Can scented candles cause respiratory harm?

Respiratory Risks of Scented Candles

Scented candles can cause respiratory harm through the emission of particulate matter, formaldehyde, and other volatile organic compounds (VOCs) that may trigger respiratory symptoms, particularly in susceptible individuals.

Emissions from Scented Candles

Scented candles release several potentially harmful substances:

• Particulate Matter (PM): Burning candles produce respirable particles that can be deposited in the lungs 1

  • PM from candles contributes to indoor air pollution
  • PM2.5 and PM10 are associated with increased respiratory mortality and hospitalizations 1

• Formaldehyde: One of the most concerning emissions

  • Can reach high concentrations when candles are lit - up to 2098 ppb in some scented candles 2
  • WHO guideline value for formaldehyde is 100 μg/m3 (0.1 mg/m3) based on 30-minute averaging time 1
  • Exposure to formaldehyde levels higher than 100 μg/m3 for long periods is associated with asthma-related respiratory symptoms like coughing and wheezing 1

• Volatile Organic Compounds (VOCs):

  • Scented candles emit various VOCs both when lit and unlit 2
  • Some candles show high TVOC (Total VOC) concentrations - up to 12,742 ppbC when lit and 2766 ppbC when unlit 2
  • Emissions include benzene, acrolein, and polycyclic aromatic hydrocarbons 3

Health Impacts and Risk Factors

Respiratory Effects:

• Irritation: VOCs and formaldehyde can cause irritant symptoms including temporary burning of the eyes or nose and sore throat 1

• Asthma and Allergic Reactions:

  • Certain biogenic VOCs (like pinene, camphor, linalool) found in scented products are associated with respiratory symptoms including reduced peak expiratory flow and increased nasal congestion 4
  • These compounds may induce respiratory inflammation and maintain it by inhibiting eosinophilic apoptosis 4

• Reactive Upper Airways Dysfunction Syndrome (RUDS):

  • High-level exposure to irritants can trigger nasal symptoms including congestion, rhinorrhea, sneezing, and nasal itching 5

Vulnerable Populations:

• Individuals with pre-existing respiratory conditions (asthma, COPD)
• Those with allergic tendencies or atopic predisposition 5
• Children and elderly people

Risk Assessment and Mitigation

Exposure Assessment:

• Risk levels depend on:

  • Candle composition (wax type and fragrance)
  • Room size and ventilation
  • Duration of exposure
  • Individual susceptibility

• In some studies, calculated indoor concentrations from candle emissions were below guidance values for most compounds, but exceptions were observed for nitrogen dioxide, acrolein, and benzo[a]pyrene in certain cases 3

Recommendations for Safer Use:

1. Limit exposure:

   • Reduce frequency and duration of candle burning
   • Avoid using multiple scented candles simultaneously

2. Improve ventilation:

   • Ensure adequate air circulation when burning candles
   • Open windows periodically to exchange indoor air

3. Choose safer alternatives:

   • Unscented candles generally produce fewer harmful emissions
   • Consider electric alternatives that don't involve combustion

4. Monitor symptoms:

   • Be aware of any respiratory symptoms that develop during or after candle use
   • Discontinue use if symptoms occur

Clinical Implications

Healthcare providers should:

1. Ask about candle use when evaluating patients with unexplained or worsening respiratory symptoms

2. Educate patients about potential respiratory irritants in the home environment, including scented candles

3. Recommend avoidance of scented candles for patients with:

   • Asthma or other chronic respiratory conditions
   • History of sensitivity to fragrances or chemical irritants
   • Unexplained respiratory symptoms that improve when away from potential triggers

4. Consider environmental modifications as part of management for patients with respiratory conditions

Conclusion

While not all individuals will experience adverse effects from scented candles, they represent a potential source of respiratory irritants that can trigger or exacerbate symptoms in susceptible individuals. The evidence suggests that limiting exposure to scented candle emissions is advisable, particularly for those with pre-existing respiratory conditions or sensitivities.