Measurements of Gas phase Acids in Diesel Exhaust:\nA Relevant Source of HNCO?
Bibliographic record
Abstract
Gas-phase\nacids in light duty diesel (LDD) vehicle exhaust were\nmeasured using chemical ionization mass spectrometry (CIMS). Fuel\nbased emission factors (EF) and NO<sub><i>x</i></sub> ratios\nfor these species were determined under differing steady state engine\noperating conditions. The derived HONO and HNO<sub>3</sub> EFs agree\nwell with literature values, with HONO being the single most important\nacidic emission. Of particular importance is the quantification of\nthe EF for the toxic species, isocyanic acid (HNCO). The emission\nfactors for HNCO ranged from 0.69 to 3.96 mg kg<sub>fuel</sub><sup>–1</sup>, and were significantly higher than previous biomass\nburning emission estimates. Further ambient urban measurements of\nHNCO demonstrated a clear relationship with the known traffic markers\nof benzene and toluene, demonstrating for the first time that urban\ncommuter traffic is a source of HNCO. Estimates based upon the HNCO-benzene\nrelationship indicate that upward of 23 tonnes of HNCO are released\nannually from commuter traffic in the Greater Toronto Area, far exceeding\nthe amount possible from LDD alone. Nationally, 250 to 770 tonnes\nof HNCO may be emitted annually from on-road vehicles, likely representing\nthe dominant source of exposure in urban areas, and with emissions\ncomparable to that of biomass burning.
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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 | 0.001 |
| 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) | 0.018 | 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".