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Short term exposure to fine particulate matter and hospital admission risks and costs in the Medicare population: time stratified, case crossover study

BMJ 2019; 367 doi: (Published 27 November 2019) Cite this as: BMJ 2019;367:l6258

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  1. Yaguang Wei, doctoral student1,
  2. Yan Wang, doctoral student1 2,
  3. Qian Di, assistant professor3,
  4. Christine Choirat, chief innovation officer4,
  5. Yun Wang, senior research scientist2,
  6. Petros Koutrakis, professor1,
  7. Antonella Zanobetti, principal research scientist1,
  8. Francesca Dominici, Clarence James Gamble professor of biostatistics, population, and data science2,
  9. Joel D Schwartz, professor1
  1. 1Department of Environmental Health, Harvard T H Chan School of Public Health, Boston, MA, USA
  2. 2Department of Biostatistics, Harvard T H Chan School of Public Health, Boston, MA 02115, USA
  3. 3Research Center for Public Health, School of Medicine, Tsinghua University, Beijing, China
  4. 4Swiss Data Science Centre (ETH Zürich and EPFL), Zürich, Switzerland
  1. Correspondence to: F Dominici fdominic{at} (or @francescadomin8 on Twitter)
  • Accepted 16 October 2019


Objective To assess risks and costs of hospital admission associated with short term exposure to fine particulate matter with diameter less than 2.5 µm (PM2.5) for 214 mutually exclusive disease groups.

Design Time stratified, case crossover analyses with conditional logistic regressions adjusted for non-linear confounding effects of meteorological variables.

Setting Medicare inpatient hospital claims in the United States, 2000-12 (n=95 277 169).

Participants All Medicare fee-for-service beneficiaries aged 65 or older admitted to hospital.

Main outcome measures Risk of hospital admission, number of admissions, days in hospital, inpatient and post-acute care costs, and value of statistical life (that is, the economic value used to measure the cost of avoiding a death) due to the lives lost at discharge for 214 disease groups.

Results Positive associations between short term exposure to PM2.5 and risk of hospital admission were found for several prevalent but rarely studied diseases, such as septicemia, fluid and electrolyte disorders, and acute and unspecified renal failure. Positive associations were also found between risk of hospital admission and cardiovascular and respiratory diseases, Parkinson’s disease, diabetes, phlebitis, thrombophlebitis, and thromboembolism, confirming previously published results. These associations remained consistent when restricted to days with a daily PM2.5 concentration below the WHO air quality guideline for the 24 hour average exposure to PM2.5. For the rarely studied diseases, each 1 µg/m3 increase in short term PM2.5 was associated with an annual increase of 2050 hospital admissions (95% confidence interval 1914 to 2187 admissions), 12 216 days in hospital (11 358 to 13 075), US$31m (£24m, €28m; $29m to $34m) in inpatient and post-acute care costs, and $2.5bn ($2.0bn to $2.9bn) in value of statistical life. For diseases with a previously known association, each 1 µg/m3 increase in short term exposure to PM2.5 was associated with an annual increase of 3642 hospital admissions (3434 to 3851), 20 098 days in hospital (18 950 to 21 247), $69m ($65m to $73m) in inpatient and post-acute care costs, and $4.1bn ($3.5bn to $4.7bn) in value of statistical life.

Conclusions New causes and previously identified causes of hospital admission associated with short term exposure to PM2.5 were found. These associations remained even at a daily PM2.5 concentration below the WHO 24 hour guideline. Substantial economic costs were linked to a small increase in short term PM2.5.


  • Contributors: YWe and YaWa are joint first authors and contributed to data preparation, data analysis, data interpretation, development of the Shiny app, and writing of this manuscript. QD and YuWa contributed to data preparation and data analysis. CC contributed to data interpretation and development of the Shiny app. PK, AZ, FD, and JDS contributed to formulation of the idea, study design, data analysis, and review of the manuscript. All authors had full access to all the data in the study. FD is the study guarantor. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.

  • Funding: This study was supported by National Institute of Health (NIH) grants P30 ES000002, R01 ES024332-01A1, R01 ES026217, R01 ES028033, and R21 ES024012; NIH/National Cancer Institute (NCI) grant R35 CA197449; Health Effects Institute (HEI) grant 4953-RFA14-3/16-4; and United States Environmental Protection Agency (US EPA) grants RD-83587201-0 and RD-83479801. The contents of this publication are solely the responsibility of the grantee and do not necessarily represent the official views of the US EPA. Further, the US EPA does not endorse the purchase of any commercial products or services mentioned in the publication. Research described in this article was conducted under contract to the HEI, an organization jointly funded by the US EPA (Assistance Award No CR-83467701) and certain motor vehicle and engine manufacturers. The contents of this article do not necessarily reflect the views of HEI, or its sponsors, nor do they necessarily reflect the views and policies of the US EPA or motor vehicle and engine manufacturers.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at and declare: support from the NIH, NIH/NCI, HEI, and US EPA 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 at the Harvard T H Chan School of Public Health and was exempt from informed consent requirements as a study of previously collected administrative data.

  • Data sharing: No additional data available.

  • The corresponding author 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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