Indoor Airborne Benzo[a]pyrene (BaP) in Different Countries and Its Influencing Factors

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants in indoor environments. Among them, benzo[a]pyrene (BaP) has the strongest toxicogenic effect. Thus, it is generally set as the representative of PAHs in air quality standards. In this study, we reviewed indoor airborne concentrations (gas-phase and particle-phase) of BaP measured in residential air. Data were collected from 13 experimental studies conducted in residences of 8 different countries. Through the comparative analysis, the differences of indoor airborne BaP concentrations and the influencing factors were summarized, including source effect and seasonal changes. The overall results demonstrated that compared to Europe and the United States, indoor airborne BaP concentration in Asian countries were much higher, the majority of which exceed the corresponding national standard. According to the influential factors, various emission sources of BaP in indoor and outdoor environments would affect indoor airborne concentrations substantially. Additionally, seasonal atmospheric conditions and people’s reaction leads to the seasonality of indoor airborne BaP concentrations.