An acute exposure to ozone impairs human olfactory functioning

Photodissociation-driven photoacoustic spectroscopy with UV-LEDs for ozone detection

This study presents the development and evaluation of a UV-LED based photoacoustic (PA) measurement system for ozone (O3) detection to demonstrate its potential for low-cost and accurate sensing while for the first time addressing the importance of photodissociation for PA signal generation for O3 in the UV range. With a detection limit of 7.9 ppbV, the system exhibits a significant advancement over state-of-the-art UV-PA O3 detection and is on par with laser-based setups. Following a novel discussion of the PA signal arising from photodissociation and its products, cross-sensitivity effects due to environmental factors such as temperature and gas composition were systematically analyzed. A digital twin driven compensation for these influences was implemented and evaluated. Despite the challenges associated with modeling the effects of H2O and CO2, the PA system shows considerable potential, though further studies in real world applications must be conducted.

Olfactory bulb microglia activation mediates neuronal pyroptosis in ozone-exposed mice with olfactory and cognitive dysfunction

In recent years, there has been a notable increase in the concentration of air pollutants in the troposphere, especially ozone. However, limited research has gone beyond examining histopathological alterations in the olfactory bulb (OB) to explore the effects of ozone exposure on olfactory and cognitive functions. In our study, we exposed nine-month-old C57BL/6 mice to ozone at a concentration of 1.0 ppm for 13 weeks to examine the effects of ozone on the OB. The results indicated that ozone exposure induces olfactory and cognitive impairments in the mice. Subsequently, microglia in the OB are activated, leading to neuroinflammation. Ozone-induced downregulation of PSD95 and Synaptophysin, which was accompanied by a decrease in dendritic length and spine density. Simultaneously, increasing in the co-labeling of C1q, Iba1, and PSD95 after ozone exposure indicated that C1q-mediated synaptic phagocytosis by microglia might play a role in synaptic damage. Furthermore, the co-labeling of GSDMD-N and NEUN results suggests that ozone exposure triggers pyroptosis in neurons. Additionally, minocycline administration can alleviate ozone-induced olfactory and cognitive impairments by suppressing microglial activation. This study illustrates that prolonged ozone exposure leads to microglial activation in the OB, causing synaptic damage, neuronal pyroptosis, and subsequent deficits in olfactory and cognitive functions.

Tropospheric ozone effect on olfactory perception and olfactory bulb dopaminergic interneuron excitability

Ozone (O3) forms in the Earth's atmosphere, both naturally and by reactions of man-made air pollutants. Deleterious effects of O3 have been found in the respiratory system. Here, we examine whether O3 alters olfactory behavior and cellular properties in the olfactory system. For this purpose, mice were exposed to O3 at a concentration found in highly polluted city air [0.8 ppm], and the behavior elicited by social and non-social odors in habituation/dishabituation tests was assessed. In addition, the electrical responses of dopaminergic olfactory bulb (OB) neurons were also evaluated. O3 differentially compromises olfactory perception to odors: it reduces responses to social and non-social odors in Swiss Webster mice, while this effect was observed in C57BL/6 J mice only for some non-social odors. Additionally, O3 reduced the rate of spontaneous spike firing in periglomerular dopaminergic cells (PG-DA) of the OB. Because this effect could reflect changes in excitability and/or synaptic inputs, the ability of O3 to alter PG-DA spontaneous activity was also tested together with cell membrane resistance, membrane potential, rheobase and chronaxie. Taken together, our data suggest the ability of O3 to affect olfactory perception.

Influence of Mild Chronic Stress and Social Isolation on Acute Ozone-Induced Alterations in Stress Biomarkers and Brain-Region-Specific Gene Expression in Male Wistar-Kyoto Rats

Individuals with psychosocial stress often experience an exaggerated response to air pollutants. Ozone (O3) exposure has been associated with the activation of the neuroendocrine stress-response system. We hypothesized that preexistent mild chronic stress plus social isolation (CS), or social isolation (SI) alone, would exacerbate the acute effects of O3 exposure on the circulating adrenal-derived stress hormones, and the expression of the genes regulating glucocorticoid stress signaling via an altered stress adaptation in a brain-region-specific manner. Male Wistar-Kyoto rats (5 weeks old) were socially isolated, plus were subjected to either CS (noise, confinement, fear, uncomfortable living, hectic activity, and single housing), SI (single housing only, restricted handling and no enrichment) or no stress (NS; double housing, frequent handling and enrichment provided) for 8 weeks. The rats were then exposed to either air or O3 (0.8 ppm for 4 h), and the samples were collected immediately after. The indicators of sympathetic and hypothalamic-pituitary axis (HPA) activation (i.e., epinephrine, corticosterone, and lymphopenia) increased with O3 exposure, but there were no effects from CS or SI, except for the depletion of serum BDNF. CS and SI revealed small changes in brain-region-specific glucocorticoid-signaling-associated markers of gene expression in the air-exposed rats (hypothalamic Nr3c1, Nr3c2 Hsp90aa1, Hspa4 and Cnr1 inhibition in SI; hippocampal HSP90aa1 increase in SI; and inhibition of the bed nucleus of the stria terminalis (BNST) Cnr1 in CS). Gene expression across all brain regions was altered by O3, reflective of glucocorticoid signaling effects, such as Fkbp5 in NS, CS and SI. The SI effects on Fkbp5 were greatest for SI in BNST. O3 increased Cnr2 expression in the hypothalamus and olfactory bulbs of the NS and SI groups. O3, in all stress conditions, generally inhibited the expression of Nr3c1 in all brain regions, Nr3c2 in the hippocampus and hypothalamus and Bdnf in the hippocampus. SI, in general, showed slightly greater O3-induced changes when compared to NS and CS. Serum metabolomics revealed increased sphingomyelins in the air-exposed SI and O3-exposed NS, with underlying SI dampening some of the O3-induced changes. These results suggest a potential link between preexistent SI and acute O3-induced increases in the circulating adrenal-derived stress hormones and brain-region-specific gene expression changes in glucocorticoid signaling, which may partly underlie the stress dynamic in those with long-term SI.

Ozone-induced neurotoxicity: In vitro and in vivo evidence

Together with cities in higher-income nations, it is anticipated that the real global ozone is rising in densely populated areas of Asia and Africa. This review aims to discuss the possible neurotoxic pollutants and ozone-induced neurotoxicity: in vitro and in vivo, along with possible biomarkers to assess ozone-related oxidative stress. As a methodical and scientific strategy for hazard identification and risk characterization of human chemical exposures, toxicological risk assessment is increasingly being implemented. While traditional methods are followed by in vitro toxicology, cell culture techniques are being investigated in modern toxicology. In both human and rodent models, aging makes the olfactory circuitry vulnerable to spreading immunological responses from the periphery to the brain because it lacks the blood-brain barrier. The ozone toxicity is elusive as it shows ventral and dorsal root injury cases even in the milder dose. Its potential toxicity should be disclosed to understand further the clear mechanism insights of how it acts in cellular aspects. Human epidemiological research has confirmed the conclusions that prenatal and postnatal exposure to high levels of air pollution are linked to behavioral alterations in offspring. O3 also enhances blood circulation. It has antibacterial action, which may have an impact on the gut microbiota. It also activates immunological, anti-inflammatory, proteasome, and growth factor signaling Prolonged O3 exposure causes oxidative damage to plasma proteins and lipids and damages the structural and functional integrity of the mitochondria. Finally, various studies need to be conducted to identify the potential biomarkers associated with ozone and the brain.

The impact of subchronic ozone exposure on serum metabolome and the mechanisms of abnormal bile acid and arachidonic acid metabolisms in the liver

Ambient ozone (O₃) pollution can induce respiratory and cardiovascular toxicity. However, its impact on the metabolome and the underlying mechanisms remain unclear. This study first investigated the serum metabolite changes in rats exposed to 0.5 ppm O₃ for 3 months using untargeted metabolomic approach. Results showed chronic ozone exposure significantly altered the serum levels of 34 metabolites with potential increased risk of digestive, respiratory and cardiovascular disease. Moreover, bile acid synthesis and secretion, and arachidonic acid (AA) metabolism became the most prominent affected metabolic pathways after O₃ exposure. Further studies on the mechanisms found that the elevated serum toxic bile acid was not due to the increased biosynthesis in the liver, but the reduced reuptake from the portal vein to hepatocytes owing to repressed Ntcp and Oatp1a1, and the decreased bile acid efflux in hepatocytes as a results of inhibited Bsep, Ostalpha and Ostbeta. Meanwhile, decreased expressions of detoxification enzyme of SULT2A1 and the important regulators of FXR, PXR and HNF4α also contributed to the abnormal bile acids. In addition, O₃ promoted the conversion of AA into thromboxane A2 (TXA2) and 20-hydroxyarachidonic acid (20-HETE) in the liver by up-regulation of Fads2, Cyp4a and Tbxas1 which resulting in decreased AA and linoleic acid (LA), and increased thromboxane B2 (TXB2) and 20-HETE in the serum. Furthermore, apparent hepatic chronic inflammation, fibrosis and abnormal function were found in ozone-exposed rats. These results indicated chronic ozone exposure could alter serum metabolites by interfering their metabolism in the liver, and inducing liver injury to aggravate metabolic disorders.

Association between outdoor air pollution and chronic rhinosinusitis patient reported outcomes

BACKGROUND

The aetiology of chronic rhinosinusitis (CRS) is multifactorial with a complex interplay between environmental, microbial endogenous and genetic factors. The impact of outdoor air pollution on prevalence or severity of CRS remains largely unknown.

METHODS

Real-life geolocation data (2017-2018, Belgium) from 278 CRS patients (2576 health records) using the mySinusitisCoach mobile application were analysed to calculate the patients' individual exposure to outdoor air pollutants (ozone (O₃), black carbon (BC), nitrogen dioxide (NO₂) and particulate matter with diameter < 2.5 μm (PM_2.5)) and to associate these pollutants with the patients' sinus related symptoms measured at multiple occasions by visual analogue scale (VAS).

RESULTS

The adjusted seasonal model for the spring-summer (n = 1000 health entries, N = 83 patients) population revealed an increase of 6.07 (p < 0.0001) in overall CRS symptom scoring for an interquartile range (IQR) increase in exposure to O₃ (26.9 μg/m³). An increase of 1.69 (p = 0.05) in total CRS symptom scoring was observed for an IQR increase of PM_2.5 (7.1 µg/m³) exposure. Sex-stratified analysis in the spring-summer population showed significant interaction between air pollution and sex with male patients having higher total CRS symptom scores for an IQR increase in exposure to PM_2.5 (3.52, p = 0.001), and O₃ (8.33, p < 0.0001), while no significant association with symptom severity was seen in the female patients. In the analysis stratified by comorbid asthma, CRS patients with comorbid asthma had higher total CRS symptoms for an IQR increase in exposure to PM_2.5 (2.58, p = 0.04) and O₃ (7.72, p < 0.0001) while the patients without comorbid asthma had no significant symptom increases.

CONCLUSION

Exposure to outdoor air pollution is associated with increased symptom severity in CRS patients. The extent to which CRS patients are sensitive to outdoor air pollution exposure varies per season and depends on their sex and comorbid asthma status. mHealth technology has the potential to reveal novel insights on the patients' exposome and disease severity in the real-life situation.

Perspectives of ozone induced neuropathology and memory decline in Alzheimer's disease: A systematic review of preclinical evidences

This systematic review aims to discover the plausible mechanism of Ozone in A.D., to boost translational research. The main focus of our review lies in understanding the effects of ozone pollution on the human brain and causing degenerative disease. Owing to the number of works carried out as preclinical evidence in association with oxidative stress and Alzheimer's disease and the lack of systematic review or meta-analysis prompted us to initiate a study on Alzheimer's risk due to ground-level ozone. We found relevant studies from PubMed, ScienceDirect, Proquest, DOAJ, and Scopus, narrowing to animal studies and the English language without any time limit. The searches will be re-run before the final analysis. This work was registered in Prospero with Reg ID CRD42022319360, followed the PRISMA-P framework, and followed the PICO approach involving Population, Intervention/Exposure, Comparison, and Outcomes data. Bibliographic details of 16 included studies were studied for Exposure dose of ozone, duration, exposure, and frequency with control and exposure groups. Primary and secondary outcomes were assessed based on pathology significance, and results were significant in inducing Alzheimer-like pathology by ozone. In conclusion, ozone altered oxidative stress, metabolic pathway, and amyloid plaque accumulation besides endothelial stress response involving mitochondria as the critical factor in ATP degeneration, caspase pathway, and neuronal damage. Thus, ozone is a criteria pollutant to be focused on in mitigating Alzheimer's Disease pathology.

Efficient mineralization of gaseous benzyl chloride by VUV/UV photodegradation in humid air

VUV/UV photodegradation technology, which is free of catalysts or oxidants, has been regarded as an efficient method to decompose gaseous VOCs. However, the mineralization of gaseous VOCs by VUV/UV photodegradation has seldom been discussed systematically. In this work, the mineralization of benzyl chloride in humid air is comprehensively investigated and the potential contributors in the system (i.e., light wavelength, O₂ and H₂O) are discussed. As a result, more than 95.0% benzyl chloride is mineralized at 40 min in humid air with 80% relative humidity (RH) despite its initial concentrations (i.e., ranging from 4 to 20 ppm). It is found that both 185-nm VUV light and H₂O significant contribute to the efficient mineralization of benzyl chloride in humid air, while O₂ only has a limited effect to the efficient mineralization of benzyl chloride in humid air. The introduction of H₂O into the VUV/UV photodegradation can reduce the emission of ozone obviously. These findings are significant inspiration to application of the VUV/UV photodegradation technology on the treatment of gaseous VOCs in the actual air atmosphere.

Efficacy of Chlorine Dioxide Gas Against Hepatitis A Virus on Blueberries, Blackberries, Raspberries, and Strawberries

Seeking a means of sanitizing berries, the effectiveness of steady state levels of gaseous chlorine dioxide (ClO₂) against hepatitis A virus (HAV) on laboratory-contaminated berries was determined. The generated ClO₂ was maintained with 1 or 2 mg/l air inside a 269-l glove box to treat 50 g batches of blueberries, raspberries, and blackberries, and 100 g batches of strawberries that were immersion coated with HAV. Normalized data for ClO₂ (ppm-h/g product) is reported as a function of ClO₂ concentration, treatment time, and weight of treated product. Treatments of ClO₂ ranging from 1.00 to 6.27 ppm-h/g berry were evaluated. When compared to untreated HAV-contaminated berries, log reductions of HAV were > 2.1 for all berry types and conditions tested indicating the gaseous ClO₂ was effective. The average log reduction with strawberries, raspberries, blueberries and blackberries treated with 1.00 ppm-h/g, the lowest ClO₂ treatment tested, were 2.44, 2.49, 3.23, and 3.45, respectively. The highest treatment of 6.27 ppm-h/g was applied at two different gas concentrations of 1 mg/l and 2 mg/l. Average log reductions for blueberries and strawberries treated with 6.27 ppm-h/g were 4.34 and 4.42, and 4.03 and 3.51, applied at 1 mg/l and 2 mg/l, respectively. For blackberries and raspberries 3.20 and 3.24, and 3.23 and 3.97 log reductions were observed for 6.27 ppm-h/g treatments applied at 1 mg/l and 2 mg/l, respectively. Results indicate that HAV contamination of berries can be substantially reduced by gaseous ClO₂ and offer industry a waterless means of sanitizing berries against HAV.

Circadian Deregulation as Possible New Player in Pollution-Induced Tissue Damage

Circadian rhythms are 24-h oscillations driven by a hypothalamic master oscillator that entrains peripheral clocks in almost all cells, tissues and organs. Circadian misalignment, triggered by industrialization and modern lifestyles, has been linked to several pathological conditions, with possible impairment of the quality or even the very existence of life. Living organisms are continuously exposed to air pollutants, and among them, ozone or particulate matters (PMs) are considered to be among the most toxic to human health. In particular, exposure to environmental stressors may result not only in pulmonary and cardiovascular diseases, but, as it has been demonstrated in the last two decades, the skin can also be affected by pollution. In this context, we hypothesize that chronodistruption can exacerbate cell vulnerability to exogenous damaging agents, and we suggest a possible common mechanism of action in deregulation of the homeostasis of the pulmonary, cardiovascular and cutaneous tissues and in its involvement in the development of pathological conditions.