Ozone has the potential to cause many health problems. Most of the human population exposure to ozone occurs indoors. It has been previously reported that the average ozone penetration factor into the occupied space is 0.79. However, this value does not account for the pathway by which ozone enters the occupied space. A model to determine the amount that unoccupied spaces contribute to the ozone concentration in the occupied space is presented in this thesis. A literature review was then performed to identify parameters for the model as well as gaps that exist in the literature pertaining to the model developed. One of the biggest gaps was the lack of ozone decay rates in unoccupied spaces, such as garages, attics and crawl spaces. Because of this, a field study was designed and completed to determine the ozone decay rate in garages. It was determined that the average ozone decay rate in garages is 2.7 (Β± 1.1) hr-1. This value is comparable to previous data for occupied space ozone decay rates. Using these data as well as other published data, it was determined that, under normal conditions, ozone penetration through unoccupied spaces to the occupied space is not a significant pathway. However, there are some conditions for which unoccupied spaces may be a major pathway for ozone entry into homes. One example of this is when both the garage door and the door connecting to garage to the occupied space is opened for a long time. Under these conditions, the occupied space can reach an indoor/outdoor (IO) concentration of 0.46. As can be seen, under this condition, unoccupied spaces do provide substantial contribution of ozone to the occupied spaceCivil, Architectural, and Environmental Engineerin
