Ozone reaction with clothing and its initiated particle generation in an environmental 4 chamber 5

12 Ozone-initiated chemistry in indoor air can produce sub-micron particles, which are potentially harmful 13 for human health. Occupants in indoor spaces constitute potential sites for particle generation through 14 ozone reactions with human skin and clothing. This investigation conducted chamber experiments to 15 examine particle generation from ozone reactions with clothing (a T-shirt) under different indoor 16 conditions. We studied the effect of various factors such as ozone concentration, relative humidity, soiling 17 levels of T-shirt with human skin oils, and air change rate on particle generation. The results showed that 18 ozone reactions with the T-shirt generated sub-micron particles, which were enhanced by the soiling of 19 the T-shirt with human skin oils. In these reactions, a burst of ultrafine particles was observed about one 20 hour after ozone injection, and then the particles grew to larger sizes. The particle generation from the 21 ozone reactions with the soiled T-shirt was significantly affected by the different factors studied and these 22 reactions were identified as another potential source for indoor ultrafine particles. 23