BBC reports that frequent burning of paraffin candles over time linked to cancer:
To investigate candle emissions, the researchers burned a range of candles in the laboratory and collected the mixture of substances they gave off.
Paraffin-based candles produced "clear sharp peaks" for many chemicals, mainly because burning candles does not produce high enough temperatures to combust hazardous molecules such as toluene and benzene.
The scientists suggested switching to candles made from beeswax or soy, which did not release significant levels of the chemicals.
Researcher Amid Hamidi said people who frequently used candles, for instance to help them relax in the bath or provide the right ambience for dinner, [or frequency in a sacred space or temple room - added by me] were most at risk.
He told the American Chemical Society in Washington: "An occasional paraffin candle and its emissions will not likely affect you.
"But lighting many paraffin candles every day for years or lighting them frequently in an un-ventilated bathroom around a tub, for example, may cause problems."
Read more at link above.