Ozone Pollution: A Major Health Hazard Worldwide

In the paper

“In contrast, animal studies with high ozone exposures have generated more consistent findings on cardiovascular effects of ozone through altering vascular tone (60–62), mRNA for genes encoding thrombogenic factors (63), and atherogenesis (60).”

What the sources say

• Supported

  This source is cited for vascular tone and atherogenesis, not for thrombogenic-factor mRNA, which the sentence attributes to citation 63. The Abstract reports altered vascular tone regulation and increased atherogenesis after ozone exposure; the Discussion specifies a 0.5 ppm exposure. (LLM, conf=0.91)

  cites [60] Chuang, 2009, Pulmonary ozone exposure induces vascular dysfunction, mitochondrial damage, and atherogenesis, Am J Physiol Lung Cell Mol Physiol. source
• Supported

  This paper supports the vascular-tone part of the sentence, for which citations 60–62 are given. In “Ozone Inhalation Enhances Tone at Baseline,” coronary arteries from ozone-exposed rats developed greater basal tone than those from filtered-air controls. The sentence cites a different source, citation 60, for atherogenesis. (LLM, conf=0.92)

  cites [61] Paffett, 2015, Ozone inhalation impairs coronary artery dilation via intracellular oxidative stress: evidence for serum-borne factors as drivers of systemic toxicity, Toxicol Sci. source
• Supported

  The Results section (‘Loss of CD36 Prevents Vascular Endothelial Dysfunction Following Exposure to O3’; page unavailable) reports impaired aortic relaxation in ozone-exposed mice, supporting the vascular-tone finding for which this paper is cited. The separate claims about thrombogenic-gene mRNA and atherogenesis have different citations in the citing sentence and are not attributed to this source. (LLM, conf=0.92)

  cites [62] Robertson, 2013, CD36 mediates endothelial dysfunction downstream of circulating factors induced by O3 exposure, Toxicol Sci. source
• Supported

  This paper supports the thrombogenic-factor mRNA clause, the part of the citing sentence associated with citation 63. Its Conclusion (page unavailable) reports increased aortic mRNA biomarkers of microvascular thrombosis after episodic ozone exposure in rats. The sentence assigns atherogenesis to a different citation, so that is not part of this verdict. (LLM, conf=0.91)

  cites [63] Kodavanti, 2010, Vascular and cardiac impairments in rats inhaling ozone and diesel exhaust particles, Environ Health Perspect. source

In the paper

“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).”

What the sources say

• Not checked yetcites [13] Ma, 2016, Significant increase of surface ozone at a rural site, north of eastern China, Atmos Chem Phys source

In the paper

“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).”

In the paper

“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).”

What the sources say

• Not checked yetcites [6] Li, 2019, Anthropogenic drivers of 2013–2017 trends in summer surface ozone in China, Proc Natl Acad Sci USA. source

In the paper

“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).”

What the sources say

• Not checked yetcites [7] Bell, 2007, Climate change, ambient ozone, and health in 50 US cities, Clim Change source

In the paper

“evidence suggests that global average ozone concentrations are increasing.”

In the paper

“100.6 million people nationwide (or nearly one in every three people) lived in U.S. counties where ozone levels exceeded the NAAQS standard of 70 ppb in 2017”

What the sources say

• Not checked yetcites [3] Guenther, 2000, Natural emissions of non-methane volatile organic compounds, carbon monoxide, and oxides of nitrogen from North America, Atmosph Environ. source

In the paper

“estimated an increase of 0.43 ppb (95% CI: 0.14–0.75) in average ozone concentration during the 2040s compared to 2000 due to climate change alone (9).”

What the sources say

• Not checked yetcites [9] Chang, 2010, Impact of climate change on ambient ozone level and mortality in southeastern United States, Int J Environ Res Public Health source

In the paper

“Climate change can also prolong the ozone season.”

In the paper

“ozone measured at Mt Waliguan Observatory (a global “background” site) on the Tibetan Plateau over the period of 1994–2013 has shown an increasing trend at 0.2–0.3 ppb per year during spring and autumn (11).”

What the sources say

• Not checked yetcites [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

In the paper

“ground-level ozone concentrations measured in some monitoring sites in China showed an increasing trend in the past several years.”

In the paper

“Consequently, there was a 32% decrease in national average of daily maximum 8-h averages of ozone measured at 200 monitoring sites across the United States3.”

What the sources say

• Not checked yetcites [3] Guenther, 2000, Natural emissions of non-methane volatile organic compounds, carbon monoxide, and oxides of nitrogen from North America, Atmosph Environ. source

In the paper

“However, this demonstrates that NOx and VOCs emitted in more populous regions can undergo long-range transport and affect “background” ozone level.”

What the sources say

• Not checked yetcites [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

In the paper

“More importantly, particulate matter (e.g., particles with an aerodynamic diameter equal to or smaller than 2.5 μm, noted as PM2.5) can serve as a sink of free radicals responsible for ozone formation.”

In the paper

“From 1980 to 2017, total national emissions of NOX and VOCs were reduced by 61 and 54%, respectively.”

In the paper

“Epidemiological studies have found that ozone concentrations averaged over a longer period (such as 8 h instead of 1 h) within a day are a more health-relevant indicator of ozone exposure.”

In the paper

“If the WHO-recommended 8-h limit of 50 ppb is used, there would be even more people living in places with ozone exceeding the health-based limit.”

In the paper

“it is predicted that the 95th percentile for daily 8-h maximum ozone would increase from 79 ppb in 2012 to 87 ppb in 2050 (8).”

What the sources say

• Not checked yetcites [8] Pfister, 2014, Projections of future summertime ozone over the US. JGR: atmospheres source

In the paper

“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.”

In the paper

“a warming climate favors the formation and accumulation of ozone in the atmosphere mainly through two physicochemical mechanisms.”

In the paper

“This increase was attributed to changes in anthropogenic emissions of ozone precursors as well as reductions in PM2.5 concentrations as described earlier.”

What the sources say

• Not checked yetcites [6] Li, 2019, Anthropogenic drivers of 2013–2017 trends in summer surface ozone in China, Proc Natl Acad Sci USA. source

In the paper

“This finding suggests that occurrences of a drying and warming fall in the future may lead to an extension of the ozone season from summer to fall in the regions with significant biogenic VOC emissions.”

What the sources say

• Not checked yetcites [10] Zhang, 2016, Climate-driven ground-level ozone extreme in the fall over the Southeast United States, Proc Natl Acad Sci USA. source

In the paper

“The current WHO Air Quality Guidelines for ambient (outdoor) ozone is 100 μg/m3 (~50 ppb) measured as 8-h maximum moving average within a day1.”

What the sources say

• Not checked yetcites [1] McDonald, 2018, Volatile chemical products emerging as largest petrochemical source of urban organic emissions, Science. source

In the paper

“a recent analysis of ground-level ozone concentrations measured at nearly 1,000 sites across China also found an increasing trend of summertime ozone in northeastern China from 2013 to 2017 (6).”

What the sources say

• Not checked yetcites [6] Li, 2019, Anthropogenic drivers of 2013–2017 trends in summer surface ozone in China, Proc Natl Acad Sci USA. source

In the paper

“However, ozone during the fall reached the summer level in several Octobers in the 2000s and in 2010 over the southeastern United States. This was attributed to enhanced emissions of biogenic isoprene (a VOC precursor of ozone) from water-stressed plants under a drying and warming condition (10).”

What the sources say

• Not checked yetcites [10] Zhang, 2016, Climate-driven ground-level ozone extreme in the fall over the Southeast United States, Proc Natl Acad Sci USA. source

In the paper

“in summer months, daily air quality reports released to the public in recent years have often shown more days when the ozone standard was exceeded than when PM2.5 or other regulated pollutants exceeded the standards in many cities of China.”

In the paper

“Krishna et al. further confirmed that ozone-induced neutrophil influx in human peripheral airways was partly mediated by IL-8 (38).”

What the sources say

• Not checked yetcites [38] Krishna, 1998, Effects of 0.2 ppm ozone on biomarkers of inflammation in bronchoalveolar lavage fluid and bronchial mucosa of healthy subjects, Eur Respir J source

In the paper

“Based on this assessment, the national ambient air quality standard for 8-h daily max ozone was revised from 75 to 70 ppb in 2015.”

What the sources say

• Not checked yetcites [7] Bell, 2007, Climate change, ambient ozone, and health in 50 US cities, Clim Change source

In the paper

“Long-term exposures to ozone have been associated with lower lung function and deteriorated or abnormal lung development in children (31, 32).”

What the sources say

• Not checked yetcites [31] Gauderman, 2004, The effect of air pollution on lung development from 10 to 18 years of age, N Engl J Med source
• Not checked yetcites [32] Gauderman, 2002, Association between air pollution and lung function growth in southern California children: results from a second cohort, Am J Respir Crit Care Med source

In the paper

“In contrast, for leaky buildings and for building with windows frequently open, indoor concentrations can reach >70% outdoor concentrations.”

In the paper

“A meta-analysis of 53 studies showed a weak but significant association between ozone and hospital admission and mortality from stroke (41).”

What the sources say

• Not checked yetcites [41] Shah, 2015, Short term exposure to air pollution and stroke: systematic review and meta-analysis, BMJ. source

In the paper

“Second, outdoor ozone concentrations exhibit a substantial seasonal variation in most of the places.”

In the paper

“However, VOC emissions have remained relatively unchanged.”

What the sources say

• Not checked yetcites [6] Li, 2019, Anthropogenic drivers of 2013–2017 trends in summer surface ozone in China, Proc Natl Acad Sci USA. source

In the paper

“Ozone can cause adverse respiratory effects such as difficulty of breathing (e.g., shortness of breath and pain when taking a deep breath) and inflammation of the airways in the general population.”

What the sources say

• Not checked yetcites [25] Nuvolone, 2018, The effects of ozone on human health, Environ Sci Pollut Res source
• Not checked yetcites [26] Koman, 2017, Ozone exposure, cardiopulmonary health, and obesity: a substantive review, Chem Res Toxicol source

In the paper

“Increased exposure to ambient ozone has been associated with increased levels of hemostatic markers, including fibrinogen (48–50), von Willebrand factor (49), and plasminogen activator inhibitor-1 (48).”

What the sources say

• Not checked yetcites [48] Chuang, 2007, The effect of urban air pollution on inflammation, oxidative stress, coagulation, and autonomic dysfunction in young adults, Am J Respir Crit Care Med. source
• Not checked yetcites [49] Liao, 2005, Association of criteria pollutants with plasma hemostatic/inflammatory markers: a population-based study, J Expo Anal Environ Epidemiol. source
• Not checked yetcites [50] Steinvil, 2008, Short-term exposure to air pollution and inflammation-sensitive biomarkers, Environ Res. source

In the paper

“warm-season averages have often been used (14, 15), assuming that the health risk associated with lower-level ozone in cold months is negligible.”

What the sources say

• Not checked yetcites [14] Turner, 2016, Long-term ozone exposure and mortality in a large prospective study, Am J Respir Crit Care Med source
• Not checked yetcites [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

In the paper

“In addressing exposure to low-level concentrations (such as concentrations below the current air quality standard), however, 24-h average may be another relevant measure of daily exposure, at least for certain outcomes (21–24).”

What the sources say

• Not checked yetcites [21] Day, 2017, Association of ozone exposure with cardiorespiratory pathophysiologic mechanisms in healthy adults, JAMA Intern Med source
• Not checked yetcites [22] Di, 2017, Association of short-term exposure to air pollution with mortality in older adults, JAMA. source
• Not checked yetcites [23] Dai, 2018, Age-dependent effect of ambient ozone on emergency asthma hospitalizations in Hong Kong, J Allergy Clin Immunol source
• Not checked yetcites [24] Sun, 2018, Acute effect of multiple ozone metrics on mortality by season in 34 Chinese counties in 2013–2015, J Intern Med source

In the paper

“Ozone continues to damage the lungs even when the symptoms have disappeared.”

What the sources say

• Not checked yetcites [1] McDonald, 2018, Volatile chemical products emerging as largest petrochemical source of urban organic emissions, Science. source

In the paper

“anthropogenic emissions of NOx have decreased substantially in most urban areas of China (a 21% nationwide reduction) from 2013 to 2017 (6).”

What the sources say

• Not checked yetcites [6] Li, 2019, Anthropogenic drivers of 2013–2017 trends in summer surface ozone in China, Proc Natl Acad Sci USA. source

In the paper

“Since the 2013 EPA assessment was released, several studies conducted in North America further confirmed significant positive associations, robust to controlling for co-pollutants, between short-term ozone exposure and one or more of the following mortality classifications: cardiovascular, dysrhythmia, cardiometabolic, and ischemic heart disease.”

In the paper

“In airtight buildings with doors and windows closed, indoor ozone levels are typically smaller than 20% of outdoor levels.”

In the paper

“using outdoor concentration as a surrogate for ozone exposure would lead to greater overestimation of exposure for people living or working in more airtight buildings than for those living in less airtight buildings.”

In the paper

“These immune-inflammatory responses to ozone may “spill over” to the circulatory system, which may help explain emerging evidence on the cardiovascular and neuronal effects of ozone.”

In the paper

“children, older adults, and people who are active outdoors (especially outdoor workers) are more vulnerable to ozone exposure.”

In the paper

“Ozone exposure makes the lungs more susceptible to infection.”

What the sources say

• Not checked yetcites [1] McDonald, 2018, Volatile chemical products emerging as largest petrochemical source of urban organic emissions, Science. source

In the paper

“As a potent oxidizing gas, ambient ozone is well-known to cause oxidative damages to the cells and the lining fluids of the airways, thereby inducing immune-inflammatory responses in the lung.”

In the paper

“Ozone exposure resulted in significant neutrophilic inflammation, reflected with increased levels of myeloperoxidase (MPO) in the supernatant of induced sputum samples from healthy subjects (39, 40).”

What the sources say

• Not checked yetcites [39] Fahy, 1995, Analysis of induced sputum after air and ozone exposures in healthy subjects, Environ Res source
• Not checked yetcites [40] Holz, 2010, SCH527123, a novel CXCR2 antagonist, inhibits ozone-induced neutrophilia in healthy subjects, Eur Respir J source

In the paper

“However, accumulating evidence suggests that there may not exist a threshold ozone concentration below which the risk is “zero.””

In the paper

“These effects can aggravate lung diseases such as asthma, emphysema, and chronic bronchitis [chronic obstructive pulmonary disease (COPD)].”

What the sources say

• Not checked yetcites [25] Nuvolone, 2018, The effects of ozone on human health, Environ Sci Pollut Res source
• Not checked yetcites [26] Koman, 2017, Ozone exposure, cardiopulmonary health, and obesity: a substantive review, Chem Res Toxicol source

In the paper

“A recent cohort study by Lim et al. further confirmed this association between long-term exposure to ozone and increased cardiovascular mortality (45).”

What the sources say

• Not checked yetcites [14] Turner, 2016, Long-term ozone exposure and mortality in a large prospective study, Am J Respir Crit Care Med source
• Not checked yetcites [45] Lim, 2019, Long-term exposure to ozone and cause-specific mortality risk in the U.S, Am J Respir Crit Care Med source

In the paper

“Long-term exposure to ozone is likely to be one of many causes of asthma development.”

What the sources say

• Not checked yetcites [25] Nuvolone, 2018, The effects of ozone on human health, Environ Sci Pollut Res source
• Not checked yetcites [26] Koman, 2017, Ozone exposure, cardiopulmonary health, and obesity: a substantive review, Chem Res Toxicol source

In the paper

“Additionally, deleterious effects of ozone exposure on the central nervous system (CNS) are emerging (64, 65).”

What the sources say

• Not checked yetcites [64] Martínez-Lazcano, 2013, The effects of ozone exposure and associated injury mechanisms on the central nervous system, Rev Neurosci. source
• Not checked yetcites [65] Croze, 2018, Ozone atmospheric pollution and Alzheimer's disease: from epidemiological facts to molecular mechanisms, J Alzheimers Dis. source

In the paper

“Disease burden attributable to ozone is expected to continue to rise in the future for two reasons.”

In the paper

“a study found that a 5 ppb (10 μg/m3) increase in long-term ozone concentration was associated with 0.25 year (95% CI: −0.30 to −0.19) lower life expectancy in males”

What the sources say

• Not checked yetcites [78] Li, 2016, Long-term exposure to ozone and life expectancy in the United States, 2002 to 2008, Medicine. source

In the paper

“A large multicity study in China showed that short-term exposure to ambient ozone was associated with higher non-accidental and cardiovascular mortality (20).”

What the sources say

• Not checked yetcites [20] Yin, 2017, Ambient ozone pollution and daily mortality: a nationwide study in 272 Chinese cities, Environ Health Perspect source

In the paper

“Rodríguez et al. showed that ozone exposure resulted in the activation of apoptotic death in rat hippocampus mediated by endoplasmic reticulum stress (68).”

What the sources say

• Not checked yetcites [68] Rodriguez-Martinez, 2016, The effect of chronic ozone exposure on the activation of endoplasmic reticulum stress and apoptosis in rat hippocampus, Front Aging Neurosci. source

In the paper

“These estimates were based on respiratory effects alone, due to uncertainties associated with the current evidence on the cardiovascular effects.”

In the paper

“For example, an analysis of national databases found a positive association between increase in long-term ozone concentrations and an increased risk of respiratory diseases and death (44).”

What the sources say

• Not checked yetcites [44] Jerrett, 2009, Long-term ozone exposure and mortality, N Engl J Med source

In the paper

“The first is the fact that ozone concentration is on the rise in many parts of the world as described earlier.”

In the paper

“Bello-Medina et al. found that rats chronically exposed to ozone exhibited deficits in learning and memory loss associated with deafferentation in hippocampus-related neurons (69).”

What the sources say

• Not checked yetcites [69] Bello-Medina, 2019, Effect of ozone exposure on dendritic spines of CA1 pyramidal neurons of the dorsal hippocampus and on object-place recognition memory in rats, Neuroscience. source

In the paper

“Long-term ozone exposure (3-year averages) has been associated with development of acute respiratory distress syndrome (ARDS) in at-risk critically ill patients, particularly in trauma patients and current smokers (77).”

What the sources say

• Not checked yetcites [77] Ware, 2016, Long-term ozone exposure increases the risk of developing the acute respiratory distress syndrome, Am J Respir Crit Care Med. source

In the paper

“An estimated 9–23 million (8–20% of total) asthma-related emergency room visits globally were attributable to ozone (74).”

What the sources say

• Not checked yetcites [74] Anenberg, 2018, Estimates of the global burden of ambient PM2.5, ozone, and NO2 on asthma incidence and emergency room visits, Environ Health Perspect. source

In the paper

“Using large hospital records, increased chronic ozone exposure was associated with increased asthma hospital admissions in children (27).”

What the sources say

• Not checked yetcites [27] Lin, 2008, Chronic exposure to ambient ozone and asthma hospital admissions among children, Environ Health Perspect source

In the paper

“Relative to that in 2000, there will be a 14% increase in global ozone-related mortality (75).”

What the sources say

• Not checked yetcites [75] Silva, 2017, Future global mortality from changes in air pollution attributable to climate change, Nat Clim Change. source

In the paper

“The relatively large gap in the estimates across studies is due to uncertainties associated with and inconsistence in concentration–effect relationship and ozone exposure assessment.”

In the paper

“Neurodegenerative disorders, such as Alzheimer's disease (AD) and Parkinson's disease, have been linked to ozone exposures in recent epidemiologic studies (66, 67).”

What the sources say

• Not checked yetcites [66] Jung, 2015, Ozone, particulate matter, and newly diagnosed Alzheimer's disease: a population-based cohort study in Taiwan, J Alzheimers Dis. source
• Not checked yetcites [67] Kirrane, 2015, Associations of ozone and PM2. 5 concentrations with Parkinson's disease among participants in the agricultural health study, J Occup Environ Med. source

In the paper

“The improved knowledge will likely add to ozone-associated disease burden that is currently uncounted for.”

In the paper

“Jia et al. showed that ambient ozone exposure within several minutes can decrease heart rate variability in the healthy elderly subjects, suggesting that a dysfunction of cardiac autonomic nervous system may be involved (53).”

What the sources say

• Not checked yetcites [53] Jia, 2011, Acute effect of ambient ozone on heart rate variability in healthy elderly subjects, J Expo Sci Environ Epidemiol. source

In the paper

“Ozone pollution is a worldwide health hazard.”

In the paper

“For example, an estimated increase of 0.43 ppb in average ozone concentration, during the 2040s compared to 2000 due to climate change alone, would correspond to a 0.01% increase in mortality rate in 19 urban communities in southeastern United States (9).”

What the sources say

• Not checked yetcites [9] Chang, 2010, Impact of climate change on ambient ozone level and mortality in southeastern United States, Int J Environ Res Public Health source

In the paper

“Di et al. (76) analyzed the entire US Medicare population of 60 million older adults from the years 2000 through 2012 and found a positive association between annual averages of ozone and all-cause mortality rate.”

What the sources say

• Not checked yetcites [76] Di, 2017, Air pollution and mortality in the Medicare population, N Engl J Med. source

In the paper

“Epidemiological evidence is limited to support a causal relationship between the chronic exposure and mortality or morbidity, although progresses have been made in recent years by using large datasets.”

In the paper

“The mechanistic understanding appears to be sufficient to support the use of antioxidants or ozone scavenger to alleviate the ozone effects.”

In the paper

“For example, rodent studies confirmed that the use of N-acetylcysteine and sulfide salt can help prevent or recover the lung impairment caused by ozone (82, 83).”

What the sources say

• Not checked yetcites [82] Li, 2016, Hydrogen sulfide prevents and partially reverses ozone-induced features of lung inflammation and emphysema in mice, Am J Respir Cell Mol Biol. source
• Not checked yetcites [83] Li, 2013, Effects of N-acetylcysteine in ozone-induced chronic obstructive pulmonary disease model, PLoS ONE. source

In the paper

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

What the sources say

• Not checked yetcites [79] Bell, 2006, The exposure-response curve for ozone and risk of mortality and the adequacy of current ozone regulations, Environ Health Perspect. source
• Not checked yetcites [80] Chen, 2017, Acute effect of ozone exposure on daily mortality in seven cities of Jiangsu Province, China: no clear evidence for threshold, Environ Res. source

In the paper

“Making ozone forecasting available to the general public will enhance the effectiveness of such personal protection methods to reduce ozone exposure (81).”

What the sources say

• Not checked yetcites [81] Zhang, 2017, Low-level air pollution associated with death: policy and clinical implications, JAMA. source

In the paper

“Relatively less is known to understand how ozone affects the cardiovascular health outcomes”

In the paper

“A randomized trial found that a daily supplement of vitamins C and E might provide some protection against acute nasal inflammatory response to ozone in asthmatic children (84).”

What the sources say

• Not checked yetcites [84] Sienra-Monge, 2004, Antioxidant supplementation and nasal inflammatory responses among young asthmatics exposed to high levels of ozone, Clin Exp Immunol. source

In the paper

“and 0.21 year (95% CI: −0.25 to −0.17) in females (78).”

What the sources say

• Not checked yetcites [78] Li, 2016, Long-term exposure to ozone and life expectancy in the United States, 2002 to 2008, Medicine. source

In the paper

“Or if a threshold exists, it would have to be substantially lower than the current health-based regulatory standards or guidelines.”

In the paper

“The natural fluctuation in ambient ozone concentration hence makes it challenging to examine chronic effects of short-term and long-term exposures.”

In the paper

“For all these challenges, ozone pollution in developing countries is expected to be a long-term problem”

In the paper

“In a control human exposure study (2-h exposure to 400 ppb ozone vs. filtered air), healthy adults who had received a dietary antioxidant supplementation of a mixture of vitamin C, alpha-tocopherol, and vegetable cocktail exhibited a significantly smaller ozone-induced reduction in pulmonary function (85).”

What the sources say

• Not checked yetcites [85] Samet, 2001, Effect of antioxidant supplementation on ozone-induced lung injury in human subjects, Am J Respir Crit Care Med. source

In the paper

“In the United States and developed countries with relatively better air quality, following decades of controls for NOx and VOCs emissions, further controls of anthropogenic emissions via policy, and technological tools are becoming increasingly limited.”