Detailed quality assessment of included studies using the Newcastle-Ottawa Scale (NOS) for observational studies and Critical Appraisal Skills Programme (CASP) checklists for reviews and qualitative studies.
| Study | Assessment tool | Selection (NOS) or aims/methodology (CASP) | Comparability (NOS) or data rigor (CASP) | Outcome (NOS) or findings value/ethics (CASP) | Total score/rating | Overall quality |
|---|---|---|---|---|---|---|
| Hystad et al., 2013 [3] | NOS | 4/4 (Representative cohort, secure exposure ascertainment) | 2/2 (Controlled for age, sex, smoking) | 2/3 (Independent outcome assessment, but some loss to follow-up) | 8/9 | High |
| Aguilera et al., 2021 [2] | CASP | Clear aims, appropriate review methodology | Moderate rigor in data synthesis | High value, ethical considerations addressed | N/A | Moderate |
| Palma et al., 2013 [4] | CASP | Clear aims, robust meta-analysis methods | High rigor in data collection/analysis | High value for clinical implications, ethics N/A | N/A | High |
| Cui et al., 2015 [5] | CASP | Clear aims, systematic meta-analysis approach | High rigor, but some heterogeneity in studies | Strong findings value, ethics addressed | N/A | High |
| Ohri et al., 2015 [6] | NOS | 4/4 (Well-defined cohorts, reliable exposure) | 2/2 (Adjusted for confounders) | 2/3 (Adequate follow-up, but potential attrition bias) | 8/9 | High |
| Dodd et al., 2018 [7] | CASP | Clear aims, qualitative methodology suitable | High rigor in thematic analysis | High value for policy, strong ethical focus | N/A | High |
| Black et al., 2017 [8] | NOS | 3/4 (Good representativeness, but limited non-exposed selection) | 2/2 (Controlled for key factors) | 2/3 (Long follow-up, but some incompleteness) | 7/9 | High |
| Xu et al., 2020 [9] | CASP | Clear aims, comprehensive review design | High rigor in evidence synthesis | High global health value, ethics considered | N/A | High |
| To et al., 2021 [10] | CASP | Aims are clear, scoping review is appropriate | Moderate rigor due to broad scope | Moderate value, limited depth in ethics | N/A | Moderate |
| Malone et al., 2020 [11] | CASP | Clear aims, review methodology fitting | High rigor in data appraisal | High practical value, ethics addressed | N/A | High |
| Hahn et al., 2021 [12] | CASP | Aims are clear, scoping review is appropriate | Moderate rigor due to broad scope | Moderate value, limited depth in ethics | N/A | High |
| Kulig et al., 2009 [13] | CASP | Clear aims, qualitative methods are appropriate | High rigor in data collection | High value for rural health, strong ethics | N/A | High |
| Landrigan et al., 2018 [14] | CASP | Clear aims, commission-style review | High rigor in global data synthesis | High policy value, ethics emphasized | N/A | High |
| Ohri et al., 2016 [15] | NOS | 3/4 (Solid cohorts, but some exposure ascertainment issues) | 2/2 (Adjusted well) | 2/3 (Adequate follow-up) | 7/9 | High |
| Aguilera et al., 2021 [2] | NOS | 4/4 (Representative observational data) | 2/2 (Controlled for sources of PM2.5) | 2/3 (Robust outcomes, but short-term focus) | 8/9 | High |