Source · product
Candles and incense
Also: incense, scented candles
Open flames indoors release fine and ultrafine particles, soot, carbon monoxide and, from incense, benzene and formaldehyde. Incense in particular produces particle concentrations comparable to tobacco smoke.
Why it matters indoors
Burning incense sticks emits more particulate matter per gram than cigarettes, along with polycyclic aromatic hydrocarbons and aldehydes; studies in homes and temples link regular use to respiratory symptoms and, in long-term users, elevated cancer risk. Candles emit less, but scented and paraffin candles add soot and volatile compounds; a room with several candles burning for an evening can reach PM₂.₅ levels of an urban roadside.
What the studies report
12 of 23 Findings — those with the strongest study design.
| Linked to | Effect | Population | Study design | Source | Checked |
|---|---|---|---|---|---|
| Lung cancer | OR 3.05 (1.06–8.84) | — · home | systematic review and meta-analysis of observational studies published between 2015 and 2025 on indoor air pollution and primary lung cancer: 38 studies with 475,565 participants, maximally adjusted estimates pooled with random effects models and study quality assessed with the Newcastle-Ottawa Scale | F-1344 Rusoiu et al. Indoor Air Pollution and Lung Cancer Risk-A Systematic Revie… (2026) | machine |
| Lung cancer | OR 0.91 (0.72–1.16) | — · home | case-control study of lung cancer in Chinese women: exposure to tobacco smoke, to daily cooking and to incense or mosquito coils recorded by interview, with odds ratios adjusted for potential confounders and examined for interaction between smoking and indoor inhalants | F-1727 Lung Cancer in Chinese Women: Evidence for an Interaction be… (2010) | machine |
| Lung cancer | OR 1.53 (0.97–2.41) | — · home | case-control study of lung cancer in Chinese women: exposure to tobacco smoke, to daily cooking and to incense or mosquito coils recorded by interview, with odds ratios adjusted for potential confounders and examined for interaction between smoking and indoor inhalants | F-1729 Lung Cancer in Chinese Women: Evidence for an Interaction be… (2010) | machine |
| Cardiovascular disease (CVD) | HR 0.91 (0.80–1.05) | — · home | Danish prospective cohort (Diet, Cancer and Health): frequency of candle use reported by questionnaire and first hospital contact for cardiovascular and respiratory events ascertained through national registers, with hazard ratios adjusted for smoking, socioeconomic and lifestyle factors | F-1800 Use of candles and risk of cardiovascular and respiratory ev… (2022) | machine |
| Cardiovascular disease (CVD) | HR 0.97 (0.84–1.11) | — · home | Danish prospective cohort (Diet, Cancer and Health): frequency of candle use reported by questionnaire and first hospital contact for cardiovascular and respiratory events ascertained through national registers, with hazard ratios adjusted for smoking, socioeconomic and lifestyle factors | F-1801 Use of candles and risk of cardiovascular and respiratory ev… (2022) | machine |
| Chronic obstructive pulmonary disease (COPD) | HR 1.26 (0.81–1.97) | — · home | Danish prospective cohort (Diet, Cancer and Health): frequency of candle use reported by questionnaire and first hospital contact for cardiovascular and respiratory events ascertained through national registers, with hazard ratios adjusted for smoking, socioeconomic and lifestyle factors | F-1802 Use of candles and risk of cardiovascular and respiratory ev… (2022) | machine |
| Particulate matter (PM₂.₅ and PM₁₀) | mean 145 | adult residents of Bamako in four occupational groups · home (bedroom) | personal exposure measurement study: residents of Bamako in four occupational groups (office workers, drivers, cooks, students) wore palm-sized optical PM2.5 sensors on the chest during daily activities, September 2020 to February 2021 | F-0123 Sidibe et al. Personal Exposure to Fine Particles (PM2.5) in Northwest Afr… (2022) | machine |
| Particulate matter (PM₂.₅ and PM₁₀) | other 39.9 | — · home | measurement study in residential homes in Seoul: particulate matter and airborne microbiome sampled at the candle-lit spot and at 3 m and 6 m from a burning scented candle, before, during and after burning | F-0147 Impact of scented candle use on indoor air quality and airbo… (2025) | machine |
| Particulate matter (PM₂.₅ and PM₁₀) | other 42.8 | — · home | measurement study in residential homes in Seoul: particulate matter and airborne microbiome sampled at the candle-lit spot and at 3 m and 6 m from a burning scented candle, before, during and after burning | F-0148 Impact of scented candle use on indoor air quality and airbo… (2025) | machine |
| Particulate matter (PM₂.₅ and PM₁₀) | other 30.5 | — · home | measurement study in residential homes in Seoul: particulate matter and airborne microbiome sampled at the candle-lit spot and at 3 m and 6 m from a burning scented candle, before, during and after burning | F-0149 Impact of scented candle use on indoor air quality and airbo… (2025) | machine |
| Headache | OR 1.87 (1.09–3.21) | household members (children and adults) · home | cross-sectional study in a population-based sample of 628 households in the United Arab Emirates with passive indoor sampling of SO2, NO2, H2S, HCHO, CO and particulate matter and interviews of 1,590 household members | F-0277 Indoor air pollutants and health in the United Arab Emirates (2012) | machine |
| Formaldehyde (CH₂O) | other 132 | — · home | single-run burning tests of three commercial scented candles for 60 minutes each in a closed residential room of 11 m2 (about 25 m3), pollutants read from a low-cost ZN-MT32 multi-parameter sensor | F-0318 Assessment of indoor chemical pollutant emissions from scent… (2026) | machine |
Each row is one Finding — a sentence as printed in one study, recorded with its page in the Coridum Knowledge Base. Follow the Finding number for the exact wording and the citation. Checked says who verified the row: machine means every automatic check passed and the surrounding text was read; person means someone read the sentence in the document. Rows are re-checked by a person over time. The studies are curated in the Coridum Knowledge Base; the reading of them together is a Claim, shown separately.
In the literature
- Fiore et al. The Presence of Aromatic Substances in Incense: Determining Indoor Air Quality and Its Impact on Human Health. Applied Sciences. doi:10.3390/app13127344 CKB 0964
- Incense Aerosol-Induced Neurotoxicity Disrupts α‑Synuclein Homeostasis in a Cellular Parkinson’s Disease Model, Distinct from (2026). Chem Res Toxicol. doi:10.1021/acs.chemrestox.6c00091 CKB 1216
- Assessment of indoor chemical pollutant emissions from scented candle burning… (2026). doi:10.55225/sti.754 CKB 1052
Studies in the Coridum Knowledge Base in which this term is used. The definition follows standard usage in WHO, ISO and textbook sources; it is not quoted from these papers.
CKB = document number in the Coridum Knowledge Base, our curated library of peer-reviewed studies. Follow the DOI for the original paper.
Cite this page
Coridum Research. Candles and incense. Coridum Knowledge G-0066, 16 September 2026. https://coridum.com/k/G-0066/