This page is alzhub.org's plain-English summary of a published study, not the paper itself. It is generated from the record we hold for this study, sourced and linked below — check the original for the full text and methods.

45/100

✓ Peer-reviewed alzhub usefulness score 45 out of 100. Disparities

Topic: Risk, prevention and care in population studies

Plain-language summary

Background Exposure to ambient airborne particulate matter is a major risk factor for mortality and morbidity, associated with asthma, lung cancer, heart disease, myocardial infarction, and stroke, and more recently type 2 diabetes, dementia and loss of cognitive function. Less is understood about differential effects of particulate matter from different sources. Underground railways are used by millions of people on a daily basis in many cities. Poor air exchange with the outside environment means that underground railways often have an unusually high concentration of airborne particulate matter, while a high degree of railway-associated mechanical activity produces particulate matter which is physicochemically highly distinct from ambient particulate matter. The implications of this for the health of exposed commuters and employees is unclear. Main body A literature search found 27 publications directly assessing the potential health effects of underground particulate matter, including in vivo exposure studies, in vitro toxicology studies, and studies of particulate matter which might be similar to that found in underground railways. The methodology, findings, and conclusions of these studies were reviewed in depth, along with further publications directly relevant to the initial search results. In vitro studies suggest that underground particulate matter may be more toxic than exposure to ambient/urban particulate matter, especially in terms of endpoints related to reactive oxygen species generation and oxidative stress. This appears to be predominantly a result of the metal-rich nature of underground particulate matter, which is suggestive of increased health risks. However, while there are measureable effects on a variety of endpoints following exposure in vivo, there is a lack of evidence for these effects being clinically significant as may be implied by the in vitro evidence. Conclusion There is little direct evidence that underground railway particulate matter exposure is more harmful than ambient particulate matter exposure. This may be due to disparities between in vivo exposures and in vitro models, and differences in exposure doses, as well as statistical under powering of in vivo studies of chronic exposure. Future research should focus on outcomes of chronic in vivo exposure, as well as further work to understand mechanisms and potential biomarkers of exposure.

What this study adds

Evidence grade: Low

This is a narrative review. This review found that in vitro studies suggest underground railway particulate matter may be more toxic than ambient particulate matter, but the implications for the health of exposed commuters and employees are unclear. It reports no findings on treating, curing, or preventing Alzheimer's disease.

Taken from this record’s own fields, not from reading the paper. The grade is assigned from the abstract’s wording; what that means.

Cite this study APA, Vancouver, BibTeX · download .bib or .ris

APA 7th

Loxham, M., & Nieuwenhuijsen, M. J. (2019). Health effects of particulate matter air pollution in underground railway systems - a critical review of the evidence. Particle and fibre toxicology. https://doi.org/10.1186/s12989-019-0296-2

Vancouver

Loxham M, Nieuwenhuijsen MJ. Health effects of particulate matter air pollution in underground railway systems - a critical review of the evidence. Particle and fibre toxicology. 2019. doi:10.1186/s12989-019-0296-2. PMID: 30841934.

BibTeX

@article{loxham2019-30841934,
  author  = {Loxham, M. and Nieuwenhuijsen, M. J.},
  title   = {{Health effects of particulate matter air pollution in underground railway systems - a critical review of the evidence}},
  journal = {Particle and fibre toxicology},
  year    = {2019},
  doi     = {10.1186/s12989-019-0296-2},
  pmid    = {30841934},
  url     = {https://doi.org/10.1186/s12989-019-0296-2}
}

Built from the record alzhub holds for this paper, not looked up. Volume, issue and page numbers are not held in the record. Check the citation against the original before you use it.

How to read this study

Design: this is a narrative review. It summarises a field without a fixed search method, so it shows how authors read the evidence rather than measuring it. Use it to find the primary studies, not as a result in itself.
Size: the record gives no participant count. Look for one in the original before trusting a pattern.
Effect: the record gives no effect size, so the summary above cannot say how large any difference was.

What the evidence grade means here

This page is graded low. alzhub.org assigns the grade automatically from keywords in the abstract, not from reading the paper. Low means the abstract matched neither pattern. It is the default label, and it does not mean the work is poor; many sound lab and imaging papers land here. It can add at most 5 of the 100 points in the study score, and it is a label about design, not a verdict on whether the findings are true.

New to reading papers? Six questions to ask of any Alzheimer’s study · how we score.

Key findings

Background Exposure to ambient airborne particulate matter is a major risk factor for mortality and morbidity, associated with asthma, lung cancer, heart disease, myocardial infarction, and stroke, and more recently type 2 diabetes, dementia and loss of cognitive function.
The methodology, findings, and conclusions of these studies were reviewed in depth, along with further publications directly relevant to the initial search results.
In vitro studies suggest that underground particulate matter may be more toxic than exposure to ambient/urban particulate matter, especially in terms of endpoints related to reactive oxygen species generation and oxidative stress.
This appears to be predominantly a result of the metal-rich nature of underground particulate matter, which is suggestive of increased health risks.
However, while there are measureable effects on a variety of endpoints following exposure in vivo, there is a lack of evidence for these effects being clinically significant as may be implied by the in vitro evidence.

Why it matters

This review found that in vitro studies suggest underground railway particulate matter may be more toxic than ambient particulate matter, but the implications for the health of exposed commuters and employees are unclear. It reports no findings on treating, curing, or preventing Alzheimer's disease.

New to this subject? Start with our plain-English guide: Disparities →

Study details

Evidence strengthLow

How this study scored 45/100

Published in a peer-reviewed journal. Scored zero for study design, sample size, effect reported, studied in people and randomized / blinded because the record does not state it.

Component	Points	Why
Journal tier	7 / 10	Tier 3 — peer-reviewed journal (Particle and fibre toxicology)
Journal's citation record	1 / 4	Particle and Fibre Toxicology: journal h-index 149 (OpenAlex, 2026-10-29)
Study design	0 / 12	No study design recorded — scores zero, not guessed (not stated in the record — scored 0)
Strength of evidence	1 / 5	Rated “low” in our summary
Peer-review validation	10 / 10	Peer-reviewed. Published as an article in a named peer-reviewed journal.
How recent	2 / 5	2019 — within 10 year(s) of the newest study here
Sample size	0 / 4	Participant count not stated — scores zero (not stated in the record — scored 0)
Effect reported	0 / 3	No effect size reported — scores zero (not stated in the record — scored 0)
Studied in people	0 / 3	Not stated whether this was studied in people — scores zero (not stated in the record — scored 0)
Randomized / blinded	0 / 2	No randomization or blinding stated — scores zero (not stated in the record — scored 0)
Times cited	5 / 7	Cited 139 times (OpenAlex, 2026-10-10)
Citations per year	3 / 5	15.4 citations a year over 9 year(s) since 2019
Impact for its field and year	3 / 6	Cited 7.6× the average for papers of its field and year (OpenAlex FWCI)
Cited by studies here	0 / 6	No other study in this library cites it
Still being cited	2 / 4	Cited 47 times in 2024–2026 (2026 still in progress; OpenAlex)
Senior author's track record	4 / 4	Last-listed author Mark J Nieuwenhuijsen: h-index 153 (OpenAlex, whole career)
Institution's track record	1 / 3	University of Southampton: institution h-index 938 (OpenAlex)
Multicenter collaboration	2 / 3	OpenAlex lists 7 institution(s) in 2 countries
Indexed in PubMed	2 / 2	Indexed in PubMed (PMID 30841934)
Free to read	2 / 2	Free to read
Total	45 / 100	—

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

Read the original

Full text: free to read — OpenAlex lists this copy as free to read: the link above (checked 6 Feb 1020).

Studies in the library that share something with this one. The line above each title says what.

Related studies in Disparities from nearby years

Also in Disparities

98 studies in the library are filed under Disparities with no topic tag they share with another; these are this study's neighbours in a fixed tour of them. The Disparities hub.

Similar studies

More on Disparities

See all studies in Disparities →