Characteristics and Carcinogenic Risk of PM2.5-Bound Polycyclic Aromatic Hydrocarbons from Charcoal Barbecue (Moo Kratha) Restaurants in Chiang Mai, Thailand

Abstract

Barbecue (Moo Kratha) restaurants are prevalent in Chiang Mai City, Thailand. However, their PM2.5-bound polycyclic aromatic hydrocarbon (PAH) emissions, compounded by the region’s severe seasonal smoke haze, remain poorly characterized. This study investigated the chemical composition and carcinogenic risk of PM2.5-bound PAHs in this present environment. Ten PM2.5 samples were collected from ten charcoal Moo Kratha restaurants during peak evening hours in February 2026 (early dry season) using a portable air sampler operated as a fixed-location (area) sampler positioned at the customer dining table (2 L min−1, 180 min) on quartz fiber filters, and the 16 US EPA priority PAHs were analyzed by GC-MS. Carcinogenic risk was assessed using benzo[a]pyrene toxicity equivalent (TEQBaP) concentrations and incremental lifetime cancer risk (ILCR) for adult and child customers (diners) via the inhalation pathway. The mean concentrations of PM2.5 and total PAHs were 87.64 µg m−3 and 132.74 ng m−3, respectively, with carcinogenic PAHs contributing 52.3%; the mean TEQBaP of 15.34 ng m−3 provides an internal index of the carcinogenic potency of the PAH mixture. The mean inhalation ILCR for a frequent diner was 2.82 × 10−5 for adults and 2.12 × 10−5 for children, rising to 6.16 × 10−5 and 4.62 × 10−5, respectively, at the most contaminated site; even an occasional (monthly) diner exceeded the 10−6 negligible threshold. These findings indicate that charcoal Moo Kratha restaurants are distinct, persistent sources of carcinogenic PAHs that place diners within the upper part of the tolerable cancer-risk range; worker exposure is expected to be higher but was not quantified here, underlining the need for ventilation and occupational-health strategies.