Health outcome · symptom
Respiratory symptoms
Cough, wheeze, phlegm, shortness of breath and irritation of the nose and throat — the everyday complaints that questionnaires record, and the most sensitive indicator of an indoor air problem before any disease is diagnosed.
Not reviewed by a clinician. This entry describes a disease or a symptom. We are introducing clinical review for pages of this kind; until that reviewer is in place, this page has been written and checked by the Coridum team but not reviewed by a clinician. It is general information and not medical advice. How this library is built is described in How we build this library.
Why it matters indoors
Symptom questionnaires are the workhorse of indoor air epidemiology: cheap, repeatable and sensitive. Consistent findings across decades of studies include more symptoms in damp and mouldy homes, in homes with gas cooking and no extraction, in smokers’ households, and in classrooms and offices with low ventilation. The limitation is that symptoms are subjective; the strength of the evidence comes from consistency across studies and from dose–response with measured exposure.
Indoor factors with evidence
12 of 19 Findings — those with the strongest study design.
| Factor | Effect | Population | Study design | Source | Checked |
|---|---|---|---|---|---|
| Airborne fungi | RR 1.24 (1.09–1.41) | — · home | meta-analysis of fifteen studies of indoor microbial exposure: the pooled relative risk of respiratory symptoms, with a stratified analysis by the fungal species measured | F-1682 Fakunle Association of indoor microbial aerosols with respiratory sy… (2021) | machine |
| Nitrogen dioxide (NO₂) | OR 1.16 (1.01–1.34) | school children · classroom | double-blind, cluster-randomised crossover trial in Australian school classrooms: low-NOx unflued gas heaters against non-indoor-emitting flued gas heaters, NO2 and formaldehyde measured with passive diffusion badges, children recorded symptoms, medication use and lung function twice daily | F-0691 Respiratory Health Effects of Exposure to Low-NOx Unflued Ga… (2010) | machine |
| Nitrogen dioxide (NO₂) | OR 5.51 (2.21–13.7) per 1 interquartile range of household NO2, 12 ppb | persons living with HIV and persons at risk for HIV · home | Baltimore cohort of persons living with HIV and persons at risk for HIV (SHIELD): 1997 participants with baseline questionnaires and spirometry for reported household exposures, plus a 36-home pilot (SHIELD Home) with weeklong direct measurement of household PM2.5 and NO2; logistic and quantile regression adjusted for age, sex, smoking, race, HIV serostatus and lung function | F-0701 Unraveling the impact of indoor air pollution on respiratory… (2025) | machine |
| Total volatile organic compounds (TVOC) | OR 1.06 (1.04–1.07) per 100 ppb | office employees · office | cross-sectional study of 417 employees in 87 offices in high-rise buildings in Taiwan: 8-hour indoor and outdoor CO2 and TVOC measurements with a sick building syndrome questionnaire, generalized estimating equations logistic regression | F-0384 Lu et al. Building-Related Symptoms among Office Employees Associated … (2015) | machine |
| Carbon dioxide (CO₂) | mean 1020 | adults aged 20-45 years · dwelling | cross-sectional study of 88 adults aged 20-45 years from the general population of Uppsala (Sweden), stratified random sample: room temperature, humidity, respirable dust, CO2, VOCs, formaldehyde and house dust mites measured in their homes; structured interview, spirometry, peak flow, methacholine challenge, skin prick tests and serum markers | F-0488 Asthmatic symptoms and volatile organic compounds, formaldeh… (1995) | machine |
| Carbon dioxide (CO₂) | mean 850 | adults aged 20-45 years · dwelling | cross-sectional study of 88 adults aged 20-45 years from the general population of Uppsala (Sweden), stratified random sample: room temperature, humidity, respirable dust, CO2, VOCs, formaldehyde and house dust mites measured in their homes; structured interview, spirometry, peak flow, methacholine challenge, skin prick tests and serum markers | F-0489 Asthmatic symptoms and volatile organic compounds, formaldeh… (1995) | machine |
| Carbon monoxide (CO) | OR 0.39 (0.20–0.78) | reproductive-aged women · home | descriptive cross-sectional study among 403 reproductive-aged women (15 to 49 years) in the Central Province of Sri Lanka: cooking fuel and respiratory symptoms from an interviewer-administered questionnaire, exposure assessed with a breath carbon-monoxide monitor and carboxyhaemoglobin estimated from it, with logistic regression adjusted for confounders | F-0876 Pathirathna Impact of solid fuel usage on respiratory symptoms among rep… (2022) | machine |
| Tobacco smoke (secondhand smoke) | OR 1.74 (1.17–2.60) | seventh-grade pupils · home | cross-sectional study of 5051 seventh-grade pupils in 22 randomly selected schools of the greater metropolitan area of Wuhan, China: a self-administered in-class questionnaire on respiratory health and the home environment, analysed with logistic regression | F-1319 Respiratory symptoms in relation to residential coal burning… (2004) | machine |
| Tobacco smoke (secondhand smoke) | OR 2.25 (1.36–3.72) | seventh-grade pupils · home | cross-sectional study of 5051 seventh-grade pupils in 22 randomly selected schools of the greater metropolitan area of Wuhan, China: a self-administered in-class questionnaire on respiratory health and the home environment, analysed with logistic regression | F-1320 Respiratory symptoms in relation to residential coal burning… (2004) | machine |
| Tobacco smoke (secondhand smoke) | OR 2.3 (1.3–4.2) | street sweepers · home | cross-sectional study of chronic respiratory symptoms among street sweepers in India: a questionnaire on symptoms, smoking, second-hand smoke and housing, analysed with multiple logistic regression | F-1334 Prevalence and Associated Factors of Chronic Respiratory Sym… (2024) | machine |
| Printers and photocopiers | self-reported symptoms; the study also finds excessive sputum production more common at p = 0.004 | photocopier operators · copy centre | cross-sectional study of photocopier operators in copy centres against a control group: respiratory symptoms, general health problems and lung function compared between the groups | F-1497 Chronic exposure to emissions from photocopiers in copy shop… (2013) | machine |
| Liquefied petroleum gas (LPG) | prevalence 44 | household members · home | cross-sectional study of indoor air pollution and its impact on health in households: fuel use, ventilation, crowding and neighbourhood pollution recorded together with reported respiratory symptoms of the household members | F-1505 A study on indoor air pollution and its impact on health in … (2024) | 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.
How strong is the evidence
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In dwellings, a single study suggests that house dust mites and visible dampness or microbial growth go together with more symptoms related to asthma in adults.
A Claim is Coridum reading the Findings together, not a quotation from one study — according to Coridum. The grade follows the study designs behind it: A is the strongest, D means a single study or a mechanism.
In the literature
- Aglan et al. Personal and community-level exposure to air pollution and daily changes in respiratory symptoms and oxygen saturation among adults with COPD (2023). doi:10.1016/j.heha.2023.100052 CKB 0542
- Taminskiene Indoor air pollution in kindergartens is a stronger predictor of preschool wheezing than household pets and passive smoking (2026). doi:10.3389/fpubh.2026.1835292 CKB 1113
- Unraveling the impact of indoor air pollution on respiratory health in people living with HIV within a high-prevalence HIV cohort (2025). BMC Pulm Med. doi:10.1186/s12890-025-03937-x CKB 1096
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. Respiratory symptoms. Coridum Knowledge G-0061, 16 September 2026. https://coridum.com/k/G-0061/