its initiated VOCs • Measurements of ozone initiated particles • CFD modeling of ozone removal in an aircraft cabin mockup • Conclusions

16. Section objectives • To study the ozone initiated particle generation from its reactions with human clothing • Examine the possibility of particle formation from the ozone reactions with human clothing under typical indoor conditions • Study the influence of various factors on those reactions

17. Experimental setup Exhaust Inlet T-shirt on human simulator Scanning mobility particle sizer (SMPS) Experimental setup

18. Effect of different surfaces Effect of the chamber, laundered T-shirt, and soiled T-shirt surfaces on the ozone initiated particle generation • The particle generation was highest with the soiled T-shirt, and almost negligible without the T-shirt

19. Ozone-initiated particle generation

20. Typical indoor conditions Ozone injection at t = 2.5 h • The particle generation was observed for typical building conditions (ozone ~ 22ppb at 0.5 ACH)

21. Section summary The ozone reactions with human clothing (cotton T-shirt) generated particles, which were enhanced by the soiling of T-shirt with human skin oils Those particles were initially generated in the ultrafine region and then grew to larger sizes The particle generation was observed at typical building conditions

22. Outline • Introduction • Research tasks: • Measurements of ozone removal and its initiated VOCs • Measurements of ozone initiated particles • CFD modeling of ozone removal in an aircraft cabin mockup • Conclusions

23. Section objectives • To develop a reliable modeling tool for simulating the ozone distributions in indoor air • Model development • Validation against experimental data • Simulating the ozone distribution for complicated indoor settings

24. CFD is an attractive design and analysis tool What can CFD do? • Computational Fluid Dynamics (CFD) for indoor environment can provide detailed information of: • Air velocity, temperature, and turbulence parameters • Contaminant concentrations of gases and particles • Requires validation from experimental data

25. CFD modeling of ozone removal in cabin environment Simulated aircraft cabin (Technical University Denmark)

26. Cases considered • Empty cabin with carpet only • Cabin with carpet and seats • Cabin with carpet and seats covered with T-shirts • Occupied cabin with simple human geometry • Occupied cabin with detailed human geometry

27. CFD model Case 5: Occupied cabin with detailed human geometry

28. CFD validation

29. Ozone distribution

30. Section summary • Established CFD method for simulating ozone distributions in an aircraft cabin • Reasonable agreement with experimental data in all the cases analyzed • Ozone depleted in the breathing zone of passengers by ~10% as compared to average cabin concentration

31. Outline • Introduction • Research tasks: • Measurements of ozone removal and its initiated VOCs • Measurements of ozone initiated particles • CFD modeling of ozone removal in an aircraft cabin mockup • Conclusions

32. Conclusions • Characterized the ozone-initiated VOCs emissions from its reactions with human clothing • Identified that the ozone reactions with clothing can be an important source of particles in the indoor air

33. Conclusions • Developed a CFD modeling framework to simulate the ozone distributions in complicated indoor settings