Association between ambient temperature, particulate air pollution and emergency room visits for conjunctivitis

Impact of particulate matter and air pollution on ocular surface disease: A systematic review of preclinical and clinical evidence

PURPOSE

Exposure to particulate matter (PM) and air pollution has been implicated in the etiology of ocular surface diseases (OSD). The purpose of this systematic review is to evaluate and synthesize peer-reviewed literature on the impact of PM exposure on the ocular surface, integrating results from preclinical in vitro and in vivo studies with clinical findings to provide a comprehensive understanding of molecular mechanisms, physiological effects, clinical implications, and potential therapies to target acute and chronic PM-induced ocular toxicity.

METHODS

A systematic literature search was performed using PubMed and EMBASE over the period from 2009 to 2024 following the recommendations for the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines. 102 studies were identified that met the inclusion/exclusion criteria. All studies were assessed for the risk of bias and qualitative data were analyzed.

RESULTS

Preclinical studies using models of corneal and conjunctival cells found that exposure to PM and similar air pollutants resulted in apoptosis, primarily via inflammatory and oxidative stress pathways as well as allergic and immune responses. Animal models resulted in phenotypes reminiscent of that of dry eye disease, presenting with reduced tear volumes and ocular surface damage. These results were corroborated by clinical studies, which reported that patients commonly presented with symptoms of itching, burning, and irritation, and ocular surface signs correlated with a diagnosis of dry eye disease, conjunctivitis, and allergic eye disease.

CONCLUSIONS

This systematic review provides a comprehensive summary of our current understanding of PM exposure on the ocular surface, highlighting the correlation between exposure to PM and ocular surface dysfunction.

Epidemiology and tumor microenvironment of ocular surface and orbital tumors on growth and malignant transformation

The ocular surface and orbit constitute unique microenvironments in the human body. Current advances in molecular research have deepened our understanding of tumor development in these regions. Tumors exhibit greater heterogeneity compared to normal tissues, as revealed by pathological and histological examinations. The tumor microenvironment (TME) plays a crucial role in the proliferation and progression of cancer cells. Factors from the external environment or the body's own inflammation and microcirculation interact within the TME, maintaining a delicate balance. Disruption of this balance, through uncontrolled signal pathway activation, can transform normal or benign tissues into malignant ones. In recent years, various systemic immunotherapies have been developed for cancer treatment. This study reviews the epidemiology of ocular surface and orbital tumors include squamous cell carcinoma, basal cell carcinoma, sebaceous carcinoma and lymphoma in conjunction with their occurrence, growth, and underlying mechanisms. We propose that by examining clinical histopathological images, we can identify specific and shared microscopic features of tumors. By collecting, classifying, and analyzing data from these clinical histopathological images, we can pinpoint independent diagnostic factors characteristic of tumors. We hope this study provides a basis for future exploration of the mechanisms underlying different ocular diseases.

Association Between Area Temperature and Severe Vision Impairment in a Nationally Representative Sample of Older Americans

PURPOSE

Several small studies have associated exposure to elevated average temperature with specific vision problems. However, no large-scale studies have examined the relationship between vision impairment and average area temperature in the general population. We conducted a cross-sectional analysis of a large nationally representative sample of older adults to further explore this relationship.

METHODS

Secondary analysis of the American Community Survey (ACS). The survey was conducted through mail, telephone and in-person interviews. Data from six consecutive years of the cross-sectional survey were analysed (2012-2017). The subsample analysed included community-dwelling and institutionalized older adults aged 65 and older in the coterminous US who lived in the same state in which they were born (n = 1,707,333). The question on severe vision impairment was "Is this person blind or does he/she have serious difficulty seeing even when wearing glasses?". Average annual temperature data from the National Oceanic and Atmospheric Administration was combined into a 100-year average and mapped to corresponding US Census Bureau's public use microdata areas from the ACS.

RESULTS

Higher average temperature is consistently associated with increased odds of severe vision impairment across all cohorts (i.e. age, sex, race, income, and educational attainment cohorts) with the exception of Hispanic older adults. Compared to those who lived in counties with average temperature of < 50 °F (< 10 °C) , the odds of severe vision impairment were 44% higher in counties with average temperature of 60 °F (15.5 °C) or above (OR 1.44; 95% CI 1.42-1.46).

CONCLUSION

If the association is found to be causal, the predicted rise in global temperatures could impact the number of older Americans affected by severe vision impairment and the associated health and economic burden.

Nonlinear effects of humidex on risk of outpatient visit for allergic conjunctivitis among children and adolescents in Shanghai, China: A time series analysis

Background

Various epidemiological studies have focused on the adverse health outcomes of meteorological factors. However, there has been little research on the impact of humidex on allergic conjunctivitis, especially in child and adolescent populations. We aimed to explore the impact of humidex, a comprehensive index of relative humidity and temperature, on child and adolescent allergic conjunctivitis admissions.

Methods

Outpatient visit data for allergic conjunctivitis, meteorological factors and air pollutants in Shanghai for the 2017-2022 period were retrieved. For the purpose of analysing the nonlinear connection and lag impact between humidex and admissions for paediatric and adolescent allergic conjunctivitis, the distributed lag nonlinear model (DLNM) was fitted.

Results

A total of 147 090 cases were included in our cohort. We found a significantly nonlinear effect on humidex and allergic conjunctivitis. In the single-day lag pattern, the relative risks (RR) of allergic conjunctivitis were significant at lag 0 (RR = 1.08, 95% confidence interval (CI) = 1.05-1.11) to lag 2 (RR = 1.01, 95% CI = 1.00-1.01), lag 5 (RR = 1.01, 95% CI = 1.00-1.01) to lag 9 (RR = 1.01, 95% CI = 1.00-1.01), and lag 14 (RR = 1.02, 95% CI: 1.01-1.03). In the cumulative-lag day pattern, the RR of allergic conjunctivitis were significant at lag 0-0 (RR = 1.08, 95% CI = 1.05-1.11) to lag 0-14 (RR = 1.21, 95% CI = 1.13-1.28). We found that boys, children aged 7-17 years, and children in the warm season were more vulnerable to humidex. In addition, the highest attributable fraction (AF) and attributable number (AN) of humidex are at lag 0-14 (AF = 0.17, AN = 25 026).

Conclusions

Humidex exposure markedly increased the risk of allergic conjunctivitis, especially in highly high humidex. Appropriate public health management is needed for disease management and early intervention.

TFOS Lifestyle Report: Impact of environmental conditions on the ocular surface

Environmental risk factors that have an impact on the ocular surface were reviewed and associations with age and sex, race/ethnicity, geographical area, seasonality, prevalence and possible interactions between risk factors are reviewed. Environmental factors can be (a) climate-related: temperature, humidity, wind speed, altitude, dew point, ultraviolet light, and allergen or (b) outdoor and indoor pollution: gases, particulate matter, and other sources of airborne pollutants. Temperature affects ocular surface homeostasis directly and indirectly, precipitating ocular surface diseases and/or symptoms, including trachoma. Humidity is negatively associated with dry eye disease. There is little data on wind speed and dewpoint. High altitude and ultraviolet light exposure are associated with pterygium, ocular surface degenerations and neoplastic disease. Pollution is associated with dry eye disease and conjunctivitis. Primary Sjögren syndrome is associated with exposure to chemical solvents. Living within a potential zone of active volcanic eruption is associated with eye irritation. Indoor pollution, "sick" building or house can also be associated with eye irritation. Most ocular surface conditions are multifactorial, and several environmental factors may contribute to specific diseases. A systematic review was conducted to answer the following research question: "What are the associations between outdoor environment pollution and signs or symptoms of dry eye disease in humans?" Dry eye disease is associated with air pollution (from NO2) and soil pollution (from chromium), but not from air pollution from CO or PM10. Future research should adequately account for confounders, follow up over time, and report results separately for ocular surface findings, including signs and symptoms.

TFOS lifestyle: Impact of societal challenges on the ocular surface

Societal factors associated with ocular surface diseases were mapped using a framework to characterize the relationship between the individual, their health and environment. The impact of the COVID-19 pandemic and mitigating factors on ocular surface diseases were considered in a systematic review. Age and sex effects were generally well-characterized for inflammatory, infectious, autoimmune and trauma-related conditions. Sex and gender, through biological, socio-economic, and cultural factors impact the prevalence and severity of disease, access to, and use of, care. Genetic factors, race, smoking and co-morbidities are generally well characterized, with interdependencies with geographical, employment and socioeconomic factors. Living and working conditions include employment, education, water and sanitation, poverty and socioeconomic class. Employment type and hobbies are associated with eye trauma and burns. Regional, global socio-economic, cultural and environmental conditions, include remoteness, geography, seasonality, availability of and access to services. Violence associated with war, acid attacks and domestic violence are associated with traumatic injuries. The impacts of conflict, pandemic and climate are exacerbated by decreased food security, access to health services and workers. Digital technology can impact diseases through physical and mental health effects and access to health information and services. The COVID-19 pandemic and related mitigating strategies are mostly associated with an increased risk of developing new or worsening existing ocular surface diseases. Societal factors impact the type and severity of ocular surface diseases, although there is considerable interdependence between factors. The overlay of the digital environment, natural disasters, conflict and the pandemic have modified access to services in some regions.

Long-term effects of meteorological factors and extreme weather on daily outpatient visits for conjunctivitis from 2013 to 2020: a time-series study in Urumqi, China

Conjunctivitis is a common multifactorial inflammatory ocular surface disease characterized by symptoms such as congestion, edema, and increased secretion of conjunctival tissue, and the potential effects of meteorological factors as well as extreme meteorological factors on conjunctivitis and their lagging effects have not been fully evaluated. We obtained the electronic case information of 59,731 outpatients with conjunctivitis from the Ophthalmology Department of the First Affiliated Hospital of Xinjiang Medical University (Urumqi, Xinjiang, China) for the period from January 1, 2013, to December 31, 2020. Meteorological data for daily mean temperature (°C), daily relative humidity (%), daily average wind speed (m/s), and atmospheric pressure (hPa) were obtained from the China Meteorological Data Sharing Service. The air pollutant data were obtained from 11 standard urban background fixed air quality monitors. A time-series analysis design and a quasi-Poisson generalized linear regression model combined with a distributed lagged nonlinear model (DLNM) were used to fit the effects of exposure to different meteorological factors and extreme weather on conjunctivitis outpatient visits. Subgroup analyses were performed on gender, age and season, and type of conjunctivitis. Univariate and multifactorial model results indicated that each 10-unit increase in mean temperature and relative humidity was associated with an increased risk of conjunctivitis outpatient visits, while each 10-unit increase in atmospheric pressure was associated with a decreased risk. The results of the extreme weather analysis suggested that extremely low levels of atmospheric pressure and relative humidity as well as extreme levels of temperature were associated with an increased risk of outpatient conjunctivitis visits, and extreme wind speeds were associated with a decreased risk. The results of the subgroup analysis suggested gender, age, and seasonal differences. We conducted the first large sample size time-series analysis in the large city furthest from the ocean in the world and confirmed for the first time that elevated mean temperature and extreme low levels of relative humidity in Urumqi were risk factors for local conjunctivitis outpatient visits, while elevated atmospheric pressure and extreme low levels of wind speed were protective factors, and there were lagged effects of temperature and atmospheric pressure. Multicenter studies with larger sample sizes are needed.

Size-specific particulate matter and outpatient visits for allergic conjunctivitis in children: a time-stratified case-crossover study in Guangzhou, China

This time-stratified case-crossover study aims to quantify the risk of allergic conjunctivitis (AC) associated with short-term exposure to PMs (i.e., PM₁, PM_2.5, PM_c, and PM₁₀) among children in Guangzhou, China. We collected data on children's daily AC outpatient visits from the Guangzhou Women and Children Medical Center during February 20, 2016 to December 31, 2018, and also extracted air pollution and meteorological data in the same time frame. We used conditional logistic regression model to estimate the associations between PMs and AC outpatient visits, and conducted subgroup analyses stratified by sex, age, and season. During the study period, we recorded 39,330 children's outpatient visits for AC, including 27,638 boys and 11,692 girls. The associations between PMs and AC were general linear with no clear threshold, which were largest at the current days but remained positive for lag 1 to 3 days. For every 10 μg/m³ increase in daily PM₁, PM_2.5, PM_c, and PM₁₀ concentrations, the estimated risks of AC outpatient visits at the current days increased by 2.5% (OR = 1.025, 95% CI: 1.011-1.039), 1.8% (OR = 1.018, 95% CI: 1.009-1.027), 2.1% (OR = 1.021, 95% CI: 1.004-1.039), and 1.3% (OR = 1.013, 95% CI: 1.007-1.020), respectively. In addition, our stratified analyses revealed that girls and children aged 1 to 6 years were more sensitive to PM exposure, and the PM-associated risks for AC were more apparent in autumn and winter. Our study suggests that short-term exposure to PMs may induce AC in children.

Quantifying the associations of the air pollutant SO2 on outpatient visits for conjunctivitis in Hangzhou, China

The aim of this study is to further investigate the single and cumulative associations of SO₂ on outpatient visits for conjunctivitis. Data from outpatient visits, air pollutants, and meteorology was collected by the Eye Center of the Second Affiliated Hospital of the Zhejiang University School of Medicine, the Environmental Protection Department of Zhejiang Province, and the Meteorological Administration of Zhejiang Province from July 1, 2014, to November 30, 2019. A Poisson generalized linear regression model (PGLM), combined with a distributed lag nonlinear model (DLNM), was employed to analyze the association between SO₂ and outpatient visits for conjunctivitis using PM_2.5 and NO₂ as covariates. Of the 539,649 outpatients for conjunctivitis recruited for analysis, 58.1% were female. Obvious single associations of SO₂ were observed in outpatient visits for conjunctivitis, which is consistent with our previous results using a time-stratified case crossover design. A delay in the associations of SO₂ on outpatient visits for conjunctivitis was further confirmed, with the longest lag being 12 days. The strongest lag effect was found at lag 0-11 with RR_95th vs _25th = 1.30 (1.24, 1.37), and RR_90h vs _25th = 1.23 (1.18, 1.28). Furthermore, the results showed that old people may be more sensitive to the associations of SO₂ than adults and the younger ones. Our study provides the first evidence that outpatient visits for conjunctivitis are positively associated with both single and cumulative air pollutant SO₂ exposure, suggesting that people especially elders had better to decrease outdoor activities when the SO₂ concentration is above safe level.

Smoke and the eyes: A review of the harmful effects of wildfire smoke and air pollution on the ocular surface

Wildfires are occurring worldwide with greater frequency and intensity. Wildfires, as well as other sources of air pollution including environmental tobacco smoke, household biomass combustion, agricultural burning, and vehicular emissions, release large amounts of toxic substances into the atmosphere. The ocular surface is constantly exposed to the ambient air and is hence vulnerable to damage from air pollutants. This review describes the detrimental effects of wildfire smoke and air pollution on the ocular surface and resultant signs and symptoms. The latest relevant evidence is synthesised and critically evaluated. A mechanism for the pathophysiology of ocular surface damage will be proposed considering the existing literature on respiratory effects of air pollution. Current strategies to reduce human exposure to air pollutants are discussed and specific possible approaches to protect the ocular surface and manage air pollution induced ocular surface damage are suggested. Further avenues of research are suggested to understand how acute and chronic air pollution exposure affects the ocular surface including the short and long-term implications.

Air pollution and hospital admissions for critical illness in emergency department: a tertiary-center research in Changsha, China, 2016-2020

We aimed to comprehensively investigate the associations of air pollutants with hospital admissions for critical illness in ED. Patients with critical illness including level 1 and level 2 of the Emergency Severity Index admitted in ED of Changsha Central Hospital from January 2016 to December 2020 were enrolled. Meteorological and air pollutants data source were collected from the National Meteorological Science Data Center. A Poisson generalized linear regression combined with a polynomial distributed lag model (PDLM) was utilized to explore the effect of air pollution on hospital admissions for critical illness in ED. Benchmarks as references (25th) were conducted for comparisons with high levels of pollutant concentrations (75th). At first, lagged effects of all different air pollutants were analyzed. Then, based on the most significant factor, analyses in subgroups were performed by gender (male and female), age (< 45, 45-65, and > 65), disorders (cardiovascular, neurological, respiratory), and seasons (spring, summer, autumn, and winter). A total of 47,290 patients with critical illness admitted in ED were included. The effects of air pollutants (PM_2.5, PM₁₀, SO₂, NO₂, O₃ and CO) on critical illness ED visits were statistically significant. Strong collinearity between PM_2.5 and PM₁₀ (r = 0.862) was found. Both single-day lag and cumulative-day lag day models showed that PM_2.5 had the strongest effects (lag 0, RR = 1.025, 95% CI 1.008-1.043, and lag 0-14, RR = 1.067, 95% CI 1.017-1.120, respectively). In both PM_2.5 and PM₁₀, the risks of critical illness in male, > 65 ages, respiratory diseases, and winter increased the most significant. Air pollutants, especially PM_2.5 and PM₁₀ exposure, could increase the risk of critical illness admission.