A Review of Epidemiological Research on Adverse Neurological Effects of Exposure to Ambient Air Pollution

Air pollution and neurological development in children

Pregnancy and early childhood are periods with high plasticity in neurological development. Environmental perturbations during these sensitive windows can have lifelong developmental consequences. This review summarizes key findings relevant to the effects of air pollution on neurological development. Mounting evidence suggests that exposure to air pollution, both during pregnancy and childhood, is associated with childhood developmental outcomes ranging from changes in brain structures to subclinical deficits in developmental test scores, and, ultimately, developmental disorders such as attention-deficit/hyperactivity disorders or autism spectrum disorders. Although the biological mechanisms of effects remain to be elucidated, multiple pathways are probably involved and include oxidative stress, inflammation, and/or endocrine disruption. Given the alarming global increase in developmental disorders in recent years, and increased human exposures to pollution, it is critical to reduce personal and community-level exposures through tight collaboration of interdisciplinary and multi-level bodies including community partners, physicians, industry partners, policy makers, public health practitioners, and researchers. WHAT THIS PAPER ADDS: Exposure to air pollution is associated with a range of childhood developmental complications. Biological mechanisms may include oxidative stress, inflammation, and endocrine disruption.

Defining and Intervening on Cumulative Environmental Neurodevelopmental Risks: Introducing a Complex Systems Approach

BACKGROUND

The combined effects of multiple environmental toxicants and social stressor exposures are widely recognized as important public health problems contributing to health inequities. However cumulative environmental health risks and impacts have received little attention from U.S. policy makers at state and federal levels to develop comprehensive strategies to reduce these exposures, mitigate cumulative risks, and prevent harm. An area for which the inherent limitations of current approaches to cumulative environmental health risks are well illustrated is children's neurodevelopment, which exhibits dynamic complexity of multiple interdependent and causally linked factors and intergenerational effects.

OBJECTIVES

We delineate how a complex systems approach, specifically system dynamics, can address shortcomings in environmental health risk assessment regarding exposures to multiple chemical and nonchemical stressors and reshape associated public policies.

DISCUSSION

Systems modeling assists in the goal of solving problems by improving the "mental models" we use to make decisions, including regulatory and policy decisions. In the context of disparities in children's cumulative exposure to neurodevelopmental stressors, we describe potential policy insights about the structure and behavior of the system and the types of system dynamics modeling that would be appropriate, from visual depiction (i.e., informal maps) to formal quantitative simulation models. A systems dynamics framework provides not only a language but also a set of methodological tools that can more easily operationalize existing multidisciplinary scientific evidence and conceptual frameworks on cumulative risks. Thus, we can arrive at more accurate diagnostic tools for children's' environmental health inequities that take into consideration the broader social and economic environment in which children live, grow, play, and learn. https://doi.org/10.1289/EHP7333.

A critical review of the epidemiological evidence of effects of air pollution on dementia, cognitive function and cognitive decline in adult population

Dementia is arguably the most pressing public health challenge of our age. Since dementia does not have a cure, identifying risk factors that can be controlled has become paramount to reduce the personal, societal and economic burden of dementia. The relationship between exposure to air pollution and effects on cognitive function, cognitive decline and dementia has stimulated increasing scientific interest in the past few years. This review of the literature critically examines the available epidemiological evidence of associations between exposure to ambient air pollutants, cognitive performance, acceleration of cognitive decline, risk of developing dementia, neuroimaging and neurological biomarker studies, following Bradford Hill guidelines for causality. The evidence reviewed has been consistent in reporting associations between chronic exposure to air pollution and reduced global cognition, as well as impairment in specific cognitive domains including visuo-spatial abilities. Cognitive decline and dementia incidence have also been consistently associated with exposure to air pollution. The neuro-imaging studies reviewed report associations between exposure to air pollution and white matter volume reduction. Other reported effects include reduction in gray matter, larger ventricular volume, and smaller corpus callosum. Findings relating to ischemic (white matter hyperintensities/silent cerebral infarcts) and hemorrhagic (cerebral microbleeds) markers of cerebral small vessel disease have been heterogeneous, as have observations on hippocampal volume and air pollution. The few studies available on neuro-inflammation tend to report associations with exposure to air pollution. Several effect modifiers have been suggested in the literature, but more replication studies are required. Traditional confounding factors have been controlled or adjusted for in most of the reviewed studies. Additional confounding factors have also been considered, but the inclusion of these has varied among the different studies. Despite all the efforts to adjust for confounding factors, residual confounding cannot be completely ruled out, especially since the factors affecting cognition and dementia are not yet fully understood. The available evidence meets many of the Bradford Hill guidelines for causality. The reported associations between a range of air pollutants and effects on cognitive function in older people, including the acceleration of cognitive decline and the induction of dementia, are likely to be causal in nature. However, the diversity of study designs, air pollutants and endpoints examined precludes the attribution of these adverse effects to a single class of pollutant and makes meta-analysis inappropriate.

Air Pollution Health Risk Assessment (AP-HRA), Principles and Applications

Air pollution is a major public health problem. A significant number of epidemiological studies have found a correlation between air quality and a wide variety of adverse health impacts emphasizing a considerable role of air pollution in the disease burden in the general population ranging from subclinical effects to premature death. Health risk assessment of air quality can play a key role at individual and global health promotion and disease prevention levels. The Air Pollution Health Risk Assessment (AP-HRA) forecasts the expected health effect of policies impacting air quality under the various policy, environmental and socio-economic circumstances, making it a key tool for guiding public policy decisions. This paper presents the concept of AP-HRA and offers an outline for the proper conducting of AP-HRA for different scenarios, explaining in broad terms how the health hazards of air emissions and their origins are measured and how air pollution-related impacts are quantified. In this paper, seven widely used AP-HRA tools will be deeply explored, taking into account their spatial resolution, technological factors, pollutants addressed, geographical scale, quantified health effects, method of classification, and operational characteristics. Finally, a comparative analysis of the proposed tools will be conducted, using the SWOT (strengths, weaknesses, opportunities, and threats) method.

Early-Life Exposure to Environmental Air Pollution and Autism Spectrum Disorder: A Review of Available Evidence

The number of children diagnosed with Autism Spectrum Disorder (ASD) has rapidly increased globally. Genetic and environmental factors both contribute to the development of ASD. Several studies showed linkage between prenatal, early postnatal air pollution exposure and the risk of developing ASD. We reviewed the available literature concerning the relationship between early-life exposure to air pollutants and ASD onset in childhood. We searched on Medline and Scopus for cohort or case-control studies published in English from 1977 to 2020. A total of 20 articles were selected for the review. We found a strong association between maternal exposure to particulate matter (PM) during pregnancy or in the first years of the children’s life and the risk of the ASD. This association was found to be stronger with PM_2.5 and less evident with the other pollutants. Current evidence suggest that pregnancy is the period in which exposure to environmental pollutants seems to be most impactful concerning the onset of ASD in children. Air pollution should be considered among the emerging risk factors for ASD. Further epidemiological and toxicological studies should address molecular pathways involved in the development of ASD and determine specific cause–effect associations.

Review of epidemiological studies on air pollution and health effects in children

There is a growing body of literature on the adverse health effects of ambient air pollution. Children are more adversely affected by air pollution due to their biological susceptibility and exposure patterns. This review summarized the accumulated epidemiologic evidence with emphasis on studies conducted in Korea and heterogeneity in the literature. Based on systematic reviews and meta-analyses, there is consistent evidence on the association between exposure to ambient air pollution and children's health, especially respiratory health and adverse birth outcomes, and growing evidence on neurodevelopmental outcomes. Despite these existing studies, the mechanism of the adverse health effects of air pollution and the critical window of susceptibility remain unclear. There is also a need to identify causes of heterogeneity between studies in terms of measurement of exposure/outcome, study design, and the differential characteristics of air pollutants and population.

Assessing environmental epidemiology questions in practice with a causal inference pipeline: An investigation of the air pollution-multiple sclerosis relapses relationship

When addressing environmental health-related questions, most often, only observational data are collected for ethical or practical reasons. However, the lack of randomized exposure often prevents the comparison of similar groups of exposed and unexposed units. This design barrier leads the environmental epidemiology field to mainly estimate associations between environmental exposures and health outcomes. A recently developed causal inference pipeline was developed to guide researchers interested in estimating the effects of plausible hypothetical interventions for policy recommendations. This article illustrates how this multistaged pipeline can help environmental epidemiologists reconstruct and analyze hypothetical randomized experiments by investigating whether an air pollution reduction intervention decreases the risk of multiple sclerosis relapses in Alsace region, France. The epidemiology literature reports conflicted findings on the relationship between air pollution and multiple sclerosis. Some studies found significant associations, whereas others did not. Two case-crossover studies reported significant associations between the risk of multiple sclerosis relapses and the exposure to air pollutants in the Alsace region. We use the same study population as these epidemiological studies to illustrate how appealing this causal inference approach is to estimate the effects of hypothetical, but plausible, environmental interventions.

Association between short-term exposure to ambient particulate air pollution and biomarkers of oxidative stress: A meta-analysis

BACKGROUND

Exposure to ambient particulate air pollution contributes substantially to the mortality and morbidity due to cardiovascular diseases (CVD), respiratory diseases and neurodegenerative diseases. Several hypothetical mechanisms have been proposed to explain these associations, particularly oxidative stress. Malondialdehyde (MDA), 8-hydroxy-2'-deoxyguanosine (8-OHdG), and Superoxide Dismutase (SOD) are typical biomarkers of oxidative stress and have been frequently investigated. However, the association between exposure to ambient particulate matter (PM) and these biomarkers has not been well established.

OBJECTIVES

Evaluate the association between ambient particulate air pollution and biomarkers of oxidative stress based on existing epidemiological studies.

METHODS

A systematic literature search was conducted in databases of Science Direct, PubMed, Web of Science, and Scopus up to April 24, 2020 to summarize epidemiological studies reporting the association between exposure to ambient PM (PM_2.5, PM₁₀, or both) and biomarkers of oxidative stress, and a meta-analysis was performed for the associations reported in individual studies using a random-effect model.

RESULTS

This meta-analysis included 23 epidemiological studies (13 identified for 8-OHdG, 11 identified for MDA and 5 identified for SOD). A 10 μg/m³ increase in short-term exposure to ambient PM_2.5 was associated with pooled percent changes of 2.10% (95% CIs: -0.13%, 4.38%), 1.60% (95% CIs: 0.21%, 3.01%) and -0.61% (95% CIs: -1.92%, 0.72%) in 8-OHdG, MDA and SOD, respectively.

CONCLUSION

Short-term exposure to ambient PM_2.5 was associated with a significantly increased level of MDA, indicating that ambient particulate air pollution may contribute to increased oxidative stress.

Notch1-mediated inflammation is associated with endothelial dysfunction in human brain microvascular endothelial cells upon particulate matter exposure

Exposure to atmospheric particulate matter (PM) is an emerging risk factor for the pathogenesis of several diseases in humans, including cerebrovascular diseases. However, the mechanisms underlying PM-induced endothelial dysfunction are currently unclear. In this study, we examined how PM leads to endothelial dysfunction in human brain microvascular endothelial cells (HBMECs). We demonstrated that PM₁₀ exposure (up to 25 μg/mL) increase Notch1 cleavage, and it regulates endothelial dysfunction through NICD-mediated inflammation and senescence. PM₁₀-induced NICD signaling causes increased expression of interleukin-1 beta (IL-1β) and enhances characteristics of cellular senescence, which leads to increased endothelial permeability in HBMECs. Knockdown of Notch1 by siRNA blocks PM₁₀-induced endothelial dysfunction via the suppression of inflammation and senescence. Furthermore, we found that Notch1-mediated inflammation accelerates endothelial senescence, which eventually leads to endothelial dysfunction. Altogether, our data suggest that Notch1 and NICD are potential target regulators for the prevention of cerebrovascular endothelial dysfunction induced by ambient air pollutants such as PM.

Identifying the Transcriptional Response of Cancer and Inflammation-Related Genes in Lung Cells in Relation to Ambient Air Chemical Mixtures in Houston, Texas

Atmospheric pollution represents a complex mixture of air chemicals that continually interact and transform, making it difficult to accurately evaluate associated toxicity responses representative of real-world exposure. This study leveraged data from a previously published article and reevaluated lung cell transcriptional response induced by outdoor atmospheric pollution mixtures using field-based exposure conditions in the industrialized Houston Ship Channel. The tested hypothesis was that individual and co-occurring chemicals in the atmosphere relate to altered expression of critical genes involved in inflammation and cancer-related processes in lung cells. Human lung cells were exposed at an air-liquid interface to ambient air mixtures for 4 h, with experiments replicated across 5 days. Real-time monitoring of primary and secondary gas-phase pollutants, as well as other atmospheric conditions, was simultaneously conducted. Transcriptional analysis of exposed cells identified critical genes showing differential expression associated with both individual and chemical mixtures. The individual pollutant identified with the largest amount of associated transcriptional response was benzene. Tumor necrosis factor (TNF) and interferon regulatory factor 1 (IRFN1) were identified as key upstream transcription factor regulators of the cellular response to benzene. This study is among the first to measure lung cell transcriptional responses in relation to real-world, gas-phase air mixtures.

Particulate matter (PM10) enhances RNA virus infection through modulation of innate immune responses

Sensing of pathogens by specialized receptors is the hallmark of the innate immunity. Innate immune response also mounts a defense response against various allergens and pollutants including particulate matter present in the atmosphere. Air pollution has been included as the top threat to global health declared by WHO which aims to cover more than three billion people against health emergencies from 2019 to 2023. Particulate matter (PM), one of the major components of air pollution, is a significant risk factor for many human diseases and its adverse effects include morbidity and premature deaths throughout the world. Several clinical and epidemiological studies have identified a key link between the PM existence and the prevalence of respiratory and inflammatory disorders. However, the underlying molecular mechanism is not well understood. Here, we investigated the influence of air pollutant, PM10 (particles with aerodynamic diameter less than 10 μm) during RNA virus infections using Highly Pathogenic Avian Influenza (HPAI) - H5N1 virus. We thus characterized the transcriptomic profile of lung epithelial cell line, A549 treated with PM10 prior to H5N1infection, which is known to cause severe lung damage and respiratory disease. We found that PM10 enhances vulnerability (by cellular damage) and regulates virus infectivity to enhance overall pathogenic burden in the lung cells. Additionally, the transcriptomic profile highlights the connection of host factors related to various metabolic pathways and immune responses which were dysregulated during virus infection. Collectively, our findings suggest a strong link between the prevalence of respiratory illness and its association with the air quality.

Long-Term Ambient Air Pollution Exposures and Brain Imaging Markers in Korean Adults: The Environmental Pollution-Induced Neurological EFfects (EPINEF) Study

BACKGROUND

Only a limited number of neuroimaging studies have explored the effects of ambient air pollution in adults. The prior studies have investigated only cortical volume, and they have reported mixed findings, particularly for gray matter. Furthermore, the association between nitrogen dioxide (NO2) and neuroimaging markers has been little studied in adults.

OBJECTIVES

We investigated the association between long-term exposure to air pollutants (NO2, particulate matter (PM) with aerodynamic diameters of ≤10μm (PM10) and ≤2.5μm (PM2.5), and neuroimaging markers.

METHODS

The study included 427 men and 530 women dwelling in four cities in the Republic of Korea. Long-term concentrations of PM10, NO2, and PM2.5 at residential addresses were estimated. Neuroimaging markers (cortical thickness and subcortical volume) were obtained from brain magnetic resonance images. A generalized linear model was used, adjusting for potential confounders.

RESULTS

A 10-μg/m3 increase in PM10 was associated with reduced thicknesses in the frontal [-0.02mm (95% CI: -0.03, -0.01)] and temporal lobes [-0.06mm (95% CI: -0.07, -0.04)]. A 10-μg/m3 increase in PM2.5 was associated with a thinner temporal cortex [-0.18mm (95% CI: -0.27, -0.08)]. A 10-ppb increase in NO2 was associated with reduced thicknesses in the global [-0.01mm (95% CI: -0.01, 0.00)], frontal [-0.02mm (95% CI: -0.03, -0.01)], parietal [-0.02mm (95% CI: -0.03, -0.01)], temporal [-0.04mm (95% CI: -0.05, -0.03)], and insular lobes [-0.01mm (95% CI: -0.02, 0.00)]. The air pollutants were also associated with increased thicknesses in the occipital and cingulate lobes. Subcortical structures associated with the air pollutants included the thalamus, caudate, pallidum, hippocampus, amygdala, and nucleus accumbens.

DISCUSSION

The findings suggest that long-term exposure to high ambient air pollution may lead to cortical thinning and reduced subcortical volume in adults. https://doi.org/10.1289/EHP7133.

Effects of PM2.5 on Third Grade Students' Proficiency in Math and English Language Arts

Fine particulate air pollution is harmful to children in myriad ways. While evidence is mounting that chronic exposures are associated with reduced academic proficiency, no research has examined the frequency of peak exposures. It is also unknown if pollution exposures influence academic proficiency to the same degree in all schools or if the level of children's social disadvantage in schools modifies the effects, such that some schools' academic proficiency levels are more sensitive to exposures. We address these gaps by examining the percentage of third grade students who tested below the grade level in math and English language arts (ELA) in Salt Lake County, Utah primary schools (n = 156), where fine particulate pollution is a serious health threat. More frequent peak exposures were associated with reduced math and ELA proficiency, as was greater school disadvantage. High frequency peak exposures were more strongly linked to lower math proficiency in more advantaged schools. Findings highlight the need for policies to reduce the number of days with peak air pollution.

Urban airborne PM2.5-activated microglia mediate neurotoxicity through glutaminase-containing extracellular vesicles in olfactory bulb

Emerging evidence has showed that exposure to airborne particulate matter (PM) with an aerodynamic diameter less than 2.5 μm (PM_2.5) is associated with neurodegeneration. Our previous studies in vitro found that PM_2.5 exposure causes primary neurons damage through activating microglia. However, the molecular mechanism of microglia-mediated neurotoxicity remains to elucidate. In this study, five groups (N = 13 or 10) of six-week-old male C57BL/6 mice were daily exposed to PM_2.5 (0.1 or 1 mg/kg/day body weight), Chelex-treated PM_2.5 (1 mg/kg/day body weight), PM_2.5 (1 mg/kg/day body weight) plus CB-839 (glutaminase inhibitor), or deionized water by intranasal instillation for 28 days, respectively. Compared with the control groups, We found that PM_2.5 triggered reactive oxygen species (ROS) generation and microglia activation evidenced by significant increase of ionized calcium binding adaptor molecule-1 (IBa-1) staining in the mouse olfactory bulbs (OB). Data from transmission electron microscope (TEM) images and Western blot analysis showed that PM_2.5 significantly increased extracellular vesicles (EVs) release from OB or murine microglial line BV2 cells, and glutaminase C (GAC) expression and glutamate generation in isolated OB and BV2 cells. However, treatment with N-acetylcysteine (NAC) or CB-839 significantly diminished the number of EVs and the expression of GAC and abolished PM_2.5-induced neurotoxicity. These findings provide new insights that PM_2.5 induces oxidative stress and microglia activation through its metal contents and glutaminase-containing EVs in OBs, which may serve as a potential pathway/mechanism of excessive glutamate generation in PM_2.5-induced neurotoxicity.

An exploratory evaluation of the potential pulmonary, neurological and other health effects of chronic exposure to emissions from municipal solid waste fires at a large dumpsite in Olusosun, Lagos, Nigeria

Open municipal solid waste (MSW) combustion is a major emission source of particulate air pollution, polycyclic aromatic hydrocarbons, and more exotic hazardous organic pollutants including polychlorinated biphenyls and brominated flame retardants. However, the adverse impact of MSW combustion emission on health among the general population is unknown. Therefore, a cross-sectional study was conducted to explore the associations between potential exposure to MSW combustion-related air pollution and symptoms of adverse health effects among residents of a community adjacent to a large open landfill in Lagos, Nigeria. Using ordinal logistic regression and controlling for age, sex, and smoking, it was observed that residence for ≥ 11 years had increased odds (p < 0.05) of daily occurrence of tingling/numbness/whiteness of fingers (2.614), headaches (2.725), memory problems (2.869), tremor/cramps (2.748), and confusion (3.033) among other symptoms. These results indicate adverse health impacts of chronic exposure to MSW combustion emission.

Association between short-term exposure to ambient air pollution and hospital visits for depression in China

Depression is one of the leading causes of disability, but the etiology remains unclear. Recently, it has been suggested that air pollution is a potential risk factor for depression. However, the results remained inconsistent. So we conducted this study to assess the association between short-term exposure to ambient air pollution and hospital visits for depression in China. Daily hospital visits for depression from January 18, 2013 to June 10, 2018 were extracted from a regional health information system (HIS) covered 1.34 million population in Ningbo, China. We collected daily air pollutant concentrations and meteorological data from environmental air quality monitoring sites and meteorological stations in the study area. Quasi-Poisson regression models with generalized additive models (GAM) were applied to explore the associations between air pollution and hospital visits for depression. Stratified analyses were also conducted by gender, age, and season to examine the effects modification. The results disclosed that air pollutants including PM_2.5, PM₁₀, SO₂, CO, and NO₂ were positively correlated with hospital visits for depression. The strongest effects all occurred on lag0 (the same) day, and the corresponding excess risks (ERs) were 2.59 (95%CI: 0.72, 4.49) for PM_2.5, 3.08 (95%CI: 1.05, 5.16) for PM₁₀, 3.22 (95%CI: 1.16, 5.32) for SO₂, 4.38 (95%CI: 1.83, 6.99) for CO, and 4.94 (95%CI: 2.03, 7.92) for NO₂ per IQR increase, respectively. The associations were found to be stronger in the elderly (≥65 years) and cold season. Furthermore, the effects of CO and NO₂ remained significant in most two-pollutant models, suggesting that traffic-related air pollutants might be more important triggers of depression.

Associations of Air Pollution and Noise with Local Brain Structure in a Cohort of Older Adults

BACKGROUND

Despite the importance of understanding associations of air pollution and noise exposure with loss of neurocognitive performance, studies investigating these exposures and local brain structure are limited.

OBJECTIVE

We estimated associations of residential air pollution and noise exposures with neurocognitive test performance and the local gyrification index (lGI), a marker for local brain atrophy, among older adults.

METHODS

For n=615 participants from the population-based 1000BRAINS study, based on the German Heinz Nixdorf Recall study, we assessed residential exposures to particulate matter (PM10, PM2.5, PM2.5abs), accumulation mode particle number (PNAM), and nitrogen oxides (NOx, NO2), using land-use regression and chemistry transport models. Weighted 24-h and nighttime noise were modeled according to the European noise directive. We evaluated associations of air pollution and noise exposure at the participants' 2006-2008 residential addresses with neurocognitive test performance and region-specific lGI values (n=590) from magnetic resonance imaging, both assessed in 2011-2015, using linear regression and adjusting for demographic and personal characteristics.

RESULTS

Air pollution and noise were associated with language and short-term/working memory and with local atrophy of the fronto-parietal network (FPN), a functional resting-state network associated with these cognitive processes. For example, per 2-μg/m3 PM10, local brain atrophy was more pronounced in the posterior brain regions of the FPN, with a -0.02 [95% confidence interval (CI): -0.04, 0.00] lower lGI. In contrast, in the anterior regions of the FPN, weighted 24-h and nighttime noise were associated with less local brain atrophy [e.g., 0.02 (95% CI: 0.00, 0.04) for 10 dB(A) 24-h noise].

CONCLUSIONS

Air pollution and noise exposures were associated in opposite directions with markers of local atrophy of the FPN in the right brain hemisphere in older adults, suggesting that both chronic air pollution and noise exposure may influence the physiological aging process of the brain. https://doi.org/10.1289/EHP5859.

Concentrated ambient fine particulate matter (PM2.5) exposure induce brain damage in pre and postnatal exposed mice

Air pollution is a public health concern that has been associated with adverse effects on the development and functions of the central nervous system (CNS). However, studies on the effects of exposure to pollutants on the CNS across the entire developmental period still remain scarce. In this study, we investigated the impacts of prenatal and/or postnatal exposure to fine particulate matter (PM_2.5) from São Paulo city, on the brain structure and behavior of juvenile male mice. BALB/c mice were exposed to PM_2.5 concentrated ambient particles (CAP) at a daily concentration of 600 μg/m³ during the gestational [gestational day (GD) 1.5-18.5] and the postnatal periods [postnatal day (PND) 22-90] to filtered air (FA) in both periods (FA/FA), to CAP only in the postnatal period (FA/CAP), to CAP only in the gestational period (CAP/FA), and to CAP in both periods (CAP/CAP). Behavioral tests were performed when animals were at PND 30 and PND 90. Glial activation, brain volume, cortical neuron number, serotonergic and GABAergic receptors, as well as oxidative stress, were measured. Mice at PND 90 presented greater behavioral changes in the form of greater locomotor activity in the FA-CAP and CAP-CAP groups. In general, these same groups explored objects longer and the CAP-FA group presented anxiolytic behavior. There was no difference in total brain volume among groups, but a lower corpus callosum (CC) volume was observed in the CAP-FA group. Also, the CAP-CAP group presented an increase in microglia in the cortex and an increased in astrocytes in the cortex, CC, and C1A and dentate gyrus of hippocampus regions. Gene expression analysis showed a decrease in BDNF in the hippocampus of CAP-CAP group. Treatment of immortalized glial cells with non-cytotoxic doses of ambient PM_2.5 increased micronuclei frequencies, indicating genomic instability. These findings highlight the potential for negative neurodevelopmental outcomes induced by exposure to moderate levels of PM_2.5 in Sao Paulo city.

Attributable risk and economic cost of hospital admissions for mental disorders due to PM2.5 in Beijing

BACKGROUND

Few studies have estimated the attributable risk and economic cost of mental disorders (MDs) due to particulate matters with aerodynamic diameter of <2.5 μm (PM_2.5) exposure in Beijing.

OBJECTIVES

This study aims to identify the possible correlation between PM_2.5 and risk of hospital admissions (HAs) for MDs in Beijing and calculate the attributable risk and economic cost.

METHODS

A generalized additive model (GAM) with controlling for time trend, meteorological conditions, holidays and day of the week was used to estimate the associations. Stratified analyses were performed by age, gender and season. We further estimated the health and economic burden of HAs for MDs attributable to PM_2.5.

FINDINGS

A total of 17,252 HAs for MDs were collected. A 10 μg/m³ daily increase in PM_2.5 was associated with a statistically significant risk increase of 3.55% for HAs for MDs. The effects of PM_2.5 exposures on HAs for MDs were more pronounced in males, elderly (≥65 years old) individuals and in cold seasons. Using WHO's air quality guidelines as the reference, 15.12% of HAs and 16.19% of the related medical expenses for MDs were attributed to PM_2.5 during the study period.

NOVELTY

PM_2.5 accounts for substantial morbidity and economic burden of MDs for both the society and households, which shows environmental protections are essential to improve mental health status of the population.

The relationship between aerosol concentration and atmospheric potential gradient in urban environments

Urban aerosol is a growing concern for people living within cities; aerosol have been implicated in many ill health conditions, including that of the lung and of the heart. Atmospheric potential gradient is a consequence of charge carried to the ionosphere through thunderstorms, and its value depends on highly electrically mobile ion concentrations, hence local conductivity of the air. Ions attach to aerosol in the atmosphere, reducing their mobility and therefore increasing the potential gradient, and so potential gradient measurements have been suggested as a proxy for aerosol measurements. Particle number count, size distribution and potential gradient were measured for two campaigns in Manchester, U.K., and one campaign in Bristol, U.K. Using a factor based on size distribution to account for preferential attachment at larger sizes provided the best relationship with potential gradient, but particle count alone showed a weaker, but similar relationship. The increase in particle count caused by annual bonfire and fireworks celebrations (November) was evidenced in both potential gradient and particle numbers. Daily regression or correlation did not show a consistent relationship. In the larger Bristol data set, increasing humidity led to a reduction of potential gradient, while increasing particle number led to an increase.

Air pollution and hippocampal atrophy in first episode schizophrenia

Air pollution has recently been linked to central nervous system (CNS) diseases, possibly mediated by inflammation and oxidative stress. Hippocampal atrophy in individuals with first episode schizophrenia (FES) has also been associated with biomarkers of inflammation and oxidative stress, whereas hippocampal atrophy was not observed in matched healthy controls with similar biomarker levels of inflammation and oxidative stress. Fine particulate matter (PM2.5), one component of air pollution, is most strongly implicated in CNS disease. The present study examined the association between PM2.5 and hippocampal volume in individuals with FES who participated in a 52-week placebo-controlled clinical trial of citalopram added to clinician-determined antipsychotic treatment at four sites in the US and China. Left hippocampal volumetric integrity (LHVI; inversely related to atrophy) was measured at baseline and week 52 using an automated highly-reliable algorithm. Mean annual PM2.5 concentrations were obtained from records compiled by the World Health Organization. The relationships between baseline LHVI and PM2.5 and change in LHVI and PM2.5 were evaluated using regression analyses. 89 participants completed imaging at baseline and 46 participants completed imaging at week 52. Mean annual PM2.5 was significantly associated with both baseline LHVI and change in LHVI after controlling for age, sex, baseline LHVI, duration of untreated psychosis and baseline antipsychotic medication dose. Air pollution may contribute to the progression of hippocampal atrophy after a first episode of illness, but these findings should be considered preliminary since other unmeasured factors may have differed between cities and contributed to the observed effect.

Hazardous air pollutants are associated with worse performance in reading, math, and science among US primary schoolchildren

Emerging evidence demonstrates that chronic exposure to air pollution may negatively impact children's cognitive processing and memory. Little is currently known about how air pollution impacts individual children's academic performance through time. Academic performance is practically important, given its linkage to children's future life course trajectories. Individual-level, longitudinal data from 16,000 US primary school students are combined with a tract-level hazardous air pollutant (HAP) measure to assess how kindergarten exposures are associated with competencies in reading, math and science through third grade. We employed linear mixed models with repeated measures within children (e.g., five math tests across four years), clustering within census tracts, and random effects specified at the child- and census tract-levels. Controlling for a comprehensive list of time variant and time invariant covariates, we found statistically significant associations between higher levels of HAPs and lower reading (b = -0.02; p < 0.05), math (b = -0.02; p < 0.001), and science (b = -0.05; p < 0.001) scores. These negative effects of pollution on academic competency in the early primary school years add to the weight of evidence that air pollution harms children's academic potential.

Sex differences in the association between exposure to indoor particulate matter and cognitive control among children (age 6-14 years) living near coal-fired power plants

Coal fly ash consists of inhalable particulate matter with varying concentrations of neurotoxic metals. Children living near coal-fired power plants with coal fly ash storage facilities may be exposed to coal fly ash when it escapes as fugitive dust emissions into surrounding communities. Previous research on outdoor particulate matter air pollution of similar aerodynamic diameter (PM₁₀) suggests exposure may be associated with impaired cognitive control. The purpose of this research was to investigate sex-differences in the association between exposure to indoor PM₁₀ and cognitive control among children (n = 221), ages 6-14 years, living near coal-fired power plants with fly ash storage facilities. In an ongoing community-based study, we measured indoor PM₁₀ concentrations in participants' housing units and used performance measures from the BARS (Behavior Assessment and Research System) Continuous Performance Test (CPT) and Selective Attention Test (SAT) to assess neurotoxic effects on cognitive control. In adjusted negative binomial regression models, we found children living in housing units with higher indoor PM₁₀ concentrations had a higher risk of commission errors on the CPT (incidence rate ratio (IRR) = 1.22 per interquartile range difference (IQR = 0.72 μg/m³) in natural log-transformed PM₁₀ concentrations; 95% CI = 1.01, 1.46) and SAT (IRR = 1.14; 95% CI = 1.01, 1.28). Furthermore, child sex modified the association between PM₁₀ concentration and CPT commission errors. Among females, higher PM₁₀ concentration was associated with higher risk of CPT commission errors (IRR = 1.39; 95% CI = 1.06, 1.82), but we found no association among males (IRR = 1.01; 95% CI = 0.79, 1.30). We found no association between PM₁₀ concentrations and CPT or SAT response latency. Our results suggest females living near coal-fired plants with coal fly ash storage facilities may be more susceptible to impaired cognitive control associated with particulate matter exposure. Children living near coal-fired power plants with coal fly ash storage facilities who are exposed to particulate matter may have an increased risk of impulse control problems.

Climate changes reproductive and children's health: a review of risks, exposures, and impacts

Our climate has significantly changed, exceeding what the world has experienced over the last 650,000 years, and has been cited as the most significant health threat of the twenty-first century. Climate change is impacting health in unprecedented ways. While everyone is vulnerable to the health impacts associated with climate change, children are disproportionately affected because of their physical and cognitive immaturity. Climate change impacts that include rising temperatures, extreme weather, rising sea levels, and increasing carbon dioxide levels are associated with a wide range of health issues in children such as asthma, allergies, vector-borne diseases, malnutrition, low birth weight, and post-traumatic stress disorder. Pediatric health providers play a critical role in advancing the science and translating findings to improve public understanding about the link between climate changes and children's health, and establishing strategies to address these issues. This review will provide an overview of research exploring the impact of climate change on children's health impacts, as well as provide recommendations for pediatric research moving forward.

Acute versus Chronic Exposures to Inhaled Particulate Matter and Neurocognitive Dysfunction: Pathways to Alzheimer's Disease or a Related Dementia

An estimated 92% of the world's population live in regions where people are regularly exposed to high levels of anthropogenic air pollution. Historically, research on the effects of air pollution have focused extensively on cardiovascular and pulmonary health. However, emerging evidence from animal and human studies has suggested that chronic exposures to air pollution detrimentally change the functioning of the central nervous system with the result being proteinopathy, neurocognitive impairment, and neurodegenerative disease. Case analyses of aging World Trade Center responders suggests that a single severe exposure may also induce a neuropathologic response. The goal of this report was to explore the neuroscientific support for the hypothesis that inhaled particulate matter might cause an Alzheimer's-like neurodegenerative disease, in order to consider proposed mechanisms and latency periods linking inhaled particulate matter and neurodegeneration, and to propose new directions in this line of research.

Increased Dementia Mortality in West Virginia Counties with Mountaintop Removal Mining?

Atmospheric particulate matter (PM) is elevated in areas of mountaintop removal mining (MTM), a practice that has been ongoing in some counties of West Virginia (WV) USA since the 1970s. PM inhalation has been linked to central nervous system pathophysiology, including cognitive decline and dementia. Here we compared county dementia mortality statistics in MTM vs. non-MTM WV counties over a period spanning 2001–2015. We found significantly elevated age-adjusted vascular or unspecified dementia mortality/100,000 population in WV MTM counties where, after adjusting for socioeconomic variables, dementia mortality was 15.60 (±3.14 Standard Error of the Mean (S.E.M.)) times higher than that of non-MTM counties. Further analyses with satellite imaging data revealed a highly significant positive correlation between the number of distinct mining sites vs. both mean and cumulative vascular and unspecified dementia mortality over the 15 year period. This was in contrast to finding only a weak relationship between dementia mortality rates and the overall square kilometers mined. No effect of living in an MTM county was found for the rate of Alzheimer’s type dementia and possible reasons for this are considered. Based on these results, and the current literature, we hypothesize that inhalation of PM associated with MTM contributes to dementia mortality of the vascular or unspecified types. However, limitations inherent in ecological-type studies such as this, preclude definitive extrapolation to individuals in MTM-counties at this time. We hope these findings will inspire follow-up cohort and case-controlled type studies to determine if specific causative factors associated with living near MTM can be identified. Given the need for caregiving and medical support, increased dementia mortality of the magnitude seen here could, unfortunately, place great demands upon MTM county public health resources in the future.

The Impact of Inhaled Ambient Ultrafine Particulate Matter on Developing Brain: Potential Importance of Elemental Contaminants

Epidemiological studies report associations between air pollution (AP) exposures and several neurodevelopmental disorders including autism, attention deficit disorder, and cognitive delays. Our studies in mice of postnatal (human third trimester brain equivalent) exposures to concentrated ambient ultrafine particles (CAPs) provide biological plausibility for these associations, producing numerous neuropathological and behavioral features of these disorders, including male-biased vulnerability. These findings raise questions about the specific components of AP that underlie its neurotoxicity, which our studies suggest could involve trace elements as candidate neurotoxicants. X-ray fluorescence analyses of CAP chamber filters confirm contamination of AP exposures by multiple elements, including iron (Fe) and sulfur (S). Correspondingly, laser ablation inductively coupled plasma mass spectrometry of brains of male mice indicates marked postexposure elevations of Fe and S and other elements. Elevations of brain Fe and S in particular are consistent with potential ferroptotic, oxidative stress, and altered antioxidant capacity-based mechanisms of CAPs-induced neurotoxicity, supported by observations of increased serum oxidized glutathione and increased neuronal cell death in nucleus accumbens with no corresponding significant increase in caspase-3, in male brains following postnatal CAP exposures. Understanding the role of trace element contaminants of particulate matter AP as a source of neurotoxicity is critical for public health protection.

Prenatal and early life exposures to ambient air pollution and development

BACKGROUND

Residential proximity to major roadways, and prenatal exposures to particulate matter <2.5 μm (PM_2.5) and ozone (O₃) are linked to poor fetal outcomes but their relationship with childhood development is unclear.

OBJECTIVES

We investigated whether proximity to major roadways, or prenatal and early-life exposures to PM_2.5 and O₃ increase the risk of early developmental delays.

STUDY DESIGN

Prospective cohort.

SETTINGS

New York State excluding New York City.

PARTICIPANTS

4089 singletons and 1016 twins born between 2008 and 2010.

EXPOSURES

Proximity to major roadway was calculated using road network data from the NY Department of Transportation. Concentrations of PM_2.5 and O₃ estimated by the Environmental Protection Agency Downscaler models were spatiotemporally linked to each child's prenatal and early-life addresses incorporating residential history, and locations of maternal work and day-care.

OUTCOMES

Parents reported their children's development at ages 8, 12, 18, 24, 30 and 36 months in five domains using the Ages and Stages Questionnaire. Generalized mixed models estimated the relative risk (RR) and 95% CI for failing any developmental domain per 10 units increase in PM_2.5 and O₃, and for those living <1000 m away from a major roadway compared to those living further. Models adjusted for potential confounders.

RESULTS

Compared to those >1000 m away from a major roadway, those resided 50-100 m [RR: 2.12 (1.00-4.52)] and 100-500 m [RR: 2.07 (1.02-4.22)] away had twice the risk of failing the communication domain. Prenatal exposures to both PM_2.5 and ozone during various pregnancy windows had weak but significant associations with failing any developmental domain with effects ranging from 1.6% to 2.7% for a 10 μg/m³ increase in PM_2.5 and 0.7%-1.7% for a 10 ppb increase in ozone. Average daily postnatal ozone exposure was positively associated with failing the overall screening by 8 months [3.3% (1.1%-5.5%)], 12 months [17.7% (10.4%-25.5%)], and 30 months [7.6%, (1.3%-14.3%)]. Findings were mixed for postnatal PM_2.5 exposures.

CONCLUSIONS

In this prospective cohort study, proximity to major roadway and prenatal/early-life exposures to PM_2.5 and O₃ were associated with developmental delays. While awaiting larger studies with personal air pollution assessment, efforts to minimize air pollution exposures during critical developmental windows may be warranted.

Healthy Air, Healthy Brains: Advancing Air Pollution Policy to Protect Children's Health

Evidence is growing on the adverse neurodevelopmental effects of exposure to combustion-related air pollution. Project TENDR (Targeting Environmental Neurodevelopmental Risks), a unique collaboration of leading scientists, health professionals, and children's and environmental health advocates, has identified combustion-related air pollutants as critical targets for action to protect healthy brain development. We present policy recommendations for maintaining and strengthening federal environmental health protections, advancing state and local actions, and supporting scientific research to inform effective strategies for reducing children's exposures to combustion-related air pollution. Such actions not only would improve children's neurological development but also would have the important co-benefit of climate change mitigation and further improvements in other health conditions.

Air pollution and brain health: defining the research agenda

PURPOSE OF REVIEW

The literature on air pollution and brain health is rapidly expanding and it is a universal finding that greater exposure to air pollution is associated with worse outcomes, whatever the measure of brain health used (clinical dementia, neuroimaging correlates, or cognitive impairment). However, there are a number of important questions which the studies currently published are not able to answer: when in the life course does exposure to air pollution most have the most impact?; which pollutant(s) or components are most important?; and since dementia describes a heterogeneous group of conditions, which is most affected by exposure to air pollution?

RECENT FINDINGS

We briefly review and discuss the nine articles which have been published so far in 2018, so recently that they were not included in the four review articles also published this year. We highlight the variation in estimates of air pollution used but the consistency in deriving them from residential address (with or without some knowledge of an individual's previous home locations).

SUMMARY

We are now at the stage when the research agenda needs to be agreed and we believe these three questions should be the focus of future research.

Association between ambient air pollution and hospital admission for epilepsy in Eastern China

BACKGROUND

We aimed to study the short-term association between air pollutants and hospitalization for epilepsy in 47 hospitals from 10 cities in eastern China.

METHOD

We identified hospital epilepsy admissions in 2014 and 2015. A conditional Poisson regression model was used to examine the association between air pollutants and hospital admission, with temperature and relative humidity adjusted using the natural spline (ns) function. Pollutants included sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), and particulate matter (PM). The association was stratified by sex, age, and geographic region in single-pollutant and two-pollutant models.

RESULTS

An interquartile (IQR) increase of NO₂ and CO on the concurrent day is correlated with an increased admission of 2.0% (0.5%, 3.6%) and 1.1% (0.1%, 2.1%), respectively. The association is stronger in children (≤18 years) and in northern China, but did not vary with sex. A positive association was also observed on the previous day for CO [1.5%, 95% confidence interval (CI): 0.3%, 2.6%], NO₂ (2.5%, 95% CI: 0.6%, 4.3%), and PM_2.5 (1.32%, 95% CI: 0.16%, 2.48%). Moving average concentration of 7 days for all pollutants was associated with decreased admission (CO: -1.29%, NO₂: -0.4.69%, SO₂:-2.12%, PM_2.5:-0.98%, PM₁₀:-1.70%).

CONCLUSION

Exposures to NO₂ and CO on concurrent days, and PM_2.5 on the previous day, are associated with increased epilepsy hospitalization, whereas cumulative exposure appeared protective.

Risk of exposure to air pollution among British children with and without intellectual disabilities

BACKGROUND

Exposure to outdoor air pollution is a well-established risk factor for a range of adverse health conditions. No previous study has quantified the extent to which children with intellectual disability (ID) may be exposed to outdoor air pollution.

METHODS

Secondary analysis of data extracted from the UK's Millennium Cohort Study, a nationally representative sample of over 18 000 UK children born 2000-2002.

RESULTS

Averaging across ages, children with IDs were 33% more likely to live in areas with high levels of diesel particulate matter, 30% more likely to live in areas with high levels of nitrogen dioxide, 30% more likely to live in areas with high levels of carbon monoxide and 17% more likely to live in areas with high levels of sulphur dioxide.

CONCLUSIONS

Levels of exposure to outdoor air pollution among children with ID are significantly higher than those of families of children without ID. Exposure to outdoor air pollution may be one of the pathways that contributes to the health inequities experienced by people with IDs.

Long-Term Exposure to Ambient Hydrocarbons Increases Dementia Risk in People Aged 50 Years and above in Taiwan

BACKGROUND

Alzheimer's disease, the most common cause of dementia among the elderly, is a progressive and irreversible neurodegenerative disease. Exposure to air pollutants is known to have adverse effects on human health, however, little is known about hydrocarbons in the air that can trigger a dementia event.

OBJECTIVE

We aimed to investigate whether long-term exposure to airborne hydrocarbons increases the risk of developing dementia.

METHOD

The present cohort study included 178,085 people aged 50 years and older in Taiwan. Cox proportional hazards regression analysis was used to fit the multiple pollutant models for two targeted pollutants, including total hydrocarbons and non-methane hydrocarbons, and estimated the risk of dementia.

RESULTS

Before controlling for multiple pollutants, hazard ratios with 95% confidence intervals for the overall population were 7.63 (7.28-7.99, p <0.001) at a 0.51-ppm increases in total hydrocarbons, and 2.94 (2.82-3.05, p <0.001) at a 0.32-ppm increases in non-methane hydrocarbons. The highest adjusted hazard ratios for different multiple-pollutant models of each targeted pollutant were statistically significant (p <0.001) for all patients: 11.52 (10.86-12.24) for total hydrocarbons and 9.73 (9.18-10.32) for non-methane hydrocarbons.

CONCLUSION

Our findings suggest that total hydrocarbons and non-methane hydrocarbons may be contributing to dementia development.

Developmental exposure to low level ambient ultrafine particle air pollution and cognitive dysfunction

Developmental exposures to ambient ultrafine particles (UFPs) can produce multiple neuropathological and neurochemical changes that might contribute to persistent alterations in cognitive-type functions. The objective of the current study was to test the hypothesis that developmental UFP exposure produced impairments in learning, memory and impulsive-like behaviors and to determine whether these were selective and thus independent of deficits in other behavioral domains such as motor activity or motivation. Performance on measures of learning (repeated learning), memory (novel object recognition, NOR), impulsive-like behavior (differential reinforcement of low rate (DRL), schedule of reward and delay of reward (DOR)), motor activity (locomotor behavior) and motivation (progressive ratio schedule) were examined in adult mice that had been exposed to concentrated (10-20x) ambient ultrafine particles (CAPS) averaging approximately 45 ug/m3 particle mass concentrations from postnatal day (PND) 4-7 and 10-13 for 4 h/day. Given the number of behavioral tests, animals were tested in different groups. Results showed male-specific alterations in learning and memory functions (repeated learning, NOR and DRL) specifically during transitions in reinforcement contingencies (changes in rules governing behavior) that did not appear to be related to alterations in locomotor function or motivation. Females did not exhibit cognitive-like deficits at these exposure concentrations, but displayed behaviors consistent with altered motivation, including increases in response rates during repeated learning, significantly increased latencies to respond on the delay of reward paradigm, and reductions in the progressive ratio break point. Consistent with our prior findings, male-specific learning and memory-related deficits were seen and occurred even at relatively low level developmental UFP exposures, while females show alterations in motivational behaviors but not final performance. These findings add to the evidence suggesting the need to regulate UFP levels.

Impact of Maternal Air Pollution Exposure on Children's Lung Health: An Indian Perspective

Air pollution has become an emerging invisible killer in recent years and is a major cause of morbidity and mortality globally. More than 90% of the world’s children breathe toxic air every day. India is among the top ten most highly polluted countries with an average PM₁₀ level of 134 μg/m³ per year. It is reported that 99% of India’s population encounters air pollution levels that exceed the World Health Organization Air Quality Guideline, advising a PM_2.5 permissible level of 10 μg/m³. Maternal exposure to air pollution has serious health outcomes in offspring because it can affect embryonic phases of development during the gestation period. A fetus is more prone to effects from air pollution during embryonic developmental phases due to resulting oxidative stress as antioxidant mechanisms are lacking at that stage. Any injury during this vulnerable period (embryonic phase) will have a long-term impact on offspring health, both early and later in life. Epidemiological studies have revealed that maternal exposure to air pollution increases the risk of development of airway disease in the offspring due to impaired lung development in utero. In this review, we discuss cellular mechanisms involved in maternal exposure to air pollution and how it can impact airway disease development in offspring. A better understanding of these mechanisms in the context of maternal exposure to air pollution can offer a new avenue to prevent the development of airway disease in offspring.

PM2.5 levels strongly associate with multiple sclerosis prevalence in the Province of Padua, Veneto Region, North-East Italy

Background:

Incidence and prevalence trends of multiple sclerosis (MS) in the Province of Padua, North-East Italy, suggest that environmental factors may be associated with increased MS risk.

Objective:

To investigate the association of PM2.5 with MS prevalence in one of the most polluted geographical area of Italy.

Methods:

In total, 1435 Italian MS patients residing in the Province of Padua were enrolled. The province surface was classified into urban areas, isolated villages, industrialized places, and countryside. Satellite-derived dust-free and sea salt-free PM2.5 concentrations (annual average 1998–2015, μg/m3) allowed the identification of 18 classes of territorial sections with statistically evaluable numbers of inhabitants. Possible correlations between residential locality types, PM2.5 concentrations, and MS prevalence were investigated.

Results:

MS prevalence was significantly ( p < 0.0001) higher in urban areas (ranging from 219 in Padua City to 169/100,000 in other urban areas) compared to isolated villages (116/100,000) or rural domains (109/100,000) and strongly correlated with the annual average concentration of PM2.5 ( r = 0.81, p < 0.001). Regression analysis further associated MS cases with PM.2.5 average concentration ( β = 0.11, p < 0.001).

Conclusion:

In the Province of Padua, MS prevalence is strongly associated with PM2.5 exposure suggesting that air pollutants may be one of the possible environmental risk factors for MS.

Road traffic noise, air pollution, and risk of dementia - results from the Betula project

BACKGROUND

There is growing evidence for a negative impact of traffic-related air pollution on risk of dementia. However, the contribution of noise exposure to this association has been rarely examined.

OBJECTIVE

We aimed to investigate the individual and combined effect of noise and air pollution on risk of dementia.

METHODS

Data on dementia incidence over a 15 year period was obtained from the Betula project, a longitudinal study on health and ageing. Estimates of annual mean levels of nitrogen oxides (NO_x) at the participants' residential address were obtained using a land-use regression model. Modelled data provided road traffic noise levels (Leq. 24 h) at the participants' residential address at baseline. Cox proportional hazard regression was used to calculate hazard ratios (HR).

RESULTS

Of 1721 participants at baseline, 302 developed dementia during the follow up period. Exposure to noise levels (Leq. 24 h) > 55 dB had no significant effect on dementia risk (HR 0.95; CI: 0.57, 1.57). Residing in the two highest quartiles of NO_x exposure was associated with an increased risk of dementia. The risk associated with NO_x was not modified by adjusting for noise. Moreover, we found no significant interaction effects between NO_x and road traffic noise on dementia risk.

CONCLUSION

We found no evidence that exposure to road traffic noise, either independently or in combination with traffic air pollution, was associated with risk of dementia in our study area. Our results suggest that pollution should be considered the main component in the association between traffic related exposures and dementia.

Long-term exposure to air pollution and the incidence of multiple sclerosis: A population-based cohort study

BACKGROUND

Evidence of the adverse neurological effects of exposure to ambient air pollution is emerging, but little is known about its effect on the development of multiple sclerosis (MS), the most common autoimmune disease of the central nervous system.

OBJECTIVES

To investigate the associations between MS incidence and long-term exposures to fine particles (PM_2.5), nitrogen dioxide (NO₂), and ozone (O₃) METHODS: We conducted a population-based cohort study to investigate the associations between long-term exposures to PM_2.5, NO₂, and O₃ and the incidence of MS. Our study population included all Canadian-born residents aged 20-40 years who lived in the province of Ontario, Canada from 2001 to 2013. Incident MS was ascertained from a validated registry. We assigned estimates of annual concentrations of these pollutants to the residential postal codes of subjects for each year during the 13 years of follow-up. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for each pollutant separately using random-effects Cox proportional hazards models. We conducted various sensitivity analyses, such as lagging exposure up to 5 years and adjusting for access to neurological care, annual average temperature, and population density.

RESULTS

Between 2001 and 2013, we identified 6203 incident cases of MS. The adjusted HR of incident MS was 0.96 (95% CI: 0.86-1.07) for PM_2.5, 0.91(95% CI: 0.81-1.02) for NO₂, and 1.09 (95% CI: 0.98-1.23) for O₃. These results were robust to various sensitivity analyses conducted.

CONCLUSIONS

In this large population-based cohort, we did not observe significant associations between MS incidence and long-term exposures to PM_2.5, NO₂, and O₃ in adults in Ontario, 2001-2013.

Acute effects of ambient particulate matter pollution on hospital admissions for mental and behavioral disorders: A time-series study in Shijiazhuang, China

Until now, few epidemiological studies have focused on the association between ambient particulate matter pollution and mental and behavioral disorders, especially in developing countries. Thus, a time-series study on the short-term association between both fine and inhalable particles (PM_2.5 and PM₁₀) and daily hospital admissions for mental and behavioral disorders in Shijiazhuang, China was conducted, from 2014 to 2016. An over-dispersed, generalized additive model was used to analyze the associations after controlling for time trend, weather conditions, day of the week, and holidays. In addition, the modification effects of age, sex, and season were estimated. A total of 9156 cases of hospital admissions for mental and behavioral disorders were identified. A 10 μg/m³ increase in a 3-day average concentration (lag02) of PM_2.5 and PM₁₀ correspond to an increase of 0.48% (95% confidence interval (CI): 0.18-0.79%) and 0.32% (95% CI: 0.03-0.62%) in daily hospital admission for mental and behavioral disorders, respectively. We found stronger associations of PM_2.5 and PM₁₀ with mental and behavioral disorders in male and elder individuals (≥45 years) than in female and younger individuals (<45 years). Further, results indicated a generally stronger association of PM_2.5 with mental and behavioral disorders in the cool season than in the warm season. This research found a significant association between ambient PM_2.5 and PM₁₀ and hospital admission for mental and behavioral disorders in Shijiazhuang, China.

Creating individual level air pollution exposures in an anonymised data safe haven: a platform for evaluating impact on educational attainment

Introduction

There is a lack of evidence on the adverse effects of air pollution on cognition for people with air quality-related health conditions. We propose that educational attainment, as a proxy for cognition, may increase with improved air quality. This study will explore whether asthma and seasonal allergic rhinitis, when exacerbated by acute exposure to air pollution, is associated with educational attainment.

Objective

To describe the preparation of individual and household-level linked environmental and health data for analysis within an anonymised safe haven. Also to introduce our statistical analysis plan for our study: COgnition, Respiratory Tract illness and Effects of eXposure (CORTEX).

Methods

We imported daily air pollution and aeroallergen data, and individual level education data into the SAIL databank, an anonymised safe haven for person-based records. We linked individual-level education, socioeconomic and health data to air quality data for home and school locations, creating tailored exposures for individuals across a city. We developed daily exposure data for all pupils in repeated cross sectional exam cohorts (2009-2015).

Conclusion

We have used the SAIL databank, an innovative, data safe haven to create individual-level exposures to air pollution and pollen for multiple daily home and school locations. The analysis platform will allow us to evaluate retrospectively the impact of air quality on attainment for multiple cross-sectional cohorts of pupils. Our methods will allow us to distinguish between the pollution impacts on educational attainment for pupils with and without respiratory health conditions. The results from this study will further our understanding of the effects of air quality and respiratory-related health conditions on cognition.

Highlights

Cross-sectional and longitudinal analyses of outdoor air pollution exposure and cognitive function in UK Biobank

Observational studies have shown consistently increased likelihood of dementia or mild cognitive impairment diagnoses in people with higher air pollution exposure history, but evidence has been less consistent for associations with cognitive test performance. We estimated the association between baseline neighbourhood-level exposure to airborne pollutants (particulate matter and nitrogen oxides) and (1) cognitive test performance at baseline and (2) cognitive score change between baseline and 2.8-year follow-up, in 86,759 middle- to older-aged adults from the UK Biobank general population cohort. Unadjusted regression analyses indicated small but consistent negative associations between air pollutant exposure and baseline cognitive performance. Following adjustment for a range of key confounders, associations were inconsistent in direction and of very small magnitude. The largest of these indicated that 1 interquartile range higher air pollutant exposure was associated on average with 0.35% slower reaction time (95% CI: 0.13, 0.57), a 2.92% higher error rate on a visuospatial memory test (95% CI: 1.24, 4.62), and numeric memory scores that were 0.58 points lower (95% CI: -0.96, -0.19). Follow-up analyses of cognitive change scores did not show evidence of associations. The findings indicate that in this sample, which is five-fold larger than any previous cross-sectional study, the association between air pollution exposure and cognitive performance was weak. Ongoing follow-up of the UK Biobank cohort will allow investigation of longer-term associations into old age, including longitudinal tracking of cognitive performance and incident dementia outcomes.

The emerging risk of exposure to air pollution on cognitive decline and Alzheimer's disease - Evidence from epidemiological and animal studies

As incidence of Alzheimer's disease (AD) and other neurodegenerative diseases rise, there is increasing interest in environmental factors which may contribute to disease onset and progression. Air pollution has been known as a major health hazard for decades. While its effects on cardiopulmonary morbidity and mortality have been extensively studied, growing evidence has emerged that exposure to polluted air is associated with impaired cognitive functions at all ages and increased risk of AD and other dementias in later life; this association is particularly notable with traffic related pollutants such as nitrogen dioxide, nitrous oxide, black carbon, and small diameter airborne solids and liquids known as particulate matter. The exact mechanisms by which air pollutants mediate neurotoxicity in the central nervous system (CNS) and lead to cognitive decline and AD remain largely unknown. Studies using animal and cell culture models indicate that amyloid-beta processing, anti-oxidant defense, and inflammation are altered following the exposure to constituents of polluted air. In this review, we summarize recent evidence supporting exposure to air pollution as a risk for cognitive decline at all ages and AD at later lifetime. Additionally, we review the current body of work investigating the molecular mechanisms by which air pollutants mediate damage in the CNS. Understanding of the neurotoxic effects of air pollution and its constituents is still limited, and further studies will be essential to better understand the cellular and molecular mechanisms linking air pollution and cognitive decline.

Coarse particulate matter (PM2.5-10) in Los Angeles Basin air induces expression of inflammation and cancer biomarkers in rat brains

Air pollution is linked to brain inflammation, which accelerates tumorigenesis and neurodegeneration. The molecular mechanisms that connect air pollution with brain pathology are largely unknown but seem to depend on the chemical composition of airborne particulate matter (PM). We sourced ambient PM from Riverside, California, and selectively exposed rats to coarse (PM_2.5–10: 2.5–10 µm), fine (PM_<2.5: <2.5 µm), or ultrafine particles (UFPM: <0.15 µm). We characterized each PM type via atomic emission spectroscopy and detected nickel, cobalt and zinc within them. We then exposed rats separately to each PM type for short (2 weeks), intermediate (1–3 months) and long durations (1 year). All three metals accumulated in rat brains during intermediate-length PM exposures. Via RNAseq analysis we then determined that intermediate-length PM_2.5–10 exposures triggered the expression of the early growth response gene 2 (EGR2), genes encoding inflammatory cytokine pathways (IL13-Rα1 and IL-16) and the oncogene RAC1. Gene upregulation occurred only in brains of rats exposed to PM_2.5–10 and correlated with cerebral nickel accumulation. We hypothesize that the expression of inflammation and oncogenesis-related genes is triggered by the combinatorial exposure to certain metals and toxins in Los Angeles Basin PM_2.5–10.

The role of perceived air pollution and health risk perception in health symptoms and disease: a population-based study combined with modelled levels of PM10

Purpose

Adverse health impact of air pollution on health may not only be associated with the level of exposure, but rather mediated by perception of the pollution and by top-down processing (e.g. beliefs of the exposure being hazardous), especially in areas with relatively low levels of pollutants. The aim of this study was to test a model that describes interrelations between air pollution (particles < 10 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\upmu }$$\end{document}μm, PM₁₀), perceived pollution, health risk perception, health symptoms and diseases.

Methods

A population-based questionnaire study was conducted among 1000 Estonian residents (sample was stratified by age, sex, and geographical location) about health risk perception and coping. The PM₁₀ levels were modelled in 1 × 1 km grids using a Eulerian air quality dispersion model. Respondents were ascribed their annual mean PM₁₀ exposure according to their home address. Path analysis was performed to test the validity of the model.

Results

The data refute the model proposing that exposure level significantly influences symptoms and disease. Instead, the perceived exposure influences symptoms and the effect of perceived exposure on disease is mediated by health risk perception. This relationship is more pronounced in large cities compared to smaller towns or rural areas.

Conclusions

Perceived pollution and health risk perception, in particular in large cities, play important roles in understanding and predicting environmentally induced symptoms and diseases at relatively low levels of air pollution.

Neurodevelopmental and neurological effects of chemicals associated with unconventional oil and natural gas operations and their potential effects on infants and children

Heavy metals (arsenic and manganese), particulate matter (PM), benzene, toluene, ethylbenzene, xylenes (BTEX), polycyclic aromatic hydrocarbons (PAHs) and endocrine disrupting chemicals (EDCs) have been linked to significant neurodevelopmental health problems in infants, children and young adults. These substances are widely used in, or become byproducts of unconventional oil and natural gas (UOG) development and operations. Every stage of the UOG lifecycle, from well construction to extraction, operations, transportation and distribution can lead to air and water contamination. Residents near UOG operations can suffer from increased exposure to elevated concentrations of air and water pollutants. Here we focus on five air and water pollutants that have been associated with potentially permanent learning and neuropsychological deficits, neurodevelopmental disorders and neurological birth defects. Given the profound sensitivity of the developing brain and central nervous system, it is reasonable to conclude that young children who experience frequent exposure to these pollutants are at particularly high risk for chronic neurological diseases. More research is needed to understand the extent of these concerns in the context of UOG, but since UOG development has expanded rapidly in recent years, the need for public health prevention techniques, well-designed studies and stronger state and national regulatory standards is becoming increasingly apparent.

The Association of Long-Term Exposure to Particulate Matter Air Pollution with Brain MRI Findings: The ARIC Study

BACKGROUND

Increasing evidence links higher particulate matter (PM) air pollution exposure to late-life cognitive impairment. However, few studies have considered associations between direct estimates of long-term past exposures and brain MRI findings indicative of neurodegeneration or cerebrovascular disease.

OBJECTIVE

Our objective was to quantify the association between brain MRI findings and PM exposures approximately 5 to 20 y prior to MRI in the Atherosclerosis Risk in Communities (ARIC) study.

METHODS

ARIC is based in four U.S. sites: Washington County, Maryland; Minneapolis suburbs, Minnesota; Forsyth County, North Carolina; and Jackson, Mississippi. A subset of ARIC participants underwent 3T brain MRI in 2011-2013 (n=1,753). We estimated mean exposures to PM with an aerodynamic diameter less than 10 or 2.5μm (PM₁₀ and PM_2.5) in 1990-1998, 1999-2007, and 1990-2007 at the residential addresses of eligible participants with MRI data. We estimated site-specific associations between PM and brain MRI findings and used random-effect, inverse variance-weighted meta-analysis to combine them.

RESULTS

In pooled analyses, higher mean PM_2.5 and PM₁₀ exposure in all time periods were associated with smaller deep-gray brain volumes, but not other MRI markers. Higher PM_2.5 exposures were consistently associated with smaller total and regional brain volumes in Minnesota, but not elsewhere.

CONCLUSIONS

Long-term past PM exposure in was not associated with markers of cerebrovascular disease. Higher long-term past PM exposures were associated with smaller deep-gray volumes overall, and higher PM_2.5 exposures were associated with smaller brain volumes in the Minnesota site. Further work is needed to understand the sources of heterogeneity across sites. https://doi.org/10.1289/EHP2152.

Ambient air pollution and daily hospital admissions for mental disorders in Shanghai, China

Few studies have investigated the associations between ambient air pollution and mental disorders (MDs), especially in developing countries. We conducted a time-series study to explore the associations between six criteria air pollutants and daily hospital admissions for MDs in Shanghai, China, from 2013 to 2015. The MDs data were derived from the Shanghai Health Insurance System. We used over-dispersed, generalized additive models to estimate the associations after controlling for time trend, weather conditions, day of the week, and holidays. In addition, we evaluated the effect of modification by age, sex, and season. A total of 39,143 cases of hospital admissions for MDs were identified during the study period. A 10-μg/m³ increase in 2-day, moving-average concentration of inhalable particulate matter, sulfur dioxide (SO₂), and carbon monoxide was significantly associated with increments of 1.27% [95% confidence interval (CI): 0.28%, 2.26%], 6.88% (95% CI, 2.75%, 11.00%), and 0.16% (95% CI: 0.02%, 0.30%) in daily hospital admissions for MDs, respectively. We observed positive but insignificant associations of fine particulate matter, nitrogen dioxide and ozone. The estimated association of SO₂ was relatively robust to the adjustment of simultaneous exposure to other pollutants. We found generally stronger associations of air pollutants with MDs in warm seasons than in cool seasons. There were no significant differences in the associations between different sex and age groups. This study suggested that short-term exposure to air pollution, especially to sulfur dioxide, was associated with increased risk of hospital admissions for MDs in Shanghai, China.