Changes in exposure to ambient fine particulate matter after relocating and long term survival in Canada: quasi-experimental study
Bibliographic record
Abstract
Abstract Objective To investigate the association between changes in long term residential exposure to ambient fine particulate matter (PM 2.5 ) and premature mortality in Canada. Design Population based quasi-experimental study. Setting Canada. Participants 663 100 respondents to the 1996, 2001, and 2006 Canadian censuses aged 25-89 years who had consistently lived in areas with either high or low PM 2.5 levels over five years preceding census day and moved during the ensuing five years. Interventions Changes in long term exposure to PM 2.5 arising from residential mobility. Main outcome measures The primary outcome was deaths from natural causes. Secondary outcomes were deaths from any cardiometabolic cause, any respiratory cause, and any cancer cause. All outcomes were obtained from the national vital statistics database. Results Using a propensity score matching technique with numerous personal, socioeconomic, health, and environment related covariates, each participant who moved to a different PM 2.5 area was matched with up to three participants who moved within the same PM 2.5 area. In the matched groups that moved from high to intermediate or low PM 2.5 areas, residential mobility was associated with a decline in annual PM 2.5 exposure from 10.6 μg/m 3 to 7.4 and 5.0 μg/m 3 , respectively. Conversely, in the matched groups that moved from low to intermediate or high PM 2.5 areas, annual PM 2.5 increased from 4.6 μg/m 3 to 6.7 and 9.2 μg/m 3 . Five years after moving, individuals who experienced a reduction in exposure to PM 2.5 from high to intermediate levels showed a 6.8% (95% confidence interval 1.7% to 11.7%) reduction in mortality (2510 deaths in 56 025 v 4925 deaths in 101 960). A greater decline in mortality occurred among those exposed to a larger reduction in PM 2.5 . Increased mortality was found with exposure to PM 2.5 from low to high levels, and to a lesser degree from low to intermediate levels. Furthermore, the decreases in PM 2.5 exposure were most strongly associated with reductions in cardiometabolic deaths, whereas the increases in PM 2.5 exposure were mostly related to respiratory deaths. No strong evidence was found for the changes in PM 2.5 exposure with cancer related deaths. Conclusions In Canada, decreases in PM 2.5 were associated with lower mortality, whereas increases in PM 2.5 were associated with higher mortality. These results were observed at PM 2.5 levels considerably lower than many other countries, providing support for continuously improving air quality.
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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 | 0.004 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.003 | 0.003 |
| Scholarly communication | 0.001 | 0.000 |
| 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".