Indoor environment factor · measured in CFU/m³
Airborne fungi
Also: indoor fungi, fungus, fungal contamination, airborne fungi, culturable fungi
Fungal cells, spores and fragments carried in indoor air. Some are brought in from outdoors with ventilation air and settle with the seasons; the rest are grown indoors on damp material, and it is the second group that indicates a building problem.
What it is
Fungi are always present in indoor air, because outdoor air contains them and every building exchanges air with outdoors. A count on its own therefore says very little: it rises in late summer, falls under snow cover, and tracks whatever is happening in the garden.
What carries information is the comparison. An indoor count well above the outdoor count at the same time, or an indoor community whose composition differs from the outdoor one, points to a source inside the building — which in practice means material that has been wet long enough for growth, whether or not anything is visible. This is the reasoning behind every serious sampling protocol, and the reason a single indoor figure without a paired outdoor sample is not interpretable.
Mould names the growth on a surface; airborne fungi name what that growth, or the outdoor air, has put into the room.
What the studies report
12 of 13 Findings — those with the strongest study design.
| Linked to | Effect | Population | Study design | Source | Checked |
|---|---|---|---|---|---|
| Air filtration and air purifiers | difference 6.53 (-10.50–-2.55) | — · hospital room | systematic review and meta-analysis of indoor bioaerosols in hospital rooms: culturable bacteria and fungi compared between rooms without a heating, ventilation and air conditioning system, rooms with a conventional system and rooms with an enhanced system, pooled with random-effects models and assessed with the Agency for Healthcare Research and Quality checklist | F-1406 Dai et al. A systematic review and meta-analysis of indoor bioaerosols … (2021) | machine |
| Respiratory symptoms | 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 |
| — | other 776 | healthcare workers · hospital emergency room | seasonal measurement study of fine particulate matter (four-stage impactor) and culturable bacteria and fungi (Andersen sampler) in operating rooms, emergency rooms and internal wards of hospitals in Bushehr, with a Monte Carlo hazard quotient for staff | F-0191 Seasonal evaluation of culturable bioaerosols and airborne p… (2025) | machine |
| — | mean 269.0 | — · metro station platform | indoor air quality monitoring on the platforms of the ten busiest stations of the Taipei metro (TRTS) in winter and summer: CO2, CO, O3, TVOC, formaldehyde, PM10, PM2.5, bacteria and fungi | F-0380 Chen et al. Indoor Air Quality in the Metro System in North Taiwan (2016) | machine |
| — | mean 232.2 | — · metro station platform | indoor air quality monitoring on the platforms of the ten busiest stations of the Taipei metro (TRTS) in winter and summer: CO2, CO, O3, TVOC, formaldehyde, PM10, PM2.5, bacteria and fungi | F-0381 Chen et al. Indoor Air Quality in the Metro System in North Taiwan (2016) | machine |
| — | mean 2738.3 | workers of a materials recycling facility · waste processing shed | measurement campaign in a materials recycling facility in Brazil: size-fractioned particle mass and particle number, bacteria and fungi measured inside the waste processing shed (P1) and outdoors (P2) on working days in the winter and spring of 2017 and the summer of 2019, 2,400 minutes of particle mass, 1,440 minutes of particle number and 216 bioaerosol samples | F-1398 Wikuats Assessment of airborne particles and bioaerosols concentrati… (2020) | machine |
| — | median 54.0 | — · outdoors at the school | study of indoor air bioaerosols in classrooms across the wet and the dry season: total fungal and total bacterial counts sampled outdoors, in empty classrooms and in occupied classrooms, with the respirable fractions measured separately | F-1410 Morakinyo Seasonal levels and size fractions of indoor air bioaerosols… (2025) | machine |
| — | median 53.0 | — · classroom (empty) | study of indoor air bioaerosols in classrooms across the wet and the dry season: total fungal and total bacterial counts sampled outdoors, in empty classrooms and in occupied classrooms, with the respirable fractions measured separately | F-1411 Morakinyo Seasonal levels and size fractions of indoor air bioaerosols… (2025) | machine |
| — | median 57.0 | — · classroom | study of indoor air bioaerosols in classrooms across the wet and the dry season: total fungal and total bacterial counts sampled outdoors, in empty classrooms and in occupied classrooms, with the respirable fractions measured separately | F-1412 Morakinyo Seasonal levels and size fractions of indoor air bioaerosols… (2025) | machine |
| Allergic rhinitis | culturable fungi from several indoor environments, counted as presence rather than as a concentration | — · home | study of fungi isolated from the indoor environments of children with allergic rhinitis and asthma against children without them, with sampling of several indoor environments including indoor plant soil | F-1510 Allergic rhinitis and asthma in association with fungal poll… (2023) | machine |
| — | mean 24.53 | — · hospital | proposed standard for hospital bioaerosols: viable bioaerosol samples cultured indoors in wards, intensive care units, radiology suites and operating rooms and compared with outdoor reference samples | F-1549 860. A Proposed Standard for Hospital Bioaerosol Monitoring … (2020) | machine |
| — | beta 0.639 (0.285–0.993) | — · classroom | cross-sectional study of public primary school classrooms: culturable fungal load sampled indoors and related to the age of the building, the area of the classroom, the indoor temperature and humidity and the particulate matter | F-1596 Indoor Culturable Fungal Load and Associated Factors among P… (2019) | 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.
Cite this page
Coridum Research. Airborne fungi. Coridum Knowledge G-0120, 16 September 2026. https://coridum.com/k/G-0120/