Ozone decay rates in residential garages

Abstract

Ozone is a pollutant with well-known health effects on humans. The primary source of ozone inside buildings is ozone in outdoor air that enters buildings by infiltration, natural ventilation, or mechanical ventilation. For infiltration, ozone is transported from outdoors to indoors through inadvertent openings in the building envelope, some of which connect occupied and unoccupied spaces of the building. For example, ozone may enter buildings through garages, attics and crawl spaces that are connected directly to the occupied space.In this study, ozone decay rates were determined for twelve residential garages with a range of sizes, level of attachment to the occupied space, and clutter. Air exchange rates for garages were measured to have a mean of 0.47 (±0.18) hr−1. The mean ozone decay rate in these garages was 2.7 (±1.1) hr−1, a value comparable to previous data for occupied space ozone decay rates. There were differences in ozone decay rates between one-car and two-car garages, which seemed to be correlated with the volume/area ratio. Using these and previously published data, it was concluded that, under normal conditions, ozone penetration through garages to the occupied space is not a significant pathway. However, there are some conditions for which garages may be a major pathway for ozone entry into homes. One example of this is when both the garage door and the door connecting the garage to the occupied space is opened for a long period of time.