Incense Smoke: Characterization and Dynamics in Indoor Environments

Abstract

Burning incense in houses and temples for religious functions is especially common in Asia. Smoke from burning incense is a source of indoor aerosols, and extracts from this smoke are mutagenic in the Ames Salmonella test. This paper describes characterization of the smoke in terms of particle size, shape, concentration, density, and chemical composition. Our data showed that aerosols from incense smoke were spherical droplets with a count median diameter of about 0.13 μm and mass median aerodynamic diameter of 0.28 μm. The particle density was 1.06 ± 0.08 g cm⁻³. Aerosols produced from incense are therefore similar to other aerosols formed by condensation, such as environmental tobacco smoke found indoors. The aerosol concentration profiles and size distributions within a room during typical burning cycles were monitored. The air ventilation rate in the room was also measured by the SF₆ tracer gas method. Respirable aerosol concentrations up to several hundred μg m⁻³ were produced by burning one to three joss sticks. By modeling the concentration change in the room with time using mathematical equations, we estimated the incense aerosol generation rate as a function of time and the aerosol removal rate constant. This source term information can be used to estimate incense smoke concentration in indoor environments.