Sources, concentrations, and risks of naphthalene in indoor and outdoor air


Naphthalene is a ubiquitous pollutant, and very high concentrations are sometimes encountered indoors when this chemical is used as a pest repellent or deodorant. This study describes the distribution and sources of vapor-phase naphthalene concentrations in four communities in southeast Michigan, USA. Outdoors, naphthalene was measured in the communities and at a near-road site. Indoors, naphthalene levels were characterized in 288 suburban and urban homes. The median outdoor concentration was 0.15μg/m3, and a modest contribution from rush-hour traffic was noted. The median indoor long-term concentration was 0.89μg/m3, but concentrations were extremely skewed and 14% of homes exceeded 3μg/m3, the chronic reference concentration for non-cancer effects, 8% exceeded 10μg/m3, and levels reached 200μg/m3. The typical excess individual lifetime cancer risk was about 10-4 and reached 10-2 in some homes. Important sources include naphthalene's use as a pest repellent and deodorant, migration from attached garages and, to lesser extents, cigarette smoke and vehicle emissions. Excessive use as a repellent caused the highest concentrations. Naphthalene presents high risks in a subset of homes, and policies and actions to reduce exposures, for example, sales bans or restrictions, improved labeling, and consumer education, should be considered. © 2011 John Wiley & Sons A/S.

Publication Title

Indoor Air