Cited by 703Air Quality and Health ImpactsIndoor Air Quality and Microbial ExposureEnvironmental Justice and Health Disparities

The DOI matches its Crossref record; 42 of the 43 references it cites were found in a registry or an index; none of the 31 sources its claims cite is checked for support yet.

Association of Short-term Exposure to Air Pollution With Mortality in Older Adults

Open access

Abstract

Importance: The US Environmental Protection Agency is required to reexamine its National Ambient Air Quality Standards (NAAQS) every 5 years, but evidence of mortality risk is lacking at air pollution levels below the current daily NAAQS in unmonitored areas and for sensitive subgroups. Objective: To estimate the association between short-term exposures to ambient fine particulate matter (PM2.5) and ozone, and at levels below the current daily NAAQS, and mortality in the continental United States. Design, Setting, and Participants: Case-crossover design and conditional logistic regression to estimate the association between short-term exposures to PM2.5 and ozone (mean of daily exposure on the same day of death and 1 day prior) and mortality in 2-pollutant models. The study included the entire Medicare population from January 1, 2000, to December 31, 2012, residing in 39 182 zip codes. Exposures: Daily PM2.5 and ozone levels in a 1-km × 1-km grid were estimated using published and validated air pollution prediction models based on land use, chemical transport modeling, and satellite remote sensing data. From these gridded exposures, daily exposures were calculated for every zip code in the United States. Warm-season ozone was defined as ozone levels for the months April to September of each year. Main Outcomes and Measures: All-cause mortality in the entire Medicare population from 2000 to 2012. Results: During the study period, there were 22 433 862 million case days and 76 143 209 control days. Of all case and control days, 93.6% had PM2.5 levels below 25 μg/m3, during which 95.2% of deaths occurred (21 353 817 of 22 433 862), and 91.1% of days had ozone levels below 60 parts per billion, during which 93.4% of deaths occurred (20 955 387 of 22 433 862). The baseline daily mortality rates were 137.33 and 129.44 (per 1 million persons at risk per day) for the entire year and for the warm season, respectively. Each short-term increase of 10 μg/m3 in PM2.5 (adjusted by ozone) and 10 parts per billion (10-9) in warm-season ozone (adjusted by PM2.5) were statistically significantly associated with a relative increase of 1.05% (95% CI, 0.95%-1.15%) and 0.51% (95% CI, 0.41%-0.61%) in daily mortality rate, respectively. Absolute risk differences in daily mortality rate were 1.42 (95% CI, 1.29-1.56) and 0.66 (95% CI, 0.53-0.78) per 1 million persons at risk per day. There was no evidence of a threshold in the exposure-response relationship. Conclusions and Relevance: In the US Medicare population from 2000 to 2012, short-term exposures to PM2.5 and warm-season ozone were significantly associated with increased risk of mortality. This risk occurred at levels below current national air quality standards, suggesting that these standards may need to be reevaluated.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

In a case-crossover analysis of the entire US Medicare population from 2000–2012, short-term PM2.5 and warm-season ozone exposures were significantly associated with increased all-cause mortality, including at concentrations below current daily NAAQS. The authors conclude that current air quality standards may need reevaluation.

Key findings

  • Among 22,433,862 case days and 76,143,209 control days across 39,182 zip codes, each 10 μg/m3 increase in lag 01-day PM2.5 (adjusted for ozone) was associated with a 1.05% (95% CI: 0.95%, 1.15%) increase in daily mortality rate; ARD was 1.42 (95% CI: 1.29, 1.56) per 1 million persons at risk per day.
  • Each 10 ppb increase in warm-season ozone (adjusted for PM2.5) was associated with a 0.51% (95% CI: 0.41%, 0.61%) increase in daily mortality rate; ARD was 0.66 (95% CI: 0.53, 0.78) per 1 million persons at risk per day.
  • Associations remained significant below current daily standards: for PM2.5 <25 μg/m3, RR was 1.61% (95% CI: 1.48%, 1.74%) and ARD 2.17 (95% CI: 2.00, 2.34); for ozone <60 ppb, RR was 0.58% (95% CI: 0.46%, 0.70%) and ARD 0.74 (95% CI: 0.59, 0.90).
  • Higher PM2.5-associated mortality was observed in Medicaid-eligible individuals, those above 70 years, and females; exposure-response curves were almost linear with no evidence of a threshold.

Methods

  • Case-crossover design with conditional logistic regression, comparing each person’s date of death (case day) with matched control days on the same day of week, in the same month, and before/after the case day.
  • Included all Medicare deaths in the continental US from January 1, 2000 to December 31, 2012, residing in 39,182 zip codes; exposures were daily PM2.5 and ozone estimated on a 1 km × 1 km grid using validated prediction models.
  • Two-pollutant models estimated PM2.5 (adjusted for ozone) and warm-season ozone (adjusted for PM2.5) associations using lag 01-day exposure, with natural splines for air and dew point temperature; subgroup and low-exposure analyses were also conducted.

Limitations

  • Stated: the case-crossover design cannot estimate mortality risk from long-term exposure; exposure was assigned by residential zip code rather than exact home address or place of death, likely causing measurement error; the Medicare population is primarily older than 65, limiting generalizability to younger populations; Medicare files lack cause-specific mortality; and the most recent data were nearly 5 years old at publication.
  • Evident from the text: this is an observational study, so the reported associations should not be interpreted as proving causality.

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Integrity signals

Registry

Crossref · 10.1001/jama.2017.17923

Cites

42 of 42 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

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Claims the paper makes

26 Own result · 14 Not checked yet · 13 Own method · 6 Own interpretation · 3 No basis given

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  • Probably not a substantial claim. 21
  • It may state two separate claims as one. 14
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31 of 31
  • The authors state this as an assumption.

    Individual-level and zip code-level covariates that do not vary day-to-day, such as age, sex, race, socioeconomic status, smoking, and other behavioral risk factors, are not confounders in the case-crossover comparison because they remain constant between case and control days.

    “Individual-level covariates and zip code-level covariates that did not vary day-to-day (e.g., age, sex, race, socioeconomic status, smoking, and other behavioral risk factors) were not considered to be confounders as they remain constant when comparing case days vs control days.”
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Metadata

Authors
Di, Q., Dai, L., Wang, Y., Zanobetti, A., Choirat, C., Schwartz, J. D., & Dominici, F.
Affiliations
Harvard University (US)
Corresponding author
Schwartz, Joel D.
Venue
JAMA
Published
2017-12-26
Volume
318
Issue
24
Pages
2446
ISSN
  • 0002-9955 (ISSN-L)
  • 0098-7484
OpenAlex
W2779159526
Cited by
698
References
43
Citations by year
2026: 42 · 2025: 83 · 2024: 91 · 2023: 80 · 2022: 86 · 2021: 94 · 2020: 99 · 2019: 74 · 2018: 46 · 2017: 2
FWCI
32.60
Type
journal article
Language
en
Open access
Locations
  • JAMA (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (acceptedVersion)
  • PubMed Central (acceptedVersion)
Funders
  • National Institutes of Health
  • National Cancer Institute (R35CA197449)
  • National Institute of Environmental Health Sciences (R21ES024012, R01ES024332, P30ES000002, R01ES026217)
Topics
  • Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Air Quality and Health Impacts
  • Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Indoor Air Quality and Microbial Exposure
  • Social Sciences › Sociology and Political Science › Environmental Justice and Health Disparities
Keywords
short-term air pollution exposure, PM2.5, ozone, all-cause mortality, older adults, Medicare beneficiaries, National Ambient Air Quality Standards, air pollution health effects, United States, New York State, New Jersey
MeSH terms
Age Factors, Aged, Aged, 80 and over, Air Pollutants, Air Pollution, Environmental Exposure, Female, Medicare, Humans, Male, Mortality, Ozone, Risk, Seasons, United States, Logistic Models, Cross-Over Studies, Particulate Matter

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