Just about any smoke is harmful to our lungs if it's inhaled. Incense burns four times more particulate matter than cigarette smoke.
Incense is popular in Asian countries. It is common for the Buddhism and Taoism religions to burn incense daily. The air pollution in and around various temples has been documented to be harmful effects on health. But it's also popular in America. In the United States, incense is often sold in health food stores and used for religious purposes or scenting a room. However, incense is dangerous to health according to 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.
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 structure.
What's In Incense?
A typical composition of stick incense consists of 21% (by weight) of herbal and wood powder, 35% of fragrance material, 11% of adhesive powder, and 33% of bamboo stick. Like any cigarette smoke and wood smoke, incense smoke contains particulate matter, gas products (carbon monoxide, cardiodioxide, and sulfur dioxide) and other organic compounds (benzene, toluene, xylenes, aldehydes and polycyclic aromatic hydrocarbons) shown to harm human health.
A study published in the September 2001 issue of the Bulletin of Environmental Contamination and Toxicology indicates that burning incense can expose people to dangerous levels of cancer-causing chemicals.
One PAH called benzopyrene, which is linked to lung cancer in smokers, was found to be 45 times more concentrated in the indoor zones using incense than in homes where people smoked cigarettes.
In a study of more than 61,000 ethnic Chinese living in Singapore who were followed for up to 12 years, the investigators found a link between heavy incense use and various respiratory cancers.
The researchers found that incense use was associated with a statistically significant higher risk of cancers of the upper respiratory tract, with the exception of nasopharyngeal cancer.
The researchers also looked at total suspended particles (TSPs), a measurement that reflects the total weight of small and potentially harmful airborne pollutants that all of us are exposed to on an ongoing basis.
Those who used incense heavily also had higher rates of a type of cancer called squamous cell carcinoma, which refers to tumors that arise in the cells lining the internal and external surfaces of the body. The risk was seen in smokers and nonsmokers.
Part of an International Health Concern
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.
In a recent study from the Gillings School of Global Public Health, the researchers 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 room.
The researchers analyzed both particulate concentrations and levels of gases such as carbon monoxide, sulfur dioxide, oxides of nitrogen and formaldehyde.
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 cigarette smoke.
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, researchers said, indoor air pollution has become a source of increasing concern.
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 agarwood, 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 inflammatory markers.
April McCarthy is a community journalist playing an active role reporting and analyzing world events to advance our health and eco-friendly initiatives.