Going to a religious service may be healthy for the spirit, but it could prove hazardous to the body.
Church incense adds to the mood and mystery of a service, but it also produces a large quantity of airborne particles. While this is particularly true in Eastern religions incense also is an important part of the service in many orthodox and “high” Christian religions (such as Catholic, Anglican and Russian Orthodox).
So how dangerous could breathing this level of pollutants be?
For the average churchgoer who only spends a couple of hours a month in church, the risks are probably very low. But for those whose religious professions require many hours a day in such a smokey atmosphere, these risks can add up.
Incense is made of a mix of scented resins, spices, herbs and oils. It is deliberately designed to smoke as it burns. This means that the carbon molecules making up the plant material constituents do not fully combust (combine with oxygen to make carbon dioxide – CO2). This leads to the production not only of carbon monoxide (CO) but also small particles which become suspended in the air of the church or temple. With poor ventilation, the concentration of particles in the hall can build up over time, and produce that scented, smokey haze.
Along with the larger particles, there are other molecules produced by the burning incense. These are potentially even more hazardous. Many belong to the family of polycyclic aromatic hydrocarbons (PAHs) and these include naphthalene (moth balls) and a collection of other compounds, many of which are included in warnings of exhaust emissions and soil toxicity. These PAHs are known carcinogens and are also indicated in hormone system interference and in immune system damage.
If you look at places where solid fuel (such as wood) is still burnt inside the home to provide heat and cooking facilities, you can begin to see how dangerous such smoke is. World wide, indoor smoke is linked to acute respiratory infections, middle ear infection, chronic obstructive pulmonary disease (COPD), asthma, cancer, tuberculosis, and eye diseases causing blindness. Indeed it is such a big issue that conservative estimates put world deaths in 2000 due to indoor smoke risks at between 1.5 and 2 million deaths.
Certainly studies carried out in Taiwanese temples have shown an increase in respiratory illness in workers heavily exposed to incense burning.
I also wonder whether the chemical mix works as a mild hallucinogenic. Carbon monoxide and dioxide can make people feel sleepy and a little euphoric. Similarly, some chemicals from the class of PAHs can cause hallucinogenic states. Perhaps incense also affects mood and consciousness as well. Thus people who feel good after a church service may be responding to more than just the preacher’s message.
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Ho CK, Tseng WR, Yang CY. (2005) Adverse respiratory and irritant health effects in temple workers in Taiwan, J Toxicol Environ Health A. 68(17-18):1465-70
Lin TC, Chang FH, Hsieh JH, Chao HR and Chao MR (2002) Characteristics of polycyclic aromatic hydrocarbons and total suspended particulate in indoor and outdoor atmosphere of a Taiwanese temple, J Hazard Mater. 95(1-2):1-12.
Lung SC, Kao MC and Hu SC (2003) Contribution of incense burning to indoor PM10 and particle-bound polycyclic aromatic hydrocarbons under two ventilation conditions. Indoor Air. 13(2):194-9.
Weber, S (2006) Exposure of churchgoers to airborne particles, Environ Sci Technol. 40(17):5251-6.