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Cited by 838Air Quality and Health ImpactsAtmospheric chemistry and aerosolsIndoor Air Quality and Microbial Exposure

Ozone pollution: A Major health hazard worldwide

Open access
Zhang, Junfeng (Jim), Wei, Yongjie, Fang, Zhangfu·2019·Frontiers in Immunology
DOI 10.3389/fimmu.2019.02518PMC PMC6834528
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Abstract

Oxides of nitrogen (NOx) and volatile organic compounds (VOCs) released into the atmosphere can react in the presence of solar irradiation, leading to ozone formation in the troposphere. Historically before clean air regulations were implemented to control NOx and VOCs, ozone concentrations were high enough to exert acute effects such as eye and nose irritation, respiratory disease emergencies, and lung function impairment. At or above current regulatory standards, day-to-day variations in ozone concentrations have been positively associated with asthma incidence and daily non-accidental mortality rate. Emerging evidence has shown that both short-term and long-term exposures to ozone, at concentrations below the current regulatory standards, were associated with increased mortality due to respiratory and cardiovascular diseases. The pathophysiology to support the epidemiologic associations between mortality and morbidity and ozone centers at the chemical and toxicological property of ozone as a strong oxidant, being able to induce oxidative damages to cells and the lining fluids of the airways, and immune-inflammatory responses within and beyond the lung. These new findings add substantially to the existing challenges in controlling ozone pollution. For example, in the United States in 2016, 90% of noncompliance to the national ambient air quality standards was due to ozone whereas only 10% was due to particulate matter and other regulated pollutants. Climate change, through creating atmospheric conditions favoring ozone formation, has been and will continue to increase ozone concentrations in many parts of world. Worldwide, ozone is responsible for several hundreds of thousands premature deaths and tens of million asthma-related emergency room visits annually. To combat ozone pollution globally, more aggressive reductions in fossil fuel consumption are needed to cut NOx and VOCs as well as greenhouse gas emissions. Meanwhile, preventive and therapeutic strategies are needed to alleviate the detrimental effects of ozone especially in more susceptible individuals. Interventional trials in humans are needed to evaluate the efficacy of antioxidants and ozone-scavenging compounds that have shown promising results in animal studies.

AI snapshot

Written from the paper’s full text.

TL;DR

This narrative review synthesizes evidence that tropospheric ozone, formed photochemically from NOx and VOCs, is a worldwide health hazard causing respiratory and emerging cardiovascular and CNS effects, with concentrations rising in many regions despite declines in the US and Western Europe. It argues that adverse effects occur below current regulatory standards, that climate change will worsen ozone burdens, and that more aggressive precursor emission cuts plus antioxidant/scavenger strategies are needed.

Key findings

  • Ozone exposure is associated with respiratory effects (airway inflammation, aggravated asthma, emphysema, COPD), likely asthma development, and premature death, with stronger evidence for respiratory than other mortality; children are at increased risk. In the US in 2016, 90% of non-compliance with national ambient air quality standards was due to ozone versus 10% for particulate matter and other pollutants, and 100.6 million people (nearly one in three) lived in counties exceeding the 70 ppb NAAQS in 2017.
  • Despite US reductions in NOx (61%) and VOCs (54%) from 1980–2017 and a 32% decrease in national average daily max 8-h ozone, global background ozone is rising: Mt Waliguan Observatory on the Tibetan Plateau showed increases of 0.2–0.3 ppb per year during spring and autumn (1994–2013). In the North China Plain, a 40% PM2.5 reduction from 2013–2017 was partly responsible for an ozone increase of 1–3 ppb per year.
  • Climate change is projected to increase ozone: warming alone may increase ozone-standard exceedance days across the eastern US by 68% by 2050; the 95th percentile of daily 8-h max ozone is predicted to rise from 79 ppb in 2012 to 87 ppb in 2050; and climate change alone is estimated to add 0.43 ppb (95% CI: 0.14–0.75) to average ozone in 19 southeastern US urban communities in the 2040s versus 2000.
  • Global mortality estimates vary widely: a 6% increase in premature deaths attributable to ozone from 1990 (143,000) to 2010 (152,000); 700,000 ± 300,000 respiratory mortalities in 2000; 254,000 COPD deaths in 2015; 316,000 respiratory deaths in China; ~23,500 in the EU. Ozone was linked to an estimated 9–23 million (8–20% of total) asthma-related emergency room visits globally, and DALYs lost of 6.3 ± 3.0 million years in 2000 and 4.1 (95% CI: 1.6–6.8) million years from COPD alone in 2015. A 5 ppb increase in long-term ozone was associated with 0.25 year (95% CI: −0.30 to −0.19) lower life expectancy in males and 0.21 year (95% CI: −0.25 to −0.17) in females.
  • Mechanistically, ozone as a strong oxidant induces oxidative damage and immune-inflammatory responses; Koren et al. found acute exposure (0.4 ppm for 2 h) produced an 8.2-fold increase in polymorphonuclear leukocytes in BAL fluid. Emerging evidence links ozone to cardiovascular mortality, hemostatic markers, and CNS effects including neurodegenerative disorders.

Methods

  • Narrative review (no primary data collection); the paper synthesizes atmospheric chemistry, exposure/dosimetry considerations, epidemiological and toxicological evidence, and regulatory context.
  • Draws on cited studies including controlled human exposure trials, animal/rodent studies, cohort studies (e.g., American Cancer Society cohort, US Medicare population of 60 million older adults, 2000–2012), multicity time-series studies, and climate/ozone projection modeling.
  • No systematic search strategy, inclusion criteria, or meta-analytic pooling is described.

Limitations

  • Stated: the relatively large gap in mortality estimates across studies is due to uncertainties and inconsistency in the concentration–effect relationship and ozone exposure assessment; estimates were based on respiratory effects alone due to uncertainties in cardiovascular evidence; epidemiological evidence is limited for a causal relationship between chronic exposure and mortality/morbidity; determining the best measure of long-term ozone exposure is challenging given diurnal and seasonal variation; co-exposure to PM2.5 may affect repair of ozone damage.
  • Evident from the text: as a narrative review without a stated systematic search or quality appraisal, selection of cited evidence may be non-exhaustive; several cited findings are projections or model-based rather than observed outcomes; the paper notes null findings in some European studies on long-term ozone and cardiovascular mortality, indicating inconsistency in the evidence base.

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

Integrity signals

Registry

Crossref · 10.3389/fimmu.2019.02518

Cites

86 of 86 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 92 cited sources checked · 0 supported · 0 flagged

  • Premisecitation

    Observations made at a rural site (Dadianzi) 100 km northeast Beijing showed a steady increase in annual averages of the 8-h daily max ozone concentrations from 2004 to 2015.

    “observations made at a rural site (Dadianzi) 100 km northeast Beijing showed a steady increase in annual averages of the 8-h daily max ozone concentrations from 2004 to 2015 (13).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [13] Ma, 2016, Significant increase of surface ozone at a rural site, north of eastern China, Atmos Chem Phys source

      Not checked in the free run.

  • Premisenone given

    The predominant source of tropospheric ozone is photochemical reactions involving VOCs and NOx.

    “The predominant source of tropospheric ozone, however, is the photochemical reactions involving volatile organic compounds (VOCs) and oxides of nitrogen (NOx), mainly comprised of NO2 and nitric oxide (NO).”
    Quote in the paperNot a substantial claim
  • Premisecitation

    A 40% reduction in PM2.5 from 2013 to 2017 in the North China Plain was partly responsible for an increasing ozone trend (at 1-3 ppb per year) during 2013-2017 observed in megacity clusters of eastern China.

    “A recent study showed that a 40% reduction in PM2.5 from 2013 to 2017 in the North China Plain was partly responsible for an increasing ozone trend (at 1–3 ppb per year) during the period of 2013–2017 observed in megacity clusters of eastern China (6).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [6] Li, 2019, Anthropogenic drivers of 2013–2017 trends in summer surface ozone in China, Proc Natl Acad Sci USA. source

      Not checked in the free run.

  • Premisecitation

    By the year 2050, warming alone may increase by 68% the number of ozone-standard exceedance days across the eastern United States.

    “it is predicted that by the year 2050, warming alone may increase by 68% the number of ozone-standard exceedance days across the eastern United States (7).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [7] Bell, 2007, Climate change, ambient ozone, and health in 50 US cities, Clim Change source

      Not checked in the free run.

  • Premisecitation

    Global average ozone concentrations are increasing.

    “evidence suggests that global average ozone concentrations are increasing.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim. 18
  • May combine two claims. 18
  • The quote only partly states this claim. 2

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given

    Worldwide, ozone is responsible for several hundreds of thousands of premature deaths and tens of millions of asthma-related emergency room visits annually.

    “Worldwide, ozone is responsible for several hundreds of thousands of premature deaths and tens of millions of asthma-related emergency room visits annually.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisenone given

    At or above current regulatory standards, day-to-day variations in ozone concentrations are positively associated with asthma incidence and daily non-accidental mortality rate.

    “At or above current regulatory standards, day-to-day variations in ozone concentrations have been positively associated with asthma incidence and daily non-accidental mortality rate.”
    Quote in the paperSubstantial claim

  • The quote only partly states this claim.

    Premisereasoning

    VOCs or CO participate in photochemical reactions to produce free radicals that compete with ozone to react with NO, leading to net accumulation of ozone.

    “However, VOCs or CO participate in a series of complex photochemical reactions to produce free radicals that compete with ozone to react with NO.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    The springtime ozone increase at Mt Waliguan was partly (~60%) attributed to increased stratosphere-to-troposphere transport, whereas rising Asian anthropogenic emissions of ozone precursors were the key driver of increasing autumnal ozone at this site.

    “The springtime ozone increase was partly (~60%) attributed to increased stratosphere-to-troposphere transport, whereas rising Asian anthropogenic emissions of ozone precursors were the key driver of increasing autumnal ozone at this site.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [11] Xu, 2018, Long-term trends of surface ozone and its influencing factors at the Mt Waliguan GAW station, China-Part 2: the roles of anthropogenic emissions and climate variability, Atmos Chem Phys source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisenone given

    NOx and VOCs released into the atmosphere react in the presence of solar irradiation, leading to ozone formation in the troposphere.

    “Oxides of nitrogen (NOx) and volatile organic compounds (VOCs) released into the atmosphere can react in the presence of solar irradiation, leading to ozone formation in the troposphere.”
    Quote in the paperSubstantial claim

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

    Premisenone given

    In the United States, the current National Ambient Air Quality Standards for ozone include a 1-h standard at 120 ppb and an 8-h standard at 70 ppb.

    “In the United States, the current National Ambient Air Quality Standards (NAAQS) for ozone include a 1-h standard (1-h maximum within a day) at 120 ppb and an 8-h standard (8-h daily max) at 70 ppb.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisereasoning

    Ozone, as a strong oxidant, can induce oxidative damages to cells and the lining fluids of the airways and immune-inflammatory responses within and beyond the lung.

    “The pathophysiology to support the epidemiologic associations between mortality and morbidity and ozone centers at the chemical and toxicological property of ozone as a strong oxidant, being able to induce oxidative damages to cells and the lining fluids of the airways, and immune-inflammatory responses within and beyond the lung.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given

    In the United States in 2016, 90% of non-compliance to the national ambient air quality standards was due to ozone whereas only 10% was due to particulate matter and other regulated pollutants.

    “For example, in the United States in 2016, 90% of non-compliance to the national ambient air quality standards was due to ozone whereas only 10% was due to particulate matter and other regulated pollutants.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    Climate change, through creating atmospheric conditions favoring ozone formation, has been and will continue to increase ozone concentrations in many parts of the world.

    “Climate change, through creating atmospheric conditions favoring ozone formation, has been and will continue to increase ozone concentrations in many parts of world.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Children are at increased risk from ozone exposure, as children have a relatively higher dose per body mass and children's lung is still developing.

    “Children are at increased risk from ozone exposure, as children have a relatively higher dose per body mass and children's lung is still developing.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [25] Nuvolone, 2018, The effects of ozone on human health, Environ Sci Pollut Res source

      Not checked in the free run.

    • cites [26] Koman, 2017, Ozone exposure, cardiopulmonary health, and obesity: a substantive review, Chem Res Toxicol source

      Not checked in the free run.

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

    Premisereasoning

    Using 8-h daily max concentration assumes that lower concentrations during the rest of 16 h do not contribute to an adverse effect.

    “whereas using 8-h daily max concentration assumes that lower concentrations during the rest of 16 h do not contribute to an adverse effect.”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: Lower concentrations during the rest of 16 h do not contribute to an adverse effect when using 8-h daily max concentration.

  • May combine two claims.

    Premisecitation

    Ozone exposure is likely to cause premature deaths, and the evidence is stronger for mortality due to respiratory illnesses than for that due to other diseases.

    “Ozone exposure is likely to cause premature deaths, and the evidence is stronger for mortality due to respiratory illnesses than for that due to other diseases.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [25] Nuvolone, 2018, The effects of ozone on human health, Environ Sci Pollut Res source

      Not checked in the free run.

    • cites [26] Koman, 2017, Ozone exposure, cardiopulmonary health, and obesity: a substantive review, Chem Res Toxicol source

      Not checked in the free run.

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

    Premisereasoning

    Using 1-h max concentration is to assess the acute effect of peak exposure.

    “Using 1-h max concentration is to assess the acute effect of peak exposure,”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Ozone can cause coughing and sore or scratchy throat.

    “Ozone can cause coughing and sore or scratchy throat.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [1] McDonald, 2018, Volatile chemical products emerging as largest petrochemical source of urban organic emissions, Science. source

      Not checked in the free run.

  • May combine two claims.

    Premisereasoning

    Decreasing NOx would increase ozone under VOC-limited conditions, which has been the case for many urban areas of China.

    “Typically decreasing NOx would increase ozone under VOC-limited conditions, which has been the case for many urban areas of China.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    Outdoor ozone typically exhibits a distinct diurnal pattern with high concentrations during afternoon and early evening hours.

    “Third, outdoor ozone typically exhibits a distinct diurnal pattern with high concentrations during afternoon and early evening hours.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    On high ozone days, there have been increased school absences, increased visits to emergency rooms, and increased hospital admissions.

    “On high ozone days, there have been increased school absences, increased visits to emergency rooms, and increased hospital admissions (27–30).”
    Quote in the paperSubstantial claim0 of 4 sources checked
    • cites [27] Lin, 2008, Chronic exposure to ambient ozone and asthma hospital admissions among children, Environ Health Perspect source

      Not checked in the free run.

    • cites [28] Strickland, 2010, Short-term associations between ambient air pollutants and pediatric asthma emergency department visits, Am J Respir Crit Care Med source

      Not checked in the free run.

    • cites [29] Malig, 2016, A time-stratified case-crossover study of ambient ozone exposure and emergency department visits for specific respiratory diagnoses in California (2005-2008), Environ Health Perspect source

      Not checked in the free run.

    • cites [30] Tian, 2018, Association between ambient air pollution and daily hospital admissions for ischemic stroke: a nationwide time-series analysis, PLoS Med source

      Not checked in the free run.

  • May combine two claims.

    Premisenone given

    Ozone is chemically reactive and can be more effectively scavenged by building surfaces.

    “First, ozone is chemically reactive and can be more effectively scavenged by building surfaces.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    An acute exposure to ozone (0.4 ppm for 2 h) resulted in 8.2-fold increase of polymorphonuclear leukocytes in bronchial alveolar lavage fluid and enhanced level of inflammatory mediators in the lower airways of humans.

    “A seminal work by Koren et al. demonstrated that an acute exposure to ozone (0.4 ppm for 2 h) resulted in 8.2-fold increase of polymorphonuclear leukocytes (PMN) in bronchial alveolar lavage (BAL) fluid and enhanced level of inflammatory mediators in the lower airways of humans (37).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [37] Koren, 1989, Ozone-induced inflammation in the lower airways of human subjects, Am Rev Respir Dis source

      Not checked in the free run.

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

    Premisecitation

    Disability adjusted life years lost attributable to ozone were estimated to be 6.3 ± 3.0 million years in 2000.

    “Disability adjust life years (DALY) lost attributable to ozone were estimated to be 6.3 ± 3.0 million years in 2000 (58)”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [58] Brook, 2002, Inhalation of fine particulate air pollution and ozone causes acute arterial vasoconstriction in healthy adults, Circulation. source

      Not checked in the free run.

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

    Premisecitation

    Other ozone-associated mortality estimates include 316,000 respiratory deaths in China and ~23,500 in the European Union.

    “Other ozone-associated mortality estimates include 316,000 respiratory deaths in China (15) and ~23,500 in the European Union8.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [15] Malley, 2017, Updated global estimates of respiratory mortality in adults >/ = 30 years of age attributable to long-term ozone exposure, Environ Health Perspect source

      Not checked in the free run.

    • cites [8] Pfister, 2014, Projections of future summertime ozone over the US. JGR: atmospheres source

      Not checked in the free run.

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

    Premisecitation

    A study reported a 6% increase in premature deaths attributable to ozone globally from 1990 to 2010.

    “A study reported a 6% increase in premature deaths attributable to ozone globally from 1990 to 2010 (71), although the estimates (143,000 deaths in 1990 and 152,000 deaths in 2010) seem to be substantially lower than the estimated reported in other studies.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [71] Lim, 2012, A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010, Lancet. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Chronic exposure to low-dose ozone could enhance systemic and hippocampal Th17/IL-17A immune responses, which may be partly responsible for neurodegenerative effects in rats.

    “Chronic exposure to low-dose ozone, on the other hand, could enhance systemic and hippocampal Th17/IL-17A immune responses, which may be partly responsible for neurodegenerative effects in rats (70).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [70] Solleiro-Villavicencio, 2019, Systemic Th17/IL-17A response appears prior to hippocampal neurodegeneration in rats exposed to low doses of ozone, Neurología. source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Increased ambient ozone exposure was associated with increased rate of carotid wall thickness progression and risk of new plaque formation in healthy adults.

    “Wang et al. found that increased ambient ozone exposure was associated with increased rate of carotid wall thickness progression and risk of new plaque formation in healthy adults (52).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [52] Wang, 2019, Long-term exposure to ambient ozone and progression of subclinical arterial disease: the multi-ethnic study of atherosclerosis and air pollution, Environ Health Perspect source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Short-term exposure to ambient ozone can elevate serum levels of ACE and ET-1, decrease their DNA methylation, and alter the lipid metabolism, which may be partly responsible for increased blood pressure and vascular endothelial disfunction.

    “Xia et al. revealed that short-term exposure to ambient ozone can elevate serum levels of ACE and ET-1, decrease their DNA methylation, and alter the lipid metabolism, which may be partly responsible for increased blood pressure and vascular endothelial disfunction (51).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [51] Xia, 2018, Effects of personal short-term exposure to ambient ozone on blood pressure and vascular endothelial function: a mechanistic study based on DNA methylation and metabolomics, Environ Sci Technol. source

      Not checked in the free run.

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

    Premisecitation

    Exposure to ozone was responsible for 254,000 deaths from COPD alone in 2015.

    “In another study, exposure to ozone was responsible for 254,000 deaths from COPD alone in 2015 (73).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [73] Cohen, 2017, Estimates and 25-year trends of the global burden of disease attributable to ambient air pollution: an analysis of data from the Global Burden of Diseases Study 2015, Lancet. source

      Not checked in the free run.

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

    Premisecitation

    Anthropogenic ozone was associated with an estimated 700,000 ± 300,000 respiratory mortalities in 2000.

    “In one study, for example, anthropogenic ozone was associated with an estimated 700,000 ± 300,000 respiratory mortalities in 2000 (72).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [72] Anenberg, 2010, An estimate of the global burden of anthropogenic ozone and fine particulate matter on premature human mortality using atmospheric modeling, Environ Health Perspect. source

      Not checked in the free run.

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

    Interpretationreasoning

    The impact would be larger when other ozone effects were considered.

    “It is expected that the impact would be larger when other ozone effects were considered.”
    Quote in the paperNot a substantial claim

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

    Premisecitation

    An estimated 23.0-40.3 million respiratory-related deaths were attributable to long-term O3 exposure in 2016.

    “In addition, an estimated 23.0–40.3 million respiratory-related deaths were attributable to long-term O3 exposure in 2016 (15).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [15] Malley, 2017, Updated global estimates of respiratory mortality in adults >/ = 30 years of age attributable to long-term ozone exposure, Environ Health Perspect source

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    In many parts of the world, ozone concentrations are projected to increase, leading to increases in ozone-associated mortalities and morbidities.

    “In many parts of the world, as described above, ozone concentrations are projected to increase, leading to increases in ozone-associated mortalities and morbidities.”
    Quote in the paperSubstantial claim

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

    Premisecitation

    Disability adjusted life years lost from COPD alone attributable to ozone were estimated to be 4.1 (95% CI: 1.6-6.8) million years in 2015.

    “and 4.1 (95% CI: 1·6–6·8) million years from COPD alone in 2015 (73).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [73] Cohen, 2017, Estimates and 25-year trends of the global burden of disease attributable to ambient air pollution: an analysis of data from the Global Burden of Diseases Study 2015, Lancet. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). The quote only partly states this claim.

    Interpretationnone given

    Co-exposure to other air pollutants such as PM2.5 may affect the ability to repair the damage caused by acute ozone exposures.

    “The co-exposure may affect the ability to repair the damage caused by acute ozone exposures.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Some acute ozone effects are reversible.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Interpretationnone given

    Predictions of ozone levels in response to changing NOx and VOC concentrations get harder with ozone concentrations approaching their background level.

    “Meanwhile, predictions of ozone levels in response to changing NOx and VOC concentrations get harder with ozone concentrations approaching their “background” level.”
    Quote in the paperNot a substantial claim
33 of 33

  • The authors state this as an assumption.

    The health risk associated with lower-level ozone in cold months is negligible.

    “assuming that the health risk associated with lower-level ozone in cold months is negligible”

  • The authors state this as an assumption.

    Lower concentrations during the rest of 16 h do not contribute to an adverse effect when using 8-h daily max concentration.

    “using 8-h daily max concentration assumes that lower concentrations during the rest of 16 h do not contribute to an adverse effect”

  • The paper relies on this without support.

    Some acute ozone effects are reversible.

    “some of the acute ozone effects are known to be reversible”

  • The paper relies on this without support.

    The relationship of ozone production with its precursors is non-linear, so reducing one precursor may not necessarily lead to ozone reduction.

    “Part of the challenges is the “non-linear” relationship of ozone production with its precursors, as reducing one of the precursors may not necessarily lead to ozone reduction.”

  • The paper relies on this without support.

    Even within a metropolitan area, the optimal ratio of NOx to VOCs associated with minimal ozone formation changes from day to day and from upwind to downwind.

    “Even within a metropolitan area, the optimal ratio of NOx to VOCs associated with minimal ozone formation changes from day to day (even hour to hour) and from upwind to downwind.”

  • The paper relies on this without support.

    Sources of VOCs can be numerous and hard to characterize.

    “Sources of VOCs can be numerous and hard to characterize.”

  • The paper relies on this without support.

    Some known sources of VOCs, such as household use of consumer chemicals and biogenic emissions, are difficult to control through regulatory actions.

    “Some known sources, such as household use of consumer chemicals and biogenic emissions, are difficult to control through regulatory actions.”

  • The paper relies on this without support.

    Ozone concentrations and spatiotemporal distributions are specific to local meteorological conditions, local sources of NOx and VOCs, and long-range transport of ozone and associated chemical species.

    “Although the fundamental chemistry of ozone formation is clear, ozone concentrations, and spatiotemporal distributions are specific to local meteorological conditions, local sources of NOx and VOCs, and long-range transport of ozone and associated chemical species.”

  • The paper relies on this without support.

    Aggregative regulatory actions to cut down anthropogenic emissions of NOx and VOCs have not necessarily resulted in sufficient reductions in ozone concentrations in certain areas of the United States.

    “Based on the history of ozone control in the United States, aggregative regulatory actions to cut down anthropogenic emissions of NOx and VOCs have not necessarily resulted in sufficient reductions in ozone concentrations in certain areas of the United States.”

  • The paper relies on this without support.

    The immune-inflammatory responses initiated in the lung are the key in more downstream systemic effects.

    “although the immune-inflammatory responses initiated in the lung are thought to be the key in more downstream systemic effects.”
10 of 10

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?

  • Increased NOx emissions from biofuels could lead to adverse impacts on both the environment and public health because of formation of additional ozone.

    “The increased NO x emissions from biofuels could lead to adverse impacts on both the environment and public health because of formation of additional ozone, which is a component of photochemical smog and powerful oxidant [81,82].”

    From Investigation of Biofuel as a Potential Renewable Energy Source (2021) · cites this paper as [82]

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Global annual ozone death estimates differ by orders of magnitude

    Major

    The abstract puts worldwide premature deaths at several hundred thousand annually, but the discussion attributes 23.0-40.3 million respiratory-related deaths to ozone in 2016. These cannot both describe the annual worldwide burden at the stated scale.

1 of 1

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Authors
Zhang, J. (., Wei, Y., & Fang, Z.
Affiliations
  • Duke University (US)
  • Chinese Research Academy of Environmental Sciences (CN)
  • Guangzhou Institute of Respiratory Health (CN)
Corresponding author
  • Zhang, Junfeng (Jim)
  • Wei, Yongjie
ORCID
Venue
Frontiers in Immunology
Publisher
Frontiers Media SA
Published
2019-10-31
Volume
10
Pages
2518-2518
ISSN
1664-3224 (ISSN-L)
DOI
10.3389/fimmu.2019.02518
PMC
PMC6834528
OpenAlex
W2981938452
Semantic Scholar
af6cf2853c494aaf65433b19c213b76f4250fe97
Cited by
828
References
89
Citations by year
2026: 103 · 2025: 165 · 2024: 185 · 2023: 136 · 2022: 121 · 2021: 79 · 2020: 37 · 2019: 1 · 2013: 1
FWCI
5.68
Type
journal article
Language
en
Open access
Licence
Locations
  • Frontiers in Immunology (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
Innovative Research Group Project of the National Natural Science Foundation of China
Topics
  • Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Air Quality and Health Impacts
  • Physical Sciences › Earth and Planetary Sciences › Atmospheric Science › Atmospheric chemistry and aerosols
  • Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Indoor Air Quality and Microbial Exposure
Keywords
tropospheric ozone, ozone pollution, air pollution health effects, nitrogen oxides, volatile organic compounds, asthma, respiratory mortality, cardiovascular mortality, oxidative stress, airway inflammation, immune response, ambient air quality standards, antioxidants, fossil fuel emissions, premature mortality
MeSH terms
Air Pollutants, Air Pollution, Animals, Asthma, Humans, Ozone, United States, Global Health

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-10.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-10.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

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