Introduction Exposure to secondhand smoke (SHS) is a health risk to non-smokers. Indoor particulate matter (PM2.5) is associated with SHS exposure and is used as a proxy measure. However, PM2.5 is non-specific and influenced by a number of environmental factors, which are subject to geographical variation. The nature of association between SHS exposure and indoor PM2.5—studied primarily in high-income countries (HICs) context—may not be globally applicable. We set out to explore this association in a low/middle-income country setting, Dhaka, Bangladesh.
Methods A cross-sectional study was conducted among households with at least one resident smoker. We inquired whether smoking was permitted inside the home (smoking-permitted homes, SPH) or not (smoke-free homes, SFH), and measured indoor PM2.5 concentrations using a low-cost instrument (Dylos DC1700) for at least 22 hours. We describe and compare SPH and SFH and use multiple linear regression to evaluate which variables are associated with PM2.5 level among all households.
Results We surveyed 1746 households between April and August 2018; 967 (55%) were SPH and 779 (45%) were SFH. The difference between PM2.5 values for SFH (median 27 µg/m3, IQR 25) and SPH (median 32 µg/m3, IQR 31) was 5 µg/m3 (p<0.001). Lead participant’s education level, being a non-smoker, having outdoor space and smoke-free rule at home and not using kerosene oil for cooking were significantly associated with lower PM2.5.
Conclusions We found a small but significant difference between PM2.5 concentrations in SPH compared with SFH in Dhaka, Bangladesh—a value much lower than observed in HICs.
- low/middle income country
- secondhand smoke
- global health
- socioeconomic status
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Contributors TF cooridinated the study data collection and management, prepared the manuscript, developed the analytical strategy, contributed to the statistical analysis and interpretation of the results, and wrote the first draft of the report. KS and RH conceptualised the study. SS led the design of obtaining PM2.5 measurements. CF, RD and SMA contributed to statistical analysis and interpretation of the results. NM and A-MM contributed to the interpretation of results and revision of the report. All authors participated in manuscript revisions, and read and approved the final manuscript.
Funding This work was supported by the ‘Medical Research Council’ (grant number MR/P008941/1).
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval Ethics approval was received from the Health Sciences Research Governance Committee at University of York (approval date 8 August 2017) and Bangladesh Medical Research Council (BMRC) (Reference: BMRC/NREC/2016–2019/358) prior to the study.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request. The data used in this study are the baseline data of a cluster randomised controlled trial (cRCT) study. The protocol manuscript link is given below https://trialsjournal.biomedcentral.com/articles/10.1186/s13063-018-3100-y. The final analysis of the post-intervention data is ongoing. Data could be made available upon reasonable request after completion of all intended publication of this trial. It would be best to contact the trial chief PI (Siddiqi, Kamran, email: email@example.comORCiD ID: 0000-0003-1529-7778) for further queries.
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