Evidence map›Paper›PMID 34058577›Full record

SynthesisThe Science of the total environment2021

Effectiveness of indoor air purification intervention in improving cardiovascular health: A systematic review and meta-analysis of randomized controlled trials.

Xi Xia, Ka Hung Chan, Kin Bong Hubert Lam, Hong Qiu, Zhiyuan Li, Steve Hung Lam Yim, Kin-Fai Ho

Abstract readMeta-AnalysisSystematic Review
PubMed Full text at PMC Publisher
In one paragraph

Synthesis in The Science of the total environment, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 19 papers, 1 of them a synthesis that pooled it.

0numbers the graph read from it
0cells of the map it votes in
19citing papers in PubMed, 1 pooled it
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

19 citing papers in PubMed, 1 synthesis or guideline pooled it.

  1. Pooled it
  2. Trial
  3. Article
  4. Review
  5. Article
  6. Review
  7. The Impact of Home Interventions on Dry Eye Disease (DED) Symptoms and Signs in United States Veterans.International journal of environmental research and public health · 2025
    Article
  8. Article
  9. Article
  10. Review
  11. Article
  12. Article
  13. Review
  14. Article
  15. Review
  16. Article
  17. Portable air cleaner use and biomarkers of inflammation: A systematic review and meta-analysis.American heart journal plus : cardiology research and practice · 2022
    Article
  18. Article
  19. Negative Ion Purifier Effects on Indoor Particulate Dosage to Small Airways.International journal of environmental research and public health · 2021
    Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

7 authors.

Xi XiaThe Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong Special Administrative Region. Electronic address: xiaxi@link.cuhk.edu.hk.
Ka Hung ChanClinical Trial Service Unit and Epidemiological Studies Unit, Nuffield Department of Population Health, University of Oxford, UK; Oxford British Heart Foundation Centre of Research Excellence, University of Oxford, UK. Electronic address: kahung.chan@ndph.ox.ac.uk.
Kin Bong Hubert LamClinical Trial Service Unit and Epidemiological Studies Unit, Nuffield Department of Population Health, University of Oxford, UK. Electronic address: hubert.lam@ndph.ox.ac.uk.
Hong QiuInstitute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Hong Kong Special Administrative Region. Electronic address: hongqiu@cuhk.edu.hk.
Zhiyuan LiInstitute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Hong Kong Special Administrative Region. Electronic address: zhiyuanli@cuhk.edu.hk.
Steve Hung Lam YimInstitute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Hong Kong Special Administrative Region; The Department of Geography and Resource Management, The Chinese University of Hong Kong, Hong Kong Special Administrative Region; Asian School of the Environment, Nanyang Technological University, Singapore. Electronic address: steveyim@cuhk.edu.hk.
Kin-Fai HoThe Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong Special Administrative Region. Electronic address: kfho@cuhk.edu.hk.

Funding

British Heart Foundation RE/18/3/34214Cancer Research UK 16896
6 · The paper itself

Abstract

Indoor air purifiers are increasingly marketed for their health benefits, but their cardiovascular effects remain unclear. We systematically reviewed and meta-analysed randomized controlled trials (RCTs) on the cardiovascular effects of indoor air purification interventions in humans of all ages. We searched Embase, Medline, PubMed, and Web of Science from inception to 22 August 2020. Fourteen cross-over RCTs (18 publications) were included. Systolic blood pressure (SBP) was significantly reduced after intervention (-2.28 (95% CI: -3.92, -0.64) mmHg). There were tendencies of reductions in diastolic blood pressure (-0.35 [-1.52, 0.83] mmHg), pulse pressure (PP) (-0.86 [-2.07, 0.34] mmHg), C-reactive protein (-0.23 [-0.63, 0.18] mg/L), and improvement in reactive hyperaemia index (RHI) (0.10 [-0.04, 0.24]) after indoor air purification, although the effects were not statistically significant. However, when restricting the analyses to RCTs using physical-type purifiers only, significant improvements in PP (-1.56 [-2.98, -0.15] mmHg) and RHI (0.13 [0.01, 0.25]) were observed. This study found potential evidence on the short-term cardiovascular benefits of using indoor air purifiers, especially for SBP, PP and RHI. However, under the Grading of Recommendations Assessment, Development and Evaluation framework, the overall certainty of evidence was very low, which discourage unsubstantiated claims on the cardiovascular benefits of air purifiers. We have also identified several key methodological limitations, including small sample size, short duration of intervention, and the lack of wash-out period. Further RCTs with larger sample size and longer follow-up duration are needed to clarify the cardiovascular benefits of air purification interventions.

Indexed as

Air FiltersAir Pollution, IndoorCardiovascular DiseasesBlood PressureHumansRandomized Controlled Trials as TopicAir purificationCardiovascular healthIndoor airMeta-analysisRandomized controlled trial

Identifiers

PMID34058577
PMCPMC7611692

What OpenQuestion holds

Textmetadata
LicenceTDM
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.