Inhaling fumes from burning incense may cause lung problems, a scientist has said.
Dr Joseph Yung Ka-fu, from Polytechnic University's department of applied biology and chemical technology, says that incense-burning produces dangerous suspended particles which may accumulate in the lungs and affect their functioning.
A Taiwanese study in 2006 showed that the amount of cancer-causing substances and suspended particles in a packed temple could be five times as high as in a room in which someone is smoking a cigarette.
The harmful material could cause coughing, nasal inflammation, asthma and rashes.
In comparison, 'environmentally-friendly' sticks produce less smoke and a better smell, according to sellers. They are generally shorter than their traditional counterparts. However, some burn out in half an hour, one shopkeeper said.
Their effects on health have yet to be studied: chemicals or herbs - the effects of burning which have not been established - are used as a substitute for sandalwood.