Burning incense, a popular cultural practice in Arabian Gulf
countries and elsewhere, generates indoor air pollutants that may cause
inflammation in human lung cells, say researchers in the Gillings School of
Global Public Health at the University of North Carolina at Chapel Hill.
“Hazard assessment of United Arab Emirates (UAE) incense
smoke” appears in the August 2013 issue of Science of the Total Environment.
Rebecca Cohen, master’s student in environmental sciences and engineering
(ESE); her adviser, Kenneth G. Sexton, now retired ESE research assistant
professor; and Karin B. Yeatts, research assistant professor of epidemiology,
co-authored the study.
Previous studies, some by Yeatts and other UNC colleagues,
have associated incense smoke with a number of health problems, including eye,
nose, throat and skin irritation; respiratory symptoms, including asthma;
headaches; exacerbation of cardiovascular disease; and changes in lung-cell
Indoor air pollution is an international health concern. The
World Health Organization estimates that more than 1 million people a year die
from chronic obstructive respiratory disease (COPD), primarily a result of
exposure to pollutants from cook stoves and open hearths. Burning incense
releases similar pollutants, including carbon monoxide.
Particles and gases
In the current study, the authors identified and measured
the particles and gases emitted from two kinds of incense typically used in UAE
homes. The testing was done over three hours, the typical timeframe during
which incense is burned, in a specially designed indoor environmental chamber
with a concentration of smoke that might be present in a typical UAE living
The researchers analysed both particulate concentrations and
levels of gases such as carbon monoxide, sulphur dioxide, oxides of nitrogen and
Human lung cells were placed in the chamber to expose them
to the smoke, then incubated for 24 hours to allow particulates to settle and
the cells to respond. The resulting inflammatory response, a hallmark of asthma
and other respiratory problems, was similar to that of lung cells exposed to
Incense is burned weekly in about 94% of households in the
UAE as a cultural practice to perfume clothing and air and to remove cooking
odours. Since people there spend more than 90% of their time indoors,
researchers said, indoor air pollution has become a source of increasing
Adding to the concern is that charcoal briquettes frequently
are used to ignite and burn the incense. That adds significantly to potentially
harmful levels of carbon monoxide and other pollutants, they noted.
Two types of incense (Oudh and Bahkoor) are most often used.
Both are made with agar wood, which is taken from trees that develop an aromatic
smell in response to fungal infection. 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 the cellular inflammatory response.
The authors recommended implementing better ventilation in
UAE homes when incense is burned, such as opening a door or window to improve
air flow. They also suggested using alternatives to charcoal, including
electric combustion devices.
Future studies, they proposed, should measure additional
compounds caused by incense burning and offer a more in-depth analysis of