The impact of long-term exposure to NO2, O3, and their oxidative potential on adolescents' mental health, and the protective role of school-based greenness

Recent increases in nitrogen dioxide (NO2) and ozone (O3), two highly reactive and oxidative pollutants, have raised concerns about their potential impact on adolescent mental health. This study leveraged data from the Chinese National Survey on Students' Constitution and Health (CNSSCH) in 2019, a nationally representative cross-sectional survey of Chinese adolescents. A total of 149,697 adolescents aged 10-18 years were included in this study. NO2 and O3 were sourced from the ChinaHighAirPollutants dataset, and the combined oxidative potential (OX) was subsequently calculated using the concentrations of NO2 and O3. The study quantitively examined the association of NO2, O3, and OX with adolescent mental health using the Dual Factor Model of Mental Health (DFM), which was derived from a questionnaire. According to the DFM, mental health status was divided into four groups: complete mental health, vulnerable, symptomatic but content, and troubled. Greenness around schools, measured by the Normalized Difference Vegetation Index (NDVI), was examined for its potential effect modification on the association between NO2, O3, OX, and mental health. Each IQR (Interquartile Range) increase in OX was related to adverse mental health outcomes, with ORs of 1.17 (95 % CI: 1.06, 1.29) for being vulnerable, 1.20 (95 % CI: 1.12, 1.28) for being more symptomatic but content, and 1.15 (95 % CI: 1.07, 1.23) for being troubled. Similar findings emerged in relation to O3 exposure. A positive association was observed between NO2 exposure and being vulnerable (OR = 1.07; 95 % CI: 1.01, 1.16). Additionally, the impact of exposure to NO2, O3, and OX on mental health outcomes was significantly stronger in the low-level NDVI group compared to the high-level NDVI group (P for interaction < 0.05). The joint effects analysis revealed that adolescents exposed to high levels of air pollutants and low NDVI had the highest odds of adverse mental health outcomes. These results highlight the complex relationship between NO2, O3, OX, and mental health, with particular emphasis on the underexplored role of OX. Notably, the findings suggest that reducing pollution and increasing greenery could offer significant benefits for improving adolescent mental health.

Short-term ambient ozone exposure increases the risk of hospitalization with depression: a multi-city time-stratified case-crossover study

BACKGROUND

Depression, the most common mental illness worldwide, has been studied and air pollution has been found to increase the risk of depression hospitalization, but research results on ozone (O3) remain limited. In this context, we investigated the relationship between short-term O3 exposure and depression-related hospital admissions (HAs).

METHODS

The 10,459 records of HAs for depression from medical institutions across in 9 cities, China, were collected between 1 January 2017, and 31 December 2018. Air pollutants and meteorological data was obtained from provincial ecological environment monitoring stations in the study area. Conditional Poisson regression was employed to estimate the association between O3 and hospitalizations for depression, with data stratification by sex, age, weather, and economic level.

RESULTS

Short-term O3 exposure was positively associated with the number of depression-related hospitalizations (Relative risk: 1.04 [95% CI: 1.02, 1.05]). O3 had a significant effect on the risk of depression-related hospitalizations on warm days (P = 0.021, Relative risk: 1.05 [1.03, 1.08]). The high gross domestic product group was more likely to be affected by O3 exposure-associated depression-related hospitalizations (P = 0.005, Relative risk: 1.03 [1.01, 1.05]).

CONCLUSIONS

Short-term changes to O3 exposure may increase the risk of depression related hospitalizations, especially on warm days.

Unraveling the ozone impact and oxidative stress on the nervous system

Ozone (O₃), a potent oxidant, can penetrate the body through breathing, generating reactive oxygen species (ROS) and triggering inflammatory processes. Oxidative stress, an imbalance between the production of ROS and the body's antioxidant capacity, plays a crucial role in the pathophysiology of various neurodegenerative diseases. This phenomenon can negatively impact the Central Nervous System (CNS), inducing structural and functional alterations that contribute to the development of neurological pathologies. This review examines how O₃-induced oxidative stress affects the nervous system by analyzing existing literature on the involved molecular mechanisms and potential antioxidant systems to mitigate its effects. Through a comprehensive review of experimental studies, our objective is to shed light on the interaction between O₃ and the nervous system, as well as its signaling pathways and altered genes, providing a foundation for future research in this field. Several studies have demonstrated that prolonged exposure to O₃ leads to increased expression of reactive oxygen species, causing alterations in the blood-brain barrier and damage to astrocytes and microglia. These effects can lead to an increase in the production of proinflammatory cytokines, neurotoxins, and genes, exacerbating neuronal damage and accelerating the progression of neurodegenerative diseases such as Alzheimer's, Parkinson's, and other neurological disorders. The results of this review suggest that exposure to O₃ may induce oxidative damage to the nervous system, which could have significant implications for public health.

Neuroendocrine contribution to sex-related variations in adverse air pollution health effects

Air pollution exposure is ranked as a leading environmental risk factor for not only cardiopulmonary diseases but also for systemic health ailments including diabetes, reproductive abnormalities, and neuropsychiatric disorders, likely mediated by central neural stress mechanisms. Current experimental evidence links many air pollution health outcomes with activation of neuroendocrine sympathetic-adrenal-medullary and hypothalamic-pituitary-adrenal (HPA) stress axes associated with resultant increases in adrenal-derived hormone levels acting as circulating mediators of multi-organ stress reactions. Epidemiological and experimental investigations also demonstrated sex-specific responses to air pollutant inhalation, which may be attributed to hormonal interactions within the stress and reproductive axes. Sex hormones (androgens and estrogens) interact with neuroendocrine functions to influence hypothalamic responses, subsequently augmenting stress-mediated metabolic and immune changes. These neurohormonal interactions may contribute to innate sex-specific responses to inhaled irritants, inducing differing individual susceptibility. The aim of this review was to: (1) examine neuroendocrine co-regulation of the HPA axis by gonadal hormones, (2) provide experimental evidence demonstrating sex-specific respiratory and systemic effects attributed to air pollutant inhalation exposure, and (3) postulate proposed mechanisms of stress and sex hormone interactions during air pollution-related stress.

Mechanistic insights regarding neuropsychiatric and neuropathologic impacts of air pollution

Air pollution is a significant environmental health risk for urban areas and developing countries. Air pollution may contribute to the incidence of cardiopulmonary and metabolic diseases. Evidence also points to the role of air pollution in worsening or developing neurological and neuropsychiatric conditions. Inhaled pollutants include compositionally differing mixtures of respirable gaseous and particulate components of varied sizes, solubilities, and chemistry. Inhalation of combustibles and volatile organic compounds (VOCs) or other irritant particulate matter (PM) may trigger lung sensory afferents which initiate a sympathetic stress response via activation of the hypothalamic-pituitary-adrenal (HPA) and sympathetic-adrenal-medullary (SAM) axes. Activation of SAM and HPA axes are associated with selective inhibition of hypothalamic-pituitary-gonadal (HPG) and hypothalamic-pituitary-thyroid (HPT) axes following exposure. Regarding chronic exposure in susceptible hosts, these changes may become pathological by causing neuroinflammation, neurotransmitter, and neuroendocrine imbalances. Soluble PM, such as metals and nano-size particles may translocate across the olfactory, trigeminal, or vagal nerves through retrograde axonal transport, or through systemic circulation which may disrupt the blood-brain barrier (BBB) and deposit in neural tissue. Neuronal deposition of metallic components can have a negative impact through multiple molecular mechanisms. In addition to systemic translocation, the release of pituitary and stress hormones, altered metabolic hormonal status and resultant circulating metabolic milieu, and sympathetically and HPA-mediated changes in immune markers, may secondarily impact the brain through a variety of regulatory adrenal hormone-dependent mechanisms. Several reviews covering air pollution as a risk factor for neuropsychiatric disorders have been published, but no reviews discuss the in-depth intersection between molecular and stress-related neuroendocrine mechanisms, thereby addressing adaptation and susceptibility variations and link to peripheral tissue effects. The purpose of this review is to discuss evidence regarding neurochemical, neuroendocrine, and molecular mechanisms which may contribute to neuropathology from air pollution exposure. This review also covers bi-directional neural and systemic interactions which may raise the risk for air pollution-related systemic illness.

Associations between short-term exposure to PM2.5, NO2 and O3 pollution and kidney-related conditions and the role of temperature-adjustment specification: A case-crossover study in New York state

Epidemiologic evidence on the relationship between air pollution and kidney disease remains inconclusive. We evaluated associations between short-term exposure to PM_2.5, NO₂ and O₃ and unplanned hospital visits for seven kidney-related conditions (acute kidney failure [AKF], urolithiasis, glomerular diseases [GD], renal tubulo-interstitial diseases, chronic kidney disease, dysnatremia, and volume depletion; n = 1,209,934) in New York State (2007-2016). We applied a case-crossover design with conditional logistic regression, controlling for temperature, dew point temperature, wind speed, and solar radiation. We used a three-pollutant model at lag 0-5 days of exposure as our main model. We also assessed the influence of model adjustment using different specifications of temperature by comparing seven temperature metrics (e.g., dry-bulb temperature, heat index) and five intraday temperature measures (e.g., daily mean, daily minimum, nighttime mean), according to model performance and association magnitudes between air pollutants and kidney-related conditions. In our main models, we adjusted for daytime mean outdoor wet-bulb globe temperature, which showed good model performance across all kidney-related conditions. We observed the odds ratios (ORs) for 5 μg/m³ increase in daily mean PM_2.5 to be 1.013 (95% confidence interval [CI]: 1.001, 1.025) for AKF, 1.107 (95% CI: 1.018, 1.203) for GD, and 1.027 (95% CI: 1.015, 1.038) for volume depletion; and the OR for 5 ppb increase in daily 1-hour maximum NO₂ to be 1.014 (95% CI; 1.008, 1.021) for AKF. We observed no associations with daily 8-hour maximum O₃ exposure. Association estimates varied by adjustment for different intraday temperature measures: estimates adjusted for measures with poorer model performance resulted in the greatest deviation from estimates adjusted for daytime mean, especially for AKF and volume depletion. Our findings indicate that short-term exposure to PM_2.5 and NO₂ is a risk factor for specific kidney-related conditions and underscore the need for careful adjustment of temperature in air pollution epidemiologic studies.

Sex-specific respiratory and systemic endocrine effects of acute acrolein and trichloroethylene inhalation

Acrolein and trichloroethylene (TCE) are priority hazardous air pollutants due to environmental prevalence and adverse health effects; however, neuroendocrine stress-related systemic effects are not characterized. Comparing acrolein, an airway irritant, and TCE with low irritancy, we hypothesized that airway injury would be linked to neuroendocrine-mediated systemic alterations. Male and female Wistar-Kyoto rats were exposed nose-only to air, acrolein or TCE in incremental concentrations over 30 min, followed by 3.5-hr exposure to the highest concentration (acrolein - 0.0, 0.1, 0.316, 1, 3.16 ppm; TCE - 0.0, 3.16, 10, 31.6, 100 ppm). Real-time head-out plethysmography revealed acrolein decreased minute volume and increased inspiratory-time (males>females), while TCE reduced tidal-volume. Acrolein, but not TCE, inhalation increased nasal-lavage-fluid protein, lactate-dehydrogenase activity, and inflammatory cell influx (males>females). Neither acrolein nor TCE increased bronchoalveolar-lavage-fluid injury markers, although macrophages and neutrophils increased in acrolein-exposed males and females. Systemic neuroendocrine stress response assessment indicated acrolein, but not TCE, increased circulating adrenocorticotrophic hormone, and consequently corticosterone, and caused lymphopenia, but only in males. Acrolein also reduced circulating thyroid-stimulating hormone, prolactin, and testosterone in males. In conclusion, acute acrolein inhalation resulted in sex-specific upper respiratory irritation/inflammation and systemic neuroendocrine alterations linked to hypothalamic-pituitary-adrenal axes activation, which is critical in mediating extra-respiratory effects.

Plasma sterols and vitamin D are correlates and predictors of ozone-induced inflammation in the lung: A pilot study

BACKGROUND

Ozone (O3) exposure causes respiratory effects including lung function decrements, increased lung permeability, and airway inflammation. Additionally, baseline metabolic state can predispose individuals to adverse health effects from O3. For this reason, we conducted an exploratory study to examine the effect of O3 exposure on derivatives of cholesterol biosynthesis: sterols, oxysterols, and secosteroid (25-hydroxyvitamin D) not only in the lung, but also in circulation.

METHODS

We obtained plasma and induced sputum samples from non-asthmatic (n = 12) and asthmatic (n = 12) adult volunteers 6 hours following exposure to 0.4ppm O3 for 2 hours. We quantified the concentrations of 24 cholesterol precursors and derivatives by UPLC-MS and 30 cytokines by ELISA. We use computational analyses including machine learning to determine whether baseline plasma sterols are predictive of O3 responsiveness.

RESULTS

We observed an overall decrease in the concentration of cholesterol precursors and derivatives (e.g. 27-hydroxycholesterol) and an increase in concentration of autooxidation products (e.g. secosterol-B) in sputum samples. In plasma, we saw a significant increase in the concentration of secosterol-B after O3 exposure. Machine learning algorithms showed that plasma cholesterol was a top predictor of O3 responder status based on decrease in FEV1 (>5%). Further, 25-hydroxyvitamin D was positively associated with lung function in non-asthmatic subjects and with sputum uteroglobin, whereas it was inversely associated with sputum myeloperoxidase and neutrophil counts.

CONCLUSION

This study highlights alterations in sterol metabolites in the airway and circulation as potential contributors to systemic health outcomes and predictors of pulmonary and inflammatory responsiveness following O3 exposure.

Modulation of insulin signaling pathway genes by ozone inhalation and the role of glucocorticoids: A multi-tissue analysis

Air pollution is associated with increased risk of metabolic diseases including type 2 diabetes, of which dysregulation of the insulin-signaling pathway is a feature. While studies suggest pollutant exposure alters insulin signaling in certain tissues, there is a lack of comparison across multiple tissues needed for a holistic assessment of metabolic effects, and underlying mechanisms remain unclear. Air pollution increases plasma levels of glucocorticoids, systemic regulators of metabolic function. The objectives of this study were to 1) determine effects of ozone on insulin-signaling genes in major metabolic tissues, and 2) elucidate the role of glucocorticoids. Male Fischer-344 rats were treated with metyrapone, a glucocorticoid synthesis inhibitor, and exposed to 0.8 ppm ozone or clean air for 4 h, with tissue collected immediately or 24 h post exposure. Ozone inhalation resulted in distinct mRNA profiles in the liver, brown adipose, white adipose and skeletal muscle tissues, including effects on insulin-signaling cascade genes (Pik3r1, Irs1, Irs2) and targets involved in glucose metabolism (Hk2, Pgk1, Slc2a1), cell survival (Bcl2l1), and genes associated with diabetes and obesity (Serpine1, Retn, Lep). lucocorticoid-dependent regulation was observed in the liver and brown and white adipose tissues, while effects in skeletal muscle were largely unaffected by metyrapone treatment. Gene expression changes were accompanied by altered phosphorylation states of insulin-signaling proteins (BAD, GSK, IR-β, IRS-1) in the liver. The results show that systemic effects of ozone inhalation include tissue-specific regulation of insulin-signaling pathway genes via both glucocorticoid-dependent and independent mechanisms, providing insight into mechanisms underlying adverse effects of pollutants.

Air Pollutant impacts on the brain and neuroendocrine system with implications for peripheral organs: a perspective

Air pollutants are being increasingly linked to extrapulmonary multi-organ effects. Specifically, recent studies associate air pollutants with brain disorders including psychiatric conditions, neuroinflammation and chronic diseases. Current evidence of the linkages between neuropsychiatric conditions and chronic peripheral immune and metabolic diseases provides insights on the potential role of the neuroendocrine system in mediating neural and systemic effects of inhaled pollutants (reactive particulates and gases). Autonomically-driven stress responses, involving sympathetic-adrenal-medullary and hypothalamus-pituitary-adrenal axes regulate cellular physiological processes through adrenal-derived hormones and diverse receptor systems. Recent experimental evidence demonstrates the contribution of the very stress system responding to non-chemical stressors, in mediating systemic and neural effects of reactive air pollutants. The assessment of how respiratory encounter of air pollutants induce lung and peripheral responses through brain and neuroendocrine system, and how the impairment of these stress pathways could be linked to chronic diseases will improve understanding of the causes of individual variations in susceptibility and the contribution of habituation/learning and resiliency. This review highlights effects of air pollution in the respiratory tract that impact the brain and neuroendocrine system, including the role of autonomic sensory nervous system in triggering neural stress response, the likely contribution of translocated nano particles or metal components, and biological mediators released systemically in causing effects remote to the respiratory tract. The perspective on the use of systems approaches that incorporate multiple chemical and non-chemical stressors, including environmental, physiological and psychosocial, with the assessment of interactive neural mechanisms and peripheral networks are emphasized.

Neuroendocrine stress hormones associated with short-term exposure to nitrogen dioxide and fine particulate matter in individuals with and without chronic obstructive pulmonary disease: A panel study in Beijing, China

Air pollution is a major trigger of chronic obstructive pulmonary disease (COPD). Dysregulation of the neuroendocrine hypothalamic-pituitary-adrenal (HPA) and sympathetic-adrenal medullary (SAM) axes is essential in progression of COPD. However, it is not clear whether air pollution exposure is associated with neuroendocrine responses in individuals with and without COPD. Based on a panel study of 51 stable COPD patients and 78 non-COPD participants with 384 clinical visits, we measured the morning serum levels of corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH), cortisol, norepinephrine, and epinephrine as indicators of stress hormones released from the HPA and SAM axes. Ambient nitrogen dioxide (NO₂), fine particulate matter (PM_2.5), and meteorological conditions were continuously monitored at the station from 2 weeks before the start of clinical visits. Linear mixed-effects models were used to estimate associations between differences in stress hormones following an average of 1-14-day exposures to NO₂ and PM_2.5. The average 1 day air pollutant levels prior to the clinical visits were 24.4 ± 14.0 ppb for NO₂ and 55.6 ± 41.5 μg/m³ for PM_2.5. We observed significant increases in CRH, ACTH, and norepinephrine, and decreases in cortisol and epinephrine with interquartile range increase in the average NO₂ and PM_2.5 concentrations in all participants. In the stratified analyses, we identified significant between-group difference in epinephrine following NO₂ exposure in individuals with and without COPD. These results may suggest the susceptibility of COPD patients to the neuroendocrine responses associated with short-term air pollution exposure.

Early-life environmental exposures and anaemia among children under age five in Sub-Saharan Africa: An insight from the Demographic & Health Surveys

BACKGROUND

Reports show that the majority (60%) of children under age five years in Sub-Saharan Africa are anaemic. Studies in the region have mainly focused on the effect of individual, maternal and household socioeconomic status on the prevalence of anaemia. Currently, there is limited understanding of the association between early-life environmental exposures and anaemia among children in Sub-Saharan Africa.

OBJECTIVE

The study examines the association between early-life environmental exposures and anaemia among children under five in Sub-Saharan Africa.

METHODS

The study used health and demographic data from the Demographic and Health Survey (DHS) program and environmental data from NASA's Geospatial Interactive Online Visualization ANd aNalysis Infrastructure (GIOVANNI) and Atmospheric Composition Analysis Group. Three exposure periods were defined for the study, namely: in-utero, post-utero and cumulative life exposures. Multilevel mixed-effect models were used to assess the associations between environmental exposures and anaemia in each exposure period.

RESULTS

The findings show that 63% of children in the study were anaemic. It also reveals that mean PM 2.5 exposure for in-utero (34.93 μgm^-3), post-utero (35.23 μgm^-3) and cumulative exposure (35.08 μgm^-3) were seven times higher than the new air quality guideline WHO recommended. A 10 μgm^-3 increase in in-utero, post-utero and cumulative PM 2.5 exposures was associated with 4% to 5% increase in the prevalence of anaemia among children. A 10ppbv increase in in-utero, post-utero and cumulative carbon monoxide exposures was associated with 1% increase in the prevalence of anaemia among children. The spatial risk distribution maps show that socioeconomic factors modify the spatial risk distribution pattern.

CONCLUSION

The findings of the study suggest that early-life exposure to ambient air pollution is significantly associated with anaemia among children in Sub-Saharan Africa. Thus, policies aimed at addressing air quality should be incorporated into targeted interventions for anaemia among children in the region.

Ozone exposure and blood transcriptome: A randomized, controlled, crossover trial among healthy adults

RATIONALE

Transcriptome-wide analysis is powerful in studying systemic RNA changes following environmental exposures. However, impacts of ozone inhalation on circulating transcriptome have not yet been examined.

OBJECTIVES

To explore the impact of acute ozone exposure on circulating transcriptome using RNA sequencing (RNA-seq).

METHODS

We recruited 32 healthy young adults in a randomized, crossover, controlled exposure trial. Each participant completed two 2-h exposure sessions of ozone (200 ppb) and clean air, respectively. Blood samples were collected at the end of each session and were used for RNA-seq. The differentially expressed genes associated with ozone exposure were assessed using Bayesian adjusted statistics from linear models in the limma R package.

RESULTS

A total of 29 participants finished this trial and donated their blood samples for transcriptome analysis. The average concentration of ozone was 7.8 ± 2.6 ppb under clean air and 201.1 ± 1.7 ppb under ozone exposure session. A total of 1899 genes were significantly changed (1067 up-regulated and 832 down-regulated) by ozone exposure at a false discovery rate < 0.05, in which 403 genes had a fold change of > 1.2 or < 0.8. The top 10 terms of biological processes showed that most of the differentially expressed genes were related to various functions, such as neutrophil degranulation, immune response, and neutrophil activation. Pathway enrichment analysis showed dozens of pathways were dysregulated after ozone exposure, including mitochondrial dysfunction, and glucocorticoid receptor signaling.

CONCLUSION

For the first time this trial characterized the genome-wide changes of mRNA in response to ozone exposure. We identified a range of differentially expressed genes that were involved in dozens of biological processes and pathways, providing novel biological insights into the systemic health effects of ozone.

Co-Expression Network Modeling Identifies Specific Inflammation and Neurological Disease-Related Genes mRNA Modules in Mood Disorder

Objectives: Mood disorders are a kind of serious mental illness, although their molecular factors involved in the pathophysiology remain unknown. One approach to examine the molecular basis of mood disorders is co-expression network analysis (WGCNA), which is expected to further divide the set of differentially expressed genes into subgroups (i.e., modules) in a more (biologically) meaningful way, fascinating the downstream enrichment analysis. The aim of our study was to identify hub genes in modules in mood disorders by using WGCNA.

Methods: Microarray data for expression values of 4,311,721 mRNA in peripheral blood mononuclear cells drawn from 21 MDD, 8 BD, and 24 HC individuals were obtained from GEO (GSE39653); data for genes with expression in the bottom third for 80% or more of the samples were removed. Then, the top 70% most variable genes/probs were selected for WGCNA: 27,884 probes representing 21,840 genes; correlation between module genes and mood disorder (MDD+BD vs. HC) was evaluated.

Results: About 52% of 27,765 genes were found to form 50 co-expression modules with sizes 42–3070. Among the 50 modules, the eigengenes of two modules were significantly correlated with mood disorder (p < 0.05). The saddlebrown module was found in one of the meta-modules in the network of the 50 eigengenes along with mood disorder, 6 (IER5, NFKBIZ, CITED2, TNF, SERTAD1, ADM) out of 12 differentially expressed genes identified in Savitz et al. were found in the saddlebrown module.

Conclusions: We found a significant overlap for 6 hub genes (ADM, CITED2, IER5, NFKBIZ, SERTAD1, TNF) with similar co-expression and dysregulation patterns associated with mood disorder. Overall, our findings support other reports on molecular-level immune dysfunction in mood disorder and provide novel insights into the pathophysiology of mood disorder.

Impact of ozone exposure on heart rate variability and stress hormones: A randomized-crossover study

The biological mechanisms underlying the associations between atmospheric ozone exposure and adverse cardiometabolic outcomes are yet to be identified. Imbalanced autonomic nervous system (ANS) as well as activations of the sympatho-adrenomedullary (SAM) and hypothalamic-pituitary-adrenal (HPA) axes are among possible early biological responses triggered by ozone, and may eventually lead to cardiometabolic abnormalities. To determine whether acute ozone exposure causes ANS imbalance and increases the secretion of neuroendocrine stress hormones, we conducted a randomized, double-blind, crossover trial, under controlled 2-hour exposure to either ozone (200 ppb) or clean air with intermittent exercise among 22 healthy young adults. Here we found that, compared to clean air exposure, acute ozone exposure significantly decreased the high-frequency band of heart rate variability, even after adjusting for heart rate and pre-exposure to ambient air pollutants and meteorological factors. Ozone exposure also significantly increased the serum levels of stress hormones, including corticotrophin-releasing factor, adrenocorticotropic hormone, adrenaline, and noradrenaline. Metabolomics analysis showed that acute ozone exposure led to alterations in stress hormones, systemic inflammation, oxidative stress, and energy metabolism. Our results suggest that acute ozone exposure may trigger ANS imbalance and activate the HPA and SAM axes, offering potential biological explanations for the adverse cardiometabolic effects following acute ozone exposure.

Modulation by Ozone of Glucocorticoid-Regulating Factors in the Lungs in Relation to Stress Axis Reactivity

Exposure to air pollutants increases levels of circulating glucocorticoid stress hormones that exert profound effects relevant to health and disease. However, the nature and magnitude of tissue-level effects are modulated by factors that regulate local glucocorticoid activity; accordingly, inter-individual differences could contribute to susceptibility. In the present study, we characterized effects of ozone (O₃) inhalation on glucocorticoid-regulating factors in the lungs of rat strains with contrasting hypothalamic–pituitary–adrenal stress axis responses. Hyper-responsive Fischer (F344) and less responsive Lewis (LEW) rats were exposed to air or 0.8 ppm O₃ for 4 h by nose-only inhalation. Levels of the high-specificity and -affinity corticosteroid-binding globulin protein increased in the lungs of both strains proportional to the rise in corticosterone levels following O₃ exposure. Ozone reduced the ratio of 11β-hydroxysteroid dehydrogenase type 1 (HSDB1)/HSDB2 mRNA in the lungs of F344 but not LEW, indicating strain-specific transcriptional regulation of the major glucocorticoid metabolism factors that control tissue-level action. Intercellular adhesion molecule (ICAM)-1 and total elastase activity were increased by O₃ in both strains, consistent with extravasation and tissue remodeling processes following injury. However, mRNA levels of inflammatory markers were significantly higher in the lungs of O₃-exposed LEW compared to F344. The data show that strain differences in the glucocorticoid response to O₃ are accompanied by corresponding changes in regulatory factors, and that these effects are collectively associated with a differential inflammatory response to O₃. Innate differences in glucocorticoid regulatory factors may modulate the pulmonary effects of inhaled pollutants, thereby contributing to differential susceptibility.

Homeostatic and endocrine responses as the basis for systemic therapy with medical gases: ozone, xenon and molecular hydrogen

Among medical gases, including gases used therapeutically, this review discusses the comparative physiological activity of three gases - ozone (O3), xenon (Xe) and molecular hydrogen (H2), which together form representatives of three types of substances - typical oxidizing, inert, and typical reducing agents. Upon analysis of published and proprietary data, we concluded that these three medical gases can manipulate the neuroendocrine system, by modulating the production or release of hormones via the hypothalamic-pituitary-adrenal, hypothalamic-pituitary-thyroid, hypothalamic-pituitary-gonadal axes, or the gastrointestinal pathway. With repeated administration of the gases over time, these modulations become a predictable consequence of conditioned homeostatic reflexes, resulting in regulation of physiological activity. For example, the regular activation of the unconditioned defense reflex in response to repeated intoxication by ozone leads to the formation of an anticipatory stable conditioned response, which counteracts the toxic action of O3. The concept of a Pavlovian conditioned reflex (or hormoligosis) is a brief metaphor for the understanding the therapeutic effect of systemic ozone therapy.

Does ozone inhalation cause adverse metabolic effects in humans? A systematic review

We utilized a practical, transparent approach for systematically reviewing a chemical-specific evidence base. This approach was used for a case study of ozone inhalation exposure and adverse metabolic effects (overweight/obesity, Type 1 diabetes [T1D], Type 2 diabetes [T2D], and metabolic syndrome). We followed the basic principles of systematic review. Studies were defined as "Suitable" or "Supplemental." The evidence for Suitable studies was characterized as strong or weak. An overall causality judgment for each outcome was then determined as either causal, suggestive, insufficient, or not likely. Fifteen epidemiologic and 33 toxicologic studies were Suitable for evidence synthesis. The strength of the human evidence was weak for all outcomes. The toxicologic evidence was weak for all outcomes except two: body weight, and impaired glucose tolerance/homeostasis and fasting/baseline hyperglycemia. The combined epidemiologic and toxicologic evidence was categorized as weak for overweight/obesity, T1D, and metabolic syndrome,. The association between ozone exposure and T2D was determined to be insufficient or suggestive. The streamlined approach described in this paper is transparent and focuses on key elements. As systematic review guidelines are becoming increasingly complex, it is worth exploring the extent to which related health outcomes should be combined or kept distinct, and the merits of focusing on critical elements to select studies suitable for causal inference. We recommend that systematic review results be used to target discussions around specific research needs for advancing causal determinations.

Ozone-dependent increases in lung glucocorticoids and macrophage response: Effect modification by innate stress axis function

Although considerable inter-individual variability exists in health effects associated with air pollutant exposure, underlying reasons remain unclear. We examined whether innate differences in stress axis function modify lung glucocorticoid and macrophage responses to ozone (O3). Highly-stress responsive Fischer (F344) and less responsive Lewis (LEW) rats were exposed for 4 h by nose-only inhalation to air or O3 (0.8 ppm). Ozone increased corticosterone recovered by bronchoalveolar lavage in both strains (F344 > LEW). Higher corticosterone in F344 was associated with a blunted response to O3 of macrophage pro-inflammatory genes compared to LEW. Pharmacological inhibition of O3-dependent corticosterone production in F344 enhanced the inflammatory gene response to O3, mimicking the LEW phenotype. Examination of potential impacts of glucocorticoids on macrophage function using a human monocyte-derived macrophage cell line (THP-1) showed that cortisol modified phagocytosis in a macrophage phenotype-dependent manner. Overall, our data implicate endogenous glucocorticoids in the regulation of pulmonary macrophage responses to O3.

Air Pollution Neurotoxicity in the Adult Brain: Emerging Concepts from Experimental Findings

Epidemiological studies are associating elevated exposure to air pollution with increased risk of Alzheimer's disease and other neurodegenerative disorders. In effect, air pollution accelerates many aging conditions that promote cognitive declines of aging. The underlying mechanisms and scale of effects remain largely unknown due to its chemical and physical complexity. Moreover, individual responses to air pollution are shaped by an intricate interface of pollutant mixture with the biological features of the exposed individual such as age, sex, genetic background, underlying diseases, and nutrition, but also other environmental factors including exposure to cigarette smoke. Resolving this complex manifold requires more detailed environmental and lifestyle data on diverse populations, and a systematic experimental approach. Our review aims to summarize the modest existing literature on experimental studies on air pollution neurotoxicity for adult rodents and identify key gaps and emerging challenges as we go forward. It is timely for experimental biologists to critically understand prior findings and develop innovative approaches to this urgent global problem. We hope to increase recognition of the importance of air pollution on brain aging by our colleagues in the neurosciences and in biomedical gerontology, and to support the immediate translation of the findings into public health guidelines for the regulation of remedial environmental factors that accelerate aging processes.

Ambient air pollutants are associated with morning serum cortisol in overweight and obese Latino youth in Los Angeles

BACKGROUND

Hypothalamic-pituitary-adrenal (HPA)-axis dysfunction has been associated with a variety of mental health and cardio-metabolic disorders. While causal models of HPA-axis dysregulation have been largely focused on either pre-existing health conditions or psychosocial stress factors, recent evidence suggests a possible role for central nervous system activation via air pollutants, such as nitrogen dioxide (NO2), ozone (O3) and particulate matter (PM). Therefore, in an observational study of Latino youth, we investigated if monthly ambient NO2, O3, and PM with aerodynamic diameter ≤ 2.5 (PM2.5) exposure were associated with morning serum cortisol levels.

METHODS

In this cross-sectional study, morning serum cortisol level was assessed after a supervised overnight fast in 203 overweight and obese Latino children and adolescents (female/male: 88/115; mean age: 11.1 ± 1.7 years; pre-pubertal/pubertal/post-pubertal: 85/101/17; BMI z-score: 2.1 ± 0.4). Cumulative concentrations of NO2, O3 and PM2.5 were spatially interpolated at the residential addresses based on measurements from community monitors up to 12 months prior to testing. Single and multi-pollutant linear effects models were used to test the cumulative monthly lag effects of NO2, O3, and PM2.5 on morning serum cortisol levels after adjusting for age, sex, seasonality, social position, pubertal status, and body fat percent by DEXA.

RESULTS

Single and multi-pollutant models showed that higher O3 exposure (derived from maximum 8-h exposure windows) in the prior 1-7 months was associated with higher serum morning cortisol (p < 0.05) and longer term PM2.5 exposure (4-10 months) was associated with lower serum morning cortisol levels (p < 0.05). Stratification by pubertal status showed associations in pre-pubertal children compared to pubertal and post-pubertal children. Single, but not multi-pollutant, models showed that higher NO2 over the 4-10 month exposure period associated with lower morning serum cortisol (p < 0.05).

CONCLUSIONS

Chronic ambient NO2, O3 and PM2.5 differentially associate with HPA-axis dysfunction, a mechanism that may serve as an explanatory pathway in the relationship between ambient air pollution and metabolic health of youth living in polluted urban environments. Further research that uncovers how ambient air pollutants may differentially contribute to HPA-axis dysfunction are warranted.

Subchronic exposure to concentrated ambient PM2.5 perturbs gut and lung microbiota as well as metabolic profiles in mice

Exposure to ambient fine particular matter (PM2.5) are linked to an increased risk of metabolic disorders, leading to enhanced rate of many diseases, such as inflammatory bowel disease (IBD), cardiovascular diseases, and pulmonary diseases; nevertheless, the underlying mechanisms remain poorly understood. In this study, BALB/c mice were exposed to filtered air (FA) or concentrated ambient PM2.5 (CPM) for 2 months using a versatile aerosol concentration enrichment system(VACES). We found subchronic CPM exposure caused significant lung and intestinal damage, as well as systemic inflammatory reactions. In addition, serum and BALFs (bronchoalveolar lavage fluids) metabolites involved in many metabolic pathways in the CPM exposed mice were markedly disrupted upon PM2.5 exposure. Five metabolites (glutamate, glutamine, formate, pyruvate and lactate) with excellent discriminatory power (AUC = 1, p < 0.001) were identified to predict PM2.5 exposure related toxicities. Furthermore, subchronic exposure to CPM not only significantly decreased the richness and composition of the gut microbiota, but also the lung microbiota. Strong associations were found between several gut and lung bacterial flora changes and systemic metabolic abnormalities. Our study showed exposure to ambient PM2.5 not only caused dysbiosis in the gut and lung, but also significant systemic and local metabolic alterations. Alterations in gut and lung microbiota were strongly correlated with metabolic abnormalities. Our study suggests potential roles of gut and lung microbiota in PM2.5 caused metabolic disorders.

Self-rated stress, distress, mental health, and health as modifiers of the association between long-term exposure to ambient pollutants and mortality

BACKGROUND

Individual and neighbourhood-scale socioeconomic characteristics modify associations between exposure to air pollution and mortality. The role of stress, which may integrate effects of social and environmental exposures on health, is unknown. We examined whether an individual's perspective on their own well-being, as assessed using self-rated measures of stress and health, modifies the pollutant-mortality relationship.

METHODS

The Canadian Community Health Survey (CCHS)-mortality cohort includes respondents from surveys administered between 2001 and 2012 linked to vital statistics and postal codes from 1981 until 2016. Annual fine particulate matter (PM_2.5), nitrogen dioxide (NO₂), and ozone (O₃) exposure estimates were attached to a sample of cohort members aged 30-89 years (n = 398,300 respondents/3,848,400 person-years). We examined whether self-rated stress, distress, mental health, and general health modified associations between long-term exposure to each pollutant (three-year moving average with one-year lag) and non-accidental mortality using Cox survival models, adjusted for individual- (i.e. socioeconomic and behavioural) and neighbourhood-scale covariates.

RESULTS

In fully-adjusted models, the relationship between exposure to pollutants and mortality was stronger among those with poor self-rated mental health, including a significant difference for NO₂ (hazard ratio (HR) = 1.15, 95% CI 1.06-1.25 per IQR) compared to those with very good/excellent mental health (HR = 1.05, 95% CI 1.01-1.08; Cochran's Q = 4.01; p < 0.05). Poor self-rated health was similarly associated with higher pollutant-associated HRs, but only in unadjusted models. Stress and distress did not modify pollutant-mortality associations.

CONCLUSIONS

Poor self-rated mental and general health were associated with increased mortality attributed to exposure to ambient pollutants.

Air Pollution, Stress, and Allostatic Load: Linking Systemic and Central Nervous System Impacts

 Air pollution is a risk factor for cardiovascular and respiratory morbidity and mortality. A growing literature also links exposure to diverse air pollutants (e.g., nanoparticles, particulate matter, ozone, traffic-related air pollution) with brain health, including increased incidence of neurological and psychiatric disorders such as cognitive decline, dementia (including Alzheimer’s disease), anxiety, depression, and suicide. A critical gap in our understanding of adverse impacts of pollutants on the central nervous system (CNS) is the early initiating events triggered by pollutant inhalation that contribute to disease progression. Recent experimental evidence has shown that particulate matter and ozone, two common pollutants with differing characteristics and reactivity, can activate the hypothalamic-pituitary-adrenal (HPA) axis and release glucocorticoid stress hormones (cortisol in humans, corticosterone in rodents) as part of a neuroendocrine stress response. The brain is highly sensitive to stress: stress hormones affect cognition and mental health, and chronic stress can produce profound biochemical and structural changes in the brain. Chronic activation and/or dysfunction of the HPA axis also increases the burden on physiological stress response systems, conceptualized as allostatic load, and is a common pathway implicated in many diseases. The present paper provides an overview of how systemic stress-dependent biological responses common to particulate matter and ozone may provide insight into early CNS effects of pollutants, including links with oxidative, inflammatory, and metabolic processes. Evidence of pollutant effect modification by non-chemical stressors (e.g., socioeconomic position, psychosocial, noise), age (prenatal to elderly), and sex will also be reviewed in the context of susceptibility across the lifespan.

Ozone increases plasma kynurenine-tryptophan ratio and impacts hippocampal serotonin receptor and neurotrophic factor expression: Role of stress hormones

Air pollution is associated with adverse impacts on the brain, including cognitive decline and increased incidence of dementia, depression and anxiety; however, underlying mechanisms remain unclear. We have shown that both ozone and particulate matter activate the hypothalamic-pituitary-adrenal (HPA) axis, increasing plasma glucocorticoids and altering mRNA profiles in multiple tissues including the brain. HPA axis dysregulation has been associated with central nervous system impacts, including key effects in the hippocampus; accordingly, we hypothesized that pollutant-dependent increases in glucocorticoid levels impact biological pathways relevant to brain health. Fischer-344 rats were treated with metyrapone (0 or 50 mg/kg), a glucocorticoid synthesis inhibitor, and exposed to ozone (0 or 0.8 ppm) for 4 h (n = 5/group) to investigate the role of glucocorticoids in ozone-dependent effects on tryptophan metabolism and expression of serotonin receptors and neurotrophic factors. Ozone increased plasma levels of the tryptophan metabolite kynurenine (~2-fold) and decreased tryptophan levels (~1.2 fold). Hippocampal expression of serotonin receptors exhibited differential regulation following exposure, and expression of key neurotrophic factors (brain-derived neurotrophic factor, vascular endothelial growth factor A, insulin-like growth factor-1, tyrosine kinase receptor B, b-cell lymphoma 2) was decreased. Some, but not all effects were abrogated by metyrapone treatment, suggesting both glucocorticoid-dependent and -independent regulation. Exposure to exogenous corticosterone (10 mg/kg) followed by clean air reproduced the ozone effects that were blocked with metyrapone, confirming the specificity of effects to glucocorticoids. These results indicate that ozone can modify pathways relevant to brain health and establish a role for the HPA axis in mediating these effects.

Prenatal air pollution exposure and growth and cardio-metabolic risk in preschoolers

OBJECTIVES

We investigated the association between outdoor air pollutants exposure in the first trimester of pregnancy, and growth and cardio-metabolic risk at four years of age, and evaluated the mediating role of birth weight.

METHODS

We included mother-child pairs (N = 1,724) from the Spanish INMA birth cohort established in 2003-2008. First trimester of pregnancy nitrogen dioxide (NO₂) and fine particles (PM_2.5) exposure levels were estimated. Height, weight, waist circumference, blood pressure, and lipids were measured at four years of age. Body mass index (BMI) trajectories from birth to four years were identified.

RESULTS

Increased PM_2.5 exposure in the first trimester of pregnancy was associated with decreased z-scores of weight (zWeight) and BMI (zBMI) (zWeight change per interquartile range increase in PM_2.5 exposure = -0.12; 95% CI: -0.23, -0.01; zBMI change = -0.12; 95% CI: -0.23, -0.01). Higher NO₂ and PM_2.5 exposure was associated to a reduced risk of being in a trajectory with accelerated BMI gain, compared to children with the average trajectory. Birth weight partially mediated the association between PM_2.5 and zWeight and zBMI. PM_2.5 and NO₂ were not associated with the other cardio-metabolic risk factors.

CONCLUSIONS

This comprehensive study of many growth and cardio-metabolic risk related outcomes suggests that air pollution exposure during pregnancy may be associated with delays in physical growth in the early years after birth. These findings imply that pregnancy exposure to air pollutants has a lasting effect on growth after birth and require follow-up at later child ages.

Maternal exposure to air pollution during pregnancy and cortisol level in cord blood

Exposure to air pollution has been associated with disorders of the endocrine system and hypothalamic-pituitary-adrenal (HPA) axis; however, the available evidence on these associations is still scarce. This study aimed to investigate, for the first time, the association of exposure to PM₁, PM_2.5, and PM₁₀, as well as traffic indicators (distance to major roads and total street length in different buffers around maternal residential address) during pregnancy with cortisol level in cord blood samples. This cross-sectional study was carried out based on 150 mother-newborn pairs in Sabzevar, Iran (2018). Land use regression models were applied to estimate air pollution exposure during the entire pregnancy at maternal residential addresses. Multiple linear regression models were applied to estimate the association of exposure to air pollution during pregnancy and cord blood cortisol levels, controlled for relevant covariates. There was a significant positive association between exposure to PM_2.5 and PM₁₀ and cortisol levels in cord blood (β = 2.55, 95% confidence intervals (CI) = 0.57, 4.52, P-value = 0.01, and β = 3.09, 95% CI: 1.28, 4.90, P-value < 0.01, respectively). Moreover, there was a significant positive association between total street length in a 100 m buffer around maternal residence and cortisol level. Each one interquartile range (IQR) increase in distance from home to major roads was associated with a -2.58 (95% CI: -4.85, -0.30, P-value = 0.03) decrease in cord blood cortisol level. The median (IQR) of the cord blood cortisol levels for the first and fourth quartiles of distance to major roads were 50.7 (19.5) and 38.2 (20.4) ng/mL, respectively. The associations for total street length in 300 m and 500 m buffers and PM₁ exposure were not statistically significant. Our findings suggest a direct association of exposure to air pollution during pregnancy and cortisol levels at cord blood.

Investigating potential associations between O3 exposure and lipid profiles: A longitudinal study of older adults in Beijing

BACKGROUND

Little information exists on the lipidemic effects of ozone exposure. Few studies have focused on the different patterns of the association among older adults population, and little attention has been given to comprehensive lipid indices when evaluating the effect of O3 exposure on the metabolism.

METHODS

We conducted a longitudinal study involving 201 older adults in Beijing, China between 2016 and 2018. A mixed regression model was applied with random effects to investigate the relationship between O3 and lipid profiles.

RESULTS

O3 exposure positively correlated with TC, LDL-C, CRI-I, CRI-II and AC at short-term and medium-term exposure periods. The largest increases in TC, LDL-C, CRI-I and CRI-II were found in the 28-days moving average indicating accumulative effects over prolonged exposure period. A 10 μg/m³ increase of O3 at the 28-days moving average was associated with a significant increase of 3.9% (95% CI: 1.0, 6.9) in TC, 8.2% (95% CI: 4.2, 12.4) in LDL-C, 4.8% (95% CI: 1.1, 8.5) in CRI-I and 7.0% (95% CI: 2.7, 11.5) in CRI-II. Stratification by health status and characteristics revealed different patterns of lipid changes among older adults, lipid status, age, sex and BMI may modify the relationship between O3 exposure and lipid profiles.

CONCLUSIONS

Our findings suggest that short-term and medium-term O3 exposure is associated with lipid profiles abnormalities among the older adults. Evidence also suggests there are patterns within population which differ according to both health status and demographic characteristics.

Susceptibility Variations in Air Pollution Health Effects: Incorporating Neuroendocrine Activation

Diverse host factors/phenotypes may exacerbate or diminish biological responses induced by air pollutant exposure. We lack an understanding of biological indicators of environmental exposures that culminate in a physiological response versus those that lead to adversity. Variations in response phenotype might arise centrally and/or at the local tissue level. In addition to genetic differences, the current evidence supports the roles of preexisting cardiopulmonary diseases, diabetes, diet, adverse prenatal environments, neurobehavioral disorders, childhood infections, microbiome, sex, and psychosocial stressors in modifying the susceptibility to air pollutant exposures. Animal models of human diseases, obesity, nutritional inadequacies, and neurobehavioral conditions have been compared with healthy controls to understand the causes of variations in susceptibility. Although psychosocial stressors have been associated with increased susceptibility to air pollutant effects, the contribution of neuroendocrine stress pathways in mediating these effects is just emerging. The new findings of neuroendocrine activation leading to systemic metabolic and immunological effects of air pollutants, and the potential contribution to allostatic load, emphasize the consideration of these mechanisms into susceptibility. Variations in susceptibility to air pollution health effects are likely to underlie host genetic and physiological conditions in concert with disrupted neuroendocrine circuitry that alters physiological stability under the influence of stressors.

Beta-2 Adrenergic and Glucocorticoid Receptor Agonists Modulate Ozone-Induced Pulmonary Protein Leakage and Inflammation in Healthy and Adrenalectomized Rats

We have shown that acute ozone inhalation activates sympathetic-adrenal-medullary and hypothalamus-pituitary-adrenal stress axes, and adrenalectomy (AD) inhibits ozone-induced lung injury and inflammation. Therefore, we hypothesized that stress hormone receptor agonists (β2 adrenergic-β2AR and glucocorticoid-GR) will restore the ozone injury phenotype in AD, while exacerbating effects in sham-surgery (SH) rats. Male Wistar Kyoto rats that underwent SH or AD were treated with vehicles (saline + corn oil) or β2AR agonist clenbuterol (CLEN, 0.2 mg/kg, i.p.) + GR agonist dexamethasone (DEX, 2 mg/kg, s.c.) for 1 day and immediately prior to each day of exposure to filtered air or ozone (0.8 ppm, 4 h/day for 1 or 2 days). Ozone-induced increases in PenH and peak-expiratory flow were exacerbated in CLEN+DEX-treated SH and AD rats. CLEN+DEX affected breath waveform in all rats. Ozone exposure in vehicle-treated SH rats increased bronchoalveolar lavage fluid (BALF) protein, N-acetyl glucosaminidase activity (macrophage activation), neutrophils, and lung cytokine expression while reducing circulating lymphocyte subpopulations. AD reduced these ozone effects in vehicle-treated rats. At the doses used herein, CLEN+DEX treatment reversed the protection offered by AD and exacerbated most ozone-induced lung effects while diminishing circulating lymphocytes. CLEN+DEX in air-exposed SH rats also induced marked protein leakage and reduced circulating lymphocytes but did not increase BALF neutrophils. In conclusion, circulating stress hormones and their receptors mediate ozone-induced vascular leakage and inflammatory cell trafficking to the lung. Those receiving β2AR and GR agonists for chronic pulmonary diseases, or with increased circulating stress hormones due to psychosocial stresses, might have altered sensitivity to air pollution.

Stress hormones as potential mediators of air pollutant effects on the brain: Rapid induction of glucocorticoid-responsive genes

Air pollution is associated with adverse effects on brain health including cognitive decline, dementia, anxiety, depression, and suicide. While toxicological studies have demonstrated the potential for repeated or chronic pollutant exposure to lead to disease states, characterisation of initial biological responses to exposure is needed to better understand underlying mechanisms. The brain is highly sensitive to glucocorticoids (primarily cortisol in humans, corticosterone in rodents), stress hormones that play important roles in cognition and mental health. We tested whether glucocorticoids could be implicated in central nervous system (CNS) effects of pollutant exposure by examining glucocorticoid-dependent signaling across brain regions after exposure to the common pollutant ozone. Male Fischer-344 rats were exposed for 4 h to air or 0.8 ppm ozone ± metyrapone (50 mg/kg), a drug that blocks corticosterone synthesis (n = 5/group). Key glucocorticoid-responsive genes (serum- and glucocorticoid-inducible kinase, SGK; glucocorticoid-inducible leucine zipper, GILZ), and a gene responsive to both glucocorticoids and oxidative stress (metallothionein (MT)-1), were increased by ozone in all brain regions (olfactory bulb, frontal lobe, cortex, midbrain, hippocampus, cerebellum, brainstem), correlating with plasma corticosterone levels. Metyrapone prevented the increase in SGK and GILZ, and reduced but did not eliminate the effect on MT-1, suggesting glucocorticoid-dependent and -independent regulation. Administering exogenous corticosterone (10 mg/kg) to air-exposed rats reproduced the ozone effects, confirming specificity. The results demonstrate that early pollutant effects include stress hormone-dependent signaling. As both ozone and particulate matter activate the hypothalamic-pituitary-adrenal axis, and elevated glucocorticoids are implicated in brain pathologies, stress hormones could contribute to CNS impacts of air pollutants.

Transcriptional Effects of Ozone and Impact on Airway Inflammation

Epidemiological and challenge studies in healthy subjects and in individuals with asthma highlight the health impact of environmental ozone even at levels considered safe. Acute ozone exposure in man results in sputum neutrophilia in 30% of subjects particularly young children, females, and those with ongoing cardiopulmonary disease. This may be associated with systemic inflammation although not in all cases. Chronic exposure amplifies these effects and can result in the formation of asthma-like symptoms and immunopathology. Asthmatic patients who respond to ozone (responders) induce a greater number of genes in bronchoalveolar (BAL) macrophages than healthy responders with up-regulation of inflammatory and immune pathways under the control of cytokines and chemokines and the enhanced expression of remodeling and repair programmes including those associated with protease imbalances and cell-cell adhesion. These pathways are under the control of several key transcription regulatory factors including nuclear factor (NF)-κB, anti-oxidant factors such as nuclear factor (erythroid-derived 2)-like 2 NRF2, the p38 mitogen activated protein kinase (MAPK), and priming of the immune system by up-regulating toll-like receptor (TLR) expression. Murine and cellular models of acute and chronic ozone exposure recapitulate the inflammatory effects seen in humans and enable the elucidation of key transcriptional pathways. These studies emphasize the importance of distinct transcriptional networks in driving the detrimental effects of ozone. Studies indicate the critical role of mediators including IL-1, IL-17, and IL-33 in driving ozone effects on airway inflammation, remodeling and hyperresponsiveness. Transcription analysis and proof of mechanisms studies will enable the development of drugs to ameliorate the effects of ozone exposure in susceptible individuals.

Neuroendocrine Regulation of Air Pollution Health Effects: Emerging Insights

Air pollutant exposures are linked to cardiopulmonary diseases, diabetes, metabolic syndrome, neurobehavioral conditions, and reproductive abnormalities. Significant effort is invested in understanding how pollutants encountered by the lung might induce effects in distant organs. The role of circulating mediators has been predicted; however, their origin and identity have not been confirmed. New evidence has emerged which implicates the role of neuroendocrine sympathetic-adrenal-medullary (SAM) and hypothalamic-pituitary-adrenal (HPA) stress axes in mediating a wide array of systemic and pulmonary effects. Our recent studies using ozone exposure as a prototypical air pollutant demonstrate that increases in circulating adrenal-derived stress hormones (epinephrine and cortisol/corticosterone) contribute to lung injury/inflammation and metabolic effects in the liver, pancreas, adipose, and muscle tissues. When stress hormones are depleted by adrenalectomy in rats, most ozone effects including lung injury/inflammation are diminished. Animals treated with antagonists for adrenergic and glucocorticoid receptors show inhibition of the pulmonary and systemic effects of ozone, whereas treatment with agonists restore and exacerbate the ozone-induced injury/inflammation phenotype, implying the role of neuroendocrine activation. The neuroendocrine system is critical for normal homeostasis and allostatic activation; however, chronic exposure to stressors may lead to increases in allostatic load. The emerging mechanisms by which circulating mediators are released and are responsible for producing multiorgan effects of air pollutants insists upon a paradigm shift in the field of air pollution and health. Moreover, since these neuroendocrine responses are linked to both chemical and nonchemical stressors, the interactive influence of air pollutants, lifestyle, and environmental factors requires further study.

Inflammatory Effects of Subacute Exposure of Roundup in Rat Liver and Adipose Tissue

Roundup is a popular herbicide containing glyphosate as an active ingredient. The formulation of Roundup is speculated to have critical toxic effects, one among which is chronic inflammation. The present study analyzed adverse inflammatory effects in the liver and adipose tissue of rats after a subacute exposure of Roundup. Adult male rats were exposed to various doses of Roundup (0, 5, 10, 25, 50, 100 and 250 mg/kg bodyweight [bw] glyphosate) orally, everyday for 14 days. On day 15, liver and adipose tissues from dosed rats were analyzed for inflammation markers. C-reactive protein in liver, cytokines IL-1β, TNF-α, IL-6, and inflammatory response marker, and prostaglandin–endoperoxide synthase were upregulated in liver and adipose of rats exposed to higher (100 and 250 mg/kg bw/d) doses of Roundup. Cumulatively, our data suggest development of inflammation in lipid and hepatic organs upon exposure to Roundup. Furthermore, liver histological studies showed formation of vacuoles, fibroid tissue, and glycogen depletion in the groups treated with doses of higher Roundup. These observations suggest progression of fatty liver disease in Roundup-treated adult rats. In summary, our data suggest progression of multiorgan inflammation, liver scarring, and dysfunction post short-term exposure of Roundup in adult male rats.

Aging Exacerbates Neuroinflammatory Outcomes Induced by Acute Ozone Exposure

The role of environmental stressors, particularly exposure to air pollution, in the development of neurodegenerative disease remains underappreciated. We examined the neurological effects of acute ozone (O3) exposure in aged mice, where increased blood-brain barrier (BBB) permeability may confer vulnerability to neuroinflammatory outcomes. C57BL/6 male mice, aged 8-10 weeks or 12-18 months were exposed to either filtered air or 1.0 ppm O3 for 4 h; animals received a single IP injection of sodium fluorescein (FSCN) 20 h postexposure. One-hour post-FSCN injection, animals were transcardially perfused for immunohistochemical analysis of BBB permeability. β-amyloid protein expression was assessed via ELISA. Flow cytometric characterization of infiltrating immune cells, including neutrophils, macrophages, and microglia populations was performed 20 h post-O3 exposure. Flow cytometry analysis of brains revealed increased microglia "activation" and presentation of CD11b, F4/80, and MHCII in aged animals relative to younger ones; these age-induced differences were potentiated by acute O3 exposure. Cortical and limbic regions in aged brains had increased reactive microgliosis and β-amyloid protein expression after O3 insult. The aged cerebellum was particularly vulnerable to acute O3 exposure with increased populations of infiltrating neutrophils, peripheral macrophages/monocytes, and Ly6C+ inflammatory monocytes after insult, which were not significantly increased in the young cerebellum. O3 exposure increased the penetration of FSCN beyond the BBB, the infiltration of peripheral immune cells, and reactive gliosis of microglia. Thus, the aged BBB is vulnerable to insult and becomes highly penetrable in response to O3 exposure, leading to greater neuroinflammatory outcomes.

Stress axis variability is associated with differential ozone-induced lung inflammatory signaling and injury biomarker response

Ozone (O₃), a ubiquitous urban air pollutant, causes adverse pulmonary and extrapulmonary effects. A large variability in acute O₃-induced effects has been observed; however, the basis for interindividual differences in susceptibility is unclear. We previously demonstrated a role for the hypothalamic-pituitary-adrenal (HPA) stress axis and glucocorticoid response in acute O₃ toxicity. Glucocorticoids have important anti-inflammatory actions, and have been shown to regulate lung inflammatory responses. We hypothesised that a hyporesponsive HPA axis would be associated with greater O₃-dependent lung inflammatory signaling. Two genetically-related rat strains with known differences in stress axis reactivity, highly-stress responsive Fischer (F344) and less responsive Lewis (LEW), were exposed for 4 h by nose-only inhalation to clean air or 0.8 ppm O₃, and euthanized immediately after exposure. As expected, baseline (air-exposed) plasma corticosterone was significantly lower in the hypo-stress responsive LEW. Although O₃ exposure increased plasma corticosterone in both strains, corticosterone remained significantly lower in LEW when compared to F334. LEW exhibited greater O₃-induced inflammatory cytokine/chemokine signaling compared to F344, consistent with the lower corticosterone levels. Since we observed strain-specific differences in inflammatory signaling, we further investigated injury biomarkers (total protein, albumin and lactate dehydrogenase). Although the hyper-responsive F344 exhibited lower inflammatory signaling in response to O₃ compared with LEW, they had greater levels of lung injury biomarkers. Our results indicate that stress axis variability is associated with differential O₃-induced lung toxicity. Given the large variability in stress axis reactivity among humans, stress axis regulation could potentially be a determining factor underlying O₃ sensitivity.

Air pollution and resistance to inhaled glucocorticoids: Evidence, mechanisms and gaps to fill

Substantial evidence indicates that cigarette smoke exposure induces resistance to glucocorticoids, the primary maintenance medication in asthma treatment. Modest evidence also suggests that air pollution may reduce the effectiveness of these critical medications. Cigarette smoke, which has clear parallels with air pollution, has been shown to induce glucocorticoid resistance in asthma and it has been speculated that air pollution may have similar effects. However, the literature on an association of air pollution with glucocorticoid resistance is modest to date. In this review, we detail the evidence for, and against, the effects of air pollution on glucocorticoid effectiveness, focusing on results from epidemiology and controlled human exposure studies. Epidemiological studies indicate a correlation between increased air pollution exposure and worse asthma symptoms. But these studies also show a mix of beneficial and harmful effects of glucocorticoids on spirometry and asthma symptoms, perhaps due to confounding influences, or the induction of glucocorticoid resistance. We describe mechanisms that may contribute to reductions in glucocorticoid responsiveness following air pollution exposure, including changes to phosphorylation or oxidation of the glucocorticoid receptor, repression by cytokines, or inflammatory pathways, and epigenetic effects. Possible interactions between air pollution and respiratory infections are also briefly discussed. Finally, we detail a number of therapies that may boost glucocorticoid effectiveness or reverse resistance in the presence of air pollution, and comment on the beneficial effects of engineering controls, such as air filtration and asthma action plans. We also call attention to the benefits of improved clean air policy on asthma. This review highlights numerous gaps in our knowledge of the interactions between air pollution and glucocorticoids to encourage further research in this area with a view to reducing the harm caused to those with airways disease.

Ambient air pollution exposure and emergency department visits for substance abuse

There is growing evidence supporting the notion that exposure to air pollution can contribute to cognitive and psychiatric disorders, including depression and suicide. Given the relationship between exposure to acute stressors and substance abuse, the present study assessed the association between exposure to ambient air pollution and emergency department (ED) visits for alcohol and drug abuse. ED visit data selected according to International Classification of Disease (ICD-9) coding 303 (alcohol dependence syndromes) and 305 (non-dependent abuse of drugs) were collected in five hospitals in Edmonton, Canada. A time-stratified case crossover design was used. Conditional logistic regression was applied to calculate odds ratios (OR) and 95% confidence intervals (95% CI). Season, temperature, and relative humidity were adjusted for using natural splines.

Results are reported for an increase in pollutant concentrations equivalent to one interquartile range (IQR). Statistically significant positive associations with substance abuse were observed for CO, NO₂ and particulate matter with an aerodynamic diameter less than 10 μm (PM₁₀) and 2.5 μm (PM_2.5). The strongest results were obtained in the cold period (October–March) for 1-day lagged CO (OR = 1.03, 95% CI: 1.01, 1.05, IQR = 0.4 ppm) and NO₂ (OR = 1.04, 95% CI: 1.01, 1.07, IQR = 12.8 ppb); ORs were also significant for CO and NO₂ with lags of 2 to 6 days and 2 to 7 days, respectively. The study suggests that, even at low levels, increases in ambient CO, NO₂, and PMs are associated with increased hospital admissions for substance abuse, possibly as a result of impacts of air quality on mental health or depression.

Environmental pollution and kidney diseases

The burden of disease and death attributable to environmental pollution is becoming a public health challenge worldwide, especially in developing countries. The kidney is vulnerable to environmental pollutants because most environmental toxins are concentrated by the kidney during filtration. Given the high mortality and morbidity of kidney disease, environmental risk factors and their effect on kidney disease need to be identified. In this Review, we highlight epidemiological evidence for the association between kidney disease and environmental pollutants, including air pollution, heavy metal pollution and other environmental risk factors. We discuss the potential biological mechanisms that link exposure to environmental pollutants to kidney damage and emphasize the contribution of environmental pollution to kidney disease. Regulatory efforts should be made to control environmental pollution and limit individual exposure to preventable or avoidable environmental risk. Population studies with accurate quantification of environmental exposure in polluted regions, particularly in developing countries, might aid our understanding of the dose-response relationship between pollutants and kidney diseases.

Association between PM10, PM2.5, NO2, O3 and self-reported diabetes in Italy: A cross-sectional, ecological study

INTRODUCTION

Air pollution represents a serious threat to health on a global scale, being responsible for a large portion of the global burden of disease from environmental factors. Current evidence about the association between air pollution exposure and Diabetes Mellitus (DM) is still controversial. We aimed to evaluate the association between area-level ambient air pollution and self-reported DM in a large population sample in Italy.

MATERIALS AND METHODS

We extracted information about self-reported and physician diagnosed DM, risk factors and socio-economic status from 12 surveys conducted nationwide between 1999 and 2013. We obtained annual averaged air pollution levels for the years 2003, 2005, 2007 and 2010 from the AMS-MINNI national integrated model, which simulates the dispersion and transformation of pollutants. The original maps, with a resolution of 4 x 4 km2, were normalized and aggregated at the municipality class of each Italian region, in order to match the survey data. We fit logistic regression models with a hierarchical structure to estimate the relationship between PM10, PM2.5, NO2 and O3 four-years mean levels and the risk of being affected by DM.

RESULTS

We included 376,157 individuals aged more than 45 years. There were 39,969 cases of DM, with an average regional prevalence of 9.8% and a positive geographical North-to-South gradient, opposite to that of pollutants' concentrations. For each 10 μg/m3 increase, the resulting ORs were 1.04 (95% CI 1.01-1.07) for PM10, 1.04 (95% CI 1.02-1.07) for PM2.5, 1.03 (95% CI 1.01-1.05) for NO2 and 1.06 (95% CI 1.01-1.11) for O3, after accounting for relevant individual risk factors. The associations were robust to adjustment for other pollutants in two-pollutant models tested (ozone plus each other pollutant).

CONCLUSIONS

We observed a significant positive association between each examined pollutant and prevalent DM. Risk estimates were consistent with current evidence, and robust to sensitivity analysis. Our study adds evidence about the effects of air pollution on diabetes and suggests a possible role of ozone as an independent factor associated with the development of DM. Such relationship is of great interest for public health and deserves further investigation.

The correlations between air pollution and depression

Introduction: In the 21st century there is an increased prevalence of depression in the world. So far the mechanism of developing depression has not been exactly known. Risk factors of depression occurrence are complex and nowadays it has been emphasized that air pollution can affect the intensity of depressive symptoms.

Objective: The analysis of the scientific works investigating the correlations between air pollution and depression.

Material and method: The material consisted of the studies published between 2007 and 2017. A systematic review of Medline database (using PubMed search engine) was conducted by typing the English phrase (air pollution) and (depression), and 154 results were obtained. Those results which concerned nicotine addiction or dementia diseases were rejected. The inclusion criterion was the number of people tested, n>500 in case of adults, and n>200 in case of children (a small number of publications). All in all, 9 research in the population of adults and 1 research in the group of children were included to the final analysis. In the discussion part of this work some research carried out on animals and related to the subject matter of own analyses were also investigated.

Results: As many as 8 out of 10 analyzed research demonstrated statistically significant correlation between long-term exposure to air pollution (mainly to fine particulate matter, PM) and depression. This correlation mainly concerned intensification of depressive symptoms during long exposure to air pollution. The exposure also resulted in changes in the neuro-transfer of serotonin and as well in neurodegenerative changes in children exposed to long-term pollution with polycyclic aromatic hydrocarbons (PAH) in prenatal life. Testing on animals indicates that air pollution affects the activation of proinflammatory processes in hippocampus, what may incidentally contribute to the formation of depressive and cognitive symptoms.

Conclusions: In view of the increase of depression incidence and constantly sustained air pollution in the world, there is a need for further research on the correlation between air pollution and depression, taking into account the genetic, social and psychological factors.

Does air pollution trigger suicide? A case-crossover analysis of suicide deaths over the life span

In addition to underlying health disorders and socio-economic or community factors, air pollution may trigger suicide mortality. This study evaluates the association between short-term variation in air pollution and 10 years of suicide mortality in Belgium. In a bidirectional time-stratified case-crossover design, 20,533 suicide deaths registered between January 1st 2002 and December 31st 2011 were matched by temperature with control days from the same month and year. We used municipality-level air pollution [particulate matter (PM₁₀) and O₃ concentrations] data and meteorology data. We applied conditional logistic regression models adjusted for duration of sunshine and day of the week to obtain odds ratios (OR) and their 95% CI for an increase of 10 µg/m³ in pollutant concentrations over different lag periods (lag 0, 0-1, 0-2, 0-3, 0-4, 0-5, and 0-6 days). Effect modification by season and age was investigated by including interaction terms. We observed significant associations of PM₁₀ and O₃ with suicide during summer (OR ranging from 1.02 to 1.07, p-values <0.05). For O₃, significant associations were also observed during spring and autumn. Age significantly modified the associations with PM₁₀, with statistically significant associations observed only among 5-14 year old children (lag 0-6: OR = 1.45; 95% CI: 1.03-2.04) and ≥85 years old (e.g. lag 0-4: OR = 1.17; 95% CI: 1.06-1.29). Recent increases in outdoor air pollutants such as PM₁₀ or O₃ can trigger suicide, particularly during warm periods, even at concentrations below the European thresholds. Furthermore, PM₁₀ may have strong trigger effects among children and elderly population.

Adrenal-derived stress hormones modulate ozone-induced lung injury and inflammation

Ozone-induced systemic effects are modulated through activation of the neuro-hormonal stress response pathway. Adrenal demedullation (DEMED) or bilateral total adrenalectomy (ADREX) inhibits systemic and pulmonary effects of acute ozone exposure. To understand the influence of adrenal-derived stress hormones in mediating ozone-induced lung injury/inflammation, we assessed global gene expression (mRNA sequencing) and selected proteins in lung tissues from male Wistar-Kyoto rats that underwent DEMED, ADREX, or sham surgery (SHAM) prior to their exposure to air or ozone (1ppm), 4h/day for 1 or 2days. Ozone exposure significantly changed the expression of over 2300 genes in lungs of SHAM rats, and these changes were markedly reduced in DEMED and ADREX rats. SHAM surgery but not DEMED or ADREX resulted in activation of multiple ozone-responsive pathways, including glucocorticoid, acute phase response, NRF2, and PI3K-AKT. Predicted targets from sequencing data showed a similarity between transcriptional changes induced by ozone and adrenergic and steroidal modulation of effects in SHAM but not ADREX rats. Ozone-induced increases in lung Il6 in SHAM rats coincided with neutrophilic inflammation, but were diminished in DEMED and ADREX rats. Although ozone exposure in SHAM rats did not significantly alter mRNA expression of Ifnγ and Il-4, the IL-4 protein and ratio of IL-4 to IFNγ (IL-4/IFNγ) proteins increased suggesting a tendency for a Th2 response. This did not occur in ADREX and DEMED rats. We demonstrate that ozone-induced lung injury and neutrophilic inflammation require the presence of circulating epinephrine and corticosterone, which transcriptionally regulates signaling mechanisms involved in this response.

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.

Influence of exposure to coarse, fine and ultrafine urban particulate matter and their biological constituents on neural biomarkers in a randomized controlled crossover study

BACKGROUND

Epidemiological studies have reported associations between air pollution and neuro-psychological conditions. Biological mechanisms behind these findings are still not clear.

OBJECTIVES

We examined changes in blood and urinary neural biomarkers following exposure to concentrated ambient coarse, fine and ultrafine particles.

METHODS

Fifty healthy non-smoking volunteers, mean age 28years, were exposed to coarse (2.5-10μm, mean 213μg/m³) and fine (0.15-2.5μm, mean 238μg/m³) concentrated ambient particles (CAPs), and filtered ambient and/or medical air. Twenty-five participants were exposed to ultrafine CAP (mean size 59.6nm, range 47.0-69.8nm), mean (136μg/m³) and filtered medical air. Exposures lasted 130min, separated by ≥2weeks, and the biological constituents endotoxin and β-1,3-d-glucan of each particle size fraction were measured. Blood and urine samples were collected pre-exposure, and 1-hour and 21-hour post-exposure to determine neural biomarker levels. Mixed-model regressions assessed associations between exposures and changes in biomarker levels.

RESULTS

Results were expressed as percent change from daily pre-exposure biomarker levels. Exposure to coarse CAP was significantly associated with increased urinary levels of the stress-related biomarkers vanillylmandelic acid (VMA) and cortisol when compared with exposure to filtered medical air [20% (95% confidence interval: 1.0%, 38%) and 64% (0.2%, 127%), respectively] 21hours post-exposure. However exposure to coarse CAP was significantly associated with decreases in blood cortisol [-26.0% (-42.4%, -9.6%) and -22.4% (-43.7%, -1.1%) at 1h and 21h post-exposure, respectively]. Biological molecules present in coarse CAP were significantly associated with blood biomarkers indicative of blood brain barrier integrity. Endotoxin content was significantly associated with increased blood ubiquitin C-terminal hydrolase L1 [UCHL1, 11% (5.3%, 16%) per ln(ng/m³+1)] 1-hour post-exposure, while β-1,3-d-glucan was significantly associated with increased blood S100B [6.3% (3.2%, 9.4%) per ln(ng/m³+1)], as well as UCHL1 [3.1% (0.4%, 5.9%) per ln(ng/m³+1)], one-hour post-exposure. Fine CAP was marginally associated with increased blood UCHL1 when compared with exposure to filtered medical air [17.7% (-1.7%, 37.2%), p=0.07] 21hours post-exposure. Ultrafine CAP was not significantly associated with changes in any blood and urinary neural biomarkers examined.

CONCLUSION

Ambient coarse particulate matter and its biological constituents may influence neural biomarker levels that reflect perturbations of blood-brain barrier integrity and systemic stress response.

Endocrine Aspects of Environmental "Obesogen" Pollutants

Growing evidence suggests the causal link between the endocrine-disrupting chemicals (EDCs) and the global obesity epidemics, in the context in the so-called “obesogenic environment”. Dietary intake of contaminated foods and water, especially in association with unhealthy eating pattern, and inhalation of airborne pollutants represent the major sources of human exposure to EDCs. This is of particular concern in view of the potential impact of obesity on chronic non-transmissible diseases, such as type 2 diabetes, cardiovascular disease, and hormone-sensitive cancers. The key concept is the identification of adipose tissue not only as a preferential site of storage of EDCs, but also as an endocrine organ and, as such, susceptible to endocrine disruption. The timing of exposure to EDCs is critical to the outcome of that exposure, with early lifetime exposures (e.g., fetal or early postnatal) particularly detrimental because of their permanent effects on obesity later in life. Despite that the mechanisms operating in EDCs effects might vary enormously, this minireview is aimed to provide a general overview on the possible association between the pandemics of obesity and EDCs, briefly describing the endocrine mechanisms linking EDCs exposure and latent onset of obesity.

Air Pollution and Emergency Department Visits for Depression: A Multicity Case-Crossover Study

BACKGROUND

The aim of this study was to investigate the associations between ambient air pollution and emergency department (ED) visits for depression.

METHODS

Health data were retrieved from the National Ambulatory Care Reporting System. ED visits for depression were retrieved from the National Ambulatory Care Reporting System using the International Classification of Diseases (ICD-10), Tenth revision codes; ICD-10: F32 (mild depressive episode) and ICD-10: F33 (recurrent depressive disorder). A case-crossover design was employed for this study. Conditional logistic regression models were used to estimate odds ratios.

RESULTS

For females, exposure to ozone was associated with increased risk of an ED visit for depression between 1 and 7 days after exposure, for males, between 1 and 5, and 8 days after exposure, with odds ratios ranging between 1.02 and 1.03.

CONCLUSIONS

These findings suggest that, as hypothesized, there is a positive association between exposure to air pollution and ED visits for depression.