Health Risks of Burning Incense: Particulate Matter, Lung Function, and Cardiovascular Effects

Particulate Matter and Smoke Composition

Burning incense generates approximately 4 times more particulate matter than cigarettes. The smoke contains ultrafine particles that peak in the danger range, allowing them to penetrate deep into the lungs.

Chemical Composition

• Carbon monoxide
• Nitric oxides
• Sulfur dioxide
• Carcinogenic polycyclic aromatic hydrocarbons (PAHs)
• Volatile organic compounds including benzene and formaldehyde

Formaldehyde levels: Even with windows open during burning, formaldehyde concentrations exceed the WHO safety limit of 80 parts per billion.

Respiratory Effects

Children and Adolescents

Studies of thousands of children followed over time found that household incense exposure was associated with:

• Impaired lung function
• Reduced lung function growth
• Increased risks of respiratory diseases and symptoms
• Higher childhood asthma rates

Note: Children with pets (dogs or cats) showed better lung function, potentially offering some protective effect.

Daily Exposure in Adolescents

Daily exposure is associated with impaired lung function, though the presence of household pets appears to provide protective benefits.

Cardiovascular Mortality

Long-term exposure (daily incense burning for more than 20 years) was associated with increased risk of cardiovascular death:

• 8% of heart disease deaths potentially attributable to incense use
• 12% of stroke deaths potentially attributable to incense use

Cancer Risk

Temple Workers

Workers exposed to incense daily showed significantly more DNA damage, including DNA strand breaks.

Lung Cancer

While the association between incense use and lung cancer remains inconclusive (despite high lung cancer rates in non-smoking Asian women), incense is linked to:

• Cancers of the upper respiratory tract
• Brain tumors in children whose mothers were exposed to incense during pregnancy

Brain tumor risk: Children exposed to incense showed 3 times higher odds of brain tumors, exceeding the risk from:

• Second-hand smoke exposure
• Processed meat consumption (which at most doubles risk)

Brain Development and Cognitive Function

Infants

A study of 15,000 infants found that household incense burning was associated with delays in brain development milestones such as when children start to walk.

Older Adults

Incense exposure among seniors was associated with:

• Reduced cognitive performance
• Adverse structural changes in the brain

”Environmentally Friendly” Incense

So-called eco-friendly incense alternatives were tested and found to contain even higher concentrations of several potentially carcinogenic polycyclic aromatic hydrocarbons compared to traditional incense.

Safer Alternatives

Scented Candles

Under normal conditions of use, scented candles do not appear to pose known health risks to consumers.

Electronic Incense

Similar to e-cigarettes, electronic incense provides fragrance without combustion by-products. However, given the thousands of lung injury cases associated with vaping (with causes still unclear), experts recommend waiting until safety is better understood before recommending e-incense.

Recommendations

Researchers conclude that safer practices should include:

• Avoiding burning incense indoors when susceptible individuals are present
• Protecting vulnerable populations:
  • Young children
  • Older adults
  • People with family history of allergies
  • Individuals with pre-existing cardiovascular or respiratory disease

Despite being a recognized health hazard, burning incense remains in widespread use, highlighting the need for greater public awareness of these risks.