The contribution of traffic to indoor concentrations of polycyclic aromatic hydrocarbons

A photoelectric aerosol sensor (PAS) was used to measure real-time indoor c oncentrations of polycyclic aromatic hydrocarbons (PAHs) at three residence s. Semi-quantitative measurements of total indoor particle-bound PAH and te mperature were collected continuously every minute for approximately 2 week s at each location. The purpose of this study was to examine the effect of traffic on indoor concentrations of PAHs. This was accomplished by collecti ng indoor measurements at an urban, semi-urban, and suburban residential lo cation with varying levels of, and proximity to, traffic. Since the homes w ere occupied, the effects of cooking, the dominant indoor source, were also examined among the three nonsmoking households. The results indicate that traffic was the main outdoor source of PAH concentrations measured indoors for all locations. In fact, a significant (p<0.001) traffic-related trend i n weekday PAH concentration was detected with a geometric mean concentratio n at the urban location (31 ng/m(3)) nearly two times that at the semi-urba n location (19 ng/m(3)) and over three times larger than the suburban locat ion (8.0 ng/m(3)), once adjusted for indoor sources. Hourly average concent ration profiles also revealed weekday rush hour peaks of PAHs at all locati ons. No pronounced peaks and significantly lower concentrations (10, 10, an d 4.9 ng/m(3)) were seen during the weekends for all locations i.e., the ur ban, semi-urban and suburban locations, respectively. Indoor sources includ ing frying/sauteing, broiling, and candle-burning were characterized by pea k concentration, duration of PAH elevation, and potential dose. This analys is suggests that cooking, and especially frying/sauteing, may be an importa nt source of indoor PAH concentrations.