Tire-Derived Organic Chemicals in Urban Air at the Source-Sector Scale and Guidance on the Application of Polyurethane Foam Disk Passive Air Samplers
Bibliographic record
Abstract
High Resolution Image Download MS PowerPoint Slide Tire-derived chemicals (TDCs) are shown to be elevated in urban environments. In this study, we analyzed 6PPD-quinone, 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), hexa(methoxy)methylmelamine (HMMM), as well as selected benzothiazoles and benzotriazoles, in different urban source-sectors. The chemical analyses were conducted on archived extracts of polyurethane foam (PUF) disk passive air samplers deployed across eight locations (including residential, industrial, semiurban, and traffic areas) over successive 2-month periods in the Greater Toronto Area, Canada. Principal component analysis showed distinct profiles in traffic-heavy locations, where benzothiazole and 6PPD-quinone had maximal concentrations of 2100 pg/m 3 and 3.4 pg/m 3, and where several TDCs including 6PPD-quinone, benzotriazoles, and some benzothiazoles were elevated during winter months. HMMM had elevated concentrations in nontraffic sectors, suggesting anthropogenic sources other than tires. This study recognizes the unique challenges to accurately quantifying TDCs in ambient air and that results presented here should be considered semiquantitative. To reduce uncertainty, temperature-dependent PUF disk-air partition coefficients (K PUF-AIR ) and gas-particle partitioning fractions of TDCs in ambient air are presented. These are calculated from K OA values derived from quantum chemical methods using COSMOtherm and show that TDCs span a wide range of volatilities and gas-particle partitioning behavior, with implications for atmospheric fate and exposure. Lastly, guidance is provided on future measures to evaluate and minimize degradation losses of TDCs during sampling, extraction, and storage.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".