The relation between past exposure to fine particulate air pollution and prevalent anxiety: observational cohort study
BMJ 2015; 350 doi: https://doi.org/10.1136/bmj.h1111 (Published 24 March 2015) Cite this as: BMJ 2015;350:h1111
- Melinda C Power, postdoctoral fellow123,
- Marianthi-Anna Kioumourtzoglou, postdoctoral fellow2,
- Jaime E Hart, instructor24,
- Olivia I Okereke, assistant professor145,
- Francine Laden, associate professor124,
- Marc G Weisskopf, associate professor12
- 1Department of Epidemiology, Harvard School of Public Health, Boston MA, USA
- 2Department of Environmental Health, Harvard School of Public Health, Boston MA, USA
- 3Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore MD, USA
- 4Channing Division of Network Medicine, Department of Medicine at Brigham and Women’s Hospital and Harvard Medical School, Boston MA, USA
- 5Department of Psychiatry, Brigham and Women’s Hospital and Harvard Medical School, Boston MA, USA
- Correspondence to: M C Power Johns Hopkins University, Phipps 446D, 600 North Wolfe Street, Baltimore, MD 21287, USA melindacpower{at}gmail.com
- Accepted 5 February 2015
Abstract
Objective To determine whether higher past exposure to particulate air pollution is associated with prevalent high symptoms of anxiety.
Design Observational cohort study.
Setting Nurses’ Health Study.
Participants 71 271 women enrolled in the Nurses’ Health Study residing throughout the contiguous United States who had valid estimates on exposure to particulate matter for at least one exposure period of interest and data on anxiety symptoms.
Main outcome measures Meaningfully high symptoms of anxiety, defined as a score of 6 points or greater on the phobic anxiety subscale of the Crown-Crisp index, administered in 2004.
Results The 71 271 eligible women were aged between 57 and 85 years (mean 70 years) at the time of assessment of anxiety symptoms, with a prevalence of high anxiety symptoms of 15%. Exposure to particulate matter was characterized using estimated average exposure to particulate matter <2.5 μm in diameter (PM2.5) and 2.5 to 10 μm in diameter (PM2.5-10) in the one month, three months, six months, one year, and 15 years prior to assessment of anxiety symptoms, and residential distance to the nearest major road two years prior to assessment. Significantly increased odds of high anxiety symptoms were observed with higher exposure to PM2.5 for multiple averaging periods (for example, odds ratio per 10 µg/m3 increase in prior one month average PM2.5: 1.12, 95% confidence interval 1.06 to 1.19; in prior 12 month average PM2.5: 1.15, 1.06 to 1.26). Models including multiple exposure windows suggested short term averaging periods were more relevant than long term averaging periods. There was no association between anxiety and exposure to PM2.5-10. Residential proximity to major roads was not related to anxiety symptoms in a dose dependent manner.
Conclusions Exposure to fine particulate matter (PM2.5) was associated with high symptoms of anxiety, with more recent exposures potentially more relevant than more distant exposures. Research evaluating whether reductions in exposure to ambient PM2.5 would reduce the population level burden of clinically relevant symptoms of anxiety is warranted.
Footnotes
We thank Peter James for his help with the Rural Urban Commuting Area codes.
Contributors: All authors made substantial contributions to the conception and design (MCP, MGW, MAK, JEH, OIO, and FL), acquisition of the data (FL, JEH), or analysis and interpretation (MCP, MGW, MAK, JEH, OIO, and FL). MCP drafted the article and all other authors revised it critically for important intellectual content. MCP is guarantor. All authors had full access to all of the data in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis.
Funding: This work was supported by grants from the National Institute of Environmental Health Sciences (R21 ES019982, R01 ES017017). MCP was supported by a training grant from the National Institute of Aging (T32 AG027668). The funding agencies had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; or decision to submit the manuscript for publication. The authors were independent of the study funders.
Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: no support from any organization for the submitted work; no financial relationships with any organizations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.
Ethical approval: This study was approved by the institutional review board of the Brigham and Women’s Hospital and the human subjects committee of the Harvard School of Public Health.
Data sharing: The statistical code is available from the corresponding author at melindacpower{at}gmail.com.
Transparency: The lead author (MCP) affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.
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