Incense might do more than just smell good. In a study, to be published in the October issue of the journal Cancer, that involved more than 61,000 Singaporeans, incense burning nearly doubled the risk of upper respiratory cancers -- whether subject smoked cigarettes or not. Although there was no evidence to suggest that incense burning increased the risk of lung cancer, the American Lung Association plans to add incense burning to the list of risk factors for the disease. But casual incense users don't necessarily have to stub out that sandlewood: Only people who burn incense regularly and heavily are at risk. Casual use is probably harmless.