Controlled exposure of healthy young volunteers to ozone causes cardiovascular effects

Controlled human exposures to diesel exhaust: a human epigenome-wide experiment of target bronchial epithelial cells

Diesel exhaust (DE) is a major contributor to ambient air pollution around the world. It is a known human carcinogen that targets the respiratory system and increases risk for many diseases, but there is limited research on the effects of DE exposure on the epigenome of human bronchial epithelial cells. Understanding the epigenetic impact of this environmental pollutant can elucidate biological mechanisms involved in the pathogenesis of harmful DE-related health effects. To estimate the causal effect of short-term DE exposure on the bronchial epithelial epigenome, we conducted a controlled single-blinded randomized crossover human experiment of exposure to DE and used bronchoscopy and Illumina 450K arrays for data collection and analysis, respectively. Of the 13 participants, 11 (85%) were male and 2 (15%) were female, and 12 (92%) were White and one (8%) was Hispanic; the mean age was 26 years (SD = 3.8 years). Eighty CpGs were differentially methylated, achieving the minimum possible exact P-value of P = 2.44 × 10-4 (i.e. 2/213). In regional analyses, we found two differentially methylated regions (DMRs) annotated to the chromosome 5 open reading frame 63 genes (C5orf63; 7-CpGs) and unc-45 myosin chaperone A gene (UNC45A; 5-CpGs). Both DMRs showed increased DNA methylation after DE exposure. The average causal effects for the DMRs ranged from 1.5% to 6.0% increases in DNA methylation at individual CpGs. In conclusion, we found that short-term DE alters DNA methylation of genes in target bronchial epithelial cells, demonstrating epigenetic level effects of exposure that could be implicated in pulmonary pathologies.

Acute ozone exposure can cause cardiotoxicity: Mitochondria play an important role in mediating myocardial apoptosis

OBJECTIVE

To clarify the cardiotoxicity induced by acute exposure to different concentrations of ozone in both gender rats and explore the underlying mechanisms.

METHODS

A total of 240 rats were randomly sorted into 6 groups with equal numbers of male and female rats in each group. The rats were subjected to ozone inhalation at concentrations of 0, 0.12, 0.5, 1.0, 2.0 and 4.0 ppm, respectively, for 6 h. After ozone exposure, function indicators, myocardial injury indexes and risk factors of cardiovascular disease in blood were assayed.

RESULTS

High ozone exposure resulted in sustained ventricular tachycardia in male and female rats. Myocardial apoptosis in male rats started from 1.0 ppm ozone, and that in female rats started from 2.0 ppm ozone (p < 0.05). Caspase-9 increased significantly from 0.12 ppm ozone (p < 0.01) in both gender rats, while caspase-3 was initially activated at 0.5 ppm ozone. From 1.0 ppm ozone, mitochondrial cristae and myofilaments dissolved. The ratio of Bcl-2/Bax decreased significantly from 0.12 ppm and MRCC-IV decreased significantly from 2.0 ppm by ozone.

CONCLUSION

Acute ozone exposure can cause paroxysmal ventricular tachycardia in rats. Moreover, the changes of inflammatory factors in the heart tissues of female and male rats after ozone exposure were greater than those of oxidative stress. This study reported for the first time that 6 h ozone exposure does not cause acute cardiomyocyte necrosis, but promotes cardiomyocyte apoptosis in a mitochondrial-dependent manner. Ozone could regulate caspases-3 dependent cardiomyocyte apoptosis by affecting the balance between caspase-9 and XIAP.

Ambient air pollution exposure and radiographic pulmonary vascular volumes

Supplemental Digital Content is available in the text.

Exposure to higher levels of ambient air pollution is a known risk factor for cardiovascular disease but long-term effects of pollution exposure on the pulmonary vessels are unknown.

Interstitial Lung Diseases and Air Pollution: Narrative Review of Literature

Air pollution has been associated with respiratory diseases such as chronic obstructive pulmonary disease (COPD) and lung malignancies. The aim of this narrative review is to analyze the current data on the possible association between air pollution and interstitial lung disease (ILD). There are multiple studies showing the association of ILD with air pollution but the mechanism remains unclear. Although some of the environmental factors have been associated with idiopathic pulmonary fibrosis (IPF), hypersensitivity pneumonitis (HP), and pneumoconiosis, data about other ILDs are scarce and not well known. Air pollution as an etiology for ILD may act in multiple ways, leading to disease pathogenesis or exacerbation of underlying ILD. Clinical implications of this association are manifold; limiting the exposure to poor-quality air could possibly reduce the fall in lung functions and the risk of acute exacerbations of the underlying ILD.

Air pollution is a major problem worldwide. Pollutants are vented out in the ambient air by sources like vehicular fume exhaust, factory pollution, combustion by burning of biomass fuels, and indoor pollution. The probable constituents responsible for respiratory diseases are particulate matter 2.5 and 10, nitrogen dioxide (NO₂), and ozone present in polluted air. The role of these pollutants in pathogenesis of interstitial lung disease (ILD) is complex. The probable pathways include: oxidative stress, inflammation, and telomere shortening. ILD is a heterogeneous group of diseases, and the effect of pollution on various types is also varied. Air pollution has been associated with poor lung function and exacerbations in idiopathic pulmonary fibrosis (IPF), increased prevalence of hypersensitivity pneumonitis (HP), and presence of pulmonary fibrosis in healthy adults and children. The incidence rate of IPF has also been associated with pollutant levels such as NO₂. Thus, patients with ILD should be cautious during bad-quality air days and they are advised to avoid outdoor activities and use facemasks during this period.

Association of change in air quality with hospital admission for acute exacerbation of chronic obstructive pulmonary disease in Guangdong, China: A province-wide ecological study

AIMS

To assess possible effect of air quality improvements, we investigated the temporal change in hospital admissions for acute exacerbations of chronic obstructive pulmonary disease (AECOPD) associated with pollutant concentrations.

METHODS

We collected daily concentrations of particulate matter (i.e., PM_2.5, PM₁₀ and PM_coarse), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), ozone (O₃), and admissions for AECOPD for 21 cities in Guangdong from 2013 to 2017. We examined the association of air pollution with AECOPD admissions using two-stage time-series analysis, and estimated the annual attributable fractions, numbers, and direct hospitalization costs of AECOPD admissions with principal component analysis.

RESULTS

From 2013-2017, mean daily concentrations of SO₂, PM₁₀ and PM_2.5 declined by nearly 40%, 30%, and 26% respectively. As the average daily 8 h O₃ concentration increased considerably, the number of days exceeding WHO target (i.e.,100 μg/m³) increased from 103 in 2015-152 in 2017. For each interquartile range increase in pollutant concentration, the relative risks of AECOPD admission at lag 0-3 were 1.093 (95% CI 1.06-1.13) for PM_2.5, 1.092 (95% CI 1.08-1.11) for O₃, and 1.092 (95% CI 1.05-1.14) for SO₂. Attributable fractions of AECOPD admission advanced by air pollution declined from 9.5% in 2013 to 4.9% in 2016, then increased to 6.0% in 2017. A similar declining trend was observed for direct AECOPD hospitalization costs.

CONCLUSION

Declined attributable hospital admissions for AECOPD may be associated with the reduction in concentrations of PM_2.5, PM₁₀ and SO₂ in Guangdong, while O₃ has emerged as an important risk factor. Summarizes the main finding of the work： Reduction in PM may result in declined attributable hospitalizations for AECOPD, while O₃ has emerged as an important risk factor following an intervention.

Fish oil and olive oil-enriched diets alleviate acute ozone-induced cardiovascular effects in rats

Fish oil (FO) and olive oil (OO) supplementations attenuate the cardiovascular responses to inhaled concentrated ambient particles in human volunteers. This study was designed to examine the cardiovascular effects of ozone (O₃) exposure and the efficacy of FO and OO-enriched diets in attenuating the cardiovascular effects from O₃ exposure in rats. Rats were fed either a normal diet (ND), a diet enriched with 6% FO or OO starting at 4 weeks of age. Eight weeks following the start of these diet, animals were exposed to filtered air (FA) or 0.8 ppm O₃, 4 h/day for 2 consecutive days. Immediately after exposure, cardiac function was measured as the indices of left-ventricular developed pressure (LVDP) and contractility (dP/dt_max and dP/dt_min) before ischemia. In addition, selective microRNAs (miRNAs) of inflammation, endothelial function, and cardiac function were assessed in cardiac tissues to examine the molecular alterations of diets and O₃ exposure. Pre-ischemic LVDP and dP/dt_max were lower after O₃ exposure in rats fed ND but not FO and OO. Cardiac miRNAs expressions were altered by both diet and O₃ exposure. Specifically, O₃-induced up-regulation of miR-150-5p and miR-208a-5p were attenuated by FO and/or OO. miR-21 was up-regulated by both FO and OO after O₃ exposure. This study demonstrated that O₃-induced cardiovascular responses appear to be blunted by FO and OO diets. O₃-induced alterations in miRNAs linked to inflammation, cardiac function, and endothelial dysfunction support these pathways are involved, and dietary supplementation with FO or OO may alleviate these adverse cardiovascular effects in rats.

A novel soft sensor based warning system for hazardous ground-level ozone using advanced damped least squares neural network

Estimation of hazardous air pollutants in the urban environment for maintaining public safety is a significant concern to mankind. In this paper, we have developed an efficient air quality warning system based on a low-cost and robust ground-level ozone soft sensor. The soft sensor was developed based on a novel technique of damped least squares neural network (DLSNN) with greedy backward elimination (GBE) for the estimation of hazardous ground-level ozone. Only three meteorological factors were used as input variables in the estimation of ground-level ozone and we have used weighted k-nearest neighbors (WkNN) classifier with fast response for development of air quality warning system. We have chosen the urban areas of Taiwan for this study and have analyzed seasonal variations in the ground-level ozone concentration of various cities in Taiwan as part of this work. Moreover, descriptive statistics and linear dependence of ozone concentration based on Spearman correlation coefficient, Kendall's tau coefficient, and Pearson coefficient are calculated. The proposed DLSNN/GBE method exhibited excellent performance resulting in very low mean square error (MSE), mean absolute error (MAE), and high coefficient of determination (R²) compared to other traditional approaches in ozone concentration estimation. We have achieved a good fit in the determination of ozone concentration from meteorological features of atmosphere. Moreover, the excellent performance of proposed urban air quality warning system was evident from the good F1-score value of 0.952 achieved by the WkNN classifier.

Temporal changes in short-term associations between cardiorespiratory emergency department visits and PM2.5 in Los Angeles, 2005 to 2016

BACKGROUND

Emissions control programs targeting certain air pollution sources may alter PM_2.5 composition, as well as the risk of adverse health outcomes associated with PM_2.5.

OBJECTIVES

We examined temporal changes in the risk of emergency department (ED) visits for cardiovascular diseases (CVDs) and asthma associated with short-term increases in ambient PM_2.5 concentrations in Los Angeles, California.

METHODS

Poisson log-linear models with unconstrained distributed exposure lags were used to estimate the risk of CVD and asthma ED visits associated with short-term increases in daily PM_2.5 concentrations, controlling for temporal and meteorological confounders. The models were run separately for three predefined time periods, which were selected based on the implementation of multiple emissions control programs (EARLY: 2005-2008; MIDDLE: 2009-2012; LATE: 2013-2016). Two-pollutant models with individual PM_2.5 components and the remaining PM_2.5 mass were also considered to assess the influence of changes in PM_2.5 composition on changes in the risk of CVD and asthma ED visits associated with PM_2.5 over time.

RESULTS

The relative risk of CVD ED visits associated with a 10 μg/m³ increase in 4-day PM_2.5 concentration (lag 0-3) was higher in the LATE period (rate ratio = 1.020, 95% confidence interval = [1.010, 1.030]) compared to the EARLY period (1.003, [0.996, 1.010]). In contrast, for asthma, relative risk estimates were largest in the EARLY period (1.018, [1.006, 1.029]), but smaller in the following periods. Similar temporal differences in relative risk estimates for CVD and asthma were observed among different age and season groups. No single component was identified as an obvious contributor to the changing risk estimates over time, and some components exhibited different temporal patterns in risk estimates from PM_2.5 total mass, such as a decreased risk of CVD ED visits associated with sulfate over time.

CONCLUSIONS

Temporal changes in the risk of CVD and asthma ED visits associated with short-term increases in ambient PM_2.5 concentrations were observed. These changes could be related to changes in PM_2.5 composition (e.g., an increasing fraction of organic carbon and a decreasing fraction of sulfate in PM_2.5). Other factors such as improvements in healthcare and differential exposure misclassification might also contribute to the changes.

Associations of long-term exposure to ambient air pollution with cardiac conduction abnormalities in Chinese adults: The CHCN-BTH cohort study

BACKGROUND

Evidence regarding the effects of long-term and high-level ambient air pollution exposure on cardiac conduction systems remains sparse.

OBJECTIVES

To investigate the associations of long-term exposure to air pollution and cardiac conduction abnormalities in Chinese adults and explore the susceptibility characteristics.

METHODS

In 2017, a total of 27,047 participants aged 18-80 years were recruited from the baseline survey of the Cohort Study on Chronic Disease of Communities Natural Population in Beijing, Tianjin and Hebei (CHCN-BTH). The three year (2014-2016) average pollutant concentrations were assessed by a spatial statistical model for PM_2.5 and air monitoring stations for PM₁₀, SO₂, NO₂, O₃ and CO. Residential proximity to a roadway was calculated by neighborhood analysis. Associations were estimated by two-level generalized linear mixed models. Stratified analyses related to demographic characteristics, health behaviors, and cardiometabolic risk factors were performed. Two-pollutant models were used to evaluate the possible role of single pollutants.

RESULTS

We detected significant associations of long-term air pollutant exposure with increased heart rate (HR), QRS and QTc, such that an interquartile range increase in PM_2.5 was associated with 3.63% (95% CI: 3.07%, 4.19%), 1.21% (95% CI: 0.83%, 1.60%), and 0.13% (95% CI: 0.07%, 0.18%) changes in HR, QRS and QTc, respectively. Compared to the other pollutants, the estimates of PM_2.5 remained the most stable across all two-pollutant models. Similarly, significant associations were observed between living closer to a major roadway and higher HR, QRS and QTc. Stratified analyses showed generally greater association estimates in older people, males, smokers, alcohol drinkers, and those with obesity, hypertension and diabetes.

CONCLUSIONS

Long-term exposure to ambient air pollution was associated with cardiac conduction abnormalities in Chinese adults, especially in older people, males, smokers, alcohol drinkers, and those with cardiometabolic risk factors. PM_2.5 may be the most stable pollutant to reflect the associations.

Heterogeneous ozone effects on the DNA methylome of bronchial cells observed in a crossover study

We used a randomized crossover experiment to estimate the effects of ozone (vs. clean air) exposure on genome-wide DNA methylation of target bronchial epithelial cells, using 17 volunteers, each randomly exposed on two separated occasions to clean air or 0.3-ppm ozone for two hours. Twenty-four hours after exposure, participants underwent bronchoscopy to collect epithelial cells whose DNA methylation was measured using the Illumina 450 K platform. We performed global and regional tests examining the ozone versus clean air effect on the DNA methylome and calculated Fisher-exact p-values for a series of univariate tests. We found little evidence of an overall effect of ozone on the DNA methylome but some suggestive changes in PLSCR1, HCAR1, and LINC00336 DNA methylation after ozone exposure relative to clean air. We observed some participant-to-participant heterogeneity in ozone responses.

Environmental Factors Such as Noise and Air Pollution and Vascular Disease

Significance: According to the World Health Organization, noncommunicable diseases are the globally leading cause of mortality. Recent Advances: About 71% of 56 million deaths that occurred worldwide are due to noncommunicable cardiovascular risk factors, including tobacco smoking, unhealthy diets, lack of physical activity, overweight, arterial hypertension, diabetes, and hypercholesterolemia, which can be either avoided or substantially reduced. Critical Issues: Thus, it is estimated that 80% of premature heart disease, stroke, and diabetes can be prevented. More recent evidence indicates that environmental stressors such as noise and air pollution contribute significantly to the global burden of cardiovascular disease. In the present review, we focus primarily on important environmental stressors such as transportation noise and air pollution. We discuss the pathophysiology of vascular damage caused by these environmental stressors, with emphasis on early subclinical damage of the vasculature such as endothelial dysfunction and the role of oxidative stress. Future Directions: Lower legal thresholds and mitigation measures should be implemented and may help to prevent vascular damage.

When possible, report a Fisher-exact P value and display its underlying null randomization distribution

Statistical analyses of randomized experiments often rely on asymptotic P values instead of using the actual randomization procedure that led to the observed data. Fisher-exact and asymptotic P values can differ dramatically: The former should be preferred because it is calculated using the exact null randomization distribution, which, in small samples, can substantially differ from its approximating Student’s t distribution. Moreover, we may learn something scientifically interesting from examining the shape of the null randomization distribution.

In randomized experiments, Fisher-exact P values are available and should be used to help evaluate results rather than the more commonly reported asymptotic P values. One reason is that using the latter can effectively alter the question being addressed by including irrelevant distributional assumptions. The Fisherian statistical framework, proposed in 1925, calculates a P value in a randomized experiment by using the actual randomization procedure that led to the observed data. Here, we illustrate this Fisherian framework in a crossover randomized experiment. First, we consider the first period of the experiment and analyze its data as a completely randomized experiment, ignoring the second period; then, we consider both periods. For each analysis, we focus on 10 outcomes that illustrate important differences between the asymptotic and Fisher tests for the null hypothesis of no ozone effect. For some outcomes, the traditional P value based on the approximating asymptotic Student’s t distribution substantially subceeded the minimum attainable Fisher-exact P value. For the other outcomes, the Fisher-exact null randomization distribution substantially differed from the bell-shaped one assumed by the asymptotic t test. Our conclusions: When researchers choose to report P values in randomized experiments, 1) Fisher-exact P values should be used, especially in studies with small sample sizes, and 2) the shape of the actual null randomization distribution should be examined for the recondite scientific insights it may reveal.

Association between ambient air pollution and out-of-hospital cardiac arrest: are there potentially susceptible groups?

This study aimed to examine the association between air pollution and out-of-hospital cardiac arrest (OHCA), and the effects of underlying diseases. Between January 2015 and December 2016, data on particulate matter (PM)_2.5 and other air pollutants in Kaohsiung City were collected, and an emergency medical service database was used for information on patients who experienced OHCA. Overall, 3566 patients were analyzed and subgroup analyses by sex, age, and preexisting morbidities were performed. Interquartile increments in PM_2.5, PM₁₀, and O₃ levels on lag 1 and NO₂ level on lag 3 were associated with increments of 10.8%, 11.3%, 6.2%, and 1.7% in OHCA incidence, respectively. Subgroup analyses showed that patients with diabetes (1.363; interaction p = 0.009), heart disease (1.612; interaction p = 0.001), and advanced age (≥70 years, 1.297; interaction p = 0.003) were more susceptible to NO₂ on lag 3. Moreover, patients were more susceptible to O₃ during the cold season (1.194; interaction p = 0.001). We found that PM_2.5, PM₁₀, NO₂, and O₃ may play an important role in OHCA events, and the effects vary by underlying condition, age and season.

[Monitoring metrics for short-term exposure to ambient ozone and pulmonary function and airway inflammation in healthy young adults]

OBJECTIVE

To assess the associations of different monitoring metrics for short-term exposure to ambient ozone (O3) with pulmonary function and airway inflammation in healthy young adults.

METHODS

A total of 97 healthy young college students were recruited and followed in a panel study conducted from December 2017 to June 2018. Each participant underwent 3 follow-up visits, and lung function and fractional exhaled nitric oxide (FeNO) were measured at each visit. Ambient air pollutant concentrations were obtained from the environment monitoring station of Beijing closest to the participant residences, and meteorological data were collected from China Meteorological Data Service Center. Linear mixed-effect models were applied to assess the associations between different monitoring metrics for ambient O3 short-term exposure with pulmonary function or airway inflammation in the healthy young adults.

RESULTS

During the study period, the P50 (P25, P75) values for ambient O3 concentration expressed as daily 1-hour maximum (O3-1 h max), daily maximum 8-hour average (O3-8 h max) and 24-hour average (O3-24 h avg) were 102.5 (76.8, 163.0) μg/m3, 91.1 (68.3, 154.3) μg/m3 and 61.6 (36.9, 81.7) μg/m3, respectively. The different monitoring metrics for short-term exposure to ambient O3 were significantly associated with reduced forced expiratory volume in the first second (FEV1) and increased FeNO. An interquartile range (IQR) increase in 6-d moving average of O3-1 h max (IQR=71.5 μg/m3) was associated with a 6.2% (95%CI: －11.8%, －0.5%) decrease in FEV1 and a 63.3% (95%CI: 13.8%, 134.3%) increase in FeNO. An IQR increase in 7-d moving average of O3-8 h max (IQR=62.0 μg/m3) was associated with a 6.2% (95%CI: －11.6%, －0.7%) decrease in FEV1and a 75.5% (95%CI: 19.3%, 158.0%) increase in FeNO. An IQR increase in 5-d moving average of O3-24 h avg (IQR=32.9 μg/m3) was associated with a 3.7% (95%CI: －7.1%, －0.2%) decrease in FEV1and a 25.3% (95%CI: 3.6%, 51.6%) increase in FeNO. There was no significant association between the three monitoring metrics for O3 exposure and peak expiratory flow (PEF).

CONCLUSION

Short-term exposure to ambient O3 was associated with decreased lung function and increased airway inflammation among the healthy young adults, and daily 1-hour maximum was more sensitively to the respiratory effects of O3.

Relationship between air pollution and hospitalizations for congestive heart failure in elderly people in the city of São Paulo

To evaluate the effects of air pollutants on hospitalizations of elderly people for congestive heart failure (CHF) in the city of São Paulo, stratified by sex, exploring lag structures, from 2000 to 2013. Ecological time series study using information on hospitalization of elderly patients for CHF (ICD-10th: I50) obtained from DATASUS for the city of São Paulo. Information on O₃, PM₁₀, NO₂, SO₂, CO, temperature and humidity was obtained from CETESB. Descriptive analyses, Pearson correlation, and generalized linear Poisson regression model were applied to estimate the effects of pollutants. The interquartile variations of O₃ (52.45 μg/m³), PM₁₀ (24.28 μg/m³), NO₂ (7.63 μg/m³), SO₂ (50.22 μg/m³), and CO (1.28 ppm) were associated with increased hospitalizations for CHF. Air pollutants continue to be a factor that contributes to the increase in the number of hospitalizations due to CHF.

Short time exposure to ambient ozone and associated cardiovascular effects: A panel study of healthy young adults

The evidence that exposure to ambient ozone (O₃) causes acute cardiovascular effects appears inconsistent. A repeated-measure study with 61 healthy young volunteers was conducted in Xinxiang, Central China. Real-time concentrations of O₃ were monitored. Cardiovascular outcomes including blood pressure (BP), heart rate (HR), serum levels of high sensitivity C-reactive protein (hs-CRP), 8-hydroxy-2'-deoxyguanosine (8-OHdG), tissue-type plasminogen activator (t-PA), and platelet-monocyte aggregation (PMA) were repeated measured. Linear mixed-effect models were used to analyze the association of ambient O₃ with these cardiovascular outcomes. Additionally, the modifying effects of glutathione S-transferase mu 1 (GSTM1) and glutathione S-transferase theta 1 (GSTT1) polymorphisms were estimated to explore the potential mechanisms and role of the association between O₃ exposure and the above cardiovascular outcomes. A 10 μg/m³ increase in O₃ was associated with increases of 9.2 mmHg (95% confidence interval [CI]: 2.5, 15.9), 7.2 mmHg (95% CI: 0.8, 13.6), and 21.2 bpm (95% CI: 5.8, 36.6) in diastolic BP (DBP, lag1), mean arterial BP (MABP, lag1), and HR (lag01), respectively. Meanwhile, the serum concentrations of hs-CRP, 8-OHdG, and t-PA were all increased by O₃ exposure, but the PMA level was decreased. Stratification analyses showed that the estimated effects of O₃ on DBP, MABP, and HR in GSTM1-sufficient subjects were significantly higher than in GSTM1-null subjects. Moreover, GSTM1-null genotype enhanced O₃-induced increases, albeit insignificant, in levels of serum hs-CRP, 8-OHdG, and t-PA compared with GSTM1-sufficient genotype. Insignificant increases in hs-CRP and t-PA were also detected in GSTT1-null subjects. Taken together, our findings indicate that acute exposure to ambient O₃ induces autonomic alterations, systemic inflammation, oxidative stress, and fibrinolysis in healthy young subjects. GSTM1 genotype presents the trend of modifying O₃-induced cardiovascular effects.

Ozone Exposure During Implantation Increases Serum Bioactivity in HTR-8/SVneo Trophoblasts

Implantation is a sensitive window in reproductive development during which disruptions may increase the risk of adverse pregnancy outcomes including intrauterine growth restriction. Ozone exposure during implantation in rats reduces fetal weight near the end of gestation, potentially though impaired trophoblast migration and invasion and altered implantation. The current study characterized changes in ventilation, pulmonary injury, and circulating factors including hormonal, inflammatory, and metabolic markers related to exposure to ozone (0.4-1.2 ppm) for 4-h on gestation days 5 and 6 (window of implantation) in Long-Evans dams. To determine the effects of this exposure on trophoblast function, placental-derived, first trimester, HTR-8/SVneo cells were exposed to serum from air- or ozone (0.8 ppm×4 h)-exposed dams and examined for impacts on metabolic capacity, wound-closure, and invasion. Peri-implantation exposure to ozone induced ventilatory dysfunction and lung vascular leakage in pregnant rats, with little effect on most of the circulating markers measured. However, ozone inhalation induced a significant reduction in several serum cytokines (interferon-γ, interleukin-6, and interleukin-13). Treatment of HTR-8/SVneo trophoblasts with serum from ozone-exposed dams for 16-h downregulated metabolic capacity, wound-closure, and invasion through a Matrigel membrane compared with both air-serum and fetal bovine serum-treated cells. Ozone-serum treated cells increased the release of a critical inhibitor of invasion and angiogenesis (soluble fms-like receptor 1; sFlt1) compared with air-serum treatment. Together, our data suggest that circulating factors in the serum of pregnant rats exposed to ozone during implantation receptivity can hinder critical processes of implantation (eg, invasion and migration) and impair trophoblast metabolic capacity.

Mortality burdens in California due to air pollution attributable to local and nonlocal emissions

Limited research has been conducted on the contributions of local and nonlocal emission sources to ambient fine particulate matter (PM_2.5) and ozone (O₃) and their associated mortality. In this study, we estimated the total mortality resulting from long-term PM_2.5 and O₃ exposures in California in 2012 using multiple concentration response functions (CRFs) and attributed the estimated mortality to different emission groups. The point estimates of PM_2.5-associated mortality in California ranged from 12,700 to 26,700, of which 53% were attributable to in-state anthropogenic emissions. Based on new epidemiological evidence, we estimated that O₃ could be associated with up to 13,700 deaths from diseases of both the respiratory and cardiovascular systems in California. In addition, 75% of the ambient O₃ in California was due to distant emissions outside the western United States, leading to 92% of the O₃-associated mortality. Overall, distant emissions lead to greater mortality burdens of air pollution in California than local anthropogenic emissions.

Ozone Pollution: A Major Health Hazard Worldwide

Oxides of nitrogen (NO_x) 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 NO_x 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 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. 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 of premature deaths and tens of millions of asthma-related emergency room visits annually. To combat ozone pollution globally, more aggressive reductions in fossil fuel consumption are needed to cut NO_x 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.

Long-Term Exposure to Ozone and Cause-Specific Mortality Risk in the United States

Rationale: Many studies have linked short-term exposure to ozone (O3) with morbidity and mortality, but epidemiologic evidence of associations between long-term O3 exposure and mortality is more limited.Objectives: To investigate associations of long-term (annual or warm season average of daily 8-h maximum concentrations) O3 exposure with all-cause and cause-specific mortality in the NIH-AARP Diet and Health Study, a large prospective cohort of U.S. adults with 17 years of follow-up from 1995 to 2011.Methods: The cohort (n = 548,780) was linked to census tract-level estimates for O3. Associations between long-term O3 exposure (averaged values from 2002 to 2010) and multiple causes of death were evaluated using multivariate Cox proportional hazards models, adjusted for individual- and census tract-level covariates, and potentially confounding copollutants and temperature.Measurements and Main Results: Long-term annual average exposure to O3 was significantly associated with deaths caused by cardiovascular disease (per 10 ppb; hazard ratio [HR], 1.03; 95% confidence interval [CI], 1.01-1.06), ischemic heart disease (HR, 1.06; 95% CI, 1.02-1.09), respiratory disease (HR, 1.04; 95% CI, 1.00-1.09), and chronic obstructive pulmonary disease (HR, 1.09; 95% CI, 1.03-1.15) in single-pollutant models. The results were robust to alternative models and adjustment for copollutants (fine particulate matter and nitrogen dioxide), although some evidence of confounding by temperature was observed. Significantly elevated respiratory disease mortality risk associated with long-term O3 exposure was found among those living in locations with high temperature (Pinteraction < 0.05).Conclusions: This study found that long-term exposure to O3 is associated with increased risk for multiple causes of mortality, suggesting that establishment of annual and/or seasonal federal O3 standards is needed to more adequately protect public health from ambient O3 exposures.

Cardiorespiratory responses to low-level ozone exposure: The inDoor Ozone Study in childrEn (DOSE)

BACKGROUND

Indoor air pollution has emerged as a significant environmental and public health concern in recent years. However, evidence regarding the cardiorespiratory effects of indoor ozone is limited, and the underlying biological mechanisms are unclear, especially in children. Our study aimed to assess the cardiorespiratory responses to indoor ozone exposure in children.

METHODS

A repeated-measure study was conducted in 46 middle-school children in Beijing, China. Real-time concentrations of ozone, along with co-pollutants including particulate matter (PM) and black carbon (BC), were monitored in classrooms from Monday to Friday. Three repeated health measurements of cardiorespiratory functions, including ambulatory electrocardiogram (ECG), blood pressure, fractional exhaled nitric oxide (FeNO) and lung function, were performed on each participant. Mixed-effect models were used to evaluate the effects of indoor ozone exposure.

RESULTS

The mean (SD) indoor ozone concentration was 8.7 (6.6) ppb during the study period, which was largely below the current guideline and standards. However, even this low-level ozone exposure was associated with reduced cardiac autonomic function and increased heart rate (HR) in children. For instance, per interquartile range (IQR) increase in ozone at 2-hour moving average was associated with -7.8% (95% CI: -9.9%, -5.6%) reduction in standard deviation of all normal-to-normal intervals (SDNN), and 2.6% (95% CI: 1.6%, 3.6%) increment in HR. In addition, the associations were stronger at high BC levels (BC ≥ 3.7 μg/m³). No significant associations were found for airway inflammation and pulmonary function.

CONCLUSIONS

Exposure to low-level indoor ozone that is not associated with respiratory effects was significantly related to disturbed cardiac autonomic function and increased HR in children, which suggested a possible mechanism through which ozone may affect cardiovascular health in children, and indicated more protective measures should be taken to alleviate the acute adverse effects of indoor ozone in this susceptible population.

Ozone effects on blood biomarkers of systemic inflammation, oxidative stress, endothelial function, and thrombosis: The Multicenter Ozone Study in oldEr Subjects (MOSES)

The evidence that exposure to ozone air pollution causes acute cardiovascular effects is mixed. We postulated that exposure to ambient levels of ozone would increase blood markers of systemic inflammation, prothrombotic state, oxidative stress, and vascular dysfunction in healthy older subjects, and that absence of the glutathione S-transferase Mu 1 (GSTM1) gene would confer increased susceptibility. This double-blind, randomized, crossover study of 87 healthy volunteers 55-70 years of age was conducted at three sites using a common protocol. Subjects were exposed for 3 h in random order to 0 parts per billion (ppb) (filtered air), 70 ppb, and 120 ppb ozone, alternating 15 min of moderate exercise and rest. Blood was obtained the day before, approximately 4 h after, and approximately 22 h after each exposure. Linear mixed effect and logistic regression models evaluated the impact of exposure to ozone on pre-specified primary and secondary outcomes. The definition of statistical significance was p<0.01. There were no effects of ozone on the three primary markers of systemic inflammation and a prothrombotic state: C-reactive protein, monocyte-platelet conjugates, and microparticle-associated tissue factor activity. However, among the secondary endpoints, endothelin-1, a potent vasoconstrictor, increased from pre- to post-exposure with ozone concentration (120 vs 0 ppb: 0.07 pg/mL, 95% confidence interval [CI] 0.01, 0.14; 70 vs 0 ppb: -0.03 pg/mL, CI -0.09, 0.04; p = 0.008). Nitrotyrosine, a marker of oxidative and nitrosative stress, decreased with increasing ozone concentrations, with marginal significance (120 vs 0 ppb: -41.5, CI -70.1, -12.8; 70 vs 0 ppb: -14.2, CI -42.7, 14.2; p = 0.017). GSTM1 status did not modify the effect of ozone exposure on any of the outcomes. These findings from healthy older adults fail to identify any mechanistic basis for the epidemiologically described cardiovascular effects of exposure to ozone. The findings, however, may not be applicable to adults with cardiovascular disease.

Ambient Air Pollution and the Risk of Atrial Fibrillation and Stroke: A Population-Based Cohort Study

BACKGROUND

Although growing evidence links air pollution to stroke incidence, less is known about the effect of air pollution on atrial fibrillation (AF), an important risk factor for stroke.

OBJECTIVES

We assessed the associations between air pollution and incidence of AF and stroke. We also sought to characterize the shape of pollutant-disease relationships.

METHODS

The population-based cohort comprised 5,071,956 Ontario residents, age 35–85 y and without the diagnoses of both outcomes on 1 April 2001 and was followed up until 31 March 2015. AF and stroke cases were ascertained using health administrative databases with validated algorithms. Based on annual residential postal codes, we assigned 5-y running average concentrations of fine particulate matter ([Formula: see text]), nitrogen dioxide ([Formula: see text]), and ozone ([Formula: see text]) from satellite-derived data, a land-use regression model, and a fusion-based method, respectively, as well as redox-weighted averages of [Formula: see text] and [Formula: see text] ([Formula: see text]) for each year. Using Cox proportional hazards models, we estimated the hazard ratios (HRs) and 95% confidence intervals (95% CIs) of AF and stroke with each of these pollutants, adjusting for individual- and neighborhood-level variables. We used newly developed nonlinear risk models to characterize the shape of pollutant–disease relationships.

RESULTS

Between 2001 and 2015, we identified 313,157 incident cases of AF and 122,545 cases of stroke. Interquartile range increments of [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] were associated with increases in the incidence of AF [HRs (95% CIs): 1.03 (1.01, 1.04), 1.02 (1.01, 1.03), 1.01 (1.00, 1.02), and 1.01 (1.01, 1.02), respectively] and the incidence of stroke [HRs (95% CIs): 1.05 (1.03, 1.07), 1.04 (1.01, 1.06), 1.05 (1.03, 1.06), and 1.05 (1.04, 1.06), respectively]. Associations of similar magnitude were found in various sensitivity analyses. Furthermore, we found a near-linear association for stroke with [Formula: see text], whereas [Formula: see text], [Formula: see text]-, and [Formula: see text] relationships exhibited sublinear shapes.

CONCLUSIONS

Air pollution was associated with stroke and AF onset, even at very low concentrations. https://doi.org/10.1289/EHP4883.

Associations between respiratory health and ozone and fine particulate matter during a wildfire event

Wildfires have been increasing in frequency in the western United States (US) with the 2017 and 2018 fire seasons experiencing some of the worst wildfires in terms of suppression costs and air pollution that the western US has seen. Although growing evidence suggests respiratory exacerbations from elevated fine particulate matter (PM_2.5) during wildfires, significantly less is known about the impacts on human health of ozone (O₃) that may also be increased due to wildfires. Using machine learning, we created daily surface concentration maps for PM_2.5 and O₃ during an intense wildfire in California in 2008. We then linked these daily exposures to counts of respiratory hospitalizations and emergency department visits at the ZIP code level. We calculated relative risks of respiratory health outcomes using Poisson generalized estimating equations models for each exposure in separate and mutually-adjusted models, additionally adjusted for pertinent covariates. During the active fire periods, PM_2.5 was significantly associated with exacerbations of asthma and chronic obstructive pulmonary disease (COPD) and these effects remained after controlling for O₃. Effect estimates of O₃ during the fire period were non-significant for respiratory hospitalizations but were significant for ED visits for asthma (RR = 1.05 and 95% CI = (1.022, 1.078) for a 10 ppb increase in O₃). In mutually-adjusted models, the significant findings for PM_2.5 remained whereas the associations with O₃ were confounded. Adjusted for O₃, the RR for asthma ED visits associated with a 10 μg/m³ increase in PM_2.5 was 1.112 and 95% CI = (1.087, 1.138). The significant findings for PM_2.5 but not for O₃ in mutually-adjusted models is likely due to the fact that PM_2.5 levels during these fires exceeded the 24-hour National Ambient Air Quality Standard (NAAQS) of 35 μg/m³ for 4976 ZIP-code days and reached levels up to 6.073 times the NAAQS, whereas our estimated O₃ levels during the fire period only occasionally exceeded the NAAQS of 70 ppb with low exceedance levels. Future studies should continue to investigate the combined role of O₃ and PM_2.5 during wildfires to get a more comprehensive assessment of the cumulative burden on health from wildfire smoke.

Ambient air pollution is associated with cardiac repolarization abnormalities in healthy adults

BACKGROUND

Ambient air pollution has been associated with acute cardiovascular events; however, the underlying mechanisms remain incompletely understood. We aimed to examine the impacts of ambient air pollutants on cardiac ventricular repolarization in a highly polluted urban region.

METHODS

Seventy-three healthy non-smoking young adults (66% female, mean age of 23.3 ± 5.4 years) were followed with four repeated 24-h electrocardiogram recordings in 2014-2016 in Beijing, China. Continuous concentrations of ambient particulates in size fractions of 5-560 nm diameter, black carbon (BC), nitrogen dioxide (NO₂), carbon monoxide (CO), sulfur dioxide (SO₂), and ozone (O₃) were measured at a fixed-location air pollution monitoring station. Generalized linear mixed models, with adjustment for individual risk factors, time-varying factors and meteorological parameters, were used to evaluate the effects of air pollution on 5-min segments of heart rate-corrected QT interval (QTc), an index of cardiac ventricular repolarization.

RESULTS

During the study period, the mean levels of number concentrations of particulates in size range of 5-560 nm (PNC_5-560) were 20,711 particles/cm³. Significant increases in QTc of 0.56% (95% CI: 0.27, 0.84) to 1.76% (95% CI: 0.73, 2.79) were associated with interquartile range increases in PNC_50-560 at prior 1-5 moving average days. Significant increases in QTc were also associated with increases in exposures to traffic-related air pollutants (BC, NO₂ and CO), a combustion pollutant SO₂, and the secondary pollutant O₃. The associations were stronger in participants who were male, overweight, with abdominal obesity, and with higher levels of high-sensitivity C-reactive protein.

CONCLUSIONS

Our findings suggest that exposures to higher levels of ambient particulates in small size fractions and traffic pollutants were associated with cardiac repolarization abnormalities in healthy adults, and the cardio-metabolic risks may modify the adverse cardiac effects attributable to air pollution.

Causal Modeling in Environmental Health

The field of environmental health has been dominated by modeling associations, especially by regressing an observed outcome on a linear or nonlinear function of observed covariates. Readers interested in advances in policies for improving environmental health are, however, expecting to be informed about health effects resulting from, or more explicitly caused by, environmental exposures. The quantification of health impacts resulting from the removal of environmental exposures involves causal statements. Therefore, when possible, causal inference frameworks should be considered for analyzing the effects of environmental exposures on health outcomes.

Ozone and cardiac arrest: The role of previous hospitalizations

BACKGROUND

Several studies have reported associations between exposure to particulate matter and incidence of out-of-hospital cardiac arrest (OHCA) and some have observed associations with ozone (O₃). There are no studies investigating susceptibility based on previous disease history to short-term O₃ exposure and the risk of OHCA.

AIM

To investigate the role of previous cardiovascular-related hospitalizations in modifying the associations between the risk of OHCA and short-term increase in O₃ concentrations.

METHODS

A time-stratified case-crossover analysis of 11,923 OHCA registered in the Swedish Register for Cardiopulmonary Resuscitation from 2006 to 2014 was performed. Using personal identification numbers, OHCA were linked to all previous hospitalizations in Sweden since 1987 to create susceptible groups based on the principal diagnosis code at discharge. Susceptibility was based on hospitalization for i) acute myocardial infarction; ii) heart failure; iii) arrhythmias; iv) diabetes; v) hypertension; and vi) stroke. Moving 2 and 24-h averages for O₃, PM_2.5, PM₁₀, and NO₂ were constructed from hourly averages.

RESULTS

A 10 μg/m³ higher 2-h average O₃ concentration was associated with a 2% higher risk of OHCA (95% CI, 0% 3%). Associations were similar for 24-h average O₃ and in individuals with or without hospitalizations for AMI, heart failure, diabetes, hypertension or stroke. Individuals with previous hospitalizations for arrhythmias had a lower risk of OHCA with higher O₃. No associations were observed for other pollutants.

CONCLUSIONS

Short-term exposure to O₃ was associated with an elevated risk of OHCA, however, previous hospitalizations for cardiovascular diseases were not associated with additionally augmented risks.

Roadside Exposure and Inflammation Biomarkers among a Cohort of Traffic Police in Kathmandu, Nepal

Air pollution is a major environmental problem in the Kathmandu Valley. Specifically, roadside and traffic-related air pollution exposure levels were found at very high levels exceeding Nepal air quality standards for daily PM_2.5. In an exposure study involving traffic police officers, we collected 78 blood samples in a highly polluted spring season (16 February 2014–4 April 2014) and 63 blood samples in the less polluted summer season (20 July 2014–22 August 2014). Fourteen biomarkers, i.e., C-reactive protein (CRP), serum amyloid A (SAA), intracellular adhesion molecule (ICAM-1), vascular cell adhesion molecule (VCAM-1), interferon gamma (IFN-γ), interleukins (IL1-β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-13), and tumor necrosis factor (TNF-α) were analyzed in collected blood samples using proinflammatory panel 1 kits and vascular injury panel 2 kits. All the inflammatory biomarker levels were higher in the summer season than in the spring season, while particulate levels were higher in the spring season than in the summer season. We did not find significant association between 24-hour average PM_2.5 or black carbon (BC) exposure levels with most of analyzed biomarkers for the traffic volunteers working and residing near busy roads in Kathmandu, Nepal, during 2014. Inflammation and vascular injury marker concentrations were generally higher in females, suggesting the important role of gender in inflammation biomarkers. Because of the small sample size of female subjects, further investigation with a larger sample size is required to confirm the role of gender in inflammation biomarkers.

Interstitial Lung Diseases in Developing Countries

More than 100 different conditions are grouped under the term interstitial lung disease (ILD). A diagnosis of an ILD primarily relies on a combination of clinical, radiological, and pathological criteria, which should be evaluated by a multidisciplinary team of specialists. Multiple factors, such as environmental and occupational exposures, infections, drugs, radiation, and genetic predisposition have been implicated in the pathogenesis of these conditions. Asbestosis and other pneumoconiosis, hypersensitivity pneumonitis (HP), chronic beryllium disease, and smoking-related ILD are specifically linked to inhalational exposure of environmental agents. The recent Global Burden of Disease Study reported that ILD rank 40th in relation to global years of life lost in 2013, which represents an increase of 86% compared to 1990. Idiopathic pulmonary fibrosis (IPF) is the prototype of fibrotic ILD. A recent study from the United States reported that the incidence and prevalence of IPF are 14.6 per 100,000 person-years and 58.7 per 100,000 persons, respectively. These data suggests that, in large populated areas such as Brazil, Russia, India, and China (the BRIC region), there may be approximately 2 million people living with IPF. However, studies from South America found much lower rates (0.4–1.2 cases per 100,000 per year). Limited access to high-resolution computed tomography and spirometry or to multidisciplinary teams for accurate diagnosis and optimal treatment are common challenges to the management of ILD in developing countries.

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

Short-term exposure to ambient ozone is associated with adverse cardiovascular effects, with inconsistent evidence on the molecular mechanisms. We conducted a longitudinal panel study among 43 college students in Shanghai to explore the effects of personal ozone exposure on blood pressure (BP), vascular endothelial function, and the potential molecular mechanisms. We measured real-time personal ozone exposure levels, serum angiotensin-converting enzyme (ACE) and endothelin-1 (ET-1), and locus-specific DNA methylation of ACE and EDN1 (coding ET-1). We used an untargeted metabolomic approach to explore potentially important metabolites. We applied linear mixed-effect models to examine the effects of ozone on the above biomarkers. An increase in 2 h-average ozone exposure was significantly associated with elevated levels of BP, ACE, and ET-1. ACE and EDN1 methylation decreased with ozone exposure, but the magnitude differed by genomic loci. Metabolomics analysis showed significant changes in serum lipid metabolites following ozone exposure that are involved in maintaining vascular endothelial function. Our findings suggested that acute 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 the effects of ozone on BP and vascular endothelial function.

An acute exposure to ozone impairs human olfactory functioning

INTRODUCTION

Ozone is a ubiquitous and irritant gas. We questioned whether an acute exposure to 0.2 ppm ozone impaired olfactory functioning.

METHODS

Healthy, normosmic subjects were exposed according to a parallel group design either to 0.2 ppm ozone (n = 15) or to sham (n = 13) in an exposure chamber for two hours. Possible irritating effects were assessed by questionnaire (range 0-5). The detection threshold of n-butanol was measured with the Sniffin' Sticks test before and after exposure. Olfactory thresholds were logarithmized and a two-way analysis of variance (ANOVA) with repeated measurements was carried out to test the effects of exposure (ozone vs. sham) and time (before vs. after exposure). Additionally, nasal secretions were taken at a preliminary examination and after exposure to determine interleukins 1ß and 8.

RESULTS

No irritating effects to the upper airways were observed. In the ozone group, the median score for cough increased from 0 to 2 at the end of exposure (sham group 0 and 0, respectively, p < 0.001). The ANOVA showed a main effect for ozone exposure (F (1, 26) = 27.6, p = 0.0002), indicating higher olfactory thresholds in the ozone group. Concentrations of interleukins in nasal secretions did not increase following ozone exposure.

CONCLUSIONS

This study shows a clear impairment of olfactory functioning following an acute exposure to 0.2 ppm ozone.

Short-term effects of fine particulate matter and ozone on the cardiac conduction system in patients undergoing cardiac catheterization

BACKGROUND

Air pollution-induced changes in cardiac electrophysiological properties could be a pathway linking air pollution and cardiovascular events. The evidence of air pollution effects on the cardiac conduction system is incomplete yet. We investigated short-term effects of particulate matter ≤ 2.5 μm in aerodynamic diameter (PM_2.5) and ozone (O₃) on cardiac electrical impulse propagation and repolarization as recorded in surface electrocardiograms (ECG).

METHODS

We analyzed repeated 12-lead ECG measurements performed on 5,332 patients between 2001 and 2012. The participants came from the Duke CATHGEN Study who underwent cardiac catheterization and resided in North Carolina, United States (NC, U.S.). Daily concentrations of PM_2.5 and O₃ at each participant's home address were predicted with a hybrid air quality exposure model. We used generalized additive mixed models to investigate the associations of PM_2.5 and O₃ with the PR interval, QRS interval, heart rate-corrected QT interval (QTc), and heart rate (HR). The temporal lag structures of the associations were examined using distributed-lag models.

RESULTS

Elevated PM_2.5 and O₃ were associated with four-day lagged lengthening of the PR and QRS intervals, and with one-day lagged increases in HR. We observed immediate effects on the lengthening of the QTc interval for both PM_2.5 and O₃, as well as delayed effects for PM_2.5 (lagged by 3 - 4 days). The associations of PM_2.5 and O₃ with the PR interval and the association of O₃ with the QRS interval persisted until up to seven days after exposure.

CONCLUSIONS

In patients undergoing cardiac catheterization, short-term exposure to air pollution was associated with increased HR and delays in atrioventricular conduction, ventricular depolarization and repolarization.

Cardiovascular function and ozone exposure: The Multicenter Ozone Study in oldEr Subjects (MOSES)

BACKGROUND

To date, there have been relatively few studies of acute cardiovascular responses to controlled ozone inhalation, although a number of observational studies have reported significant positive associations between both ambient ozone levels and acute cardiovascular events and long-term ozone exposure and cardiovascular mortality.

OBJECTIVES

We hypothesized that short-term controlled exposure to low levels of ozone in filtered air would induce autonomic imbalance, repolarization abnormalities, arrhythmia, and vascular dysfunction.

METHODS

This randomized crossover study of 87 healthy volunteers 55-70 years of age was conducted at three sites using a common protocol, from June 2012 to April 2015. Subjects were exposed for 3 h in random order to 0 ppb (filtered air), 70 ppb ozone, and 120 ppb ozone, alternating 15 min of moderate exercise with 15 min of rest. A suite of cardiovascular endpoints was measured the day before, the day of, and up to 22 h after each exposure. Mixed effect linear and logit models evaluated the impact of exposure to ozone on pre-specified primary and secondary outcomes. Site and time were included in the models.

RESULTS

We found no significant effects of ozone exposure on any of the primary or secondary measures of autonomic function, repolarization, ST segment change, arrhythmia, or vascular function (systolic blood pressure and flow-mediated dilation).

CONCLUSIONS

In this multicenter study of older healthy women and men, there was no convincing evidence for acute effects of 3-h, relatively low-level ozone exposures on cardiovascular function. However, we cannot exclude the possibility of effects with higher ozone concentrations, more prolonged exposure, or in subjects with underlying cardiovascular disease. Further, we cannot exclude the possibility that exposure to ambient ozone and other pollutants in the days before the experimental exposures obscured or blunted cardiovascular biomarker response to the controlled ozone exposures.

Changes in Metabolites Present in Lung-Lining Fluid Following Exposure of Humans to Ozone

Controlled human exposure to the oxidant air pollutant ozone causes decrements in lung function and increased inflammation as evidenced by neutrophil influx into the lung and increased levels of proinflammatory cytokines in the airways. Here we describe a targeted metabolomics evaluation of human bronchoalveolar lavage fluid (BALF) following controlled in vivo exposure to ozone to gain greater insight into its pulmonary effects. In a 2-arm cross-over study, each healthy adult human volunteer was randomly exposed to filtered air (FA) and to 0.3 ppm ozone for 2 h while undergoing intermittent exercise with a minimum of 4 weeks between exposures. Bronchoscopy was performed and BALF obtained at 1 (n = 9) or 24 (n = 23) h postexposure. Metabolites were detected using ultrahigh performance liquid chromatography-tandem mass spectroscopy. At 1-h postexposure, a total of 28 metabolites were differentially expressed (DE) (p < .05) following ozone exposure compared with FA-exposure. These changes were associated with increased glycolysis and antioxidant responses, suggesting rapid increased energy utilization as part of the cellular response to oxidative stress. At 24-h postexposure, 41 metabolites were DE. Many of the changes were in amino acids and linked with enhanced proteolysis. Changes associated with increased lipid membrane turnover were also observed. These later-stage changes were consistent with ongoing repair of airway tissues. There were 1.37 times as many metabolites were differentially expressed at 24 h compared with 1-h postexposure. The changes at 1 h reflect responses to oxidative stress while the changes at 24 h indicate a broader set of responses consistent with tissue repair. These results illustrate the ability of metabolomic analysis to identify mechanistic features of ozone toxicity and aspects of the subsequent tissue response.

Acute effect of multiple ozone metrics on mortality by season in 34 Chinese counties in 2013-2015

BACKGROUND

Although numerous multicentre studies have estimated the association between ozone exposure and mortality, there are currently no nationally representative multicentre studies of the ozone-mortality relationship in China.

OBJECTIVE

To investigate the effect on total (nonaccidental) and cause-specific mortality of short-term exposure to ambient ozone, and examine different exposure metrics.

METHODS

The effects of short-term exposure to ozone were analysed using various metrics (daily 1-h maximum, daily 8-h maximum and daily average) on total (nonaccidental) and cause-specific (circulatory and respiratory) mortality from 2013 to 2015 in 34 counties in 10 cities across China. We used distributed lag nonlinear models for estimating county-specific relative risk of mortality and combined the county-specific relative rates by conducting a random-effects meta-analysis.

RESULTS

In all-year analyses, a 10 μg m^-3 increase in daily average, daily 1-h maximum and daily 8-h maximum ozone at lag02 corresponded to an increase of 0.6% (95% CI: 0.33, 0.88), 0.26% (95% CI: 0.12, 0.39) and 0.37% (95% CI: 0.2, 0.55) in total (nonaccidental) mortality, 0.66% (95% CI: 0.28, 1.04), 0.31% (95% CI: 0.11, 0.51) and 0.39% (95% CI: 0.16, 0.62) in circulatory mortality, and 0.57% (95% CI: -0.09, 1.23), 0.11% (95% CI: -0.22, 0.44) and 0.22% (95% CI: -0.28, 0.72) in respiratory mortality, respectively. These estimates had a different seasonal pattern by cause of death. In general, the seasonal patterns were consistent with the times of year when ozone concentrations are highest.

CONCLUSIONS

Our findings suggest that in China, the acute effects of ozone are more closely related to daily average exposure than any other metric.

Susceptibility to short-term ozone exposure and cardiovascular and respiratory mortality by previous hospitalizations

BACKGROUND

Ozone (O₃) has been associated with cardiorespiratory mortality although few studies have explored susceptible populations based on prior disease. We aimed to investigate the role of previous hospitalization on the association between short-term exposure to O₃ and cardiovascular (CV) and respiratory mortality.

METHODS

We performed time series analyses using generalized additive models and case-crossover on 136,624 CV and 23,281 respiratory deaths in Stockholm County (1990-2010). Deaths were linked to hospital admissions data. We constructed 2-day and 7-day averages using daily 8-h maximum for O₃ and hourly values for PM_2.5, PM₁₀, NO₂, and NO_x from a fixed monitor.

RESULTS

We observed a 0.7% (95% CI: 0.1%, 1.3%) and 2.7% (95% CI: 0.8%, 4.6%) higher risk of CV and respiratory death per 10 μg/m³ higher 2-day and 7-day average O₃ respectively. Individuals previously hospitalized for myocardial infarction demonstrated 1.8% (95% CI: 0.4%, 3.4%) higher risk of CV death per 10 μg/m³ higher 2-day average O₃ and similar associations were observed in individuals with no previous hospitalization for any cause. Individuals with previous hospitalizations did not show susceptibility towards O₃-related risk of respiratory mortality. We observed no associations for other pollutants.

CONCLUSION

Short-term ozone exposure is associated with CV and respiratory mortality and our results may suggest higher susceptibility to CV mortality following O₃ exposure in individuals previously hospitalized for myocardial infarction. Higher risks were also observed in individuals with cardiovascular death as their first presentation of disease.

Comparative Cardiopulmonary Effects of Particulate Matter- And Ozone-Enhanced Smog Atmospheres in Mice

This study was conducted to compare the cardiac effects of particulate matter (PM)- (SA-PM) and ozone(O₃)-enhanced (SA-O₃) smog atmospheres in mice. Based on our previous findings of filtered diesel exhaust we hypothesized that SA-O₃ would cause greater cardiac dysfunction than SA-PM. Radiotelemetered mice were exposed to either SA-PM, SA-O₃, or filtered air (FA) for 4 h. Heart rate (HR) and electrocardiogram were recorded continuously before, during and after exposure. Both SA-PM and SA-O₃ increased heart rate variability (HRV) but only SA-PM increased HR. Normalization of responses to total hydrocarbons, gas-only hydrocarbons and PM concentration were performed to assess the relative contribution of each phase given the compositional variability. Normalization to PM concentration revealed that SA-O₃ was more potent in increasing HRV, arrhythmogenesis, and causing ventilatory changes. However, there were no differences when the responses were normalized to total or gas-phase only hydrocarbons. Thus, this study demonstrates that a single exposure to smog causes cardiac effects in mice. Although the responses of SA-PM and SA-O₃ are similar, the latter is more potent in causing electrical disturbances and breathing changes potentially due to the effects of irritant gases, which should therefore be accounted for more rigorously in health assessments.

Short-term Exposure to Ozone and Mortality in Subjects With and Without Previous Cardiovascular Disease

BACKGROUND

Exposure to ground level ozone (O3) is a public health problem associated with a range of risks across population subgroups. Our aim was to investigate the role of previous cardiovascular diseases (CVDs) in mortality related to short-term O3 exposure.

METHODS

Deaths between 1990 and 2010 in Stockholm County were matched with previous hospitalizations in Swedish registries. An urban background monitoring station provided hourly values of air quality data, from which we calculated 8-hour running averages and daily 8-hour maximum. We analyzed associations between daily O3 concentrations and mortality among persons with and without previous CVD hospitalization with a generalized additive model adjusted for time trend, influenza, and weather. We also performed two-pollutant models.

RESULTS

There were 302,283 nontrauma-related deaths, out of which 196,916 had previous CVD hospitalization. The mean concentration of daily maximum 8-hour O3 was 62.9 μg/m. An average 10 μg/m increase in the same and preceding day was associated with an increased mortality of 1.72% (95% confidence interval: 0.44%, 3.02%) in those with prior admission for acute myocardial infarction (AMI), which was more than three times higher than for those with no previous AMI (0.50, 95% confidence interval: 0.10%, 0.89%, P value for interaction 0.098). The association between O3 and mortality remained essentially unchanged in two-pollutant models with NO2, NOx, and PM10.

CONCLUSIONS

Our study indicates that short-term exposure to O3 is associated with increased mortality in those with a previous hospitalization for AMI.

Ambient air pollution and thrombosis

Air pollution is a growing public health concern of global significance. Acute and chronic exposure is known to impair cardiovascular function, exacerbate disease and increase cardiovascular mortality. Several plausible biological mechanisms have been proposed for these associations, however, at present, the pathways are incomplete. A seminal review by the American Heart Association (2010) concluded that the thrombotic effects of particulate air pollution likely contributed to their effects on cardiovascular mortality and morbidity. The aim of the current review is to appraise the newly accumulated scientific evidence (2009-2016) on contribution of haemostasis and thrombosis towards cardiovascular disease induced by exposure to both particulate and gaseous pollutants.Seventy four publications were reviewed in-depth. The weight of evidence suggests that acute exposure to fine particulate matter (PM_2.5) induces a shift in the haemostatic balance towards a pro-thrombotic/pro-coagulative state. Insufficient data was available to ascertain if a similar relationship exists for gaseous pollutants, and very few studies have addressed long-term exposure to ambient air pollution. Platelet activation, oxidative stress, interplay between interleukin-6 and tissue factor, all appear to be potentially important mechanisms in pollution-mediated thrombosis, together with an emerging role for circulating microvesicles and epigenetic changes.Overall, the recent literature supports, and arguably strengthens, the contention that air pollution contributes to cardiovascular morbidity by promoting haemostasis. The volume and diversity of the evidence highlights the complexity of the pathophysiologic mechanisms by which air pollution promotes thrombosis; multiple pathways are plausible and it is most likely they act in concert. Future research should address the role gaseous pollutants play in the cardiovascular effects of air pollution mixture and direct comparison of potentially susceptible groups to healthy individuals.

Differential expression of pro-inflammatory and oxidative stress mediators induced by nitrogen dioxide and ozone in primary human bronchial epithelial cells

CONTEXT

NO2 and O3 are ubiquitous air toxicants capable of inducing lung damage to the respiratory epithelium. Due to their oxidizing capabilities, these pollutants have been proposed to target specific biological pathways, but few publications have compared the pathways activated.

OBJECTIVE

This work will test the premise that NO2 and O3 induce toxicity by activating similar cellular pathways.

METHODS

Primary human bronchial epithelial cells (HBECs, n = 3 donors) were exposed for 2 h at an air-liquid interface to 3 ppm NO2, 0.75 ppm O3, or filtered air and harvested 1 h post-exposure. To give an overview of pathways that may be influenced by each exposure, gene expression was measured using PCR arrays for toxicity and oxidative stress. Based on the results, genes were selected to quantify whether expression changes were changed in a dose- and time-response manner using NO2 (1, 2, 3, or 5 ppm), O3 (0.25, 0.50, 0.75, or 1.00 ppm), or filtered air and harvesting 0, 1, 4 and 24 h post-exposure.

RESULTS

Using the arrays, genes related to oxidative stress were highly induced with NO2 while expression of pro-inflammatory and vascular function genes was found subsequent to O3. NO2 elicited the greatest HMOX1 response, whereas O3 more greatly induced IL-6, IL-8 and PTGS2 expression. Additionally, O3 elicited a greater response 1 h post-exposure and NO2 produced a maximal response after 4 h.

CONCLUSION

We have demonstrated that these two oxidant gases stimulate differing mechanistic responses in vitro and these responses occur at dissimilar times.

Ozone exposure is associated with acute changes in inflammation, fibrinolysis, and endothelial cell function in coronary artery disease patients

BACKGROUND

Air pollution is a major risk factor for cardiovascular disease, of which ozone is a major contributor. Several studies have found associations between ozone and cardiovascular morbidity, but the results have been inconclusive. We investigated associations between ozone and changes across biological pathways associated with cardiovascular disease.

METHODS

Using a panel study design, 13 participants with coronary artery disease were assessed for markers of systemic inflammation, heart rate variability and repolarization, lipids, blood pressure, and endothelial function. Daily measurements of ozone and particulate matter (PM2.5) were obtained from central monitoring stations. Single (ozone) and two-pollutant (ozone and PM2.5) models were used to assess percent changes in measurements per interquartile ranges of pollutants.

RESULTS

Per interquartile increase in ozone, changes in tissue plasminogen factor (6.6%, 95% confidence intervals (CI) = 0.4, 13.2), plasminogen activator inhibitor-1 (40.5%, 95% CI = 8.7, 81.6), neutrophils (8.7% 95% CI = 1.5, 16.4), monocytes (10.2%, 95% CI = 1.0, 20.1), interleukin-6 (15.9%, 95% CI = 3.6, 29.6), large-artery elasticity index (-19.5%, 95% CI = -34.0, -1.7), and the baseline diameter of the brachial artery (-2.5%, 95% CI = -5.0, 0.1) were observed. These associations were robust in the two-pollutant model.

CONCLUSIONS

We observed alterations across several pathways associated with cardiovascular disease in 13 coronary artery disease patients following ozone exposures, independent of PM2.5. The results support the biological plausibility of ozone-induced cardiovascular effects. The effects were found at concentrations below the EPA National Ambient Air Quality Standards for both ozone and PM2.5.

Effects of ozone exposure on human epithelial adenocarcinoma and normal fibroblasts cells

Previous studies show variable ozone cytotoxicity and genotoxicity in cell cultures, laboratory animals and humans directly exposed to tropospheric ozone. The aim of this study was therefore to investigate and compare the cyto and genotoxic effects of ozone using adenocarcinoma human alveolar basal epithelial cells A549 and normal human fibroblasts Hs27. A cell culture chamber with controlled atmosphere (a simulation reactor) was built to inject a flow of 120 ppb of ozone, which is two times the threshold value for the protection of human health, fixed by the EU legislation. Cell proliferation was evaluated by a luminescent cell viability assay while we assessed the genotoxic potential of ozone by the induction of micronuclei as well as evaluating DNA strand breaks by the induction of micronuclei evaluated by means of the cytokinesis-block micronucleus (CBMN) assay as well as evaluating DNA strand breaks by Alkaline Comet Assay (CA) or Comet Assay. A549 cells viability decreases significantly at 24 hours treatment with 120 ppb of O₃ while at 48 hours and 72 hours O₃ treated cells viability doesn’t differ in respect to the control. However a significative decrease of A549 viability is shown at 72 hours vs. 48 hours in both treated and not-treated cells. The viability trend in the Hs27 cells did not show any significant changes in treated samples compared to the control in all conditions. The two genotoxicity biomarkers, the micronucleus and the comet tests, showed in both the cell types exposed to ozone, a significant increase in the number of micronuclei and in the tail DNA % in respect to the control even if at different times/cell type. Moreover, we found that O₃ provokes genotoxic effects more evident in A549 cancer cells than in normal fibroblasts Hs27 ones. We applied a cell growth simulation model referred to ozone treated or not cell lines to confirm that the ozone exposure causes a slackening in the cells replication.

Associations Between Air Quality Changes and Biomarkers of Systemic Inflammation During the 2014 Nanjing Youth Olympics: A Quasi-Experimental Study

There is increasing interest in quasi-experimental research to evaluate whether actions taken to improve air quality will benefit public health. We conducted a quasi-experimental study to evaluate inflammatory response to changes in air quality during the 2014 Nanjing Youth Olympics in China. We repeatedly measured 8 biomarkers of systemic inflammation in 31 healthy adults and obtained hourly air pollutant concentrations from a nearby fixed-site monitoring station. We used linear mixed-effect models to examine the associations between air quality changes and blood biomarkers. Air pollutant concentrations decreased apparently during the Youth Olympics. Concomitantly, we observed significant decreases in levels of soluble cluster of differentiation 40 (CD40) ligand and interleukin 1β (geometric means ratios were 0.45 and 0.24, respectively) from the pre-Olympic period to the intra-Olympic period. Afterwards, levels of C-reactive protein and vascular cell adhesion molecule 1 increased significantly (geometric means ratios were 2.22 and 1.29, respectively) in the post-Olympic period. Fine particulate matter and ozone were significantly associated with soluble CD40 ligand, P-selectin, interleukin 1β, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1. Other pollutants showed positive but nonsignificant associations. Our study indicated that reduced air pollution, especially fine particulate matter and ozone, during the 2014 Nanjing Youth Olympics was associated with alleviated systemic inflammation in healthy adults.

Serum amyloid A: an ozone-induced circulating factor with potentially important functions in the lung-brain axis

Accumulating evidence suggests that O₃ exposure may contribute to CNS dysfunction. Here, we posit that inflammatory and acute-phase proteins in the circulation increase after O₃ exposure and systemically convey signals of O₃ exposure to the CNS. To model acute O₃ exposure, female Balb/c mice were exposed to 3 ppm O₃ or forced air for 2 h and were studied after 6 or 24 h. Of 23 cytokines and chemokines, only KC/CXCL1 was increased in blood 6 h after O₃ exposure. The acute-phase protein serum amyloid A (A-SAA) was significantly increased by 24 h, whereas C-reactive protein was unchanged. A-SAA in blood correlated with total leukocytes, macrophages, and neutrophils in bronchoalveolar lavage from O₃-exposed mice. A-SAA mRNA and protein were increased in the liver. We found that both isoforms of A-SAA completely crossed the intact blood-brain barrier, although the rate of SAA2.1 influx was approximately 5 times faster than that of SAA1.1. Finally, A-SAA protein, but not mRNA, was increased in the CNS 24 h post-O₃ exposure. Our findings suggest that A-SAA is functionally linked to pulmonary inflammation in our O₃ exposure model and that A-SAA could be an important systemic signal of O₃ exposure to the CNS.-Erickson, M. A., Jude, J., Zhao, H., Rhea, E. M., Salameh, T. S., Jester, W., Pu, S., Harrowitz, J., Nguyen, N., Banks, W. A., Panettieri, R. A., Jr., Jordan-Sciutto, K. L. Serum amyloid A: an ozone-induced circulating factor with potentially important functions in the lung-brain axis.

Ozone Exposure Increases Circulating Stress Hormones and Lipid Metabolites in Humans

RATIONALE

Air pollution has been associated with increased prevalence of type 2 diabetes; however, the mechanisms remain unknown. We have shown that acute ozone exposure in rats induces release of stress hormones, hyperglycemia, leptinemia, and glucose intolerance that are associated with global changes in peripheral glucose, lipid, and amino acid metabolism.

OBJECTIVES

To examine ozone-induced metabolic derangement in humans using serum metabolomic assessment, establish human-to-rodent coherence, and identify novel nonprotein biomarkers.

METHODS

Serum samples were obtained from a crossover clinical study that included two clinic visits (n = 24 each) where each subject was blindly exposed in the morning to either filtered air or 0.3 parts per million ozone for 2 hours during 15-minute on-off exercise. Serum samples collected within 1 hour after exposure were assessed for changes in metabolites using a metabolomic approach.

MEASUREMENTS AND MAIN RESULTS

Metabolomic analysis revealed that ozone exposure markedly increased serum cortisol and corticosterone together with increases in monoacylglycerol, glycerol, and medium- and long-chain free fatty acids, reflective of lipid mobilization and catabolism. Additionally, ozone exposure increased serum lysolipids, potentially originating from membrane lipid breakdown. Ozone exposure also increased circulating mitochondrial β-oxidation-derived metabolites, such as acylcarnitines, together with increases in the ketone body 3-hydroxybutyrate. These changes suggested saturation of β-oxidation by ozone in exercising humans.

CONCLUSIONS

As in rodents, acute ozone exposure increased stress hormones and globally altered peripheral lipid metabolism in humans, likely through activation of a neurohormonally mediated stress response pathway. The metabolomic assessment revealed new biomarkers and allowed for establishment of rodent-to-human coherence. Clinical trial registered with www.clinicaltrials.gov (NCT 01492517).

Newly divided eosinophils limit ozone-induced airway hyperreactivity in nonsensitized guinea pigs

Ozone causes vagally mediated airway hyperreactivity and recruits inflammatory cells, including eosinophils, to lungs, where they mediate ozone-induced hyperreactivity 1 day after exposure but are paradoxically protective 3 days later. We aimed to test the role of newly divided eosinophils in ozone-induced airway hyperreactivity in sensitized and nonsensitized guinea pigs. Nonsensitized and sensitized guinea pigs were treated with 5-bromo-2-deoxyuridine (BrdU) to label newly divided cells and were exposed to air or ozone for 4 h. Later (1 or 3 days later), vagally induced bronchoconstriction was measured, and inflammatory cells were harvested from bone marrow, blood, and bronchoalveolar lavage. Ozone induced eosinophil hematopoiesis. One day after ozone, mature eosinophils dominate the inflammatory response and potentiate vagally induced bronchoconstriction. However, by 3 days, newly divided eosinophils have reached the lungs, where they inhibit ozone-induced airway hyperreactivity because depleting them with antibody to IL-5 or a TNF-α antagonist worsened vagally induced bronchoconstriction. In sensitized guinea pigs, both ozone-induced eosinophil hematopoiesis and subsequent recruitment of newly divided eosinophils to lungs 3 days later failed to occur. Thus mature eosinophils dominated the ozone-induced inflammatory response in sensitized guinea pigs. Depleting these mature eosinophils prevented ozone-induced airway hyperreactivity in sensitized animals. Ozone induces eosinophil hematopoiesis and recruitment to lungs, where 3 days later, newly divided eosinophils attenuate vagally mediated hyperreactivity. Ozone-induced hematopoiesis of beneficial eosinophils is blocked by a TNF-α antagonist or by prior sensitization. In these animals, mature eosinophils are associated with hyperreactivity. Thus interventions targeting eosinophils, although beneficial in atopic individuals, may delay resolution of airway hyperreactivity in nonatopic individuals.

Modeling vascular inflammation and atherogenicity after inhalation of ambient levels of ozone: exploratory lessons from transcriptomics

BACKGROUND

Epidemiologic studies have linked inhalation of air pollutants such as ozone to cardiovascular mortality. Human exposure studies have shown that inhalation of ambient levels of ozone causes airway and systemic inflammation and an imbalance in sympathetic/parasympathetic tone.

METHODS

To explore molecular mechanisms through which ozone inhalation contributes to cardiovascular mortality, we compared transcriptomics data previously obtained from bronchoalveolar lavage (BAL) cells obtained from healthy subjects after inhalational exposure to ozone (200 ppb for 4 h) to those of various cell samples from 11 published studies of patients with atherosclerotic disease using the Nextbio genomic data platform. Overlapping gene ontologies that may be involved in the transition from pulmonary to systemic vascular inflammation after ozone inhalation were explored. Local and systemic enzymatic activity of an overlapping upregulated gene, matrix metalloproteinase-9 (MMP-9), was measured by zymography after ozone exposure.

RESULTS

A set of differentially expressed genes involved in response to stimulus, stress, and wounding were in common between the ozone and most of the atherosclerosis studies. Many of these genes contribute to biological processes such as cholesterol metabolism dysfunction, increased monocyte adherence, endothelial cell lesions, and matrix remodeling, and to diseases such as heart failure, ischemia, and atherosclerotic occlusive disease. Inhalation of ozone increased MMP-9 enzymatic activity in both BAL fluid and serum.

CONCLUSIONS

Comparison of transcriptomics between BAL cells after ozone exposure and various cell types from patients with atherosclerotic disease reveals commonly regulated processes and potential mechanisms by which ozone inhalation may contribute to progression of pre-existent atherosclerotic lesions.

Linking physiological parameters to perturbations in the human exposome: Environmental exposures modify blood pressure and lung function via inflammatory cytokine pathway

Human biomonitoring is an indispensable tool for evaluating the systemic effects derived from external stressors including environmental pollutants, chemicals from consumer products, and pharmaceuticals. The aim of this study was to explore consequences of environmental exposures to diesel exhaust (DE) and ozone (O₃) and ultimately to interpret these parameters from the perspective of in vitro to in vivo extrapolation. In particular, the objective was to use cytokine expression at the cellular level as a biomarker for physiological systemic responses such as blood pressure and lung function at the systemic level. The values obtained could ultimately link in vivo behavior to simpler in vitro experiments where cytokines are a measured parameter. Human exposures to combinations of DE and O₃ and the response correlations between forced exhaled volume in 1 second (FEV₁), forced vital capacity (FVC), systolic and diastolic blood pressure (SBP and DBP, respectively), and 10 inflammatory cytokines in blood (interleukins 1β, 2, 4, 5, 8, 10, 12p70 and 13, IFN-γ, and TNF-α) were determined in 15 healthy human volunteers. Results across all exposures revealed that certain individuals displayed greater inflammatory responses compared to the group and, generally, there was more between-person variation in the responses. Evidence indicates that individuals are more stable within themselves and are more likely to exhibit responses independent of one another. Data suggest that in vitro findings may ultimately be implemented to elucidate underlying adverse outcome pathways (AOP) for linking high-throughput toxicity tests to physiological in vivo responses. Further, this investigation supports assessing subjects based upon individual responses as a complement to standard longitudinal (pre vs. post) intervention grouping strategies. Ultimately, it may become possible to predict a physiological (systemic) response based upon cellular-level (in vitro) observations.