Indoor aerosol

1. Indoor aerosol Min Zhong Apr. 8th. 2010 Indoor aerosol

2. Outline The importance of study indoor aerosol Source of indoor aerosol Particle size Transport and behavior Case study 5.1 Environmental tobacco smoke 5.2 Cooking aerosol 5.3 Bioaerosol contaminants 5.4 Indoor chemistry as a particle source Indoor aerosol

3. What is indoor aerosol • An indoor aerosol usually refers to that in residences and offices as distinguished from that in industrial workplaces. • Indoor vs Outdoor • Concentration • Chemical components • Less oxidized than outdoor • Humidity Indoor aerosol

4. Why study indoor aerosol • We live indoor • The national human activity pattern survey 1996 Indoor aerosol

5. Why study indoor aerosol • Health concerns • According to the EPA -“Indoor air pollution is one the top 5 most serious environmental problems affecting the health of humans in America”   • According to the WHO- 40 percent of all buildings,pose a "serious health hazard” due to indoor air pollution.  • Sick Building Syndrome is often linked to unhealthy Indoor Air Quality.  Indoor aerosol

6. Health effect • Sick Building Syndrome (SBS) • --Acute health and comfort effects experienced • by building occupants that are apparently linked • to time spent in the building. (EPA) • --headache, fatigue, cough, sneezing…. • --No specific illness identified • --Syndrome diminish rapidly when people leave the building • Causes • -- Indoor particles, Tobacco smoke, biological contaminants, VOCs… www.home-air-purifier-expert.com/ Indoor aerosol

7. Health effect cont. • Infants and young children are the groups shown to be more susceptible to indoor pollutants. • Baby and children generally breathe more rapidly than adults, which • increases their exposure to any pollutants in the air • A baby's lungs are still developing and therefore are more sensitive • than an adult's. www.home-air-purifier-expert.com/ Indoor aerosol

8. Source of indoor aerosol • Outdoor source • Suspended particles: soil, sea salt, road dust, SOA, biological aerosols • Indoor source Can you give some examples? Indoor aerosol Source: U.S. Environmental Protection Agency

9. Source of indoor aerosol • Indoor source • Tobacco combustion • Cooking • Biological contaminants: mold, dust mite • Plants, pets: pollen, spores, bacteria • Building material, especially mineral fibers, asbestos • Combustion appliances: wood stoves, fireplaces • Residues from personal care and household cleaning • Pesticides • Radon decay products • Activities • Indoor chemistry Indoor aerosol

10. Particle size of indoor aerosol • Submicrometer particles: small than 1 um generated mainly from combustion, gas to particle conversion, nucleation process • Supermicrometer particles: larger than 1 um mainly from mechanical process The most frequent sizein number conc. Wallace, 2000 Abt et. Al 2000 Indoor aerosol

11. Transport and Behavior • The highest significance processes in affecting indoor particle include: • Penetration of outdoor particles through open doors, windows as well as through the building envelope • Deposition of particles on indoor surfaces. • Resuspension of particles deposited on surfaces. • Removal of particles from an indoor environment by ventilation and filtration • Chemical reactions involving vapors and gases leading to particle generation. • Coagulation Indoor aerosol

12. Transport and Behavior cont. • Penetration of outdoor particles indoors Particle penetration through narrow horizontal slits (0.58×102×433mm) Mosley et al. 2001 Indoor aerosol

13. Transport and Behavior cont. • Deposition • Particle deposition on indoor surface strongly depends on particle size. Small: diffusion, large: gravitational sedimentation • Also depend on the surface area and surface characteristics. Furnished room will have higher deposition rate than bare rooms. • Depend on the presence and speeds of any air flows in indoor environment. For example, increase the mean air speed from 5 to 19 cm/s, by increasing fan speed, the deposition rate increases by factor of 1.3 to 2.4 Thatcher et,al. 2002 Indoor aerosol

14. Transport and Behavior cont. • Resuspensionof particle • To resuspend the particles, a certain force must be applied to detach the particles from the surface. • Adhere force ∝ d, • Detached force ∝ dn n=2 for vibration, n=3 for air currents • Large particles are being more readily detached than small ones • All the normal activities of the occupants, such as walking, moving around, children playing, result in an increase in the indoor super micrometer particles. Baron and Willeke, 2001 Indoor aerosol

15. Case study Environmental tobacco smoke Cooking aerosol Bioaerosolcontaminants Indoor chemistry as a particle source Indoor aerosol

16. Environmental tobacco smoke • know as second hand smoke • one of the most significant indoor aerosols • small liquid droplets, • Mostly in size range of 0.02 ~2 um • Comprised of low vapor pressure organic compounds ETS Indoor aerosol

17. Contribution of ETS to indoor conc. PM2.5(ug/m3) in smoking and non smoking homes • Most of the studies have indicated an increase in average fine particle levels indoors From: Harvard Six-City Study Indoor aerosol

18. ETS particle size Size distribution of ETS measured 18 and 300 min after generation Source: The Handbook of Environmental Chemistry Indoor aerosol

19. ETS chemical composition • The chemistry of a cigarette smoke is very complex, with a vast number of elements and compounds generated in particles. Reported Chemical composition of ETS particles Nicotine: make up about 8% of SS smoke particles, a chemical tracer of ETS SS smoke: side stream smoke, classified as a Class A carcinogen by the EPA Indoor aerosol Kleeman et.al(1999)

20. Case study Environmental tobacco smoke Cooking aerosol Bioaerosolcontaminants Indoor chemistry as a particle source Indoor aerosol

21. Cooking aerosol • One of the most important indoor activity generating fine particles in doors with non-smokers is cooking • Incomplete combustion of fuel, oil, and food emits various inorganic and organic compounds. Indoor aerosol

22. Cooking aerosol Typical temporal profiles of number and mass concentration S.W. Seea, R. Balasubramanian 2006 Indoor aerosol

23. Size of cooking aerosol Size distribution of number concentration during (a) cooking and (b) non-cooking hours, and mass concentration during (c) cooking and (d) non cooking hours. Sample from a Chinese restaurant within the National University of Singapore S.W. Seea, R. Balasubramanian 2006 Indoor aerosol

24. Chem.comp. of cooking aerosol • The chemistry of a cooking aerosol is very complex, with a lot of organic and inorganic compounds. Distribution of PAHs based on the number of rings in the cooking aerosol when different cooking styles applied. Yi Chen, 2007 • Cooking fume is a risk factor of the lung cancer in women non smokers Indoor aerosol

25. Case study Environmental tobacco smoke Cooking aerosol Bioaerosol contaminants Indoor chemistry as a particle source Indoor aerosol

26. Bioaerosol contaminants • ‘Bioaerosolcontaminants’ refers to a diverse variety of agents from biological sources found in indoor environments. Such as : • Viruses and molds • bacteria, including endotoxins from bacteria • (3) allergens, including house dust mite allergen and allergens from animal • (4) fungi which may contain allergens, toxins, and irritants. Mold ( http://www.mrsars.usda.gov) Indoor aerosol

27. Bioaerosol contaminants cont. • Always present in the ambient environment • Abundant in soil, rotting vegetation and potted plants • Any building where damp conditions exist will have biological contamination problems • Microbial growthtrigger illness, cause asthma / allergies Indoor aerosol

28. Bioaerosol contaminants cont. • Microbial growth in a building as a source of bioaerosol Release of fungal spores from agar and ceiling tile surfaces at air velocities of 0.3 and 29.1 m/s during 30 min experiments R.L. Gornyet al 2001 Indoor aerosol

29. Indoor chemistry as a source of particles • Ozone can oxidize terpenes, producing various chemical compounds • The low volatile compounds can homogenously nucleate or condense onto the surface of preexisting particlesto form SOA Terpene (C5H8)n α-pinene d-limonene Indoor aerosol

30. Indoor chemistry cont. • Source of O3 and terpene Indoor environment, 2003 www.inhabitots.com Indoor aerosol

31. Indoor chemistry cont. Particle concentration in the 0.1-0.2 um size range in Office A (dashed-dotted line, no limonene) and Office B (solid line, with limonene). Right y-axis: Ozone concentrations in Office A (dashed line) and Office B (dotted line) Discussion: What is the difference between office and residential indoor aerosol ? Charles J. 1999 Indoor aerosol

32. Review The importance of study indoor aerosol Source of indoor aerosol Particle size Transport and behavior Environmental tobacco smoke Cooking aerosol Bioaerosol contaminants Indoor chemistry as a particle source Indoor aerosol

33. Thank you! Indoor aerosol