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Cited by 78Air Quality and Health ImpactsClimate Change and Health ImpactsIndoor Air Quality and Microbial Exposure

Acute effect of ozone exposure on daily mortality in seven cities of Jiangsu Province, China: no clear evidence for threshold

Open access
Chen, Kai, Zhou, Lian, Chen, Xiaodong, Bi, Jun, Kinney, Patrick L.·2017·Environmental Research
DOI 10.1016/j.envres.2017.02.009PMC PMC5387109
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Abstract

Background: Few multicity studies have addressed the health effects of ozone in China due to the scarcity of ozone monitoring data. A critical scientific and policy‐relevant question is whether a threshold exists in the ozone‐mortality relationship. Methods: Using a generalized additive model and a univariate random‐effects meta‐analysis, this research evaluated the relationship between short‐term ozone exposure and daily total mortality in seven cities of Jiangsu Province, China during 2013–2014. Spline, subset, and threshold models were applied to further evaluate whether a safe threshold level exists. Results: This study found strong evidence that short‐term ozone exposure is significantly associated with premature total mortality. A 10 &mgr;g/m3 increase in the average of the current and previous days' maximum 8‐h average ozone concentration was associated with a 0.55% (95% posterior interval: 0.34%, 0.76%) increase of total mortality. This finding is robust when considering the confounding effect of PM2.5, PM10, NO2, and SO2. No consistent evidence was found for a threshold in the ozone‐mortality concentration‐response relationship down to concentrations well below the current Chinese Ambient Air Quality Standard (CAAQS) level 2 standard (160 &mgr;g/m3). Conclusions: Our findings suggest that ozone concentrations below the current CAAQS level 2 standard could still induce increased mortality risks in Jiangsu Province, China. Continuous air pollution control measures could yield important health benefits in Jiangsu Province, China, even in cities that meet the current CAAQS level 2 standard. HighlightsWe estimated the acute effect of ozone on total mortality in seven Jiangsu cities.Short‐term ozone exposure was significantly associated with total mortality.Ozone‐mortality relationship was not confounded by PM2.5, PM10, NO2, and SO2.No strong evidence for threshold in the ozone‐mortality relationship.Current Chinese ozone standard is not ‘safe’ enough in Jiangsu Province.

AI snapshot

Written from the paper’s full text.

TL;DR

This multicity time-series study in seven Jiangsu Province cities during 2013–2014 found that short-term ozone exposure was significantly associated with increased daily total mortality. It found no consistent evidence of a threshold in the ozone-mortality relationship down to concentrations well below the Chinese Ambient Air Quality Standard level 2 standard.

Key findings

  • A 10 μg/m³ increase in the average of current and previous days’ maximum 8-h average ozone (MDA8, lag0–1) was associated with a 0.55% (95% posterior interval: 0.34%, 0.76%) increase in daily total mortality in the full-year analysis; warm-season estimate was 0.38% (0.12%, 0.64%) and cold-season estimate was 0.88% (0.26%, 1.51%).
  • The ozone-mortality association was robust after controlling for PM2.5, PM10, NO2, and SO2; the paper reports similar increments before and after controlling for PM2.5 (0.56% vs. 0.58%).
  • For days meeting the CAAQS level 2 standard (160 μg/m³), a 10 μg/m³ increase in MDA8 ozone was still associated with a 0.68% (95% PI: 0.40%, 0.96%) increase in total mortality.
  • No consistent threshold was found: significant ozone-mortality risk estimates persisted as the threshold decreased from 160 to 110 μg/m³; the averaged Q-AIC was minimized at 90 μg/m³ (4273.9) but differed from the no-threshold value (4275.1) by less than 2 and accounted for only 0.03% of the no-threshold Q-AIC.

Methods

  • Two-stage design: city-specific generalized additive models with quasi-Poisson regression controlled for long-term trends, temperature, relative humidity, and day of week; city-specific estimates were pooled using a univariate random-effects meta-analysis.
  • Study area and data: urban districts of Nanjing, Wuxi, Changzhou, Suzhou, Lianyungang, Yancheng, and Zhenjiang, China; daily mortality from January 1, 2013 to December 31, 2014; air pollution data from January 18, 2013 to December 31, 2014; 42 national air quality monitoring sites; study-area population 25.51 million by end of 2010.
  • Threshold assessment used spline models, subset analyses for thresholds from 60 to 160 μg/m³ in 10 μg/m³ increments, and threshold models from 0 to 160 μg/m³ in 10 μg/m³ increments, with Q-AIC used to compare model fit.

Limitations

  • The paper states exposure measurement error is inevitable because mean pollutant concentrations from monitoring stations were used to represent population exposure, likely biasing risk estimates toward the null; limited data may lead to uncertainty; cause-specific mortality was not explored; and results from seven Jiangsu cities may not apply to other regions of China.
  • Evident from the text: the study period covered only 2013–2014, and the paper notes weaker evidence at low and high ozone concentrations where data were sparse, with low data density below 100 μg/m³ in the subset approach, which may limit threshold detection.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1016/j.envres.2017.02.009

Cites

47 of 47 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 26 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    A 10 μg/m3 increase in MDA8 ozone is associated with a 0.55% (95% PI 0.34%, 0.76%) increase in daily total mortality in the full year period in the seven cities.

    “A 10 μg/m3 increase in the average of the current and previous days’ maximum 8-h average ozone concentration was associated with a 0.55% (95% posterior interval: 0.34%, 0.76%) increase of total mortality.”
    • Also stated in: § 3. Results · plain
      “On average, using the lag0–14 for temperature, a 10 μg/m3 increase in short-term exposure to MDA8 ozone was found to be associated with an increase of 0.55% (95% posterior interval (PI): 0.34%, 0.76%) in daily total mortality in the full year period”
    Quote in the paperSubstantial claim
  • Findingown data

    Significant ozone-mortality risk estimates were found when the threshold decreased from 160 to 110 μg/m3.

    “Significant ozone-mortality risk estimates were found when the threshold decreased from 160 to 110 μg/m3”
    Quote in the paperSubstantial claim
  • Findingown data

    In Changzhou, Lianyungang, and Zhenjiang, no obvious threshold below which ozone has no effect on total mortality was found.

    “In Changzhou, Lianyungang, and Zhenjiang, no obvious threshold below which ozone has no effect on total mortality was found.”
    Quote in the paperSubstantial claim
  • Findingown data

    The mortality effect of short-term ozone exposure is stronger in the cold season than in the warm season.

    “we found a stronger mortality effects of short-term ozone exposure in cold season than in warm season (Apr.–Sept.).”
    Quote in the paperSubstantial claim
  • Findingown data

    Evidence for an association between ozone and total mortality was generally weaker at both low and high concentrations, where ozone data were sparse.

    “But evidence for an association were generally weaker at both low and high concentrations, where ozone data were sparse.”
    Quote in the paperNot a substantial claim
  • May combine two claims. 8
  • Classified as probably not a substantial claim. 7

  • May combine two claims.

    Findingown data

    The difference in Q-AIC between the threshold of 90 μg/m3 and no threshold (0 μg/m3) was smaller than 2 and accounted for only 0.03% of the Q-AIC for the no-threshold assumption.

    “However, this difference in Q-AIC between 90 and 0 μg/m3 (no threshold assumption) was smaller than 2 and only accounts 0.03% of the Q-AIC for the no threshold assumption (Q-AIC value: 4275.1).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The association between thresholds and Q-AIC did not follow a U-shaped curve; a flat curve was observed at low thresholds.

    “The association between thresholds and Q-AIC did not follow a U-shaped curve as a flat curve was observed at low thresholds.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingcitation

    The potential thresholds around 80 μg/m3 in the spline approach and 90 μg/m3 in the threshold approach are near the mean total background ozone level over China (44.1 ppb, approximately 88 μg/m3).

    “In the present study, potential thresholds around 80 μg/m3 in the spline approach and 90 μg/m3 in the threshold approach were suggested, both of which are near the mean total background ozone level over China (44.1 ppb, approximately 88 μg/m3) (Wang et al., 2011).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Wang et al., 2011 source

      Not checked in the free run.

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductreasoning

    The study used a generalized additive model with quasi-Poisson regression to evaluate the association between ozone and total mortality in each city, controlling for long-term trends, temperature, relative humidity, and day of week.

    “Thus, we used a generalized additive model (GAM) with a quasi-Poisson regression to evaluate the association between ozone and total mortality in each city, while controlling the confounding effects of long-term trends, temperature, relative humidity, and day of week effect.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: Daily mortality counts follow an over-dispersed Poisson distribution.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The limited amount of data may lead to some uncertainty.

    “Second, the limited amount of data may lead to some uncertainty.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductown data

    The study applied spline, subset, and threshold models to evaluate whether a threshold exists in the ozone-mortality concentration-response curve.

    “Spline, subset, and threshold models were applied to further evaluate whether a safe threshold level exists.”
    • Also stated in: § 2.3 Statistical analysis · plain
      “We applied three approaches to evaluate whether a threshold exists in the ozone-mortality concentration-response curve.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: In the threshold analysis, a linear ozone-mortality relationship is only observed above the threshold h and not below it.
    • The authors state this as an assumption: If a threshold exists, the model with the appropriate threshold value h should generate the best model fit.

  • Classified as probably not a substantial claim.

    Study design and conductcitation

    City-specific estimates across seven cities were combined using a univariate random-effects meta-analysis to estimate the average risk of ozone-related mortality, accounting for variations across cities.

    “In the second stage, city-specific estimates across seven cities were combined to estimate the average risk of ozone-related mortality using a univariate random-effects meta-analysis (Gasparrini et al., 2012).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Gasparrini et al., 2012 source

      Not checked in the free run.

  • May combine two claims.

    Study design and conductown data

    The study used lag0-14 for temperature to control the lag effect of temperature on daily mortality, selected by the smallest GCV.

    “The smallest GCV was found in the moving average of the current-day and previous 14 days (lag0–14) for temperature. Thus, the lag0–14 was used to control the lag effect of temperature on daily mortality in this study.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Previous studies also supported the linear association between ozone and mortality in Chinese cities.

    “In accordance with our finding, previous studies also supported the linear association between ozone and mortality in Chinese cities (Wong et al., 2008; Yang et al., 2012).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Wong et al., 2008 source

      Not checked in the free run.

    • cites Yang et al., 2012 source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    The significant association between low-level cold season ozone (mean level 72.3 μg/m3) and daily mortality suggests that there is no threshold or a very low threshold in the ozone-mortality relationship in Jiangsu Province, China.

    “The significant association between low level cold season ozone (mean level: 72.3 μg/m3) and daily mortality observed in this study suggests that there is no threshold or a very low threshold in the ozone-mortality relationship in Jiangsu Province, China.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Recent studies found evidence of a threshold effect around 30 ppb (approximately 60 μg/m3) using the 24-hour average metric in the U.S., 30-40 ppb (approximately 60-80 μg/m3) in Korea and Japan, and 65 μg/m3 using the MDA8 metric in London, U.K.

    “On the contrary, recent studies found evidence of a threshold effect around 30 ppb (approximately 60 μg/m3) using the 24-hour average metric in U.S. (Moolgavkar et al., 2013; Stylianou and Nicolich, 2009), 30–40 ppb (approximately 60–80 μg/m3) using the 24-hour average metric in Korea and Japan (Bae et al., 2015), and 65 μg/m3 using the MDA8 metric in London, U.K. (Atkinson et al., 2012).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Moolgavkar et al., 2013 source

      Not checked in the free run.

    • cites Stylianou and Nicolich, 2009

      Not checked in the free run.

    • cites Bae et al., 2015 source

      Not checked in the free run.

  • May combine two claims.

    Study design and conductown data

    Heterogeneity among cities was nonsignificant for the full year and warm season analyses, but moderate for the cold season analysis.

    “Thus, nonsignificant heterogeneity was observed for the full year analysis and warm season analyses, but a moderate heterogeneity was noticed for the cold season analysis.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Previous time-series studies showed lack of evidence of an ozone threshold in the U.S., Canada, and Europe.

    “This is consistent with previous time-series studies showing lack of evidence of ozone threshold in the U.S., Canada, and Europe (Bell et al., 2006; Katsouyanni et al., 2009).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Bell et al., 2006 source

      Not checked in the free run.

    • cites Katsouyanni et al., 2009

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductreasoning

    The association between short-term ozone exposure and cause-specific mortality was not explored in this study.

    “Third, the association between short-term ozone exposure and cause-specific mortality is not explored here, as our main focus was to quantify the association between ozone and total mortality and to explore whether this association diminished below a certain threshold.”
    Quote in the paperNot a substantial claim
14 of 14

  • The authors state this as an assumption.

    Daily mortality counts follow an over-dispersed Poisson distribution.

    “Because daily mortality counts were very low, they were usually assumed to follow an over-dispersed Poisson distribution.”

  • The authors state this as an assumption.

    In the threshold analysis, a linear ozone-mortality relationship is only observed above the threshold h and not below it.

    “Finally, we performed a threshold analysis applied in a previous study (Bell et al., 2006), assuming that a linear ozone-mortality relationship is only observed above the threshold (h) and not below it.”

  • The authors state this as an assumption.

    If a threshold exists, the model with the appropriate threshold value h should generate the best model fit.

    “If a threshold exists, the model with an appropriate threshold value h should generate the best model fit (Bell et al., 2006).”

  • The paper relies on this without support.

    This is the first multicity study in China to systematically examine the evidence of threshold in the concentration-response function for ozone and daily mortality.

    “To the best of our knowledge, this is the first multicity study in China to systematically examine the evidence of threshold in the concentration-response function for ozone and daily mortality.”

  • The authors state this as an assumption.

    The difference between the deviances of the fitted linear and spline models follows a chi-square distribution with 2 df.

    “To compare spline models with linear models, we computed the difference between the deviances of the fitted linear and spline models for each city, which follows a chi-square distribution with 2 (the difference in the df of the spline model and linear model) df (Samoli et al., 2005).”
5 of 5

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Emerging evidence does not support a threshold for adverse effects of ozone.

    “Yet, emerging evidence does not support a threshold for adverse effects of ozone (79, 80).”

    From Ozone pollution: A Major health hazard worldwide (2019) · cites this paper as [80]

Cites

Flagged first, then by citations

Research works printed but not linked: 1

  1. U.S. EPA, 2013. Final report: integrated science assessment of ozone and related photochemical oxidants. In: U.S. Environmental Protection Agency, (Ed.). EPA/600/R-10/076F, Washington, DC, 2013.

Cited by

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Related

Authors
Chen, K., Zhou, L., Chen, X., Bi, J., & Kinney, P. L.
Affiliations
  • State Key Laboratory of Pollution Control and Resource Reuse (CN)
  • Jiangsu Provincial Center for Disease Control and Prevention (CN)
  • Columbia University (US)
Corresponding author
  • Bi, Jun
  • Kinney, Patrick L.
ORCID
Venue
Environmental Research
Publisher
Elsevier BV
Published
2017-05
Volume
155
Pages
235-241
ISSN
0013-9351 (ISSN-L)
DOI
10.1016/j.envres.2017.02.009
PMC
PMC5387109
OpenAlex
W2591627306
Semantic Scholar
e5fa41aabbb90f991c80fec39f171360d4847bf4
Cited by
75
References
47
Citations by year
2026: 4 · 2025: 10 · 2024: 3 · 2023: 8 · 2022: 12 · 2021: 9 · 2020: 9 · 2019: 8 · 2018: 9 · 2017: 3
FWCI
4.27
Type
journal article
Language
en
Open access
Licence
www.elsevier.com/tdm/userlicense/1.0/ (tdm)
Locations
  • Environmental Research (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (acceptedVersion)
  • PubMed Central (acceptedVersion)
Funders
  • China National Natural Science Foundation (71433007)
  • China National Key Research & Development Program (2016YFC0207600)
  • US National Institute of Environmental Health Sciences (ES009089, T32ES023770)
  • Shanghai Tongji Gao Tingyao Environmental Science & Technology Development Foundation
Topics
  • Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Air Quality and Health Impacts
  • Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Climate Change and Health Impacts
  • Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Indoor Air Quality and Microbial Exposure
Keywords
ozone exposure, daily mortality, threshold, concentration-dependent effects, ambient air quality standards, Jiangsu Province, air pollution health effects, air pollution control
MeSH terms
Air Pollutants, China, Cities, Environmental Exposure, Humans, Mortality, Ozone, Seasons

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