July 25, 2013
Gillings School of Global Public Health researchers have examined incense as a source of indoor air pollution in the Arabian Gulf Peninsula and found that the common practice may cause an inflammatory response in the cells of people exposed to its smoke and gaseous combustion products.
Rebecca Cohen, master’s student in environmental sciences and engineering (ESE); her adviser, Kenneth G. Sexton, PhD, now retired ESE research assistant professor; and Karin B. Yeatts, PhD, research assistant professor of epidemiology, co-authored the study, which appears in the August 2013 issue of Science of the Total Environment.
Previous studies, some by Yeatts and other UNC colleagues, have associated incense smoke with a number of health effects, including irritation of the eyes, nose and throat, contact dermatitis, respiratory symptoms, asthma, headaches, exacerbation of cardiovascular disease and changes in lung cell structure.
In the current study, the authors characterized, over periods of three hours, the particles and gases emitted from two kinds of smoke typically used in homes in the United Arab Emirates (UAE). The testing was done in a specially designed indoor environmental chamber with a concentration of smoke that might be present in a typical UAE living room.
The researchers analyzed both particulate concentrations and levels of the gases carbon monoxide, sulfur dioxide, oxides of nitrogen, formaldehyde and other carbonyls.
Incense is burned weekly in about 94 percent of households in the UAE as a cultural practice to perfume clothing and air and to remove cooking odors. Since people there spend more than 90 percent of their time indoors, indoor air pollution has become a source of increasing concern, especially since charcoal briquettes frequently are used to ignite and burn the incense.
Two types of incense (Oudh and Bahkoor) are most often used. Both are made with agarwood, which is taken from trees that develop an aromatic smell in response to fungal infection. One of the versions (Bahkoor) has a number of additives, including sandalwood tree resin, essential oils and other substances. Researchers found that both types of incense emitted significant amounts of particles, carbon monoxide, formaldehyde, and oxides of nitrogen, resulting in an induced inflammatory response.
An aggravating factor appeared to be the charcoal, as greater amounts of charcoal caused larger and longer particle and gas emissions. The authors recommend implementation of better ventilation in UAE homes where incense is burned and suggest using alternatives to charcoal, including electric combustion devices. Future studies, they propose, should measure additional compounds caused by incense burning and offer a more in-depth analysis of inflammatory markers.

Gillings School of Global Public Health contact: David Pesci, director of communications, (919) 962-2600 or dpesci@unc.edu
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