Associations between residential fossil fuel combustion and indoor concentrations of nitrogen dioxide, carbon monoxide, and aldehydes in Canadian homes
Bibliographic record
Abstract
Abstract Background There is increasing attention on the effects of residential fossil fuel combustion, particularly the use of natural gas or oil, on indoor air quality. Given the prevalent use of natural gas in Canadian homes, understanding its influence on indoor air quality is important. Objective This study investigated associations between indoor levels of nitrogen dioxide (NO2), carbon monoxide (CO), formaldehyde, and acetaldehyde with potential emission sources and other influencing factors in 344 homes in four Canadian cities. Methods Using mixed models and general linear models, we evaluated the associations between potential sources and pollutant concentrations, conducting both city-specific and pooled analyses for winter and summer seasons. Results Our findings indicated that gas stoves, present in 24% of the homes, were significantly associated with increased indoor NO2 concentrations, resulting in a 191% increase in winter and a 114% increase in summer. Additionally, the presence of gas stoves was strongly associated with a 43% increase in peak hourly CO levels in winter. The presence of gas clothes dryers was significantly associated with increased indoor NO2 levels (47% in summer and 54% in winter). Oil heating was significantly associated with a 58% increase in winter indoor NO2 levels. Gas heating was associated with a 62% increase in winter NO2 levels in older homes (built before 1949), with marginal significance. Aldehyde levels were primarily associated with off-gassing from building materials and household activities. Other factors associated with indoor pollutant levels included housing characteristics, occupant behaviors, indoor environmental conditions, and outdoor sources. Impact This study enhances understanding of the association between fossil fuel combustion and indoor air quality in predominantly detached homes. It highlights differences in pollutant levels between homes with gas and electric cooking, which can inform advice on cooking practices to reduce emissions in homes.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".