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69/100

✓ Peer-reviewed alzhub usefulness score 69 out of 100. Prevention and risk

Topic: Risk, prevention and care in population studies

Background A rapidly evolving evidence base suggests that exposure to outdoor air pollution is a risk factor for the onset of dementia, with an upturn in publications since 2022. Study-level risk of bias and confidence in the overall body of evidence were assessed with the Office of Health Assessment and Translation tool, and publication bias was examined. In meta-analyses of incident dementia, we identified a dementia diagnosis to be significantly associated with long-term exposure to PM 2·5 (21 studies, n=24 030 527, pooled adjusted hazard ratio (HR) per 5 μg/m 3 increase in exposure, 1·08 [95% CI 1·02-1·14]; I 2 =95%), nitrogen dioxide (16 studies, n=17 228 429, pooled adjusted HR per 10 μg/m 3 increase, 1·03 [1·01-1·05]; I 2 =84%), and black carbon/PM 2·5 absorbance (six studies, n=19 421 865, pooled adjusted HR per 1 μg/m 3 increase, 1·13 [1·01-1·27]; I 2 =97%). We found no significant association for exposure to nitrogen oxides (five studies, n=241 409, pooled adjusted HR per 10 μg/m 3 increase, 1·05 [0·97-1·13]; I 2 =44%), PM 10 (four studies, n=246 440, pooled adjusted HR per 15 μg/m 3 increase, 1·52 [0·80-2·87]; I 2 =82%), or annual ozone (four studies, n=419 972, pooled adjusted HR per 45 μg/m 3 increase, 0·82 [0·35-1·92]; I 2 =69%), with moderate to considerable heterogeneity between studies in these pooled analyses. Of the 32 studies overall, three (9%) had a probably high risk of bias in one of seven domains; all other studies had ratings of probably to definitely low risk of bias. The overall certainty of evidence of studies in the systematic review was moderate.

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APA 7th

Best Rogowski, C. B., Bredell, C., Shi, Y., Tien-Smith, A., Szybka, M., Fung, K. W., et al. (2025). Long-term air pollution exposure and incident dementia: a systematic review and meta-analysis. Lancet Planetary Health. https://doi.org/10.1016/S2542-5196(25)00118-4

Vancouver

Best Rogowski CB, Bredell C, Shi Y, Tien-Smith A, Szybka M, Fung KW, et al. Long-term air pollution exposure and incident dementia: a systematic review and meta-analysis. Lancet Planetary Health. 2025. doi:10.1016/S2542-5196(25)00118-4. PMID: 40716448.

BibTeX

@article{bestrogowski2025-40716448,
  author  = {Best Rogowski, C. B. and Bredell, C. and Shi, Y. and Tien-Smith, A. and Szybka, M. and Fung, K. W. and others},
  title   = {{Long-term air pollution exposure and incident dementia: a systematic review and meta-analysis}},
  journal = {Lancet Planetary Health},
  year    = {2025},
  doi     = {10.1016/S2542-5196(25)00118-4},
  pmid    = {40716448},
  url     = {https://doi.org/10.1016/S2542-5196(25)00118-4}
}

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Key findings

Background A rapidly evolving evidence base suggests that exposure to outdoor air pollution is a risk factor for the onset of dementia, with an upturn in publications since 2022.
Study-level risk of bias and confidence in the overall body of evidence were assessed with the Office of Health Assessment and Translation tool, and publication bias was examined.
In meta-analyses of incident dementia, we identified a dementia diagnosis to be significantly associated with long-term exposure to PM 2·5 (21 studies, n=24 030 527, pooled adjusted hazard ratio (HR) per 5 μg/m 3 increase in exposure, 1·08 [95% CI 1·02-1·14]; I 2 =95%), nitrogen dioxide (16 studies, n=17 228 429, pooled adjusted HR per 10 μg/m 3 increase, 1·03 [1·01-1·05]; I 2 =84%), and black carbon/PM 2·5 absorbance (six studies, n=19 421 865, pooled adjusted HR per 1 μg/m 3 increase, 1·13 [1·01-1·27]; I 2 =97%).
We found no significant association for exposure to nitrogen oxides (five studies, n=241 409, pooled adjusted HR per 10 μg/m 3 increase, 1·05 [0·97-1·13]; I 2 =44%), PM 10 (four studies, n=246 440, pooled adjusted HR per 15 μg/m 3 increase, 1·52 [0·80-2·87]; I 2 =82%), or annual ozone (four studies, n=419 972, pooled adjusted HR per 45 μg/m 3 increase, 0·82 [0·35-1·92]; I 2 =69%), with moderate to considerable heterogeneity between studies in these pooled analyses.
Of the 32 studies overall, three (9%) had a probably high risk of bias in one of seven domains; all other studies had ratings of probably to definitely low risk of bias.

Why it matters

This review found that long-term exposure to fine particulate matter, nitrogen dioxide, and black carbon was significantly associated with a dementia diagnosis, while no significant association was found for nitrogen oxides, larger particles, or ozone. The authors note that most included studies had a probable high risk of bias.

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Study details

Study designmeta-analysis
Participants24,030,527
Effect sizePM2.5 HR 1.08 per 5 ug/m3 (95% CI 1.02-1.14); NO2 HR 1.03 per 10 ug/m3 (1.01-1.05)
Evidence strengthModerate

Limitations

Very high heterogeneity; exposure estimated from residential address; cannot identify critical exposure windows.

How this study scored 69/100

Published in a peer-reviewed journal, and it is a meta-analysis pooling many studies. We have no data on free to read, so that was left out: it earned 68 of the 98 points we could judge it on, which is 69 out of 100.

Component	Points	Why
Journal tier	7 / 10	Tier 3 — peer-reviewed journal (Lancet Planetary Health)
Journal's citation record	1 / 4	The Lancet Planetary Health: journal h-index 139 (OpenAlex, 2026-10-29)
Study design	12 / 12	A meta-analysis pooling many studies
Strength of evidence	3 / 5	Rated “moderate” in our summary
Peer-review validation	10 / 10	Peer-reviewed. Published as an article in a named peer-reviewed journal.
How recent	4 / 5	2025 — within 3 year(s) of the newest study here
Sample size	4 / 4	24,030,527 participants
Effect reported	3 / 3	Effect reported with a statistic (interval, p-value, ratio or similar)
Studied in people	3 / 3	Studied in people (participant count stated)
Randomised / blinded	0 / 2	A review of other studies — randomisation is not credited here
Times cited	4 / 7	Cited 40 times (OpenAlex, 2026-10-10)
Citations per year	3 / 5	13.3 citations a year over 3 year(s) since 2025
Impact for its field and year	3 / 6	Cited 6.7× the average for papers of its field and year (OpenAlex FWCI)
Cited by studies here	1 / 6	Cited by 1 other studies in this library
Still being cited	2 / 4	Cited 40 times in 2024–2026 (2026 still in progress; OpenAlex)
Senior author's track record	2 / 4	Last-listed author Haneen Khreis: h-index 39 (OpenAlex, whole career)
Institution's track record	2 / 3	University of Cambridge: institution h-index 1,973 (OpenAlex)
Multi-centre collaboration	2 / 3	OpenAlex lists 6 institution(s) in 3 countries
Indexed in PubMed	2 / 2	Indexed in PubMed (PMID 40716448)
Free to read	— / 2	Access not recorded — left out of this score
Points	68 / 98	Scored on 19 of 20 parts. We have no data for the rest, so they are left out: 68 of the 98 points we could judge it on is 69 out of 100.
Total	69 / 100	—

What each of these 20 components measures, and what this score is not →

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