Ozone, NO, and NO2: oxidant air pollutants and more

Advancing nitrate reduction to ammonia: insights into mechanism, activity control, and catalyst design over Pt nanoparticle-based ZrO2

The reduction of nitrogen oxides (NOx) to NH3, or N2 represents a crucial step in mitigating atmospheric NO3 and NO2 emissions, a significant contributor to air pollution. Among these reduction products, ammonia (NH3) holds particular significance due to its utility in nitrogen-based fertilizers and its versatile applications in various industrial processes. Platinum-based catalysts have exhibited promise in enhancing the rate and selectivity of these reduction reactions. In this study, we employ density functional theory (DFT) calculations to explore the catalytic potential of Pt nanoparticle (PtNP)-supported ZrO2 for the conversion of NO3 to NH3. The most favorable pathway for the NO3 reduction to NH3 follows a sequence, that is, NO3 → NO2 → NO → ONH → ONH2/HNOH → NH2/NH → NH2 → NH3, culminating in the production of valuable ammonia. The introduction of low-state Fe and Co dopants into the ZrO2 support reduces energy barriers for the most challenging rate-determining hydrogenation step in NOx reduction to NH3, demonstrating significant improvements in catalytic activity. The incorporation of dopants into the ZrO2 support results in a depletion of electron density within the Pt cocatalyst resulting in enhanced hydrogen transfer efficiency during the hydrogenation process. This study aims to provide insights into the catalytic activity of platinum-based ZrO2 catalysts and will help design new high-performance catalysts for the reduction of atmospheric pollutants and for energy applications.

Exposure to Air Pollution and Survival in Follow-Up after Hepatocellular Carcinoma

INTRODUCTION

Air pollutants are classified as carcinogens by the International Agency for Research on Cancer. Long-term exposure to ambient particulate matter with an aerodiameter of 2.5 μm or lower (PM_2.5) has been reported to be linked with increased mortality due to hepatocellular carcinoma (HCC). However, the effects of air pollutants other than PM_2.5 on HCC-related mortality have not been fully investigated. Accordingly, we conducted this study to assess the effect of long-term exposure to air pollutants (PM_2.5 and nitrogen dioxide [NO₂]) on HCC-related mortality.

METHOD

In 2005, the Taiwan Liver Cancer Network (TLCN) was established by the National Research Program for Genomic Medicine to recruit liver cancer patients from 5 major medical centers in northern, central, and southern Taiwan. The TLCN had successfully recruited 9,344 patients by the end of 2018. In this study, we included 1,000 patients randomly sampled from the TLCN to assess the effect of exposure to air pollutants on HCC mortality after HCC diagnosis. Daily averages of PM_2.5 and NO₂ concentrations were retrieved from 77 air quality-monitoring stations and interpolated to the townships of patients' residences by using the Kriging method. The effect of air pollutants on HCC survival was assessed using a Cox proportional hazards model.

RESULTS

A total of 940 patients were included in the analysis. After adjusting for potential confounders and mutually adjusting for co-pollutants, we observed that the hazards ratio (95% confidence interval) for HCC-related mortality for every 1-μg/m³ increase in PM_2.5 concentration was 1.11 (1.08-1.14) and that for every 1-ppb increase in NO₂ concentration was 1.08 (1.03-1.13).

CONCLUSION

Our study suggests that long-term exposure to PM_2.5 and NO₂ was associated with decreased survival time in patients with HCC in Taiwan.

Reduced ectoparasite load, body mass and blood haemolysis in Eurasian kestrels (Falco tinnunculus) along an urban-rural gradient

Urbanisation is proceeding at an alarming rate which forces wildlife to either retreat from urban areas or cope with novel stressors linked to human presence and activities. For example, urban stressors like anthropogenic noise, artificial light at night and chemical pollution can have severe impacts on the physiology of wildlife (and humans), in particular the immune system and antioxidant defences. These physiological systems are important to combat and reduce the severity of parasitic infections, which are common among wild animals. One question that then arises is whether urban-dwelling animals, whose immune and antioxidant system are already challenged by the urban stressors, are more susceptible to parasitic infections. To assess this, we studied nestlings of Eurasian kestrels (Falco tinnunculus) in Vienna, Austria, during 2015 and 2017. We measured biomarkers of innate immune function, oxidative stress and body mass index and ectoparasite infection intensity in 143 nestlings (from 56 nests) along an urban gradient. Nestlings in more urbanised areas had overall fewer ectoparasites, lower haemolysis (complement activity) and lower body mass index compared to nestlings in less urbanised areas. None of the other immune or oxidative stress markers were associated with the urban gradient. Despite some non-significant results, our data still suggest that kestrel nestlings experience some level of reduced physiological health, perhaps as a consequence of exposure to more urban stressors or altered prey availability in inner-city districts even though they had an overall lower ectoparasite burden in these heavily urbanised areas.

Predicting Lung Cancer in the United States: A Multiple Model Examination of Public Health Factors

In this research, we take a multivariate, multi-method approach to predicting the incidence of lung cancer in the United States. We obtain public health and ambient emission data from multiple sources in 2000–2013 to model lung cancer in the period 2013–2017. We compare several models using four sources of predictor variables: adult smoking, state, environmental quality index, and ambient emissions. The environmental quality index variables pertain to macro-level domains: air, land, water, socio-demographic, and built environment. The ambient emissions consist of Cyanide compounds, Carbon Monoxide, Carbon Disulfide, Diesel Exhaust, Nitrogen Dioxide, Tropospheric Ozone, Coarse Particulate Matter, Fine Particulate Matter, and Sulfur Dioxide. We compare various models and find that the best regression model has variance explained of 62 percent whereas the best machine learning model has 64 percent variance explained with 10% less error. The most hazardous ambient emissions are Coarse Particulate Matter, Fine Particulate Matter, Sulfur Dioxide, Carbon Monoxide, and Tropospheric Ozone. These ambient emissions could be curtailed to improve air quality, thus reducing the incidence of lung cancer. We interpret and discuss the implications of the model results, including the tradeoff between transparency and accuracy. We also review limitations of and directions for the current models in order to extend and refine them.

Interactions of GST Polymorphisms in Air Pollution Exposure and Respiratory Diseases and Allergies

PURPOSE OF REVIEW

The purpose of this review is to summarize the evidence from recently published original studies investigating how glutathione S-transferase (GST) gene polymorphisms modify the impact of air pollution on asthma, allergic diseases, and lung function.

RECENT FINDINGS

Current studies in epidemiological and controlled human experiments found evidence to suggest that GSTs modify the impact of air pollution exposure on respiratory diseases and allergies. Of the nine articles included in this review, all except one identified at least one significant interaction with at least one of glutathione S-transferase pi 1 (GSTP1), glutathione S-transferase mu 1 (GSTM1), or glutathione S-transferase theta 1 (GSTT1) genes and air pollution exposure. The findings of these studies, however, are markedly different. This difference can be partially explained by regional variation in the exposure levels and oxidative potential of different pollutants and by other interactions involving a number of unaccounted environment exposures and multiple genes. Although there is evidence of an interaction between GST genes and air pollution exposure for the risk of respiratory disease and allergies, results are not concordant. Further investigations are needed to explore the reasons behind the discordancy.

Transcriptome analysis of a wild bird reveals physiological responses to the urban environment

Identifying the molecular basis of environmentally induced phenotypic variation presents exciting opportunities for furthering our understanding of how ecological processes and the environment can shape the phenotype. Urban and rural environments present free-living organisms with different challenges and opportunities, which have marked consequences for the phenotype, yet little is known about responses at the molecular level. We characterised transcriptomes from an urban and a rural population of great tits Parus major, demonstrating striking differences in gene expression profiles in both blood and liver tissues. Differentially expressed genes had functions related to immune and inflammatory responses, detoxification, protection against oxidative stress, lipid metabolism, and regulation of gene expression. Many genes linked to stress responses were expressed at higher levels in the urban birds, in accordance with our prediction that urban animals are exposed to greater environmental stress. This is one of the first studies to reveal transcriptional differences between urban- and rural-dwelling animals and suggests an important role for epigenetics in mediating environmentally induced physiological variation. The study provides valuable resources for developing further in-depth studies of the mechanisms driving phenotypic variation in the urban context at larger spatial and temporal scales.

Nitrogen dioxide pollution exposure is associated with olfactory dysfunction in older U.S. adults

BACKGROUND

Olfactory dysfunction has profound effects on quality of life, physical and social function, and mortality itself. Nitrogen dioxide (NO2 ) is a pervasive air pollutant that is associated with respiratory diseases. Given the olfactory nerve's anatomic exposure to airborne pollutants, we investigated the relationship between NO2 exposure and olfactory dysfunction.

METHODS

The ability to identify odors was evaluated using a validated test in respondents from the National Social Life, Health, and Aging Project (NSHAP), a representative probability sample of home-dwelling, older U.S. adults age 57 to 85 years. Exposure to NO2 pollution was assessed using measurements obtained from the U.S. Environmental Protection Agency (EPA) Aerometric Information Retrieval System (AIRS) ambient monitoring site closest to each respondent's home. We tested the association between NO2 exposure and olfactory dysfunction using multivariate logistic regression.

RESULTS

Among older adults in the United States, 22.6% had impaired olfactory function, defined as ≤3 correct (out of 5) on the odor identification test. Median NO2 exposure during the 365 days prior to the interview date was 14.7 ppb (interquartile range [IQR], 10.8 to 19.7 ppb). An IQR increase in NO2 exposure was associated with increased odds of olfactory dysfunction (OR, 1.35; 95% CI, 1.07 to 1.72), adjusting for age, gender, race/ethnicity, education, cognition, comorbidity, smoking, and season of the home interview (n = 1823).

CONCLUSION

We show for the first time that NO2 exposure is associated with olfactory dysfunction in older U.S. adults. These results suggest an important role for NO2 exposure on olfactory dysfunction, and, potentially, nasal disease more broadly.

The protective role of antioxidants in the defence against ROS/RNS-mediated environmental pollution

Overproduction of reactive oxygen and nitrogen species can result from exposure to environmental pollutants, such as ionising and nonionising radiation, ultraviolet radiation, elevated concentrations of ozone, nitrogen oxides, sulphur dioxide, cigarette smoke, asbestos, particulate matter, pesticides, dioxins and furans, polycyclic aromatic hydrocarbons, and many other compounds present in the environment. It appears that increased oxidative/nitrosative stress is often neglected mechanism by which environmental pollutants affect human health. Oxidation of and oxidative damage to cellular components and biomolecules have been suggested to be involved in the aetiology of several chronic diseases, including cancer, cardiovascular disease, cataracts, age-related macular degeneration, and aging. Several studies have demonstrated that the human body can alleviate oxidative stress using exogenous antioxidants. However, not all dietary antioxidant supplements display protective effects, for example, β-carotene for lung cancer prevention in smokers or tocopherols for photooxidative stress. In this review, we explore the increases in oxidative stress caused by exposure to environmental pollutants and the protective effects of antioxidants.

Role of nitric oxide and its metabolites as potential markers in lung cancer

Nitric oxide (NO) and reactive oxygen species (ROS) play important physiologic roles as mediators of signaling processes. However, high concentrations of NO and ROS result in damage to cellular and extracellular components. Excessive production of endogenous and/or exogenous ROS and NO is implicated in the pathogenesis of lung cancer. NO and its metabolites interact with ROS to generate potent nitrating agents leading to protein nitration, which is one of the several chemical modifications that occur during oxidative/nitrosative stress. Although there is considerable evidence in support of a role for NO in protein modifications and carcinogenesis, recent data suggest that NO has antagonistic cellular effects, leading to either promotion or inhibition of tumor growth. However, the role of NO in tumor biology is still poorly understood. This review demonstrates the role of NO and its metabolites as potential markers in lung cancer.

Nrf2 signaling and cell survival

Nrf2:INrf2 acts as a sensor for oxidative/electrophilic stress. INrf2 serves as an adaptor to link Nrf2 to the ubiquitin ligase Cul3-Rbx1 complex that ubiquitinate and degrade Nrf2. Under basal conditions, cytosolic INrf2/Cul3-Rbx1 is constantly degrading Nrf2. When a cell encounters stress Nrf2 dissociates from the INrf2 and translocates into the nucleus. Oxidative/electrophilic stress induced modification of INrf2Cysteine151 and/or protein kinase C (PKC)-mediated phosphorylation of Nrf2Serine40 controls Nrf2 release from INrf2 followed by stabilization and nuclear translocation of Nrf2. Nrf2 binds to the antioxidant response element (ARE) and activates a myriad of genes that protect cells against oxidative/electrophilic stress and neoplasia. A delayed response of oxidative/electrophilic stress activates GSK-3beta that phosphorylates Fyn at unknown threonine residue(s). Phosphorylated Fyn translocates to the nucleus and phosphorylates Nrf2Tyrosine568 that leads to nuclear export and degradation of Nrf2. Prothymosin-alpha mediated nuclear translocation of INrf2 also degrades nuclear Nrf2. The degradation of Nrf2 both in cytosol and nuclear compartments rapidly brings down its levels to normal resulting in suppression of Nrf2 downstream gene expression. An auto-regulatory loop between Nrf2 and INrf2 controls their cellular abundance. Nrf2 regulates INrf2 by controlling its transcription, and INrf2 controls Nrf2 by degrading it. In conclusion, switching on and off of Nrf2 combined with promoting an auto-regulatory loop between them regulates activation/deactivation of defensive genes leading to protection of cells against adverse effects of oxidative and electrophilic stress and promote cell survival.

Lung Defenses

We breathe to live, but the air we breathe carries many potentially harmful agents. To protect us against these constant challenges, our lungs have defenses that are remarkably effective, biologically complex, and scientifically fascinating. It is not hyperbole to say that the pathogenesis of most lung disease begins with a breach of these defenses. This chapter surveys these normal lung defense systems. Just as this text assumes familiarity with general pathology, we also assume knowledge of basic immunology. This chapter emphasizes the lung’s variations on themes of innate and adaptive immunity, and discusses the special role of granulomatous inflammation in lung defenses.

Associations between Short-Term Changes in Nitrogen Dioxide and Mortality in Canadian Cities

The association between daily variations in ambient concentrations of nitrogen dioxide (NO2) and mortality was examined in 12 of Canada's largest cities, using a 19-yr time-series analysis (from 1981-1999). The authors employed parametric statistical methods that are not subject to the recently discovered convergence and error estimation problems of generalized additive models. An increase in the 3-d moving average of NO2 concentrations equivalent to the population-weighted study mean of 22.4 ppb was associated with a 2.25% (t = 4.45) increase in the daily nonaccidental mortality rate and was insensitive to adjustment for ozone, sulfur dioxide, carbon monoxide, coefficient of haze, size-fractionated particulate mass, and the sulfate ion measured on an every-6th-day sampling schedule. The 3-d moving average of NO2 was sensitive to adjustment for fine particulate matter measured daily during the 1998-2000 time period.

Use of an index to reflect the aggregate burden of long-term exposure to criteria air pollutants in the United States

Air pollution control in the United States for five common pollutants--particulate matter, ground-level ozone, sulfur dioxide, nitrogen dioxide, and carbon monoxide--is based partly on the attainment of ambient air quality standards that represent a level of air pollution regarded as safe. Regulatory and health agencies often focus on whether standards for short periods are attained; the number of days that standards are exceeded is used to track progress. Efforts to explain air pollution to the public often incorporate an air quality index that represents daily concentrations of pollutants. While effects of short-term exposures have been emphasized, research shows that long-term exposures to lower concentrations of air pollutants can also result in adverse health effects. We developed an aggregate index that represents long-term exposure to these pollutants, using 1995 monitoring data for metropolitan areas obtained from the U.S. Environmental Protection Agency's Aerometric Information Retrieval System. We compared the ranking of metropolitan areas under the proposed aggregate index with the ranking of areas by the number of days that short-term standards were exceeded. The geographic areas with the highest burden of long-term exposures are not, in all cases, the same as those with the most days that exceeded a short-term standard. We believe that an aggregate index of long-term air pollution offers an informative addition to the principal approaches currently used to describe air pollution exposures; further work on an aggregate index representing long-term exposure to air pollutants is warranted.