Ultraviolet germicidal irradiation inactivation of airborne fungal spores and bacteria in upper-room air and HVAC in-duct configurations
Bibliographic record
Abstract
The efficacy of ultraviolet germicidal irradiation (UVGI) for inactivating airborne fungal spores and bacterial vegetative cells was evaluated under three configurations — intrinsic, upper-room air, and in-duct. Correspondingly, experiments were performed in (1) a pilot-scale chamber (0.8 m3), fitted with four corner UV lamps that irradiated the entire chamber (average UV fluence rate 10.6 ± 0.8 µJ s–1cm–2); (2) a full-scale room (87 m3), fitted with a UVGI system that irradiated the top 30 cm of the room (5 fixtures, 216 W total lamp power, average upper-zone UV fluence rate 26 ± 1 µJ s–1cm–2); and (3) the supply air duct of a heating ventilation and air-conditioning (HVAC) system. Fungal spores of Aspergillus versicolor and vegetative cells of bacterium Mycobacterium parafortuitum were aerosolized continuously such that their numbers and physiologic state were comparable both with and without the UVGI lamps operating. The Z value (UVGI inactivation rate normalized to UVGI fluence rate) was estimated to be 1.2 ± 0.4 x 10–4 cm2 µJ–1 for aerosolized A. versicolor. Upper-room air UVGI inactivated culturable airborne fungal spores with a first-order rate constant of 0.4 ± 0.2 h–1. Ultraviolet lamps enclosed in ventilation system ductwork inactivated fungal spores and vegetative bacterial cells at single-pass efficiencies of 75% and 87%, respectively, at an air stream velocity of 2.2 m s–1. There was no detected inactivation of fungal spores and vegetative bacterial cells at an air stream velocity of 5.1 m s–1. Key words: bioaerosols, UVGI, air disinfection.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".