Volatilization of chemicals from drinking water to indoor air: The role of residential washing machines

Previous research has indicated that residential washing machines are potential sources of pollution due to the associated use of chemicals found in consumer products, for example, ethanol in laundry detergent and chlorine in bleach.(1,2) Washing machines may also emit hazardous air pollutants found in contaminated drinking water. To better understand the extent and impact of chemical emissions from tap water 26 experiments were completed using a residential washing machine and a cocktail of chemical tracers representing a wide range of physicochemical properties. Variable operating conditions for these experiments included water temperature, amount of clothes present in the machine, water volume, and level of washwater agitation. Chemical stripping efficiencies and mass transfer coefficients were determined during each cycle (fill, wash, and rinse) of a normal washing machine event. Headspace ventilation rates were determined using an isobutylene tracer gas. Mass transfer rates were significantly influenced by operating parameters as exhibited by a wide range of chemical stripping efficiencies. Stripping efficiencies ranged from 0.74 to 36% for acetone, 8.2 to 99% for toluene, 10 to 99% for ethylbenzene, and 6.9 to 100% for cyclohexane.