Air Pollution and Respiratory Infection: An Emerging and Troubling Association

Interactive effects of air pollutants and viral exposure on daily influenza hospital visits in Mongolia

BACKGROUND

Air pollution is a well-documented public health hazard linked to various adverse health outcomes. While studies have shown associations between elevated levels of air pollutants and increased influenza incidence, there is a notable knowledge gap concerning the interactive effects of air pollution and viral exposure on respiratory viral infections.

OBJECTIVES

This study sought to examine the interactive effects of air pollution and viral exposure on influenza hospital visits in Ulaanbaatar, Mongolia.

METHODS

We conducted a time-series analysis linking daily hospital visits for influenza disease (defined as ICD10 diagnosis codes J11) with ambient concentrations of air pollutants (PM1, PM2.5, PM10, NO2, SO2, and O3) over a period of 7 years. Viral exposure for a specific geographical region was estimated based on influenza hospital visits within acute (previous day) and sub-acute (preceding 7 days) exposure windows. Covariates included long-term time trend, temperature, temperature variation, relative humidity, holiday, and raw coal ban policy. An over-dispersed generalized linear model (GLM) with a quasi-Poisson distribution was used to assess associations, exploring interactions and lag effects up to 3 days. Season-specific models and stratified analyses by sex and age were performed, with sensitivity analyses using multi-pollutant models.

RESULTS

A total of 16,364 influenza hospital visits were recorded, with significantly higher rates of visits during the winter season. All six pollutants amplified the effects of viral exposure on hospital visits in cold months, while only PM1, PM2.5, and O3 showed synergistic effects in warm months. Stronger synergistic effects were observed among children under 5 years old, particularly for O3.

CONCLUSIONS

Air pollution significantly amplified the adverse effects of viral exposure on influenza-hospital visits, particularly among young children and during high viral exposure periods. These findings underscore the need for employing protective measures against both air pollution and viral infections.

Subnational Evidence for the Attributable Burden of Respiratory Infections in China's Population under 20: Challenges from Particulate Matter Pollution

Respiratory infections and tuberculosis ranked as the second leading global causes of mortality in 2021. Following the methodology from the Global Burden of Disease Study (GBD) 2021, we aimed to estimate the attributable burden and risk factors of respiratory infections and tuberculosis among China's population under 20 from 1990 to 2021. In 2021, there were 652 million new cases and 12 699 deaths of respiratory infections and tuberculosis among people under 20 years old in China. We estimated 9054 (71.2%) deaths and 818 498 (54.6%) disability-adjusted life years (DALYs) from respiratory infections attributed to all evaluated risk factors. Mortality rates were the highest in Xizang, Xinjiang, and Qinghai in 2021, while they constantly decreased since 1990. Ambient particulate matter pollution was the second leading cause of death among males and first among females, accounting for nearly 1/5 of deaths from respiratory infections and tuberculosis in 2021. In 23 of 33 provinces, ambient particulate matter pollution was the first leading cause of death and DALY, while in Xizang and Gansu, it was not the major contributor to the burden. From 1990 to 2021, the burden from household air pollution declined remarkably in all 33 provinces except for Xizang and Gansu, while the population attributable fraction (PAF) of ambient particulate matter pollution continuously increased. The overall burden of respiratory infections and tuberculosis showed a declining trend, while it remained a fatal threat to infants in relatively less developed regions. The raised hazard of ambient particulate matter pollution underscored the necessity of the shift into the formulation of prevention and intervention strategies.

The relationship between neighborhood economic deprivation and community-acquired pneumonia related admissions in Maryland

Introduction

Community-acquired pneumonia (CAP) is a major health concern in the United States (US), with its incidence, severity, and outcomes influenced by social determinants of health, including socioeconomic status. The impact of neighborhood socioeconomic status, as measured by the Distressed Communities Index (DCI), on CAP-related admissions remains understudied in the literature.

Objective

To determine the independent association between DCI and CAP-related admissions in Maryland.

Methods

We conducted a retrospective study using the Maryland State Inpatient Database (SID) to collate data on CAP-related admissions from January 2018 to December 2020. The study included adults aged 18-85 years. We explored the independent association between community-level economic deprivation based on DCI quintiles and CAP-related admissions, adjusting for significant covariates.

Results

In the study period, 61,467 cases of CAP-related admissions were identified. The patients were predominantly White (49.7%) and female (52.4%), with 48.6% being over 65 years old. A substantive association was found between the DCI and CAP-related admissions. Compared to prosperous neighborhoods, patients living in economically deprived communities had 43% increased odds of CAP-related admissions.

Conclusion

Residents of the poorest neighborhoods in Maryland have the highest risk of CAP-related admissions, emphasizing the need to develop effective public health strategies beneficial to the at-risk patient population.

Burden and trends of infectious disease mortality attributed to air pollution, unsafe water, sanitation, and hygiene, and non-optimal temperature globally and in different socio-demographic index regions

BACKGROUND

Environmental factors greatly impact infectious disease-related mortality, yet there's a lack of comprehensive global studies on the contemporary burden and trends. This study aims to evaluate the global burden and trends of infectious disease mortality caused by air pollution, unsafe water, poor sanitation, and non-optimal temperature across Socio-Demographic Index (SDI) regions from 1990 to 2019.

METHODS

This observational study utilized data from the Global Burden of Diseases Study to examine mortality rates from infectious diseases attributed to environmental risk factors between 1990 and 2019, including air pollution, unsafe water, sanitation, handwashing facilities (UWSH), and non-optimal temperatures. Age-standardized mortality rates (ASMRs) and estimated annual percentage change (EAPC) were utilized to present infectious disease mortality, and its trajectory influenced by environmental risk factors over the years. Nonlinear regression was conducted to explore the association between the SDI and ASMRs across regions from 1990 to 2019.

RESULTS

In 2019, global infectious disease deaths linked to air pollution, UWSH, and non-optimal temperature reached a startling 2,556,992. Disease mortality varied widely across SDI regions, with the highest number of deaths due to air pollution and UWSH in Low SDI regions, and deaths from non-optimal temperature primarily in High SDI regions. Age disparities emerged, with children under five and the elderly most affected. However, an increasing mortality trend was observed among seniors (65-69, 75-79, and over 80) in High SDI regions due to enteric infections linked to UWSH. Globally, a consistent decrease in ASMR was seen from 1990 to 2019 for all diseases connected to these factors, except for respiratory infections linked to non-optimal temperature.

CONCLUSIONS

Our study underscores the significant impact of air pollution, UWSH, and non-optimal temperatures on global infectious disease mortality, particularly among vulnerable groups such as children and the elderly. It's important to tackle these challenges with targeted interventions aiming to enhance environmental quality, improve water and sanitation systems, and control extreme temperatures. In addition, international cooperation is essential for bridging regional disparities and driving global public health initiatives forward, thereby helping achieve Sustainable Development Goals more effectively.

Impact of pneumococcal conjugate vaccine 13 introduction on severe lower respiratory tract infections associated with respiratory syncytial virus or influenza virus in hospitalized children in Ulaanbaatar, Mongolia

Objectives

Limited data indicate a beneficial effect of pneumococcal conjugate vaccines (PCVs) on respiratory syncytial virus (RSV) and influenza infections in young children. We evaluated the impact of 13-valent PCV (PCV13) introduction on the incidence of severe lower respiratory tract infections (LRTIs) associated with RSV or influenza in hospitalized children.

Methods

Our study was restricted to children aged <2 years with arterial oxygen saturation <93% and children with radiologically confirmed pneumonia nested in a pneumonia surveillance project in four districts of Ulaanbaatar city, Mongolia. We tested nasopharyngeal swabs collected on admission for RSV and influenza using quantitative reverse transcription-polymerase chain reaction. The impact of PCV13 on the incidence of LRTI outcomes associated with RSV or with influenza for the period April 2015-March 2020 was estimated. Incidence rate ratios comparing pre- and post-vaccine periods were estimated for each outcome for each district using negative binomial models and for all districts combined with a mixed-effects negative binomial model. Adjusted models accounted for seasonality. Sensitivity analyses were conducted to assess the robustness of our findings.

Results

Among 5577 tested cases, the adjusted incidence rate ratios showed a trend toward a reduction in RSV-associated outcomes: all LRTIs (0.77, 95% confidence interval [CI] 0.44-1.36), severe LRTIs (0.88, 95% CI 0.48-1.62), very severe LRTIs (0.76, 95% CI 0.42-1.38), and radiologically confirmed pneumonia (0.66, 95% CI 0.32-1.38) but inconsistent trends in outcomes associated with influenza.

Conclusions

No significant reductions were observed in any outcomes associated with RSV and influenza after PCV introduction.

Impact of air pollution on ischemic heart disease: Evidence, mechanisms, clinical perspectives

Ambient air pollution, and especially particulate matter (PM) air pollution <2.5 μm in diameter (PM_2.5), has clearly emerged as an important yet often overlooked risk factor for atherosclerosis and ischemic heart disease (IHD). In this review, we examine the available evidence demonstrating how acute and chronic PM_2.5 exposure clinically translates into a heightened coronary atherosclerotic burden and an increased risk of acute ischemic coronary events. Moreover, we provide insights into the pathophysiologic mechanisms underlying PM_2.5-mediated atherosclerosis, focusing on the specific biological mechanism through which PM_2.5 exerts its detrimental effects. Further, we discuss about the possible mechanisms that explain the recent findings reporting a strong association between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, increased PM_2.5 exposure, and morbidity and mortality from IHD. We also address the possible mitigation strategies that should be implemented to reduce the impact of PM_2.5 on cardiovascular morbidity and mortality, and underscoring the strong need of clinical trials demonstrating the efficacy of specific interventions (including both PM_2.5 reduction and/or specific drugs) in reducing the incidence of IHD. Finally, we introduce the emerging concept of the exposome, highlighting the close relationship between PM_2.5 and other environmental exposures (i.e.: traffic noise and climate change) in terms of common underlying pathophysiologic mechanisms and possible mitigation strategies.

Incidence and Mortality Trends of Upper Respiratory Infections in China and Other Asian Countries from 1990 to 2019

Respiratory infections remain a major public health problem, affecting people of all age groups, but there is still a lack of studies analyzing the burden of upper respiratory infections (URIs) in Asian countries. We used the data from the Global Burden of Diseases Study 2019 results to assess the current status and trends of URI burden from 1990 to 2019 in Asian countries. We found that Thailand had the highest age-standardized incidence rate (ASIR) of URI both in 1990 (354,857.14 per 100,000) and in 2019 (344,287.93 per 100,000); and the highest age-standardized mortality rate (ASMR) was in China in 1990 (2.377 per 100,000), and in Uzbekistan in 2019 (0.418 per 100,000). From 1990 to 2019, ASIRs of URI slightly increased in several countries, with the speediest in Pakistan (estimated annual percentage change [EAPC] = 0.404%, 95% CI, 0.322% to 0.486%); and Kuwait and Singapore had uptrends of ASMRs, at a speed of an average 3.332% (95% CI, 2.605% to 4.065%) and 3.160% (95% CI, 1.971% to 4.362%) per year, respectively. The age structure of URI was similar at national, Asian and Global levels. Children under the age of five had the highest incidence rate, and the elderly had the highest mortality rate of URI. Asian countries with a Socio-demographic Index between 0.5 and 0.7 had relatively lower ASIRs but higher ASMRs of URIs. The declined rate of URI ASMR in Asian countries was more pronounced in higher baseline (ASMR in 1990) countries. Our findings suggest that there was a huge burden of URI cases in Asia that affected vulnerable and impoverished people's livelihoods. Continuous and high-quality surveillance data across Asian countries are needed to improve the estimation of the disease burden attributable to URIs, and the best public health interventions are needed to curb this burden.

Associations between air pollutants and risk of respiratory infection: patient-based bacterial culture in sputum

Air pollution is a crucial risk factor for respiratory infection. However, the relationships between air pollution and respiratory infection based on pathogen detection are scarcely explored in the available literature. We detected respiratory infections through patient-based bacterial culture in sputum, obtained hourly data of all six pollutants (PM_2.5, PM₁₀, SO₂, NO, CO, and O₃) from four air quality monitoring stations, and assessed the relationships of air pollutants and respiratory bacterial infection and multi-drug-resistant bacteria. Air pollution remains a challenge for Mianyang, China, especially PM_2.5 and PM₁₀, and there are seasonal differences; pollution is the heaviest in winter and the lowest in summer. A total of 4237 pathogenic bacteria were detected, and the positive rate of multi-drug-resistant bacteria was 0.38%. Similar seasonal differences were found with respect to respiratory infection. In a single-pollutant model, all pollutants were significantly associated with respiratory bacterial infection, but only O₃ was significantly associated with multi-drug-resistant bacteria. In multi-pollutant models (adjusted for one pollutant), the relationships of air pollutants with respiratory bacterial infection remained significant, while PM_2.5, PM₁₀, and O₃ were significantly associated with the risk of infection with multi-drug-resistant bacteria. When adjusted for other five pollutants, only O₃ was significantly associated with respiratory bacterial infection and the risk of infection with multi-drug-resistant bacteria, showing that O₃ is an independent risk factor for respiratory bacterial infection and infection with multi-drug-resistant bacteria. In summary, this study highlights the adverse effects of air pollution on respiratory infection and the risk of infection with multi-drug-resistant bacteria, which may provide a basis for the formulation of environmental policy to prevent respiratory infections.

Macro-level drivers of SARS-CoV-2 transmission: A data-driven analysis of factors contributing to epidemic growth during the first wave of outbreaks in the United States

BACKGROUND

Many questions remain unanswered about how SARS-CoV-2 transmission is influenced by aspects of the economy, environment, and health. A better understanding of how these factors interact can help us to design early health prevention and control strategies, and develop better predictive models for public health risk management of SARS-CoV-2. This study examines the associations between COVID-19 epidemic growth and macro-level determinants of transmission such as demographic, socio-economic, climate and health factors, during the first wave of outbreaks in the United States.

METHODS

A spatial-temporal data-set was created from a variety of relevant data sources. A unique data-driven study design was implemented to assess the relationship between COVID-19 infection and death epidemic doubling times and explanatory variables using a Generalized Additive Model (GAM).

RESULTS

The main factors associated with infection doubling times are higher population density, home overcrowding, manufacturing, and recreation industries. Poverty was also an important predictor of faster epidemic growth perhaps because of factors associated with in-work poverty-related conditions, although poverty is also a predictor of poor population health which is likely driving infection and death reporting. Air pollution and diabetes were other important drivers of infection reporting. Warmer temperatures are associated with slower epidemic growth, which is most likely explained by human behaviors associated with warmer locations i.e. ventilating homes and workplaces, and socializing outdoors. The main factors associated with death doubling times were population density, poverty, older age, diabetes, and air pollution. Temperature was also slightly significant slowing death doubling times.

CONCLUSIONS

Such findings help underpin current understanding of the disease epidemiology and also supports current policy and advice recommending ventilation of homes, work-spaces, and schools, along with social distancing and mask-wearing. Given the strong associations between doubling times and the stringency index, it is likely that those states that responded to the virus more quickly by implementing a range of measures such as school closing, workplace closing, restrictions on gatherings, close public transport, restrictions on internal movement, international travel controls, and public information campaigns, did have some success slowing the spread of the virus.

The Influence of Environmental Factors on the Spread of COVID-19 in Italy

The aim of this work is to investigate possible relationships between air quality and the spread of the pandemic. We evaluate the performance of machine learning techniques in predicting new cases. Specifically, we describe a cross-correlation analysis on daily COVID-19 cases and environmental factors, such as temperature, relative humidity, and atmospheric pollutants. Our analysis confirms a significant association of some environmental parameters with the spread of the virus. This suggests that machine learning models trained using environmental parameters might provide accurate predictions about the number of infected cases. Our empirical evaluation shows that temperature and ozone are negatively correlated with confirmed cases (therefore, the higher the values of these parameters, the lower the number of infected cases), whereas atmospheric particulate matter and nitrogen dioxide are positively correlated. We developed and compared three different predictive models to test whether these technologies can be useful to estimate the evolution of the pandemic.

Environmental Risk Factors for Talaromycosis Hospitalizations of HIV-Infected Patients in Guangzhou, China: Case Crossover Study

Talaromycosis is a fatal opportunistic infection prevalent in human immunodeficiency virus (HIV)-infected patients, previous studies suggest environmental humidity is associated with monthly talaromycosis hospitalizations of HIV-infected patients, but the acute risk factor remains uncertain. In this study, we evaluated the associations between talaromycosis hospitalizations of HIV-infected patients (n = 919) and environmental factors including meteorological variables and air pollutants at the event day (assumed "lag 0" since the exact infection date is hard to ascertain) and 1-7 days prior to event day (lag 1-lag 7) in conditional logistics regression models based on a case crossover design. We found that an interquartile range (IQR) increase in temperature at lag 0-lag 7 (odds ratio [OR] [95% CI] ranged from 1.748 [1.345-2.273] to 2.184 [1.672-2.854]), and an IQR increase in humidity at lag 0 (OR [95% CI] = 1.192 [1.052-1.350]), and lag 1 (OR [95% CI] = 1.199 [1.056-1.361]) were significantly associated with talaromycosis hospitalizations of HIV-infected patients. Besides, temperature was also a common predictor for talaromycosis in patients with co-infections including candidiasis (n = 386), Pneumocystis pneumonia (n = 183), pulmonary tuberculosis (n = 141), and chronic hepatitis (n = 158), while humidity was a specific risk factor for talaromycosis in patients with candidiasis, and an air pollutant, SO₂, was a specific risk factor for talaromycosis in patients with Pneumocystis pneumonia. In an age stratified evaluation (cutoff = 50 years old), temperature was the only variable positively associated with talaromycosis in both younger and older patients. These findings broaden our understanding of the epidemiology and pathogenesis of talaromycosis in HIV-infected patients.

Ambient Air Pollution and Respiratory Health in Sub-Saharan African Children: A Cross-Sectional Analysis

Ambient air pollution is projected to become a major environmental risk in sub-Saharan Africa (SSA). Research into its health impacts is hindered by limited data. We aimed to investigate the cross-sectional relationship between particulate matter with a diameter ≤ 2.5 μm (PM_2.5) and prevalence of cough or acute lower respiratory infection (ALRI) among children under five in SSA. Data were collected from 31 Demographic and Health Surveys (DHS) in 21 SSA countries between 2005–2018. Prior-month average PM_2.5 preceding the survey date was assessed based on satellite measurements and a chemical transport model. Cough and ALRI in the past two weeks were derived from questionnaires. Associations were analysed using conditional logistic regression within each survey cluster, adjusting for child’s age, sex, birth size, household wealth, maternal education, maternal age and month of the interview. Survey-specific odds ratios (ORs) were pooled using random-effect meta-analysis. Included were 368,366 and 109,664 children for the analysis of cough and ALRI, respectively. On average, 20.5% children had reported a cough, 6.4% reported ALRI, and 32% of children lived in urban areas. Prior-month average PM_2.5 ranged from 8.9 to 64.6 μg/m³. Pooling all surveys, no associations were observed with either outcome in the overall populations. Among countries with medium-to-high Human Development Index, positive associations were observed with both cough (pooled OR: 1.022, 95%CI: 0.982–1.064) and ALRI (pooled OR: 1.018, 95%CI: 0.975–1.064) for 1 μg/m³ higher of PM_2.5. This explorative study found no associations between short-term ambient PM_2.5 and respiratory health among young SSA children, necessitating future analyses using better-defined exposure and health metrics to study this important link.

Covid-19, non-Covid-19 and excess mortality rates not comparable across countries

Evidence that more people in some countries and fewer in others are dying because of the pandemic, than is reflected by reported coronavirus disease 2019 (Covid-19) mortality rates, is derived from mortality data. Using publicly available databases, deaths attributed to Covid-19 in 2020 and all deaths for the years 2015–2020 were tabulated for 35 countries together with economic, health, demographic and government response stringency index variables. Residual mortality rates (RMR) in 2020 were calculated as excess mortality minus reported mortality rates due to Covid-19 where excess deaths were observed deaths in 2020 minus the average for 2015–2019. Differences in RMR are differences not attributed to reported Covid-19. For about half the countries, RMR's were negative and for half, positive. The absolute rates in some countries were double those in others. In a regression analysis, population density and proportion of female smokers were positively associated with both Covid-19 and excess mortality while the human development index and proportion of male smokers were negatively associated with both. RMR was not associated with any of the investigated variables. The results show that published data on mortality from Covid-19 cannot be directly comparable across countries. This may be due to differences in Covid-19 death reporting and in addition, the unprecedented public health measures implemented to control the pandemic may have produced either increased or reduced excess deaths due to other diseases. Further data on cause-specific mortality is required to determine the extent to which residual mortality represents non-Covid-19 deaths and to explain differences between countries.

Air pollution and COVID-19: clearing the air and charting a post-pandemic course: a joint workshop report of ERS, ISEE, HEI and WHO

Air pollution is now recognised by governments, international institutions and civil society as a major global public health risk factor. The health burden of air pollution is large: 509 000 premature deaths every year in Europe [1] and serious aggravations of heart and lung diseases that affect millions of patients, both children and adults. The European Environmental Agency estimated that in 2018 there were 417 000 premature deaths attributable to particulate matter with diameter <2.5 µm (PM2.5), 55 000 to NO2, and 20 600 to O3 in Europe (table 10.1 in EEA Report 9/2020 [2]). In addition, 4 805 800 years of life lost could be attributed to PM2.5, 623 600 to NO2, and 246 700 to O3 (table 10.2 in [2]). This “silent killer” is one the most important determinants of health, surpassed only by high blood pressure, tobacco use and poor diet. The coronavirus disease 2019 (COVID-19) pandemic has raised concerns about whether air pollution can increase the severity of disease and risk of death after infection, as well as facilitate the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Chronic lung disease patients are in the epicentre of the current crisis, as they are more vulnerable to both the adverse effects of a SARS-CoV-2 infection and air pollution exposure, as well as their possible interactions. At the same time, the lockdown measures to control the spread of COVID-19 brought historical short-term reductions in air pollution levels around the globe, and increasing general public interest and demand for clean air policies [3]. The COVID-19 pandemic, an emerging infectious disease probably caused by a spill over from animals, and its possible interactions with air pollution, is an existential reminder that we are a part of a larger ecosystem, and that human health is closely connected with the health of our environment and planet. Here we provide a short summary on the potential role of air pollution in the spread and worsening of health impacts of COVID-19, and on the influence of the pandemic on air pollution levels in Europe. Moreover, we outline the major lessons learned to chart a healthy post-pandemic course. This work summarises the key messages from a workshop that took place on 2 December, 2020, organised by the European Respiratory Society (ERS), the International Society for Environmental Epidemiology (ISEE) and the Health Effects Institute (HEI), endorsed by the World Health Organization (WHO), and hosted by the European Parliament Lung Health Group and the European Commission (table 1).

The potential role of air pollution in the worsening of health impacts of COVID-19, and the influence of the pandemic on air pollution levels in Europe is explored. This editorial outlines the major lessons learned to chart a healthy post-pandemic course. https://bit.ly/3hmbaya

Ambient air pollution and risk of respiratory infection among adults: evidence from the multiethnic study of atherosclerosis (MESA)

BACKGROUND

Air pollution may affect the risk of respiratory infection, though research has focused on uncommon infections or infections in children. Whether ambient air pollutants increase the risk of common acute respiratory infections among adults is uncertain, yet this may help understand whether pollutants influence spread of pandemic respiratory infections like COVID-19.

OBJECTIVE

To estimate the association between ambient air pollutant exposures and respiratory infections in adults.

METHODS

During five study examinations over 12 years, 6536 participants in the multiethnic study of atherosclerosis (MESA) reported upper respiratory tract infections, bronchitis, pneumonia or febrile illness in the preceding 2 weeks. Using a validated spatiotemporal model, we estimated residential concentrations of ambient PM2.5, NOx and NO2 for the 2-6 weeks (short-term) and year (long-term) prior to each examination.

RESULTS

In this population aged 44-84 years at baseline, 10%-32% of participants reported a recent respiratory infection, depending on month of examination and study region. PM2.5, NOx and NO2 concentrations over the prior 2-6 weeks were associated with increased reporting of recent respiratory infection, with risk ratios (95% CIs) of 1.04 (1.00 to 1.09), 1.15 (1.10 to 1.20) and 1.21 (1.10 to 1.33), respectively, per increase from 25th to 75th percentile in residential pollutant concentration.

CONCLUSION

Higher short-term exposure to PM2.5 and traffic-related pollutants are associated with increased risk of symptomatic acute respiratory infections among adults. These findings may provide an insight into the epidemiology of COVID-19.

Air Pollution Is Associated with COVID-19 Incidence and Mortality in Vienna, Austria

We determined the impact of air pollution on COVID-19-related mortality and reported-case incidence, analyzing the correlation of infection case numbers and outcomes with previous-year air pollution data from the populations of 23 Viennese districts. Time at risk started in a district when the first COVID-19 case was diagnosed. High exposure levels were defined as living in a district with an average (year 2019) concentration of nitrogen dioxide (NO2) and/or particulate matter (PM10) higher than the upper quartile (30 and 20 µg/m3, respectively) of all districts. The total population of the individual districts was followed until diagnosis of or death from COVID-19, or until 21 April 2020, whichever came first. Cox proportional hazard regression was performed after controlling for percentage of population aged 65 and more, percentage of foreigners and of persons with a university degree, unemployment rate, and population density. PM10 and NO2 were significantly and positively associated with the risk of a COVID-19 diagnosis (hazard ratio (HR) = 1.44 and 1.16, respectively). NO2 was also significantly associated with death from COVID-19 (HR = 1.72). Even within a single city, higher levels of air pollution are associated with an adverse impact on COVID-19 risk.

Ambient air pollution and respiratory bacterial infections, a troubling association: epidemiology, underlying mechanisms, and future challenges

The World Health Organization attributed more than four million premature deaths to ambient air pollution in 2016. Numerous epidemiologic studies demonstrate that acute respiratory tract infections and exacerbations of pre-existing chronic airway diseases can result from exposure to ambient (outdoor) air pollution. In this context, the atmosphere contains both chemical and microbial pollutants (bioaerosols), whose impact on human health remains unclear. Therefore, this review: summarises the findings from recent studies on the association between exposure to air pollutants-especially particulate matter and ozone-and onset or exacerbation of respiratory infections (e.g. pneumonia, cystic fibrosis lung infection, and tuberculosis); discusses the mechanisms underlying the relationship between air pollution and respiratory bacterial infections, which is necessary to define prevention and treatment strategies; demonstrates the relevance of air pollution modelling in investigating and preventing the impact of exposure to air pollutants on human health; and outlines future actions required to improve air quality and reduce morbidity and mortality related to air pollution.

Titanium dioxide nanoparticles exaggerate respiratory syncytial virus-induced airway epithelial barrier dysfunction

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections in children worldwide. While most develop a mild, self-limiting illness, some develop severe acute lower respiratory infection and persistent airway disease. Exposure to ambient particulate matter has been linked to asthma, bronchitis, and viral infection in multiple epidemiological studies. We hypothesized that coexposure to nanoparticles worsens RSV-induced airway epithelial barrier dysfunction. Bronchial epithelial cells were incubated with titanium dioxide nanoparticles (TiO2-NP) or a combination of TiO2-NP and RSV. Structure and function of epithelial cell barrier were analyzed. Viral titer and the role of reactive oxygen species (ROS) generation were evaluated. In vivo, mice were intranasally incubated with TiO2-NP, RSV, or a combination. Lungs and bronchoalveolar lavage (BAL) fluid were harvested for analysis of airway inflammation and apical junctional complex (AJC) disruption. RSV-induced AJC disruption was amplified by TiO2-NP. Nanoparticle exposure increased viral infection in epithelial cells. TiO2-NP induced generation of ROS, and pretreatment with antioxidant, N-acetylcysteine, reversed said barrier dysfunction. In vivo, RSV-induced injury and AJC disruption were augmented in the lungs of mice given TiO2-NP. Airway inflammation was exacerbated, as evidenced by increased white blood cell infiltration into the BAL, along with exaggeration of peribronchial inflammation and AJC disruption. These data demonstrate that TiO2-NP exposure exacerbates RSV-induced AJC dysfunction and increases inflammation by mechanisms involving generation of ROS. Further studies are required to determine whether NP exposure plays a role in the health disparities of asthma and other lung diseases, and why some children experience more severe airway disease with RSV infection.

Air Microbiome and Pollution: Composition and Potential Effects on Human Health, Including SARS Coronavirus Infection

Polluted air poses a significant threat to human health. Exposure to particulate matter (PM) and harmful gases contributes to cardiovascular and respiratory diseases, including allergies and obstructive lung disease. Air pollution may also be linked to cancer and reduced life expectancy. Uptake of PM has been shown to cause pathological changes in the intestinal microbiota in mice and humans. Less is known about the effects of pollution-associated microbiota on human health. Several recent studies described the microbiomes of urban and rural air samples, of the stratosphere and sand particles, which can be transported over long distances, as well as the air of indoor environments. Here, we summarize the current knowledge on airborne bacterial, viral, and fungal communities and discuss their potential consequences on human health. The current data suggest that bacterial pathogens are typically too sparse and short-lived in air to pose a significant risk for infecting healthy people. However, airborne fungal spores may exacerbate allergies and asthma. Little information is available on viruses including phages, and future studies are likely to detect known and novel viruses with a yet unknown impact on human health. Furthermore, varying experimental protocols have been employed in the recent microbiome and virome studies. Therefore, standardized methodologies will be required to allow for better comparisons between studies. Air pollution has been linked to more severe outcomes of SARS (severe acute respiratory syndrome) coronavirus (SARS-CoV) infections. This may have contributed to severe SARS-CoV-2 outbreaks, especially those in China, Northern Italy, Iran, and New York City.

Atmospheric blockages as trigger of environmental contingencies in Mexico City

Atmospheric pollution in cities is due to several human factors, for instance the number of cars in circulation, fuel efficiency and industrial waste, as well as orographic and meteorological conditions that determine air circulation. Ozone contingencies cause health disorders on the population, making it important to understand the factors that trigger such contingencies. Here, we analyze meteorological (wind, temperature, relative humidity) and atmospheric composition (ozone, and NOx) data of five atmospheric monitoring stations on Mexico City, from March 2004 to May 2018, comparing normal days with the extreme days in the 90th percentile of ozone. Moreover, we present the synoptic patterns of the seasonal differences of geopotential height at 500 hPa between extreme and control days. We found that, in the dry-hot season (from March to May) an atmospheric blockage with meteorological conditions of almost no wind, low relative humidity, and small temperature fluctuations occurs. Because the air in the city permanently contains large amounts of ozone precursors like NOx, this meteorological scenario raises ozone levels to those of an environmental contingency. Thus, during the dry-hot season on Mexico City, ozone contingencies are triggered by atmospheric blocking. This scenario will be present in cities surrounded by mountains with high levels of Ozone precursors.