The Year of Ozone

Effects of Ozone on Sickness and Depressive-like Behavioral and Biochemical Phenotypes and Their Regulation by Serum Amyloid A in Mice

Ozone (O₃) is an air pollutant that primarily damages the lungs, but growing evidence supports the idea that O₃ also harms the brain; acute exposure to O₃ has been linked to central nervous system (CNS) symptoms such as depressed mood and sickness behaviors. However, the mechanisms by which O₃ inhalation causes neurobehavioral changes are limited. One hypothesis is that factors in the circulation bridge communication between the lungs and brain following O₃ exposure. In this study, our goals were to characterize neurobehavioral endpoints of O₃ exposure as they relate to markers of systemic and pulmonary inflammation, with a particular focus on serum amyloid A (SAA) and kynurenine as candidate mediators of O₃ behavioral effects. We evaluated O₃-induced dose-, time- and sex-dependent changes in pulmonary inflammation, circulating SAA and kynurenine and its metabolic enzymes, and sickness and depressive-like behaviors in Balb/c and CD-1 mice. We found that 3 parts per million (ppm) O₃, but not 2 or 1 ppm O₃, increased circulating SAA and lung inflammation, which were resolved by 48 h and was worse in females. We also found that indoleamine 2,3-dioxygenase (Ido1) mRNA expression was increased in the brain and spleen 24 h after 3 ppm O₃ and that kynurenine was increased in blood. Sickness and depressive-like behaviors were observed at all O₃ doses (1-3 ppm), suggesting that behavioral responses to O₃ can occur independently of increased SAA or neutrophils in the lungs. Using SAA knockout mice, we found that SAA did not contribute to O₃-induced pulmonary damage or inflammation, systemic increases in kynurenine post-O₃, or depressive-like behavior but did contribute to weight loss. Together, these findings indicate that acute O₃ exposure induces transient symptoms of sickness and depressive-like behaviors that may occur in the presence or absence of overt pulmonary neutrophilia and systemic increases of SAA. SAA does not appear to contribute to pulmonary inflammation induced by O₃, although it may contribute to other aspects of sickness behavior, as reflected by a modest effect on weight loss.

Au W, Zhao W, Xia ZL. A Systematic Review and Meta-Analysis of Short-Term Ambient Ozone Exposure and COPD Hospitalizations

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death globally and ozone exposure is a main cause of its disease burden. However, studies on COPD hospitalizations from short-term ambient level ozone exposure have not generated consensus results. To address the knowledge gap, comprehensive and systematic searches in several databases were conducted using specific keywords for publications up to February 14, 2020. Random-effect models were used to derive overall excess risk estimates between short-term ambient-level ozone exposure and COPD hospitalizations. The influence analyses were used to test the robustness of the results. Both meta-regression and subgroup analyses were used to explore the sources of heterogeneity and potential modifying factors. Based on the results from 26 eligible studies, the random-effect model analyses show that a 10 µg/m³ increase in maximum 8-h ozone concentration was associated with 0.84% (95% CI: 0.09%, 1.59%) higher COPD hospitalizations. The estimates were higher for warm season and multiple-day lag but lower for old populations. Results from subgroup analyses also indicate a multiple-day lag trend and bigger significant health effects during longer day intervals. Although characteristics of individual studies added modest heterogeneity to the overall estimates, the results remained robust during further analyses and exhibited no evidence of publication bias. Our systematic review and meta-analysis indicate that short-term ambient level ozone exposure was associated with increased risk of COPD hospitalizations. The significant association with multiple-day lag trend indicates that a multiple-day exposure metric should be considered for establishing ambient ozone quality and exposure standards for improvement of population health. Future investigations and meta-analysis studies should include clinical studies as well as more careful lag selection protocol.

Temporal dynamics of ground-level ozone and its impact on morbidity in Almaty city in comparison with Astana city, Kazakhstan

Respiratory diseases are nowadays much related to environmental factors such as air pollution. In this sense, it is considered that the annual and the daily courses of ground-level ozone concentrations affect the respiratory systems. A study of ground-level ozone concentration (GO) in the city of Almaty is developed attending to the general content of ozone in the atmosphere as one of sources of ground ozone. The study analyzed the annual and daily course of total ground-level ozone in Almaty. It is shown that the dynamics of its concentrations depends on many factors such as large-scale circulation in the Central Asian region, solar radiation, local mountain valley circulation, and the time of year. Geographic location, motor vehicles traffic intensity, and some specific synoptic conditions can also dramatically affect the daily course of ground-level ozone, promoting formation of two maximum concentration peaks, and one deep minimum concentration between them. The main maximum was fixated at 1:0 p.m., the secondary one at 1:0 a.m. The main minimum was not stable throughout the year. It was fixated at 7:0 p.m. in cold seasons and at 7:0 a.m. in warm seasons. The mean concentration of ground-level ozone from February to November was higher than average permitted concentrations. During 1-2 months, this measurement was higher than MAC (Maximum Allowable Concentrations). High concentration of GO is related to an increase on the number of cases with respiratory problems mainly in the city of Almaty in Kazakhstan.

Ambient PM2.5 and O3 and their combined effects on prevalence of presbyopia among the elderly: A cross-sectional study in six low- and middle-income countries

BACKGROUND

Ambient air pollutant directly contacts with the eyes, however, the effect of ambient fine particulate matter (PM_2.5) and ozone (O₃) on vision impairment, such as presbyopia, has been kept largely unknown.

METHODS

We surveyed a total of 36,620 participants aged 50 years and above in six low- and middle-income countries. Ambient annual concentrations of PM_2.5 and O₃ for the residential community were estimated using satellite data and chemical transport model. A mixed effects model was utilized to assess the effects of ambient PM_2.5 and O₃ on presbyopia, as well as their combined effects.

RESULTS

A total of 13,841 presbyopia cases were identified among the participants with a prevalence rate of 41.17%. For both PM_2.5 and O₃, we found a J-shaped exposure-response relationship with the threshold being identified at 15 μg/m³ for PM_2.5 and 55 μg/m³ for O₃. The odds ratio (OR) of presbyopia was 1.15 (95% CI: 1.09, 1.21) for each 10 μg/m³ increase in PM_2.5 above 15 μg/m³ and 1.37 (95% CI: 1.23, 1.54) for O₃ above 55 μg/m³ after adjusting for various potential confounding factors. There appeared to be a synergistic interaction between ambient PM_2.5 and O₃ on presbyopia in the additive model, the combined effect was significantly larger than the sum of their individual effects, with a synergistic index of 2.39.

CONCLUSION

This study supports that exposures to ambient PM_2.5 and O₃ might be important risk factors of presbyopia among old adults, and simultaneously exposure to high level of the two pollutants could intensify their individual effects.

The burden of ozone pollution on years of life lost from chronic obstructive pulmonary disease in a city of Yangtze River Delta, China

OBJECTIVE

Ambient ozone is one of the most important air pollutants with respect to its impacts on human health and its increasing concentrations globally. However, studies which explored the burden of ozone pollution on chronic obstructive pulmonary disease (COPD) and estimated the relevant economic loss were rare.

OBJECTIVE

We explored the relationships between ambient ozone exposure and years of life lost (YLL) from COPD mortality and estimated the relevant economic loss in Ningbo, in the Yangtze River Delta of China, 2011-2015.

METHODS

A time-series study was conducted to explore the effects of ozone on YLL from COPD. Seasonal stratified analyses were performed, and the effect modification of demographic factors was estimated. In addition, the related economic loss was calculated using the method of the value per statistical life year (VSLY).

RESULTS

Averaged daily mean maximum 8-h average ozone concentration was 40.90 ppb in Ningbo, China, 2011-2015. The effect of short term ambient ozone exposure on COPD YLL was more pronounced in the cool season than in the warm season, with 10 ppb increment of ozone corresponding to 7.09(95%CI: 3.41, 10.78) years increase in the cool season and 0.31 (95%CI: -2.15, 2.77) years change in the warm season. The effect was higher in the elderly than the young. Economic loss due to excess COPD YLL related to ozone exposure accounted for 7.30% of the total economic loss due to COPD YLL in Ningbo during the study period.

CONCLUSIONS

Our findings highlight that ozone exposure was related to tremendous disease burden of COPD in Ningbo, China. The effects were more pronounced in the cool season, and the elderly were more susceptible populations.

Assessing the associations of daily respiratory symptoms and lung function in schoolchildren using an Air Quality Index for ozone: Results from the RESPOZE panel study in Athens, Greece

BACKGROUND

Air Quality indicators or indices (AQIs) are mainly used for communicating the air pollution levels and risk to the general population. However, very few epidemiological studies have used AQIs for characterizing exposure.

OBJECTIVE

In the framework of the RESPOZE panel study we evaluated the association of daily ozone AQI levels with the daily occurrence of respiratory symptoms and Peak Expiratory Flow (PEF) and compared the effects with those estimated using measurements from fixed outdoor monitoring sites, in the city of Athens, Greece.

MATERIALS AND METHODS

A panel of 97 children, aged 10-11years, was followed intensively for 35days (5weeks) during the academic year 2013-14. PEF and symptoms were recorded daily by each child. Two ozone AQIs classifying the air quality into 7 categories of increasing severity, were calculated; one characterizing the whole Athens area and one the local area around the child's residence and school. Measurements from fixed sites were also used. Mixed effects models for repeated measurements were applied, adjusting for several confounders.

RESULTS

Increasing ozone levels were associated with increased incidence of symptoms, but the strongest and most statistically significant associations were found with the local air quality characterization with the AQI. Specifically, an increase in AQI-local by one category was associated with 34% (95% CI: 9%, 64%) increased odds of stuffy nose. When the AQI categories were "Bad" and "Severe", an increase in the incidence of cough was observed (OR 3.05 (95% CI: 1.29, 7.22) and 6.42 (95% CI: 1.47, 28.03) respectively). We did not observe a statistically significant association between AQI and PEF.

CONCLUSION

Our results show that the use of an AQI based on local conditions may be advantageous over the use of only measurements when investigating the effects of air pollution on health outcomes for improving communication of risk to the public.

Mechanistic Basis for Obesity-related Increases in Ozone-induced Airway Hyperresponsiveness in Mice

Obesity is a risk factor for asthma, especially nonallergic asthma. Ozone, a common air pollutant, is a nonallergic asthma trigger. Importantly, ozone-induced decrements in lung function are greater in obese and overweight human subjects than in lean individuals. Obese mice also exhibit exaggerated pulmonary responses to ozone. Ozone causes greater increases in pulmonary resistance, in bronchoalveolar lavage neutrophils, and in airway hyperresponsiveness in obese than in lean mice. Our data indicate that IL-33 plays a role in mediating these events. Ozone causes greater release of IL-33 into bronchoalveolar lavage fluid in obese than in lean mice. Furthermore, an antibody blocking the IL-33 receptor, ST2, attenuates ozone-induced airway hyperresponsiveness in obese but not in lean mice. Our data also indicate a complex role for tumor necrosis factor (TNF)-α in obesity-related effects on the response to ozone. In obese mice, genetic deficiency in either TNF-α or TNF-α receptor 2 augments ozone-induced airway hyperresponsiveness, whereas TNF-α receptor 2 deficiency virtually abolishes ozone-induced airway hyperresponsiveness in lean mice. Finally, obesity is known to alter the gut microbiome. In female mice, antibiotics attenuate obesity-related increases in the effect of ozone on airway hyperresponsiveness, possibly by altering microbial production of short-chain fatty acids. Asthma control is often difficult to achieve in obese patients with asthma. Our data suggest that therapeutics directed against IL-33 may ultimately prove effective in these patients. The data also suggest that dietary manipulations and other strategies (prebiotics, probiotics) that alter the microbiome and/or its metabolic products may represent a new frontier for treating asthma in obese individuals.

The impact of occupational exposure to traffic-related air pollution among professional motorcyclists from Porto Alegre, Brazil, and its association with genetic and oxidative damage

Vehicles play an important role in modern life; however, they also generate hazards. Occupational exposed subjects are in long-term contact with harmful products, which sets these professionals in a susceptible group to air pollutant damage. The aims of this study were to quantify individual exposure to pollutant gases and chemical elements and to evaluate oxidative and genetic damage in professional motorcyclists and office workers. We recruited professional motorcyclists and office workers from Porto Alegre, Brazil, between January and December 2016. Individual exposure to air pollutants was assessed by passive monitoring. Fingernail trace elements were determined by using inductively coupled plasma mass spectrometry. Oxidative stress biomarkers were quantified spectrophotometrically, and genotoxicity was evaluated by micronuclei assay. Individual exposure to NO₂ and O₃, trace element content (Sb, Pt, As, Cd, V, Mn, and Co), oxidative stress factors, and genetic damage were statistically higher in professional motorcyclists (p < 0.05). Moreover, NO₂ and O₃ levels showed very strong positive correlation with plasmatic lipid peroxidation (p < 0.001 and r = 0.8849 and 0.8995) and strong positive correlation with micronuclei frequency (p < 0.001 and r = 0.7683 and 0.7280). Results suggest that professional motorcyclists are at high risk due to long-term air pollution exposure, which implies in the onset of several harmful effects and worsening of pre-existent diseases.

Updated Global Estimates of Respiratory Mortality in Adults ≥30Years of Age Attributable to Long-Term Ozone Exposure

BACKGROUND

Relative risk estimates for long-term ozone (O₃) exposure and respiratory mortality from the American Cancer Society Cancer Prevention Study II (ACS CPS-II) cohort have been used to estimate global O₃-attributable mortality in adults. Updated relative risk estimates are now available for the same cohort based on an expanded study population with longer follow-up.

OBJECTIVES

We estimated the global burden and spatial distribution of respiratory mortality attributable to long-term O₃ exposure in adults ≥30y of age using updated effect estimates from the ACS CPS-II cohort.

METHODS

We used GEOS-Chem simulations (2×2.5º grid resolution) to estimate annual O₃ exposures, and estimated total respiratory deaths in 2010 that were attributable to long-term annual O₃ exposure based on the updated relative risk estimates and minimum risk thresholds set at the minimum or fifth percentile of O₃ exposure in the most recent CPS-II analysis. These estimates were compared with attributable mortality based on the earlier CPS-II analysis, using 6-mo average exposures and risk thresholds corresponding to the minimum or fifth percentile of O₃ exposure in the earlier study population.

RESULTS

We estimated 1.04-1.23 million respiratory deaths in adults attributable to O₃ exposures using the updated relative risk estimate and exposure parameters, compared with 0.40-0.55 million respiratory deaths attributable to O₃ exposures based on the earlier CPS-II risk estimate and parameters. Increases in estimated attributable mortality were larger in northern India, southeast China, and Pakistan than in Europe, eastern United States, and northeast China.

CONCLUSIONS

These findings suggest that the potential magnitude of health benefits of air quality policies targeting O₃, health co-benefits of climate mitigation policies, and health implications of climate change-driven changes in O₃ concentrations, are larger than previously thought. https://doi.org/10.1289/EHP1390.

Seasonal association between ambient ozone and mortality in Zhengzhou, China

Different seasonal health effects of ambient ozone (O₃) have been reported in previous studies. This might be due to inappropriate adjustment of temperature in different seasons. We used daily data on non-accidental mortality and ambient air pollution in Zhengzhou from January 19, 2013 to June 30, 2015. Season-stratified analyses using generalized additive models were conducted to evaluate the seasonal associations with adjustment of temperature with different lagged days (lag0-1 for warm season, lag0-14 for cold season). We recorded a total of 70,443 non-accidental deaths in Zhengzhou during the study period. Significant associations were observed between ambient O₃ and mortality in cold season. Every 10-μg/m³ increment of 24-h O₃ of 1-day lagged time was associated with a 1.38% (95% CI 0.60, 2.16%) increase in all cause mortality, 1.35% (95% CI 0.41, 2.30%) increase in cardiovascular mortality, and 1.78% (95% CI 0.43, 3.14%) increase in respiratory mortality. Similar associations were observed when using daily 1- and 8-h maximum concentrations of O₃. No significant association was found during warm season. This study suggests a more pronounced ozone-mortality association in cold season in Zhengzhou, and we suggest that different lagged temperatures should be considered when examining the seasonal health effects of ambient ozone.