Hazard assessment of United Arab Emirates (UAE) incense smoke

• We performed a hazard assessment of Arabian incense smoke burned indoors.
• We characterized generated pollutants over time, and cell inflammatory response.
• Emitted smoke contained prolific particles and government regulated air pollutants.
• Evidence of incense smoke-related cell inflammatory response was observed.
• These results suggest a potential health risk from burning Arabian incense indoors.

Incense burning inside the home, a common practice in Arabian Gulf countries, has been recognized as a potentially modifiable source of indoor air pollution. To better understand potential adverse effects of incense burning in exposed individuals, we conducted a hazard assessment of incense smoke exposure. The goals of this study were first to characterize the particles and gases emitted from Arabian incense over time when burned, and secondly to examine in vitro human lung cells responses to incense smoke. Two types of incense (from the United Arab Emirates) were burned in a specially designed indoor environmental chamber (22 m3) to simulate the smoke concentration in a typical living room and the chamber air was analyzed. Both particulate (PM) concentrations and sizes were measured, as were gases carbon monoxide (CO), sulfur dioxide (SO2), oxides of nitrogen (NOx), formaldehyde (HCHO), and carbonyls. During the burn, peak concentrations were recorded for PM (1.42 mg/m3), CO (122 pm), NOx (0.3 ppm), and HCHO (85 ppb) along with pentanal (71.9 μg/m3), glyoxal (84.8 μg/m3), and several other carbonyls. Particle sizes ranged from 20 to 300 nm with count median diameters ranging from 65 to 92 nm depending on time post burn-out. PM, CO, and NOx time-weighted averages exceeded current government regulation values and emissions seen previously from environmental tobacco smoke. Charcoal emissions were the main contributor to both the high CO and NOx concentrations. A significant cell inflammatory response was observed in response to smoke components formed from incense burning. Our hazard evaluation suggests that incense burning contributes to indoor air pollution and could be harmful to human health.