Changes in residential exposure to ambient fine particulate matter due to relocation and long-term survival in Canada: a quasi-experimental study
Bibliographic record
Abstract
BACKGROUND AND AIM: Despite significant advances in understanding the health burden of hypothetical changes in ambient fine particulate matter (PM2.5), less is known how actual changes in PM2.5 levels may influence its long-term adverse effects, especially on mortality. We aimed to conduct a quasi-experiment to evaluate the association between mortality and changes in PM2.5 in Canada. METHODS: We identified movers from a national cohort of Canadian census respondents (10 million) who were aged 25-89 years, had a history of either high or low exposure to PM2.5 before census day, and moved within the following five years, yielding two cohorts. Exposures were ascertained using satellite-derived PM2.5 measurements based on movers’ postal-code addresses since five years before the census day. To assess the relationship between changes in PM2.5 and mortality, we conducted a propensity score matching analysis with Cox proportional hazards model including various covariates. We did various sensitivity analyses, such as considering multiple imputation. RESULTS:Residential mobility yielded a decline in annual PM2.5 exposure from ~10 μg/m3 to 7.4 μg/m3 and to 5.0 μg/m3 in the high to intermediate (or low) movers. Conversely, annual PM2.5 increased from ~4.6 μg/m3 to 6.7 μg/m3 and to 9.2 μg/m3 in the low to intermediate (or high) movers. Over five years after the move, we observed a 6.8% reduction in mortality among individuals whose PM2.5 exposures decreased from high to intermediate levels (95% confidence interval: 1.7%-11.7%). A greater decline in mortality was observed among individuals with a larger reduction in exposures. These results were consistent in sensitivity analyses. Additionally, we found an increase in mortality with elevated PM2.5 exposure. CONCLUSIONS:Decreases in PM2.5 were associated with lowered mortality whereas increases in PM2.5 were associated with elevated mortality in Canada. These results were found at the PM2.5 levels considerably lower than many other countries, providing support for continuously improving air quality. KEYWORDS: quasi-experiment, fine particulate matter, mortality
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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 | 0.005 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.005 | 0.003 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".