Some of our experience professional cleaning and remediators have seen the literal soot buildup on walls and ceiling from burning candles and incense. When you see the impact of regular use of candles and incense, it turns you off from even casual use.
Face it, you are BURNING THINGS in your home, and that ash, soot, debris has to go somewhere. Other than the scent these items may disperse, they certainly deposit fine soot everywhere as well.
The EPA report says:
“This report summarizes available information on candles and incense as potential sources of indoor air pollution. It covers market information and a review of the scientific literature. The market information collected focuses on production and sales data, typical uses in the U.S., and data on the sources and quantities of imported products. The estimated total sales of candles in 1999 varied between $968 million and $2.3 billion, while imports were $486 million. The U.S. imports and exports of incense in 1999 were $12.4 and 4.6 million, respectively. The scientific literature review gathered information regarding the emission of various contaminants generated when burning candles and incense, as well as the potential health effects associated with exposure to these contaminants. Burning candles and incense can be sources of particulate matter. Burning candles with lead-core wicks may result in indoor air concentration of lead above EPA-recommended thresholds. Exposure to incense smoke has been linked with several illnesses, and certain brands of incense also contain chemicals suspected of causing skin irritation.”