News articles on and indicate that burning incense can expose people to dangerous levels of cancer-causing chemicals.

Both articles are based on a study that was published in a September, 2001 issue of the Bulletin of Environmental Contamination and Toxicology.

Researchers collected air samples from inside and outside of a temple in Taiwan, and found that the air inside the temple was highly concentrated with a group of cancer-causing chemicals called polycyclic aromatic hydrocarbons (PAHs).

One PAH called benzopyrene, which is linked to lung cancer in smokers, was found to be 45 times more concentrated in the temple than in homes where people smoked cigarettes.

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. They found that TSPs inside the temple was three times higher than it was at a local traffic intersection, and 11 times higher than just outside the temple. Put another way, they found that a steady volume of incense burning can create more harmful air pollution than that found at a typical traffic intersection.

Although the concentration of PAHs found in the temple in this study is almost certainly higher than it would be in a typical residence, this study serves as a good reminder about the potential dangers of burning incense and other scented products like candles in areas that are not well ventilated.

This study also serves as a good reminder to allow fresh air to circulate throughout one's living space. In the summer, windows should be kept open whenever possible. In the winter, if various factors make it difficult to keep one's windows open just a crack, it can be beneficial to one's health to simply open a few windows for a minute or two each day to allow some fresh air to enter the residence. All of this assumes that one's neighborhood is relatively pollution-free; if the residence in question is in a heavily polluted area, it may be best to look at investing in a high quality indoor air purifier.

Original study published in: Bulletin of Environmental Contamination and Toxicology (vol 67, p 332)