Burning incense can trigger a raft of health problems including allergies, asthma, headaches and lung conditions, experts have warned.
The material produces a fragrant scent and is often burned as part of religious or cultural rituals.
But research has found it typically generates 45 mg of particulate matter per gram, which is more than four times the 10 mg produced by cigarettes.
Experts at the American College of Allergy, Asthma and Immunology conference in Boston presented the case of an 87-year-old woman with a history of asthma and chronic obstructive pulmonary disease and was suffering from unexplained shortness of breath.
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Lead author Gomeo Lam said: “A detailed history revealed daily incense burning. We recommended she stop burning incense, which the patient did not want to do as burning joss stick incense daily allowed her to express homage and veneration for ancestors.
“We then advised she use electric incense devices, which resulted in improvement of her symptoms.”
The experts warned that incense fumes contain carbon, sulphur, nitrogen oxides as well as formaldehyde, and other polycyclic aromatic volatile compounds which can cause cancer.
Allergist Mary Lee-Wong said: “People who burn incense may not realise that family members, including children, who are exposed to secondhand smoke, face health consequences.
“Similar to tobacco smoke, thirdhand incense smoke may linger in furniture, clothing, and other articles, dissipating for months afterward.”
The NHS recommends that people with lung conditions avoid using incense, and that others limit its use.
Incense smoke can be harmful to health and may be comparable to or even more harmful than passive smoking.
It also contributes to air pollution and can pose a fire hazard.