Indoor environment factor
Ultrafine particles (UFP)
Part of: Particulate matter (PM₂.₅ and PM₁₀)
Also: UFP, PM0.1
Particles smaller than 0.1 micrometre. Their small size lets them travel deepest into the respiratory system.
“Indoor particle number concentrations were >1000× higher than background levels during the operation of the stove and hot plate (with no food or pans).”
What the studies report
12 of 19 Findings — those with the strongest study design.
| Linked to | Effect | Population | Study design | Source | Checked |
|---|---|---|---|---|---|
| Air filtration and air purifiers | a particle number concentration, so it is dominated by the smallest particles; the study found no statistically significant effect on the health markers | — · home | crossover filtration study in the homes of elderly subjects: custom-built particle filter units run in the living room and the bedroom, with fine particles and particle number measured and cardiovascular and lung outcomes recorded before and during each exposure scenario | F-1668 An indoor air filtration study in homes of elderly: cardiova… (2013) | machine |
| Air purifiers | difference 57 | — · classroom | experiment in a classroom with a heater: a virus-containing aerosol was generated and the particle number concentration measured under nineteen cases combining closed windows, natural ventilation through windows opened to a third of their width, and one or two air purifiers in different positions | F-1383 Park et al. Natural Ventilation and Air Purification for Effective Remov… (2022) | machine |
| Air purifiers | difference 52 | — · classroom | experiment in a classroom with a heater: a virus-containing aerosol was generated and the particle number concentration measured under nineteen cases combining closed windows, natural ventilation through windows opened to a third of their width, and one or two air purifiers in different positions | F-1384 Park et al. Natural Ventilation and Air Purification for Effective Remov… (2022) | machine |
| — | other 100000 | — · test house | experiments in the Purdue zEDGE test house: hair styling with a straightener, a curler and a waver at controlled tool temperatures while indoor nanoparticle number concentrations and the inhaled dose were measured | F-1402 Indoor Nanoparticle Emissions and Exposures during Heat-Base… (2025) | machine |
| — | a stated direction; the appliances were run empty, so the emission is the appliance itself | — · test house | measurement campaign during the HOMEChem experiment in a test house: indoor particulate matter concentrations, size distributions and exposures measured across cooking and cleaning activities, with the stove and hot plate also run empty | F-1403 Patel et al. Indoor particulate matter during HOMEChem - Concentrations, … (2020) | machine |
| Air purifiers | other 95 | — · classroom | measurement study of portable air purifiers and of ventilation systems with in-line filters in classrooms: particle mass and particle number measured indoors and outdoors, with the capture efficiency of the purifier determined by size range | F-1423 Aldekheel et al. The Role of Portable Air Purifiers and Effective Ventilation… (2022) | machine |
| Air filtration and air purifiers | difference 5 per 1 % | — · test chamber | chamber experiments with breathing simulators: personal exposure to respiratory aerosols measured under combinations of ventilation rate, portable high efficiency air cleaners, universal masking, source placement and distance | F-1426 Coyle et al. Efficacy of Ventilation, HEPA Air Cleaners, Universal Maskin… (2021) | machine |
| Air purifiers | the study calls PM1 the ultrafine fraction; the standard deviation fell from 1.6 to 0.4 μg/m3 | — · dwelling | home-based rehabilitation study with an air purifier installed in the patients' dwellings: particulate matter in several size fractions, temperature and relative humidity measured in the living room, bedroom and kitchen before and after the installation | F-1532 Ilieș et al. The Home-Based Rehabilitation of Patients Through Physical E… (2025) | machine |
| Solid fuel | median 3.6 | — · home | measurement study: indoor UFP, PM10, PM2.5, black carbon and CO measured with handheld monitors in the living areas of five non-smoking households in Guildford using four stove types and four solid fuels during winter | F-0097 Particulate matter exposure from different heating stoves an… (2025) | machine |
| Solid fuel | median 2.2 | — · home | measurement study: indoor UFP, PM10, PM2.5, black carbon and CO measured with handheld monitors in the living areas of five non-smoking households in Guildford using four stove types and four solid fuels during winter | F-0101 Particulate matter exposure from different heating stoves an… (2025) | machine |
| Solid fuel | ratio 1.5 | — · home | measurement study: indoor UFP, PM10, PM2.5, black carbon and CO measured with handheld monitors in the living areas of five non-smoking households in Guildford using four stove types and four solid fuels during winter | F-0106 Particulate matter exposure from different heating stoves an… (2025) | machine |
| — | other 0.0043 | — · test chamber | full-scale laboratory chamber experiment: tufted synthetic carpet loaded with neutralised alumina dust, PM measured with a Grimm Miniwras counter during 10 min of human walking, resuspension rates estimated from a mass balance under the well-mixed assumption | F-0275 Benabed PM10, PM2.5, PM1, and PM0.1 resuspension due to human walkin… (2022) | 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
- Spatiotemporal Mapping of Ultrafine Particle Fluxes in an Office HVAC System with a Diffusion Charger Sensor Array (2025). ACS EST Air. doi:10.1021/acsestair.4c00140 CKB 1136
- Particulate matter exposure from different heating stoves and fuels in UK homes… (2025). Sci Rep. doi:10.1038/s41598-025-05886-1 CKB 1154
- Hand eczema and skin complaints in particulate matter-exposed occupations - firefighters, chimney sweepers, and ferrosilicon smelter workers in Norway (2024). doi:10.1186/s12995-024-00407-8 CKB 0653
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. Ultrafine particles (UFP). Coridum Knowledge G-0045, 16 September 2026. https://coridum.com/k/G-0045/