Air pollution and hospitalization for epilepsy in Chile

Association of outdoor air and noise pollution with unprovoked seizures and new onset epilepsy: A systematic review and meta-analysis

Research has indicated that certain environmental exposures may increase the risk of unprovoked seizures and new onset epilepsy. This study aimed to synthesize the literature that has estimated the associations between short- and long-term exposure to outdoor air and noise pollution and the risk of unprovoked seizures and new onset epilepsy. We searched Embase, MEDLINE, Scopus, Web of Science, BIOSIS Previews, Latin American and Caribbean Health Sciences Literature, Proquest Dissertations and Theses, conference abstracts, and the gray literature and conducted citation tracing in June 2023. Observational and ecological studies assessing the associations of air and noise pollution with unprovoked seizures or new onset epilepsy were eligible. One reviewer extracted summary data. Using fixed and random effects models, we calculated the pooled risk ratios (RRs) for the studies assessing the associations between short-term exposure to air pollution and unprovoked seizures. Seventeen studies were included, 16 assessing the association of air pollution with seizures and one with epilepsy. Eight studies were pooled quantitatively. Ozone (O3; RR = .99, 95% confidence interval [CI] = .99-.99) and nitrogen dioxide (NO2) exposure adjusted for particulate matter (RR = 1.02, 95% CI = 1.01-1.02) on the same day, and carbon monoxide (CO) exposure 2 days prior (RR = 1.12, 95% CI = 1.02-1.22), were associated with seizure risk. A single study of air pollution and epilepsy did not report a significant association. The risk of bias and heterogeneity across studies was moderate or high. Short-term exposure to O3, NO2, and CO may affect the risk of seizures; however, the effect estimates for O3 and NO2 were minimal. Additional research should continue to explore these and the associations between outdoor air pollution and epilepsy and between noise pollution and seizures and epilepsy.

Zinc Oxide Nanoparticles Exacerbate Epileptic Seizures by Modulating the TLR4-Autophagy Axis

Background

Zinc oxide nanoparticles (ZnO NPs) has been widely used in various fields and has had an important impact on human public health. In addition, it inevitably damages human health, including neurological diseases. Therefore, this study explored the effect of ZnO NPs on epilepsy.

Methods

The effect of ZnO NPs on epilepsy was observed by behavioral analysis. TLR4 expression and autophagy related pathways were detected by RNA-seq and Western blot. In addition, the cell types of autophagy were detected by immunofluorescence. Further, the electrophysiological changes of ZnO NPs induced autophagy were detected by whole-cell patch-clamp. Finally, the recovery experiment was carried out by TLR4 inhibitor (TAK-242).

Results

We found that ZnO NPs enhanced epilepsy susceptibility and severity. Through RNA-seq analysis and Western blot, it was found that ZnO NPs affected the changes of TLR4 and autophagy related pathways. In addition, we found that ZnO NPs mainly affects autophagy of inhibitory neurons, resulting in excitation/inhibition imbalance. The autophagy and epileptic phenotypes were reversed with TAK-242. In general, ZnO NPs exacerbate epileptic seizures by modulating the TLR4-autophagy axis.

Conclusion

ZnO NPs enhanced the susceptibility and severity of epilepsy. Mechanistically, ZnO NPs affected autophagy by changing the expression of TLR4. In particular, the ZnO NPs mainly affected the synaptic function of inhibitory neuron, leading to excitation/inhibition imbalances.

Metabolomic alterations in healthy adults traveling to low-pollution areas: A natural experiment with ozone exposure

Numerous epidemiological studies have demonstrated links between short-term ozone exposure to various adverse health outcomes, but some ozone-induced pathological mechanisms remain unclear. To fill this knowledge gap, we enrolled 36 healthy young adults living in high-ozone areas and performed an untargeted metabolomic analysis in serum collected before, during, and after their travel to a low-ozone scenic area. Reviewing the literature, we found 16 metabolites significantly associated with ozone, pointing to neurological health, type 2 diabetes (T2D) risk, and cardiovascular health. Notably, we observed significant changes in these 16 metabolites from the ozone reduction when participants traveled from the campus to the scenic area (adjusted p-value < 0.05). However, when ozone increased after participants returned to campus from the scenic area, we observed that T2D risk and cardiovascular health-related metabolites returned to their original state (adjusted p-value < 0.05), but neurological health-related metabolites did not change significantly with ozone exposure. Our study showed that ozone exposure was linked to prompt alterations in serum metabolites related to cardiovascular health and T2D risk but less sensitive changes in neurological health-related metabolites. Among many lipids, free fatty acids and acylcarnitines were the most sensitive compounds positively associated with changes in ozone exposure.

The Effect of Maternal Exposure to Air Pollutants and Heavy Metals during Pregnancy on the Risk of Neurological Disorders Using the National Health Insurance Claims Data of South Korea

The objective of this study was to evaluate the effects of high levels of maternal exposure to ambient air pollution and heavy metals on risks of autism spectrum disorder (ASD) and epilepsy using the National Health Insurance claims data of South Korea. The data of mothers and their newborns from 2016 to 2018 provided by the National Health Insurance Service were used (n = 843,134). Data on exposure to ambient air pollutants (PM2.5, CO, SO₂, NO₂, and O₃) and heavy metals (Pb, Cd, Cr, Cu, Mn, Fe, Ni, and As) during pregnancy were matched based on the mother's National Health Insurance registration area. SO₂ (OR: 2.723, 95% CI: 1.971-3.761) and Pb (OR: 1.063, 95% CI: 1.019-1.11) were more closely associated with the incidence of ASD when infants were exposed to them in the third trimester of pregnancy. Pb (OR: 1.109, 95% CI: 1.043-1.179) in the first trimester of pregnancy and Cd (OR: 2.193, 95% CI: 1.074-4.477) in the third trimester of pregnancy were associated with the incidence of epilepsy. Thus, exposure to SO₂, NO₂, and Pb during pregnancy could affect the development of a neurologic disorder based on the timing of exposure, suggesting a relationship with fetal development. However, further research is needed.

Hospital admission risks and excess costs for neurological symptoms attributable to long-term exposure to fine particulate matter in New York State, USA

BACKGROUND

Although emerging evidence suggests that PM_2.5 is linked to neurological symptoms (NSs) via neuroinflammation, relevant studies are scarce. This study aimed to investigate the risks and excess costs of hospital admission for five NSs-fatigue, headache, dizziness, convulsion, and paralysis-attributable to long-term exposure to PM_2.5 in New York State, USA.

METHODS

We analyzed the New York Statewide Planning and Research Cooperative System (SPARCS) from 2010 to 2016. A Bayesian hierarchical model with integrated nested Laplace approximations was performed to estimate the risks and excess costs of hospital admission for NSs due to long-term exposure to PM_2.5 at the county level.

RESULTS

A 1 μg/m³ increase in lag 0-1 years PM_2.5 was associated with an increased risk of headache and convulsion by 1.06 (1.01, 1.11) and 1.04 (1.01, 1.06), respectively. The excess hospital admission cost for five NSs attributable to lag 0-1 years PM_2.5 above the new World Health Organization guideline (annual standard: 5 μg/m³) was $200.24 (95% CI: 6.00, 376.96) million during 2011-2016, recording the highest for convulsion ($153.73 [95% CI: 63.61, 244.19] million).

CONCLUSIONS

This study provides quantitative estimates of risks and excess costs for NSs attributable to long-term PM_2.5 and suggests that policies that reduce long-term PM_2.5 concentration in accordance with the new WHO air quality guidelines can yield substantial health and economic benefits related to NSs in the New York State population.

Ambient air pollution and the risk of neurological diseases in residential areas near multi-purposed industrial complexes of korea: A population-based cohort study

Emerging evidence suggest that long-term exposure to air pollution may induce adverse effects on the central nervous system. However, no study explored the associations in large industrial complex (IC) areas which are one of the major contributors to air pollution. Therefore, we aimed to investigate the pollution status and the association between residential proximity and incidence of neurological diseases near two major ICs characterized as multi-purposed ICs in Korea. A retrospective cohort of residents near the ICs was constructed using Korea's health insurance data and monitored from 2008 to 2019. Emission amounts of the ICs and the air pollution status in the nearby (exposed) and remote (control) area were evaluated using data from national regulatory networks, and hazard ratios (HRs) and 95% confidence intervals (CIs) for neurological diseases of the exposed group compared to the control group were calculated using Cox proportional regression models. Overall, the complexes emitted large amounts of VOCs, CO, NOx, and PM10, and annual levels of ambient PM (2.5, 10), gaseous substances (NO₂, SO₂), VOCs and PAHs were higher in the exposed area compared to the control and/or the national average. The risk of inflammatory disease of the CNS (G00-09) and extrapyramidal and movement disorders (G20-26) were higher in the exposed area with a HR (95% CI) of 1.36 (1.10-1.68) and 1.33 (1.27-1.39) respectively. Among the subclasses, other extrapyramidal and movement disorders (G25) and epilepsy (G40) were associated with higher risks in the exposed area (HR (95%CI): 1.11 (1.04-1.18), 1.08 (1.00-1.16)) after adjusting for potential confounders. These results suggest that people living near ICs are more likely to be exposed to higher air pollution levels and have higher risks of developing several neurological disorders. However, further epidemiological studies in these industrial areas supplemented with other indicators of environmental exposure and control of other diverse factors are warranted.

Short-term effect of air pollution on childhood epilepsy in eastern China: A space-time-stratified case-crossover and pooled analysis

BACKGROUND

Growing studies suggest that air pollution exposure is an emerging driver for neurological diseases, but existing evidence on the association between air pollution and epilepsy is scarce. Here, we aimed to quantitatively estimated the short-term effects of various air pollutants on childhood epilepsy hospitalizations in China.

METHODS

We obtained daily electronic health records on childhood epilepsy hospitalizations and air pollutants (PM_2.5, PM_10-2.5, PM₁₀, SO₂, NO₂, O₃) from 2016 through 2018 in 10 cities of Anhui Province in China. In the first stage, a space-time-stratified case-crossover analysis was employed to evaluate the short-term association of childhood epilepsy hospitalizations with each air pollutant in Anhui Province. In the second stage, short-term effect of air pollution on childhood epilepsy morbidity reported in Anhui Province and in previous studies was pooled with a random-effect meta-analysis model to get the overall effect of different air pollutants in eastern China.

RESULTS

This study included 8,181 childhood epilepsy patients from 10 cities in Anhui province of China. The first stage case-crossover analysis in Anhui province found significant associations between higher concentrations of all air pollutants (except O₃) and increased risk of childhood epilepsy hospitalizations. Each 10 μg/m³ increase in PM_2.5, PM_10-2.5, PM₁₀, SO₂, and NO₂ concentrations was associated with an increase of 1.1 % [95 % confidence interval (CI): 0.1 %-2.1 %], 1.7 % (95 %CI: 0.5 %-2.9 %), 0.8 % (95 %CI: 0.1 %-1.4 %), 8.5 % (95 %CI: 1.5 %-16.0 %), and 4.3 % (95 %CI: 2.3 %-6.3 %) in epilepsy hospitalizations, respectively. We also observed greater effects of particulate matter in cold season. The second stage meta-analysis that additionally included two prior studies with 43,002 patients from other 11 cities found a marginally significant increase in childhood epilepsy attacks associated with PM_2.5, PM₁₀, and NO₂ in eastern China.

CONCLUSIONS

Short-term exposure to both particulate matter and gaseous air pollution was associated with an increased risk of childhood epilepsy exacerbation in eastern China. Our findings suggest that air pollution exposure especially in cold season needs to be considered by children's parents or guardians to prevent epilepsy attacks.

Different components of air pollutants and neurological disorders

The harmful effects of air pollution can cause various diseases. Most research on the hazards of air pollution focuses on lung and cardiovascular diseases. In contrast, the impact of air pollution on neurological disorders is not widely recognized. Air pollution can cause various neurological conditions and diseases, such as neural inflammation, neurodegeneration, and cerebrovascular barrier disorder; however, the mechanisms underlying the neurological diseases induced by various components of air pollutants remain unclear. The present paper summarizes the effects of different components of air pollutants, including particulate matter, ozone, sulfur oxides, carbon oxides, nitrogen oxides, and heavy metals, on the nervous system and describes the impact of various air pollutants on neurological disorders, providing ideas for follow-up research.

Air Pollution and Hospital Admission for Epilepsy in Kerman, Iran

Background: This study aimed to investigate the relation between air pollution and epilepsy admissions in Kerman, Iran. Methods: In this ecological study, the concentrations of ambient air pollutants and meteorological data were obtained from Kerman Environmental Protection Agency and Kerman Meteorology Organization, respectively. Additionally, epilepsy admission data were obtained from Kerman’s Shafa hospital epilepsy registry. Generalized additive models with lags up to 7 days were used to estimate rate ratios (RRs). Results: Within 2008 to 2020, 894 epilepsy admissions occurred in Kerman, 498 cases (55.7%) of whom were male. The strongest relations of epilepsy admission were observed in the over 59-year group for carbon monoxide (CO) in lag 0 (RR = 2.1455, 95% CI: 1.5823 - 2.9091), nitrogen dioxide (NO2) in lag 0 (RR = 1.0409, 95% CI: 1.0282 - 1.0537), and particulate matter under 2.5 microns (PM2.5) in lag 5 (RR = 1.0157, 95% CI: 1.0062 - 1.0252). There were also significant associations for particulate matter under 10 microns (PM10) in the under 18-year group in lag 2 (RR = 1.0064, 95% CI: 1.0029 - 1.0098), ozone in lag 0 (RR = 0.9671, 95% CI: 0.9581 - 0.9761), and sulfur dioxide in lag 5 (RR = 0.9937, 95% CI: 0.9891 - 0.9983). Conclusions: Exposure to CO, NO2, PM2.5, or PM10 air pollutants might be a risk factor for epilepsy admissions in Kerman. Epilepsy patients should better stay away from exposure to polluted air. Staying at home on polluted days or residing in areas with less air pollution might be an option.

Environmental Pollutants and Oxidative Stress in Terrestrial and Aquatic Organisms: Examination of the Total Picture and Implications for Human Health

There is current great international concern about the contribution of environmental pollution to the global burden of disease particularly in the developing, low- and medium-income countries. Industrial activities, urbanization, developmental projects as well as various increased anthropogenic activities involving the improper generation, management and disposal of pollutants have rendered today’s environment highly polluted with various pollutants. These pollutants include toxic metals (lead, cadmium, mercury, arsenic), polycyclic aromatic hydrocarbons, polychlorinated biphenyls, pesticides and diesel exhaust particles most of which appear to be ubiquitous as well as have long-term environmental persistence with a wide range of toxicities such as oxidative stress among others. Oxidative stress, which may arise from increased production of damaging free radicals emanating from increased pollutant burden and depressed bioavailability of antioxidant defenses causes altered biochemical and physiological mechanisms and has been implicated in all known human pathologies most of which are chronic. Oxidative stress also affects both flora and fauna and plants are very important components of the terrestrial environment and significant contributors of nutrients for both man and animals. It is also remarkable that the aquatic environment in which sea animals and creatures are resident is also highly polluted, leading to aquatic stress that may affect the survival of the aquatic animals, sharing in the oxidative stress. These altered terrestrial and aquatic environments have an overarching effect on human health. Antioxidants neutralize the damaging free radicals thus, they play important protective roles in the onset, progression and severity of the unmitigated generation of pollutants that ultimately manifest as oxidative stress. Consequently, human health as well as that of aquatic and terrestrial organisms may be protected from environmental pollution by mitigating oxidative stress and employing the principles of nutritional medicine, essentially based on antioxidants derived mainly from plants, which serve as the panacea of the vicious state of environmental pollutants consequently, the health of the population. Understanding the total picture of oxidative stress and integrating the terrestrial and aquatic effects of environmental pollutants are central to sustainable health of the population and appear to require multi-sectoral collaborations from diverse disciplinary perspectives; basically the environmental, agricultural and health sectors.

Urban air pollution and emergency department visits related to central nervous system diseases

Ambient air pollution has been associated with adverse neurological health outcomes. Ambient pollutants are thought to trigger oxidative stress and inflammation to which vulnerable populations, such as elderly may be particularly susceptible. Our study investigated the possible association between concentrations of ambient air pollutants and the number of emergency department (ED) visits for nervous system disorders among people residing in a large Canadian city. A time-stratified case-crossover study design combining data from the National Ambulatory Care Reporting System (NACRS) and the National Air Pollution Surveillance (NAPS) between 2004 and 2015 was used. Two air quality health indices were considered in additional to specific pollutants, including carbon monoxide (CO), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), ozone (O₃) and fine particulate matter (PM_2.5). Weather condition data were included in the models. ED visits with a discharge diagnosis were identified using ICD-10 codes (G00-G99). The analysis was stratified by sex and age, also by seasons. The associations were investigated in arrays organized as 18 strata and 15 time lags (in days) for each pollutant. Overall, 140,511 ED visits were included for the analysis. Most ED visits were related to episodic and paroxysmal diagnoses (G40-G47, 64%), with a majority of visits for migraines (G43, 39%). Among females, an increase of 0.1ppm ambient CO was associated with an increased risk of paroxysmal diagnoses at day 1 (RR = 1.019 (95%CI 1.004–1.033)), day 6 (1.024 (1.010–1.039)) and day 7 (1.022 (1.007–1.036). PM_2.5 and SO₂, and air quality indices were similarly associated with ED visits for episodic and paroxysmal disorders in days 6 and 7. Findings highlight that ambient air pollution is associated with an increased number of ED visits for nervous system disorders, particularly visits for paroxysmal diagnoses.

Association between social deprivation and incidence of first seizures and epilepsy: a prospective population based cohort

OBJECTIVE

Epidemiologic studies have investigated whether social deprivation is associated with a higher incidence of epilepsy and results are conflicting, especially in children. The mechanisms underlying a potential association are unclear. This study examines whether there is an association between social deprivation and the incidence of first seizures (unprovoked and provoked) and new diagnosis of epilepsy by comparing incidence across an area-level measure of deprivation in a population-based cohort.

METHODS

Multiple methods of case identification followed by individual case validation and classification were carried out in a defined geographical area (population 542,868) to identify all incident cases of first provoked and first unprovoked seizures and new diagnosis of epilepsy presenting during the calendar year 2017. An area-level relative deprivation index, based on ten indicators from census data, was assigned to each patient according to registered address and categorised into quintiles from most to least deprived.

RESULTS

The annual incidence of first unprovoked seizures (n=372), first provoked seizures (n=189) and new diagnosis of epilepsy (n=336) was highest in the most deprived areas compared to the least deprived areas (incidence ratios of 1·79 (95%CI 1·26, 2·52), 1·55 (95%CI 1·04, 2·32) and 1·83 (95%CI 1·28, 2·62), respectively). This finding was evident in both adults and children and in those with structural and unknown aetiologies of epilepsy.

SIGNIFICANCE

The incidence of first seizures and new diagnosis of epilepsy is associated with more social deprivation. The reason for this higher incidence is likely multifactorial.

Ambient air pollution and epileptic seizures: a panel study in Australia

OBJECTIVE

Emerging evidence has shown that ambient air pollution affects brain health, but little is known about its effect on epileptic seizures. This work aimed to assess the association between daily exposure to ambient air pollution and the risk of epileptic seizures.

METHODS

This study used epileptic seizure data from two independent data sources (NeuroVista and Seer App seizure diary). In the NeuroVista dataset, 3273 seizures were recorded using intracranial electroencephalography (iEEG) from 15 participants with refractory focal epilepsy in Australia in 2010-2012. In the seizure diary dataset, 3419 self-reported seizures were collected through a mobile application from 34 participants with epilepsy in Australia in 2018-2021. Daily average concentrations of carbon monoxide (CO), nitrogen dioxide (NO₂ ), ozone (O₃ ), particulate matter ≤10 μm in diameter (PM₁₀ ), and sulfur dioxide (SO₂ ) were retrieved from the Environment Protection Authority (EPA) based on participants' postcodes. A patient-time-stratified case-crossover design with the conditional Poisson regression model was used to determine the associations between air pollutants and epileptic seizures.

RESULTS

A significant association between CO concentrations and epileptic seizure risks was observed, with an increased seizure risk of 4% (relative risk [RR]: 1.04, 95% confidence interval [CI]: 1.01-1.07) for an interquartile range (IQR) increase of CO concentrations (0.13 parts per million), while no significant associations were found for the other four air pollutants in the whole study population. Females had a significantly increased risk of seizures when exposing to elevated CO and NO₂ , with RR of 1.05 (95% CI: 1.01-1.08) and 1.09 (95% CI: 1.01-1.16), respectively. Additionally, a significant association was observed between CO and the risk of subclinical seizures (RR: 1.20, 95% CI: 1.12-1.28).

SIGNIFICANCE

Daily exposure to elevated CO concentrations may be associated with the increased risk of epileptic seizures, especially for subclinical seizures.

Multivariate analysis of the impact of weather and air pollution on emergency department visits for unprovoked seizure among children: A retrospective clinical observational study

BACKGROUND

An unprovoked seizure is a seizure or a cluster of seizures occurring within 24 h in a patient older than 1 month of age without precipitating factors. Recent studies have reported that extrinsic factors, such as meteorological conditions and air pollutants, may be important in seizure occurrence. Thus, this study aimed to examine the association between the number of visits to the emergency department (ED) by children for nighttime unprovoked seizures and exposure to multi-faceted factors, such as meteorological conditions and air pollution.

METHODS

We conducted a clinical observational analysis and reviewed consecutive patients younger than 16 years of age who visited the primary ED center in Kobe City, Japan, during nighttime (7:30 p.m.-7:00 a.m.) between January 1, 2011 and December 31, 2015. We investigated the effects of meteorological factors and air pollutants on the number of patients with unprovoked seizures using multivariate analysis of Poisson regression estimates.

RESULTS

In total, 151,119 children visited the ED, out of which 97 patients presented with unprovoked seizures. The mean age of the patients was 4.7 years (range, 1 month to 15.3 years), and 54.6% of them were boys. The total number of patients with unprovoked seizures showed no significant changes with the seasons; however, there were dominant peaks during the fall and fewer visits during the summer. The multivariate analysis of Poisson regression estimates revealed a significant positive relationship between the number of patients presenting with unprovoked seizures and precipitation (+1 patient/87 mm; p = 0.03) and methane (+1 patient/0.14 ppm; p = 0.03) levels and a negative relationship between the number of patients presenting with unprovoked seizures and nitrogen dioxide level (-1 patient/0.02 ppm; p = 0.04).

CONCLUSIONS

The present study is the first to evaluate the association between the number of children who presented to the ED with nighttime unprovoked seizures and environmental factors after controlling for confounding factors.

Impact of 4th of July Fireworks on Spatiotemporal PM2.5 Concentrations in California Based on the PurpleAir Sensor Network: Implications for Policy and Environmental Justice

Fireworks are often used in celebration, causing short term, extremely high particulate matter air pollution. In recent years, the rapid development and expansion of low-cost air quality sensors by companies such as PurpleAir has enabled an understanding of air pollution at a much higher spatiotemporal resolution compared to traditional monitoring networks. In this study, real-time PM2.5 measurements from 751 PurpleAir sensors operating from June to July in 2019 and 2020 were used to examine the impact of 4th of July fireworks on hourly and daily PM2.5 concentrations at the census tract and county levels in California. American Community Survey (ACS) and CalEnviroScreen 3.0 data were used to identify correlations between PM2.5 measurements and socioeconomic status (SES). A two-step method was implemented to assure the quality of raw PM2.5 sensor data and sensor calibration against co-located reference instruments. The results showed that over 67% and 81% of counties experienced immediate impacts related to fireworks in 2019 and 2020, respectively. Relative to 2019, the peak PM2.5 concentrations on July 4th and 5th 2020 were, on average, over 50% higher in California, likely due to the COVID-19-related increase in the use of household-level fireworks. This increase was most pronounced in southern counties, which tend to have less strict firework-related regulations and a greater use of illegal fireworks. Los Angeles County experienced the highest July 4th daily PM2.5 levels both in 2019 (29.9 µg·m-3) and 2020 (42.6 µg·m-3). Spatial hot spot analyses generally showed these southern counties (e.g., Los Angeles County) to be regional air pollution hotspots, whereas the opposite pattern was seen in the north (e.g., San Francisco). The results also showed PM2.5 peaks that were over two-times higher among communities with lower SES, higher minority group populations, and higher asthma rates. Our findings highlight the important role that policy and enforcement can play in reducing firework-related air pollution and protecting public health, as exemplified by southern California, where policy was more relaxed and air pollution was higher (especially in 2020 when the 4th of July coincided with the COVID-19-lockdown period), and in disadvantaged communities where disparities were greatest.

Predicting PM2.5 and PM10 Levels during Critical Episodes Management in Santiago, Chile, with a Bivariate Birnbaum-Saunders Log-Linear Model

Improving air quality is an important environmental challenge of our time. Chile currently has one of the most stable and emerging economies in Latin America, where human impact on natural resources and air quality does not go unperceived. Santiago, the capital of Chile, is one of the cities in which particulate matter (PM) levels exceed national and international limits. Its location and climate cause critical conditions for human health when interaction with anthropogenic emissions is present. In this paper, we propose a predictive model based on bivariate regression to estimate PM levels, related to PM2.5 and PM10, simultaneously. Birnbaum-Saunders distributions are used in the joint modeling of real-world PM2.5 and PM10 data by considering as covariates some relevant meteorological variables employed in similar studies. The Mahalanobis distance is utilized to assess bivariate outliers and to detect suitability of the distributional assumption. In addition, we use the local influence technique for analyzing the impact of a perturbation on the overall estimation of model parameters. In the predictions, we check the categorization for the observed and predicted cases of the model according to the primary air quality regulations for PM.

The effect of weather, air pollution and seasonality on the number of patient visits for epileptic seizures: A population-based time-series study

OBJECTIVE

The objective of the study was to explore the influences of seasonality, meteorological conditions, and air pollution exposure on the number of patients who visit the hospital due to seizures.

METHODS

Outpatient and inpatient data from the National Health Insurance Database of Taiwan from 2009 to 2013, meteorological data from the Meteorological Bureau, and air pollution exposure data from the Taiwan Air Quality Monitoring Stations were collected and integrated into daily time series data. The following data processing and analysis results are based on the mean of the 7 days' lag data of the 18 meteorological condition/air pollution exploratory factors to identify the critical meteorological conditions and air pollution exposure factors by executing univariate analysis. The average hospital visits for seizure per day by month were used as an index of observation. The effect of seasonality has also been examined.

RESULTS

The average visits per day by month had a significant association with 10 variables. Overall, the number of visits due to these factors has been estimated to be 71.529 (13.7%). The most obvious factors affecting the estimated number of visits include ambient temperature, CH₄, and NO. Six air pollutants, namely CH₄, NO, CO, NO₂, PM2.5, and NMHC had a significantly positive correlation with hospital visits due to seizures. Moreover, the average daily number of hospital visits was significantly high in January and February (winter season in Taiwan) than in other months (R² = 0.422).

CONCLUSION

The prediction model obtained in this study indicates the necessity of rigorous monitoring and early warning of these air pollutants and climate changes by governments. Additionally, the study provided a firm basis for establishing prediction models to be used by other countries or for other diseases.

Brain Disorders and Chemical Pollutants: A Gap Junction Link?

The incidence of brain pathologies has increased during last decades. Better diagnosis (autism spectrum disorders) and longer life expectancy (Parkinson's disease, Alzheimer's disease) partly explain this increase, while emerging data suggest pollutant exposures as a possible but still underestimated cause of major brain disorders. Taking into account that the brain parenchyma is rich in gap junctions and that most pollutants inhibit their function; brain disorders might be the consequence of gap-junctional alterations due to long-term exposures to pollutants. In this article, this hypothesis is addressed through three complementary aspects: (1) the gap-junctional organization and connexin expression in brain parenchyma and their function; (2) the effect of major pollutants (pesticides, bisphenol A, phthalates, heavy metals, airborne particles, etc.) on gap-junctional and connexin functions; (3) a description of the major brain disorders categorized as neurodevelopmental (autism spectrum disorders, attention deficit hyperactivity disorders, epilepsy), neurobehavioral (migraines, major depressive disorders), neurodegenerative (Parkinson's and Alzheimer's diseases) and cancers (glioma), in which both connexin dysfunction and pollutant involvement have been described. Based on these different aspects, the possible involvement of pollutant-inhibited gap junctions in brain disorders is discussed for prenatal and postnatal exposures.

Ambient air pollution and its influence on human health and welfare: an overview

Human health is closely related to his environment. The influence of exposure to air pollutants on human health and well-being has been an interesting subject and gained much volume of research over the last 50 years. In general, polluted air is considered one of the major factors leading to many diseases such as cardiovascular and respiratory disease and lung cancer for the people. Besides, air pollution adversely affects the animals and deteriorates the plant environment. The overarching objective of this review is to explore the previous researches regarding the causes and sources of air pollution, how to control it and its detrimental effects on human health. The definition of air pollution and its sources were introduced extensively. Major air pollutants and their noxious effects were detailed. Detrimental impacts of air pollution on human health and well-being were also presented.

Ambient Air Pollution Increases the Risk of Cerebrovascular and Neuropsychiatric Disorders through Induction of Inflammation and Oxidative Stress

Exposure to ambient air pollution is a well-established determinant of health and disease. The Lancet Commission on pollution and health concludes that air pollution is the leading environmental cause of global disease and premature death. Indeed, there is a growing body of evidence that links air pollution not only to adverse cardiorespiratory effects but also to increased risk of cerebrovascular and neuropsychiatric disorders. Despite being a relatively new area of investigation, overall, there is mounting recent evidence showing that exposure to multiple air pollutants, in particular to fine particles, may affect the central nervous system (CNS) and brain health, thereby contributing to increased risk of stroke, dementia, Parkinson's disease, cognitive dysfunction, neurodevelopmental disorders, depression and other related conditions. The underlying molecular mechanisms of susceptibility and disease remain largely elusive. However, emerging evidence suggests inflammation and oxidative stress to be crucial factors in the pathogenesis of air pollution-induced disorders, driven by the enhanced production of proinflammatory mediators and reactive oxygen species in response to exposure to various air pollutants. From a public health perspective, mitigation measures are urgent to reduce the burden of disease and premature mortality from ambient air pollution.

Effect modification of the short-term effects of air pollution on morbidity by season: A systematic review and meta-analysis

Studies of the health effects of air pollution have traditionally controlled for ambient temperature as a confounder, and vice versa. However, season might be an important factor contributing to adverse health effects of air pollution. Given the current inconsistencies in results of previous studies on the effect modification of air pollution on morbidity by season, a systematic review and meta-analysis was conducted to synthesize the current evidence on effects of season on air pollution and morbidity. The electronic databases including PubMed, Web of Science, Embase, CNKI, and Wanfang were used to identify papers published up to the 30st of November in 2019. We identified 4284 articles, after screening, eighty papers met the inclusion criteria. Significant effect modification of CO, O₃, SO₂ and NO₂ on morbidity by season was observed, with corresponding ratio of relative risk of 1.0009 (95% CI: 1.0001-1.0018), 1.0080 (95% CI: 1.0021-1.0138), 0.9828 (95% CI: 0.9697-0.9962) and 0.9896 (95% CI: 0.9824-0.9968), respectively. Season significantly modified the effect of CO on pneumonia, the effect of SO₂ on cardiovascular disease, the effect of PM₁₀ on stroke, and the effect of O₃ on stroke, asthma and pneumonia. The effect modifications of air pollution by season were similar among males and females, while the effect estimates seem to be higher among children under 18 years old and the elderly aged 75 or over. Further research is needed to better understand the mechanisms underlying the seasonal variance of the effect of air pollutants on morbidity.

Exposure to carbon black nanoparticles increases seizure susceptibility in male mice

Carbon black nanoparticles (CBNPs) can enter the central nervous system through blood circulation and olfactory nerves, affecting brain development or increasing neurological disease susceptibility. However, whether CBNPs exposure affects seizure is unclear. Herein, mice were exposed to two different doses of CBNPs (21 and 103 μg/animal) based on previous studies and the maximum exposure limitation (4 mg/m³) in occupational workplaces set by the Chinese government. In the pentylenetetrazol (PTZ) and kainic acid (KA) seizure models, high-dose CBNPs exposure increased seizure susceptibility in both models and increased spontaneous recurrent seizure (SRS) frequency in the KA model. In vivo local field potential (LFP) recording in KA model mice revealed that both low-dose and high-dose CBNPs exposure increased seizure-like event (SLE) frequency in the SRS interval but shortened SLE duration. Intriguingly, H&E staining and Nissl staining on brain tissue revealed that CBNPs exposure did not cause significant brain tissue morphology or neuronal damage. Detection of inflammatory factors, such as TNF-α, TGF-β1, IL-1β, and IL-6, in brain tissue showed that only high dose of CBNPs exposure increased the expression of cortical TGF-β1. By using the primary cultured neurons, we observed that CBNPs exposure not only significantly decreased the expression of the neuronal marker MAP2 but also enhanced the levels of action potential frequency in the neurons. In general, CBNPs exposure can affect abnormal epileptic discharges during the seizure interval and enhance susceptibility to frequent seizures. Our findings suggest that minimizing CBNPs exposure may be a potential way to prevent or ease seizure.

Impact of Air Pollution and Seasonal Haze on Neurological Conditions: A Review

Introduction: Air pollution is a global problem and seasonal haze from forest clearing and peat land burning in Indonesia is an annual phenomenon in Southeast Asia. As neurological disorders comprise 6.3% of the burden of disease globally, we reviewed evidence of the association between common neurological conditions and air pollution exposure, and summarised existing data on the impact of the haze phenomenon in Southeast Asia. Materials and Methods: A PubMed search for relevant studies on air pollution, Alzheimer’s disease (AD), dementia, epilepsy, haze, headache, migraine, stroke, Parkinson’s disease (PD) and neuromuscular conditions was performed. There were 52 articles which were relevant and were reviewed. Results: There were associations between short-term air pollution exposure with AD, epilepsy, ischaemic stroke and migraine. Long-term air pollution exposure was associated with AD, amyotrophic lateral sclerosis, dementia and ischaemic stroke. Evidence on the link between air pollution and PD was inconsistent. Currently, there is no specific data on the effects haze has on neurological conditions in Southeast Asia. Conclusion: Air pollution is associated with increased risk of certain common neurological disorders. More specific studies are needed to investigate the impact of seasonal haze on neurological conditions in Southeast Asia. Key words: Alzheimer’s disease, Epilepsy, Migraine, Parkinson’s disease, Stroke

Climate change and epilepsy: Time to take action

Climate change is the biggest challenge facing humanity today. The associated global warming and humidification, increases in the severity and frequency of extreme climate events, extension of the ranges of vector-borne diseases, and the consequent social and economic stresses and disruption will have major negative consequences on many aspects of health care. People whose resilience to change is already impaired may suffer disproportionately from these environmental changes, which are of unprecedented reach and magnitude. There has been little connection made so far between climate change and epilepsy. We briefly review the history of climate change science and the subsequent response of the global scientific community. We consider how climate change effects might in general affect health and disease. We consider some of the underlying complex interactions that, for example, favor the spread of vector-borne diseases and how climate models operate and may help plan for global and local changes. We then speculate specifically on how these generic ideas may apply specifically to epilepsy. We consider these impacts at levels from molecular to the epidemiological. Data are sparse, and there is undoubtedly a need for more information to enable better estimation of possible effects of climate change on care in epilepsy. We also consider how the professional activities of those involved in epilepsy health care might contribute to global carbon emissions, for example, through flying for conference attendance. Healthcare organizations across the world are already considering, and responding to, many of these issues. We argue for more research in this area, but also for action today. Actions today are likely to generate cobenefits for health care, including care in epilepsy, resulting from efforts to decarbonize, mitigate effects of climate change that has already happened, and plan for adaptation to climate change.

Respiratory gases, air pollution and epilepsy

A growing number of studies have shown that exposure to air pollutants such as particulate matter and gases can cause cardiovascular, neurodegenerative and psychiatric diseases. The severity of the changes depends on several factors such as exposure time, age and gender. Inflammation has been considered as one of the main factors associated with the generation of these diseases. Here we present some cellular mechanisms activated by air pollution that may represent risk factors for epilepsy and drug resistance associated to epilepsy.

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.

Air pollution and risk of hospitalization for epilepsy: the role of farm use of nitrogen fertilizers and emissions of the agricultural air pollutant, nitrous oxide

ABSTRACT The link between various air pollutants and hospitalization for epilepsy has come under scrutiny. We have proposed that exposure to air pollution and specifically the pervasive agricultural air pollutant and greenhouse gas, nitrous oxide (N2O), may provoke susceptibility to neurodevelopmental disorders. Evidence supports a role of N2O exposure in reducing epileptiform seizure activity, while withdrawal from the drug has been shown to induce seizure-like activity. Therefore, we show here that the statewide use of anthropogenic nitrogen fertilizers (the most recognized causal contributor to environmental N2O burden) is significantly negatively associated with hospitalization for epilepsy in all three pre-specified hospitalization categories, even after multiple pollutant comparison correction (p<.007), while the other identified pollutants were not consistently statistically significantly associated with hospitalization for epilepsy. We discuss potential neurological mechanisms underpinning this association between air pollutants associated with farm use of anthropogenic nitrogen fertilizers and hospitalization for epilepsy.

Endocannabinoid 2-arachidonoylglycerol protects inflammatory insults from sulfur dioxide inhalation via cannabinoid receptors in the brain

Sulfur dioxide (SO₂) pollution in the atmospheric environment causes brain inflammatory insult and inflammatory-related microvasculature dysfunction. However, there are currently no effective medications targeting the harmful outcomes from chemical inhalation. Endocannabinoids (eCBs) are involved in neuronal protection against inflammation-induced neuronal injury. The 2-arachidonoylglycerol (2-AG), the most abundant eCBs and a full agonist for cannabinoid receptors (CB1 and CB2), is also capable of suppressing proinflammatory stimuli and improving microvasculature dysfunction. Here, we indicated that endogenous 2-AG protected against neuroinflammation in response to SO₂ inhalation by inhibiting the activation of microglia and astrocytes and attenuating the overexpression of inflammatory cytokines, including tumor necrosis factor alpha (TNF-a), interleukin (IL)-1β, and inducible nitric oxide synthase (iNOS). In addition, endogenous 2-AG prevented cerebral vasculature dysfunction following SO₂ inhalation by inhibiting endothelin 1 (ET-1), vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) expression, elevating endothelial nitric oxide synthase (eNOS) level, and restoring the imbalance between thromboxane A2 (TXA2) and prostaglandin I2 (PGI2). In addition, the action of endogenous 2-AG on the suppression of inflammatory insult and inflammatory-related microvasculature dysfunction appeared to be mainly mediated by CB1 and CB2 receptors. Our results provided a mechanistic basis for the development of new therapeutic approaches for protecting brain injuries from SO₂ inhalation.

Chile Confronts its Environmental Health Future After 25 Years of Accelerated Growth

BACKGROUND

Chile has recently been reclassified by the World Bank from an upper-middle-income country to a high-income country. There has been great progress in the last 20 to 30 years in relation to air and water pollution in Chile. Yet after 25 years of unrestrained growth, there remain clear challenges posed by air and water pollution, as well as climate change.

OBJECTIVE

The aim of this study was to review environmental health in Chile.

METHODS

In late 2013, a 3-day workshop on environmental health was held in Santiago, Chile, bringing together researchers and government policymakers. As a follow-up to that workshop, here we review the progress made in environmental health in the past 20 to 30 years and discuss the challenges of the future. We focus on air and water pollution and climate change, which we believe are among the most important areas of environmental health in Chile.

RESULTS

Air pollution in some cities remains among the highest in the continent. Potable water is generally available, but weak state supervision has led to serious outbreaks of infectious disease and ongoing issues with arsenic exposure in some regions. Climate change modeling in Chile is quite sophisticated, and a number of the impacts of climate change can be reasonably predicted in terms of which areas of the country are most likely to be affected by increased temperature and decreased availability of water, as well as expansion of vector territory. Some health effects, including changes in vector-borne diseases and excess heat mortality, can be predicted. However, there has yet to be an integration of such research with government planning.

CONCLUSIONS

Although great progress has been made, currently there are a number of problems. We suspect that the Chilean experience in environmental health may be of some use for other Latin American countries with rapid economic development.

Acute effects of air pollution on enteritis admissions in Xi'an, China

The correlation between enteritis, a common digestive disease, and exposure to ambient air pollutants has not been examined in a comprehensive manner. The aim of this study was to determine whether an association between short-term air pollution exposure and outpatient visits for enteritis in Xi'an, China, occurred using a time-series investigation. Daily baseline data from January 1, 2013, to December 31, 2015, were obtained. The overdispersed Poisson generalized additive model was used to analyze the association between air pollutant levels and frequency of enteritis. A total of 12,815 outpatient hospital visits for enteritis were identified. A 10-µg/m³ increase in average concentrations of particulate matter (PM)₁₀, PM_2.5, nitrogen dioxide (NO₂), and sulfur dioxide (SO₂), and a 0.1-mg/m³ rise of carbon monoxide (CO) were associated with a significantly elevated number of outpatient visits for enteritis on concurrent days, while ozone (O₃) did not markedly affect the frequency of enteritis clinical visits. There were no significant positive effects between two-pollutant and single-pollutant models. Lag models showed that the most prominent responses occurred on concurrent days. Confounding factors of gender and age played a significant role in the observations. Taken together, data indicate that air pollution may result in enhanced occurrence of enteritis attack.

The Novel Relationship between Urban Air Pollution and Epilepsy: A Time Series Study

Background and purpose

The data concerning the association between environmental pollution and epilepsy attacks are limited. The aim of this study was to explore the association between acute air pollution exposure and epilepsy attack.

Methods

A hospital record-based study was carried out in Xi’an, a heavily-polluted metropolis in China. Daily baseline data were obtained. Time-series Poisson regression models were applied to analyze the association between air pollution and epilepsy.

Results

A 10 μg/m³ increase of NO₂, SO₂, and O₃ concentrations corresponded to 3.17% (95%Cl: 1.41%, 4.93%), 3.55% (95%Cl: 1.93%, 5.18%), and -0.84% (95%Cl: -1.58%, 0.09%) increase in outpatient-visits for epilepsy on the concurrent days, which were significantly influenced by sex and age. The effects of NO₂ and SO₂ would be stronger when adjusted for PM_2.5. As for O₃, a -1.14% (95%Cl: -1.90%, -0.39%) decrease was evidenced when adjusted for NO₂. The lag models showed that the most significant effects were evidenced on concurrent days.

Conclusions

We discovered previously undocumented relationships between short-term air pollution exposure and epilepsy: while NO₂ and SO₂ were positively associated with outpatient-visits of epilepsy, O₃ might be associated with reduced risk.

Association of weather and air pollution interactions on daily mortality in 12 Canadian cities

It has been well established that both meteorological attributes and air pollution concentrations affect human health outcomes. We examined all cause nonaccident mortality relationships for 28 years (1981-2008) in relation to air pollution and synoptic weather type (encompassing air mass) data in 12 Canadian cities. This study first determines the likelihood of summertime extreme air pollution events within weather types using spatial synoptic classification. Second, it examines the modifying effect of weather types on the relative risk of mortality (RR) due to daily concentrations of air pollution (nitrogen dioxide, ozone, sulfur dioxide, and particulate matter <2.5 μm). We assess both single- and two-pollutant interactions to determine dependent and independent pollutant effects using the relatively new time series technique of distributed lag nonlinear modeling (DLNM). Results display dry tropical (DT) and moist tropical plus (MT+) weathers to result in a fourfold and twofold increased likelihood, respectively, of an extreme pollution event (top 5 % of pollution concentrations throughout the 28 years) occurring. We also demonstrate statistically significant effects of single-pollutant exposure on mortality (p < 0.05) to be dependent on summer weather type, where stronger results occur in dry moderate (fair weather) and DT or MT+ weather types. The overall average single-effect RR increases due to pollutant exposure within DT and MT+ weather types are 14.9 and 11.9 %, respectively. Adjusted exposures (two-way pollutant effect estimates) generally results in decreased RR estimates, indicating that the pollutants are not independent. Adjusting for ozone significantly lowers 67 % of the single-pollutant RR estimates and reduces model variability, which demonstrates that ozone significantly controls a portion of the mortality signal from the model. Our findings demonstrate the mortality risks of air pollution exposure to differ by weather type, with increased accuracy obtained when accounting for interactive effects through adjustment for dependent pollutants using a DLNM.

A five-year study of particulate matter (PM2.5) and cerebrovascular diseases

Cerebrovascular accidents, or strokes, are the second leading cause of mortality and the leading cause of morbidity in both Chile and the rest of the world. However, the relationship between particulate matter pollution and strokes is not well characterized. The association between fine particle concentration and stroke admissions was studied. Data on hospital admissions due to cerebrovascular accidents were collected from the Ministry of Health. Air quality and meteorological data were taken from the Air Quality database of the Santiago Metropolitan Area. Santiago reported 33,624 stroke admissions between January 1, 2002 and December 30, 2006. PM2.5 concentration was markedly seasonal, increasing during the winter. This study found an association between PM2.5 exposure and hospital admissions for stroke; for every PM2.5 concentration increase of 10 μg m(-3), the risk of emergency hospital admissions for cerebrovascular causes increased by 1.29% (95% CI 0.552%-2.03%).

A review on human health perspective of air pollution with respect to allergies and asthma

The increase in cases of asthma and allergies has become an important health issue throughout the globe. Although these ailments were not common diseases a few short decades ago, they are now affecting a large part of the population in many regions. Exposure to environmental (both outdoor and indoor) pollutants may partially account for the prevalence of such diseases. In this review, we provide a multidisciplinary review based on the most up-to-date survey of literature regarding various types of airborne pollutants and their associations with asthma-allergies. The major pollutants in this respect include both chemical (nitrogen dioxide, ozone, sulfur dioxide, particulate matter, and volatile organic compounds) and biophysical parameters (dust mites, pet allergens, and mold). The analysis was extended further to describe the development of these afflictions in the human body and the subsequent impact on health. This publication is organized to offer an overview on the current state of research regarding the significance of air pollution and its linkage with allergy and asthma.

Air contaminant statistical distributions with application to PM10 in Santiago, Chile

The use of statistical distributions to predict air quality is valuable for determining the impact of air chemical contaminants on human health. Concentrations of air pollutants are treated as random variables that can be modeled by a statistical distribution that is positively skewed and starts from zero. The type of distribution selected for analyzing air pollution data and its associated parameters depend on factors such as emission source and local meteorology and topography. International environmental guideline use appropriate distributions to compute exceedance probabilities and percentiles for setting administrative targets and issuing environmental alerts. The distribution bears a relationship to the normal distribution, and there are theoretical - and physical-based mechanistic arguments that support its use when analyzing air-pollutant data. Others distribution have also been used to model air population data, such as the beta, exponential, gamma, Johnson, log-logistic, Pearson, and Weibull distribution. One model also developed from physical-mechanistic considerations that has received considerable interest in recent year is the Birnbaum-Saunders distribution. This distribution has theoretical arguments and properties similar to those of the log-normal distribution, which renders it useful for modeling air contamination data. In this review, we have addressed the range of common atmospheric contaminants and the health effects they cause. We have also reviewed the statistical distributions that have been use to model air quality, after which we have detailed the problem of air contamination in Santiago, Chile. We have illustrated a methodology that is based on the Birnbaum-Saunders distributions to analyze air contamination data from Santiago, Chile. Finally, in the conclusions, we have provided a list of synoptic statements designed to help readers understand the significance of air pollution in Chile, and in Santiago, in particular, but that can be useful to other cites and countries.

Sulfur dioxide and emergency department visits for stroke and seizure

The purpose of this study was to assess an association between ambient sulfur dioxide and the number of emergency department (ED) visits for ischemic stroke and seizure. The study used data collected in a Vancouver (Canada) hospital in the years 1999–2003. Daily ED visits diagnosed as ministroke, stroke, or seizure were investigated using the case-crossover technique. Conditional logistic regression models were applied to estimate the odds ratios (ORs) and their respective 95% confidence intervals (CIs). The models included temperature and relative humidity in the form of natural splines. The results were reported for an increase in interquartile range ((IQR), IQR = 1.9 ppb for SO₂). Positive and statistically significant associations were obtained for SO₂ and ischemic stroke for all patients (OR = 1.12; CI 1.02, 1.23; lag 3) and for female patients (OR = 1.17; CI 1.01, 1.33; lag 0). In the case of ED visits for seizure, for female patients the results were also statistically significant (OR = 1.15; CI 1.02, 1.28; lag 1 and OR = 1.18; CI 1.05, 1.32; lag 2). These findings suggest that cases of ischemic cerebrovascular accidents are associated with acute exposure to ambient sulfur dioxide.