Chemical Partitioning and Multiphase Oxidation of Organic Contaminants in the Indoor Environment
Bibliographic record
Abstract
Indoor air composition is highly dynamic and strongly influenced by human activities. Airborne chemicals undergo interactions and transformations with condensed-phase surface materials and chemicals present on surfaces, thus impacting human health via multiple chemical exposure pathways. Contrasting with the outdoor environment, indoor surfaces are huge reservoirs for gas-phase contaminants due to gas-surface partitioning and high surface area-to-volume ratios, however, systematic studies on the partitioning behavior in genuine indoor spaces are lacking. Multiphase reactions of indoor oxidants and reactive environmental pollutants on surfaces have been significantly overlooked, as compared to their transformations in the gas or aqueous phase. Thus, the goal of this thesis was to further our understanding of gas-surface partitioning and multiphase oxidation occurring in genuine indoor settings, by using specific indoor materials and pollutants. Four individual projects were conducted to achieve the goal. In the first project, the partitioning behavior of volatile organic compounds (VOCs) to cotton cloth was characterized upon exposure indoors. Under rapid equilibration time (less than a day), the equilibrium partition ratio (KCA) of three homologous series of VOCs was quantified, revealing that log KCA scales linearly with carbon number, and the logarithms of vapor pressure and the octanol-air equilibrium partition ratio (log KOA) within each series. In the second project, to simulate the short-term localized use of consumer products, VOC injections to a residential test house were monitored by online mass spectrometry to characterize the surface uptake kinetics and timescale, and to estimate the effective partitioning capacity. Faster surface uptake, larger spatial gradients and longer persistence within surface reservoirs were found for VOCs with higher log KOA. The third and fourth projects addressed the gas-to-condensed phase oxidation of one class of environmental pollutants – bisphenols – upon individual exposure to environmentally-relevant levels of ozone and OH radicals. Generalized transformation mechanisms were proposed based on product identification. The rapid nature of multiphase ozonolysis was complemented by a 3-week indoor air exposure to thin BPA films and BPA-containing thermal paper. Overall, this thesis explored two critical aspects of indoor chemistry with specific focus on genuine indoor surfaces and emerging environmental pollutants, highlighting their rapid surface partitioning and chemical transformations that can occur with complex indoor surfaces and in the presence of reactive oxidants.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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".