Field study of visitors' behavior in incense burning and its induced air pollution assessment and treatment.

This study conducted a field investigation in the behavior of visitors in the pagoda and burning incense as well as its air pollution situation in Vietnam, and revealed that 92% of people used stick form for offering incense and mainly burning either 1 or 3 sticks/time. Incense smoke exposure caused aroma, comfortable, eye irritation, or hard to breathe. There were 70% of people being aware of the hazard of incense smoke. VOCs, PM2.5, PM10, and CO2 concentrations from burning incense in the Great hall were 1.6-2.5 times higher than those in outside areas. Pollutants' concentrations on the first of the month, full moon day, and Lunar New Year were from 1.5 to 2.0 times higher than those of normal days. A model was designed to collect incense smoke emitted by burning 1 and 3 sticks of seven types of incense on an open area. Except for CO found at low concentrations, VOCs, HCHO, PM2.5, PM10, and CO2 appeared in the smoke with the maximum concentrations higher 2.5-13.5 times than their allowable values. A photocatalytic device using titania nanotubes (TNTs) impregnated with various metals (Cd, Zn, Al, Cu, and Fe) was installed for incense smoke treatment. Effect of type and amount of photocatalyst, as well as initial VOC concentration, were tested. The results show that using 2.0 g of Zn/TNT photocatalysts under UV irradiation provided the highest VOC removal efficiency of 73%, suggesting the potential of application for burning incense in open areas.