Source · category
Tobacco smoke (secondhand smoke)
Also: secondhand smoke, environmental tobacco smoke, ETS, thirdhand smoke
The mixture of smoke exhaled by smokers and released from burning tobacco. It contains thousands of compounds — fine particles, carbon monoxide, benzene, formaldehyde, nicotine — and is an established cause of lung cancer, heart disease and childhood asthma in non-smokers.
Why it matters indoors
Secondhand smoke is the indoor source with the strongest evidence of harm and the simplest remedy. Its particles settle on surfaces and re-emit for months as thirdhand smoke; ventilation and filtration reduce but do not remove the risk, which is why guidelines call for smoke-free indoor spaces rather than smoking areas.
What the studies report
12 of 89 Findings — those with the strongest study design.
| Linked to | Effect | Population | Study design | Source | Checked |
|---|---|---|---|---|---|
| Lung cancer | OR 1.97 (1.63–2.37) | — · 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-1339 Rusoiu et al. Indoor Air Pollution and Lung Cancer Risk-A Systematic Revie… (2026) | machine |
| Lung cancer | HR 1.44 (1.19–1.74) | — · 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-1340 Rusoiu et al. Indoor Air Pollution and Lung Cancer Risk-A Systematic Revie… (2026) | machine |
| Low birth weight | OR 2.63 (1.09–6.35) | pregnant women and their newborns · home | systematic review and meta-analysis of environmental exposures and adverse pregnancy outcomes in Ethiopia: seven eligible studies on active and passive cigarette smoking and low birth weight, pooled with a random effects model and checked with a sensitivity analysis | F-1347 Enyew et al. Environmental exposures and adverse pregnancy outcomes in Et… (2023) | machine |
| Particulate matter (PM₂.₅ and PM₁₀) | mean 63.89 | five patients with asthma or chronic obstructive pulmonary disease (average age 50 years, 40 % male) · home | panel study: five patients with asthma or COPD monitored over a whole year with 24 h indoor and outdoor PM2.5 measurements, daily peak expiratory flow and biweekly symptom reports (linear mixed effect models, generalized estimating equations) | F-0084 Xydi et al. Assessing the Impact of Spatial and Temporal Variability in … (2024) | machine |
| Particulate matter (PM₂.₅ and PM₁₀) | mean 137.56 | five patients with asthma or chronic obstructive pulmonary disease (average age 50 years, 40 % male) · home | panel study: five patients with asthma or COPD monitored over a whole year with 24 h indoor and outdoor PM2.5 measurements, daily peak expiratory flow and biweekly symptom reports (linear mixed effect models, generalized estimating equations) | F-0085 Xydi et al. Assessing the Impact of Spatial and Temporal Variability in … (2024) | machine |
| Birth weight | mean 2703 | pregnant women and their newborns · home | communication from Sri Lanka: pregnant women's exposure to second-hand tobacco smoke and to wood-fuel smoke recorded by questionnaire, expired-air carbon monoxide measured with a breath monitor, and neonatal birth weight and gestational age recorded at delivery | F-0988 Pathirathna et al. Effects of Prenatal Tobacco and Wood-Fuel Smoke Exposure on … (2017) | machine |
| Birth weight | mean 3125 | pregnant women and their newborns · home | communication from Sri Lanka: pregnant women's exposure to second-hand tobacco smoke and to wood-fuel smoke recorded by questionnaire, expired-air carbon monoxide measured with a breath monitor, and neonatal birth weight and gestational age recorded at delivery | F-0989 Pathirathna et al. Effects of Prenatal Tobacco and Wood-Fuel Smoke Exposure on … (2017) | machine |
| Total volatile organic compounds (TVOC) | — | — | before-and-after monitoring in billiard halls and screen golf ranges in Korea: total volatile organic compounds, nitrogen dioxide and PM2.5 measured before and after the venues were designated non-smoking, against the 24-hour guidelines of the Korean Ministry of Environment | F-1136 Environmental monitoring and smoking exposure before and aft… (2026) | machine |
| Total volatile organic compounds (TVOC) | — | — · billiard hall | before-and-after monitoring in billiard halls and screen golf ranges in Korea: total volatile organic compounds, nitrogen dioxide and PM2.5 measured before and after the venues were designated non-smoking, against the 24-hour guidelines of the Korean Ministry of Environment | F-1137 Environmental monitoring and smoking exposure before and aft… (2026) | machine |
| Total volatile organic compounds (TVOC) | — | — · screen golf range | before-and-after monitoring in billiard halls and screen golf ranges in Korea: total volatile organic compounds, nitrogen dioxide and PM2.5 measured before and after the venues were designated non-smoking, against the 24-hour guidelines of the Korean Ministry of Environment | F-1138 Environmental monitoring and smoking exposure before and aft… (2026) | machine |
| Total volatile organic compounds (TVOC) | mean 22.9 | — · billiard hall | before-and-after monitoring in billiard halls and screen golf ranges in Korea: total volatile organic compounds, nitrogen dioxide and PM2.5 measured before and after the venues were designated non-smoking, against the 24-hour guidelines of the Korean Ministry of Environment | F-1139 Environmental monitoring and smoking exposure before and aft… (2026) | machine |
| Nitrogen dioxide (NO₂) | mean 154.9 | — · billiard hall | before-and-after monitoring in billiard halls and screen golf ranges in Korea: total volatile organic compounds, nitrogen dioxide and PM2.5 measured before and after the venues were designated non-smoking, against the 24-hour guidelines of the Korean Ministry of Environment | F-1140 Environmental monitoring and smoking exposure before and aft… (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
- Human transport of thirdhand tobacco smoke: A prominent source of hazardous air pollutants into indoor nonsmoking environments. CKB 0963
- Hikisz et al. The Tobacco Smoke Component, Acrolein, as a Major Culprit in Lung Diseases and Respiratory Cancers: Molecular Mechanisms of Acrolein Cytotoxic Activity (2023). doi:10.3390/cells12060879 CKB 0960
- Antenatal environmental exposure to indoor air pollution and environmental tobacco smoke: association with birth outcomes in an African birth cohort (2026). BMJ Open Respir Res. doi:10.1136/bmjresp-2025-003721 CKB 1114
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. Tobacco smoke (secondhand smoke). Coridum Knowledge G-0065, 16 September 2026. https://coridum.com/k/G-0065/