Indoor perchloroethylene accumulation from dry cleaned clothing on residential premises

Perchloroethylene in the residential environment mainly comes from dry-cleaned clothing. The study aimed at determining the respective perchloroethylene levels and their decay characteristics in three bedrooms set-ups which represented typical Hong Kong domestic premises. Selection of the bedrooms and choices of dry-cleaned clothing arrangement were based on results from a territory wide telephone survey. Two of the bedrooms had window type air-conditioning units installed, and one relied on natural ventilation for the air movement. Four identical tests were conducted at each site including change of quantity of the dry-cleaned clothing, and the option of removing or not removing the plastic bags which came from the dry cleaning shop. The clothing was located inside the wardrobe and charcoal tubes were connected to a mini-vol pump in order to collect 24-h samples in the bedrooms for further GCMS analysis. Each test lasted for seven days and characteristics of the window and door opening habits were recorded. Perchloroethylene level as high as 494 μg m-3was found in the site where the occupants seldom opened the windows. In other sites where more frequent window opening were conducted, the indoor perchloroethylene levels varied from 0.93-29 μg m-3depending on the quantity of the dry-cleaned clothing being used. A clear decay curve was observed in cases where the plastic bags were removed before the clothing were put into the wardrobes. For cases where the plastic bags were not removed, the perchloroethylene level went up first in the first few days and then decayed in the subsequent days. The findings provided preliminary information of the health risk that the population may be exposed to due to their different practices of dry cleaning activities. The study was different from traditional chamber tests which might aim at identifying perchloroethylene emission from dry-cleaned clothing, nor was this study the same as other field measurements which reveal information of perchloroethylene levels in uncontrolled conditions. The study combined features of both field measurements on real domestic premises and controlled experiments based on results from telephone survey analysis.