Indoor environment factor · measured in CFU/m³
Airborne bacteria
Part of: Bioaerosols
Also: bacterial communities, airborne bacteria, indoor bacteria, culturable bacteria, bacterial aerosol
Bacterial cells and fragments carried in indoor air, measured either as colony-forming units that grow on a plate or as genetic material detected without culture. The two methods answer different questions and their numbers are not interchangeable.
What it is
Most bacteria indoors come from the people in the room: shed skin, exhaled air, and what is resuspended when someone walks across a floor. Occupancy therefore predicts the count better than almost anything else, and a room’s bacterial load rises and falls with the number of people in it and the rate at which their air is replaced.
Two measurements are in use and they are not the same. A culture method grows what will grow on the chosen medium at the chosen temperature, and reports colony-forming units per cubic metre — a small and selective fraction of what is present, but the fraction that is alive. A sequencing or quantitative method counts genetic material, living or not, and describes the community rather than its viability.
Coridum records the method and the unit with the value, because a count without them cannot be compared with anything.
What the studies report
12 of 18 Findings — those with the strongest study design.
| Linked to | Effect | Population | Study design | Source | Checked |
|---|---|---|---|---|---|
| Air filtration and air purifiers | difference 113.13 (-197.89–-28.38) | — · 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-1405 Dai et al. A systematic review and meta-analysis of indoor bioaerosols … (2021) | machine |
| HVAC systems | difference 40.05 (-55.52–-24.58) | — · 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-1407 Dai et al. A systematic review and meta-analysis of indoor bioaerosols … (2021) | machine |
| — | share-above 26.7 per 1000 % | — | study of non-thermal plasma disinfection of indoor air: airborne bacteria sampled in rooms with and without the device, with the occupancy of each room recorded and the counts compared against the 1000 CFU/m3 upper acceptable limit of the European residential guidelines and the Chinese Academy of Sciences | F-1409 Effects of non-thermal plasma on disinfection of indoor air … (2026) | machine |
| — | other 767 | 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-0190 Seasonal evaluation of culturable bioaerosols and airborne p… (2025) | machine |
| — | mean 184.4 | children in water-damaged dwellings · home (water-damaged) | study of 50 children and their parents in water-damaged dwellings in Seoul and Gyeonggi-do: molds, bacteria, formaldehyde, TVOC and PM10 measured in bedrooms and living rooms, ISAAC questionnaire on allergic diseases, three exposure assessment tools | F-0359 Lee Association of exposure to indoor molds and dampness with al… (2024) | machine |
| — | mean 135.3 | children in water-damaged dwellings · home (water-damaged) | study of 50 children and their parents in water-damaged dwellings in Seoul and Gyeonggi-do: molds, bacteria, formaldehyde, TVOC and PM10 measured in bedrooms and living rooms, ISAAC questionnaire on allergic diseases, three exposure assessment tools | F-0360 Lee Association of exposure to indoor molds and dampness with al… (2024) | machine |
| — | mean 478.5 | — · 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-0378 Chen et al. Indoor Air Quality in the Metro System in North Taiwan (2016) | machine |
| — | mean 995.2 | — · 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-0379 Chen et al. Indoor Air Quality in the Metro System in North Taiwan (2016) | machine |
| — | mean 1088.8 | 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-1397 Wikuats Assessment of airborne particles and bioaerosols concentrati… (2020) | machine |
| — | share-above 46 per 300 % | — · health centre | assessment of indoor air quality in four primary health care centres in Qatar: culturable airborne bacteria sampled in the cold and the warm season with genus identification by 16S ribosomal RNA sequencing | F-1408 Abdelrahman et al. Assessment of Indoor Air Quality of Four Primary Health Care… (2022) | machine |
| — | other 140 | — · apartment | seasonal study of bioaerosols in the indoor air of residential apartments: culturable bacteria with identification of Staphylococcus and meticillin-resistant Staphylococcus aureus, and respiratory viruses, sampled across the seasons | F-1413 Seasonal evaluation of bioaerosols from indoor air of reside… (2014) | machine |
| — | other 80 | — · apartment | seasonal study of bioaerosols in the indoor air of residential apartments: culturable bacteria with identification of Staphylococcus and meticillin-resistant Staphylococcus aureus, and respiratory viruses, sampled across the seasons | F-1414 Seasonal evaluation of bioaerosols from indoor air of reside… (2014) | 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 bacteria. Coridum Knowledge G-0118, 16 September 2026. https://coridum.com/k/G-0118/