Characteristics and health risk assessment of polycyclic aromatic hydrocarbons associated with dust in household evaporative coolers.

This study reports a characterization of indoor polycyclic aromatic hydrocarbons (PAHs) associated with dust (dust-PAHs) in household evaporative coolers and their associated health effects. Extensive analysis showed that the indoor dust-PAHs stemmed mostly from pyrogenic sources (vehicular emissions) with mean total concentrations limited between 131 and 429 ng g-1. The distribution pattern of PAHs based on number of rings exhibited the following order of decreasing relative abundance: 4 > 3 > 5 > 6 > 2 rings. Results indicate that the mutagenicity of dust-PAHs exceeded their carcinogenicity, but that the potential carcinogenic effects are still significant. The mean lifetime cancer risk for different age groups for three pathways based on Model 2 (dermal (1.39 × 10-1 to 1.91 × 10-2), ingestion (2.13 × 10-3 to 8.08 × 10-3) and inhalation (1.62 × 10-7 to 4.06 × 10-7)) was 7.4-146 times higher than values predicted by Model 1 (dermal (5.13 × 10-5 to 3.03 × 10-3), ingestion (9.34 × 10-5 to 1.31 × 10-3) and inhalation (7.13 × 10-20 to 1.68 × 10-20)). Hence, exposure to dust-PAHs in household evaporative coolers lead to high risk, especially for children (less than 11 years) (HQ = 2.71 × 10-20 to 54.8 and LTCRs = 7.13 × 10-20 to 1.39 × 10-1). Strategies should be considered to eliminate such pollutants to protect people, especially children, from the non-carcinogenic and carcinogenic effects by changing household evaporative coolers with other cooling systems.