Exposure to ambient air pollution and visual impairment in children: A nationwide cross-sectional study in China

Associations of green and blue spaces with visual acuity in youths from Shandong Province, China: A large population-based study

While growing evidence highlights the benefits of green and blue spaces for physical and mental health, their combined effects on youth visual acuity remain unclear. This study aimed to evaluate the associations of green and blue spaces with visual acuity in youths. We analyzed data from the 2023 Common Disease and Health Risk Factors Surveillance and Intervention Program among students in Shandong Province, China. Generalized linear mixed-effects models were employed to investigate the independent associations of green and blue spaces with visual acuity in youths. To explore potential interactions, an interaction term for green and blue spaces was incorporated. Quantile g-computation (Qgcomp) models were applied to evaluate their combined effects. Compared to the lowest quartile, higher quartiles (Q2, Q3, and Q4) of the normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), normalized difference water index (NDWI), and modified normalized difference water index (MNDWI) were significantly associated with improved visual acuity in both eyes. Additionally, each 0.1 unit increase in NDVI500, EVI500, NDWI500, and MNDWI500 was associated with 0.008 (95 % confidence interval [CI]: 0.007, 0.010), 0.003 (0.002, 0.004), 0.054 (0.028, 0.080), and 0.010 (0.002, 0.018) improvements in right-eye visual acuity, with similar findings for the left eye. A significant interaction was observed between NDVI and NDWI (all P for interaction < 0.001), and combined exposure to green and blue spaces was positively associated with visual acuity (all P < 0.001). Furthermore, demographic and lifestyle factors modified the associations of blue and green spaces with visual acuity levels in youths. Greater exposure to green and blue spaces may benefit visual health in youths, with potential interactive and combined effects. Implementing policies to enhance the availability of green and blue spaces around schools may offer opportunities to alleviate visual impairment in youths.

Association between long-term green space exposure and dry eye in China

PURPOSE

To evaluate the association between green space exposure and dry eye.

DESIGN

Part I: case-control study. Part II: cross-sectional study.

METHODS

Part I: The study contained 450 patients with dry eye and 900 controls recruited from Electronic Health Records. Logistic regression analysis was employed to investigate the relationship between green space exposure and the occurrence of dry eye. Part II: This study included 140 diabetic participants recruited from the community registry in Guangzhou, China. Linear regression analysis was used to assess the association between green space exposure and quantitative measures of the tear meniscus.

RESULTS

Part I: A total of 1,350 individuals were included in the study. On average individuals aged 31.07 ± 4.58 years and 59.33% were female. Higher 10-year green space exposure was significantly associated with lower odds of dry eye (OR = 0.96; 95% confidence interval [CI], 0.94, 0.97; P < 0.001) after adjusting for age, sex, rainfall, temperature, particulate matter, and other factors. Part II: A total of 140 diabetic patients were included in the study. On average individuals aged 64.48 ± 8.19 years and 53.57% were female. Greater 10-year green space exposure was associated with a higher tear meniscus area (β = 0.07, 95% CI, 0.02, 0.11; p = 0.007) after adjusting for age, sex, rainfall, temperature, particulate matter, and other factors.

CONCLUSIONS

Our findings suggest an association between green space exposure and diagnosis of dry eye and tear meniscus, offering novel insights into the strategies for preventing dry eye.

Impact of Ambient Air Pollution on Reduced Visual Acuity Among Children and Adolescents

PURPOSE

Previous studies have assessed the impact of air pollution on myopia from the individual level, while none of them have explored the role of air pollution in visual health disparities between different regions from the area level. This ecological study aimed to investigate the impact of ambient air pollution on reduced visual acuity (VA).

METHODS

The data were derived from the Chinese National Survey on Students' Constitution and Health (CNSSCH) conducted in 2014 and 2019, which involved 261,833 and 267,106 students respectively. The participants were 7-22 years old randomly selected from 30 mainland provinces in China. Locally weighted scatterplot smoothing (LOESS) regression models and fixed-effects panel regression models were used to explore the associations of provincial-level prevalence of reduced VA with air quality index (AQI), fine particulate matter ;(PM2.5), PM10, sulfur dioxide (SO2), carbon monoxide (CO), nitrogen dioxide (NO2) and ozone (O3) concentrations.

RESULTS

There were nearly linear positive dose-response relationships between AQI, air pollutant concentrations and the prevalence of reduced VA. After adjusting for covariates, an interquartile range increase in PM2.5 exposure was significantly associated with a 5.0% (95% confidence interval, 0.7%-9.3%) increase in the prevalence of reduced VA, whereas no significant associations were observed between AQI, the other five pollutants and the prevalence of reduced VA.

CONCLUSION

Regions with more polluted air tend to have a higher prevalence of reduced VA. Exposure to PM2.5 might be an important risk factor for myopia among children and adolescents.

Long-term exposure to PM2.5 and its constituents and visual impairment in schoolchildren: A population-based survey in Guangdong province, China

BACKGROUND

Exposure to fine particulate matter (PM2.5) has been linked to visual impairment. Nevertheless, evidence associating PM2.5 constituents with visual impairment in schoolchildren is sparse.

OBJECTIVES

To explore the effects of long-term exposure to PM2.5 and its constituents on visual impairment.

METHODS

We conducted a large cross-sectional population-based study to recruit 59,054 schoolchildren from four cities in Guangdong province, China, and used the ChinaHighAirPollutants (CHAP) dataset to estimate 3-year average concentrations of PM2.5 and its constituents (black carbon (BC), organic matter (OM), nitrate (NO3-), sulfate (SO42-) and ammonium (NH4+)) based on individuals' home addresses. Visual acuity was measured with a standardized logarithmic chart, and visual impairment was defined as visual acuity below 4.9 (Snellen 5/6 equivalent) in at least one eye. We utilized generalized linear mixed models and weighted quantile sum regression to assess the association between PM2.5 constituents and visual impairment.

RESULTS

The observed associations typically displayed a nonlinear pattern. Compared to the lowest quartile of PM2.5 and its constituents, the fourth quartile was associated with higher odds of visual impairment in schoolchildren (e.g., the adjusted odds ratio (OR) was 1.23 (95% CI: 1.13, 1.33) for PM2.5, 1.53 (95% CI: 1.40, 1.67) for OM, and 1.35 (95% CI: 1.27, 1.44) for BC), respectively. Similarly, joint exposure to PM2.5 constituents was associated with visual impairment (OR = 1.17, 95% CI: 1.13, 1.22), while BC and OM contributed more to the observed associations.

CONCLUSIONS

Long-term exposure to PM2.5 and its constituents was significantly associated with higher rates of visual impairment in schoolchildren, with combustion-related BC and OM potentially driving the observed associations.

Air pollutant exposure is associated with visual trajectories and visual impairment in children

Air pollution is associated with vision loss in children, but the relationship with vision trajectories has not been explored. The study was conducted as a prospective cohort in 16 districts of Shanghai from 2021 to 2023, involving 5612 children with complete survey data. Each child underwent 3-4 eye tests, including unaided visual acuity and computerized refraction. Children's air pollutant exposure levels (PM2.5, PM10, O3, SO2, NO2, and CO) were assessed using school addresses and examination dates. Latent class mixture modeling was used to identify the trajectories of changes in vision-related measurements in children. Multinomial logistic regression and Cox proportional hazards regression were used to examine the association of air pollutant exposure and visual trajectories, as well as visual impairment outcomes. The study identified three trajectory categories for children's unaided visual acuity, spherical equivalent, and four trajectory categories for axial length. Increased levels of PM2.5, PM10, O3, and SO2 exposure are associated with an increased risk of categorizing vision-related measurements into the "poor" category trajectory in children. Increased exposure to PM2.5, O3, and NO2 was associated with an increased risk of visual impairment outcomes in children with normal vision at baseline, and the effect was more significant in female and older children.

Residential greenness, air pollution and visual impairment: a prospective cohort study

OBJECTIVE

The aim of this study was to investigate the associations between residential greenness, air pollution (PM2.5, PM10, and NO2), and the risk of visual impairment in Chinese middle-aged and elderly adults.

METHODS

The data were used from the China Health and Retirement Longitudinal Study (CHARLS), focusing on adults aged 45 years and older. Exposure to residential greenness was assessed using the Normalized Difference Vegetation Index (NDVI), while air pollution exposure (PM2.5, PM10, and NO2) was estimated from the ChinaHighAirPollutants dataset. Visual impairment was self-reported and categorized as distance visual impairment (DVI) and near visual impairment (NVI). Cox proportional hazards models were applied to investigate the associations between residential greenness, air pollution, and visual impairment. Furthermore, we investigated the potential modification and mediation relationship between residential greenness, air pollution and visual impairment.

RESULTS

A total of 9,591 participants were included in this study. During a 7-year period, 2,650 cases of DVI and 3,130 cases of NVI were identified. In the single exposure model, a higher level of residential greenness was associated with a significantly reduced risk of both DVI and NVI. Specifically, for every 0.1 unit increase in NDVI, the hazard ratio (HR) was 0.68 (95%CI: 0.65,0.71) for DVI, and 0.67 (95%CI: 0.64,0.69) for NVI. Conversely, exposure to air pollution was positively associated with increased risks for both DVI and NVI. For each 10 µg/m3 increase in PM2.5, the HR was 1.60 (95%CI: 1.56,1.65) for DVI and 1.64 (95%CI: 1.60,1.69) for NVI. Similarly, PM10 and NO2 exposure showed elevated risks with HR of 1.28 (95%CI: 1.27,1.30) and 1.73 (95%CI: 1.62,1.85) for DVI, and 1.30 (95%CI: 1.28,1.32) and 1.82 (95%CI: 1.72,1.94) for NVI, respectively. The multiple exposure model also showed significant association between residential greenness, air pollution and visual impairment risk. Additionally, the adverse effects of PM2.5, PM10, and NO2 were attenuated in areas with the highest levels of residential greenness. Mediation analysis revealed that air pollution mediated a significant portion of the association between residential greenness and visual impairment.

CONCLUSION

This study suggests that increased residential greenness may reduce the risk of visual impairment, partially by mitigating air pollution exposure. These findings highlight the environmental benefits to improve air quality and enhance green spaces, thereby promoting visual health in aging populations.

Trends in the prevalence and burden of blindness and vision loss among adolescents aged 10-24 years in the Western Pacific Region over 30 years

BACKGROUND

This study aimed to understand the vision health status of adolescents in the Western Pacific Region (WPR) using Global Burden of Disease (GBD) data from 1990 to 2019.

METHODS

We conducted a comprehensive analysis of blindness and vision loss using GBD data from 1990 to 2019, analyzed trends in the prevalence and burden of blindness and vision loss over time using joinpoint regression, and analyzed their independent effects on blindness and vision loss in three dimensions using age-period-cohort (APC) modeling.

RESULTS

The prevalence of blindness and vision loss among adolescents in the WPR showed an increasing trend between 1990 and 2019 (AAPC: 0.56%) and a slight increase in YLD (AAPC: 0.11%). The joinpoint regression showed a decreasing trend after 2017 (AAPC: -2.45%). The prevalence and burden trended downward in most Western Pacific countries, with only China rising significantly (AAPC prevalence: 0.57%). Refractive disorders had the highest prevalence among the subgroups. The risk of blindness and vision loss in adolescents reduced with age but grew later in time and at later birth. In addition, prevalence and burden were generally higher in females than males.

CONCLUSIONS

In the context of a declining global trend in the prevalence and burden of blindness and vision loss among adolescents, there is an increasing trend among adolescents in WPR, with the most pronounced rise in China. This finding has important implications for WPR, suggesting that more attention should be given to adolescent eye health in the region.

Association between weekend catch-up outdoor duration and prevalence of myopia: evidence from a cross-sectional, multi-center study in China

BACKGROUND

This study aimed at investigating the relationship between the weekend catch-up outdoor duration (WCOD) and prevalence of myopia among students in China.

METHODS

This cross-sectional study recruited participants in 107 schools (six cities, 30 districts) from China from May to June 2021. Demographic characteristics (age, grade, sex, ethnicity, BMI, resident, and parents' myopia), optically habits (bad writing habits, working/studying time per day, continuous working/studying time per day, and screen time per day) and outdoor duration (weekday and weekend) were obtained from questionnaire. WCOD was defined as outdoor time 1 h longer on weekends than on weekdays. Spherical equivalent (SE) of refractive error were measured with non-cycloplegic refraction. Adjusted multivariate logistic regression analysis was performed to evaluate the relationship between WCOD and prevalence of myopia.

RESULTS

Students with myopia had shorter WCOD compared with those without myopia (P < 0.001). Adjusted multivariate logistic regression analyses showed negative associations between WCOD and prevalence of myopia in Chinese students, especially in students with WCOD of 2-3 h (OR = 0.577, P < 0.001) and 3-4 h (OR = 0.571, P = 0.004) when the weekday outdoor duration was 0.5-1 h, as well as students with WCOD of 2-3 h (OR = 0.614, P = 0.003) when the weekday outdoor duration was 1-2 h. Similar results were observed in students with high myopia. Students with high myopia had shorter WCOD compared with those without high myopia (P = 0.001). Negative associations between WCOD and prevalence of high myopia were significant in students with WCOD of 1-2 h when the weekday outdoor duration was < 0.5 h (OR = 0.585, P = 0.007) and 0.5-1 h (OR = 0.537, P = 0.018).

CONCLUSION

Our study, for the first time, reported that a WCOD have a potential to reduce the prevalence of myopia and high myopia in Chinese students.

Transformer-based ozone multivariate prediction considering interpretable and priori knowledge: A case study of Beijing, China

Ozone pollution is the focus of current environmental governance in China and high-quality prediction of ozone concentration is the prerequisite to effective policymaking. The studied ozone pollution time series exhibits distinct seasonality and secular trends and is associated with various factors. This study developed an interpretable hybrid model by combining STL decomposition and the Transformer (STL-Transformer) with the prior information of ozone time series and global multi-source information as prediction basis. The STL decomposition decomposes ozone time series into trend, seasonal, and remainder components. Then, the three components, along with other air quality and meteorological data, are integrated into the input sequence of the Transformer. The experiment results show that the STL-Transformer outperforms the other five state-of-the-art models, including the standard Transformer. Specially, the univariate forecasting for ozone relies on mimicking the patterns and trends that have occurred in the past. In contrast, multivariate forecasting can effectively capture complex relationships and dependencies involving multiple variables. The method successfully grasps the prior and global multi-source information and simultaneously improves the interpretability of ozone prediction with high precision. This study provides new insights for air pollution forecasting and has reliable theoretical value and practical significance for environmental governance.

Urban greenspace and visual acuity in schoolchildren: a large prospective cohort study in China

BACKGROUND

Greenspace is known to have a positive impact on human health and well-being, but its potential effects on visual acuity have not been extensively studied.

OBJECTIVES

Our aim was to examine the relationship between long-term greenspace exposure and visual acuity in children, while also exploring the potential mechanisms in this association.

METHODS

We conducted this prospective cohort study based on the Children's growth environment, lifestyle, physical, and mental health development project (COHERENCE), which screened 286,801 schoolchildren in Guangzhou, China, starting in the 2016/17 academic year and followed them up for three academic years (2017/18-2019/20). Visual acuity was measured using a standardized logarithmic chart, and visual impairment was defined as visual acuity worse than 0.0 logarithm of the minimum angle of resolution (LogMAR) units in the better eye. We used the Normalized Difference Vegetation Index (NDVI), the Soil-Adjusted Vegetation Index (SAVI), and the Enhanced Vegetation Index (EVI) to assess the greenspace surrounding child's geocoded home and school at each visit.

RESULTS

Our analysis indicated that higher greenspace exposure was associated with greater visual acuity z-score at baseline and with slower decline in visual acuity z-score during the 3-year follow-up. An interquartile range increase in home-school-based NDVI 300m was associated with a 7% decrease [hazard ratios (HRs): 0.93, 95% confidence interval (CI): 0.92, 0.94] in the risk of visual impairment. We also found that air pollution, physical activity, outdoor time, and recreational screen time partially mediated the greenspace-visual acuity association.

CONCLUSION

Our findings suggest that increasing greenspace exposure could benefit children's visual acuity development and reduce the risk of visual impairment by reducing air pollution and recreational screen time while increasing physical activity and outdoor time. All results could have potential policy implications, given the individual and societal burdens associated with visual impairment.

Association of ultraprocessed foods consumption and cognitive function among children aged 4-7 years: a cross-sectional data analysis

Background

Sugar-sweetened beverage (SSB) consumption has shown associations with cognitive function in preschool children, but effects of other ultraprocessed foods consumption are rarely discussed in China. This study aimed to investigate the relationship between ultraprocessed food consumption and cognitive function among preschool children in China.

Methods

A total of 325 children aged 4-7 years were included from Guangxi Zhuang Birth Cohort in Guangxi Zhuang Autonomous Region, China. Face-to-face interviews with parents using the Food Frequency Questionnaire (FFQ) was conducted to investigate the status of seven ultraprocessed foods consumption (i.e., chocolate, biscuits, candy, fast-food, ice cream, SSBs, and sweet bakery products). The mandarin-language version of the Wechsler Preschool and Primary Scale of Intelligence (WPPSI, Fourth Edition) was applied to assess the cognitive function of children. Multiple linear and logistic regression models were used to assess the associations between ultraprocessed food consumption and the full-scale intelligence quotient (FSIQ) and different domains and risk of cognitive deficit, respectively.

Results

We found that frequent consumption of candy (β = -3.34, 95% CI: -5.62∼-1.06; p = 0.004) and sweet bakery products (β = -2.77, 95% CI: -5.58∼0.04; p = 0.054) were significant associated with decreased FSIQ scores in the linear regression models. However, only frequent consumption of candy was statistically significantly associated with an increased risk of cognitive deficit (OR = 2.05, 95% CI: 1.11∼3.79; p = 0.023) in the logistic regression models. For the different domains, we found frequent consumption of candy (β = -3.85, 95% CI: -6.28∼-1.43; p = 0.002) and sweet bakery products (β = -3.48, 95% CI: -6.47∼-0.49; p = 0.023) was also significantly associated with lower Verbal Comprehension Index (VCI). When combining the seven ultraprocessed foods, we found children who frequently consumed more than two kinds of ultraprocessed foods had a significant decrease of VCI scores (β = -2.66; 95% CI: -5.12∼-0.19; p = 0.035) too.

Conclusion

Our results suggested that frequent consumption of individual (candy and sweet bakery products) and multiple ultraprocessed foods may decrease VCI scores and thereby impact cognitive function in children aged 4-7 years.

Long-term effects of ambient PM2.5 constituents on metabolic syndrome in Chinese children and adolescents

Metabolic syndrome (MetS) is considered a main public health issue as it remarkably adds the risk of cardiovascular disease, leading to a heavy burden of disease. There is growing evidence linking fine particulate matter (PM_2.5) exposure to MetS. However, the influences of PM_2.5 constituents, especially in children and adolescents, remain unclear. Our study was according to a national analysis among Chinese children and adolescents to examine the associations between long-term exposure to PM_2.5 main constituents and MetS. A total of 10,066 children and adolescents aged 10-18 years were recruited in 7 provinces in China, with blood tests, health exams, and questionnaire surveys. We estimated long-term exposures to PM_2.5 mass and its five constituents, containing black carbon (BC), organic matter (OM), inorganic nitrate (NO₃^-), sulfate (SO₄^2-), and soil particles (SOIL) from multi-source data fusion models. Mixed-effects logistic regression models were used with the adjustment of a variety of covariates. In the surveyed populations, 2.9% were classified as MetS. From the single-pollutant models, we discovered that long-term exposures to PM_2.5 mass, BC, OM, NO₃^-, as well as SO₄^2-, were significantly associated with the prevalence of MetS, with odds ratios (ORs) per 1 μg/m³ that were 1.02 (95% confidence interval (CI): 1.01, 1.03) for PM_2.5 mass, 1.24 (95% CI: 1.14, 1.35) for BC, 1.07 (95% CI: 1.04, 1.11) for OM, 1.09 (95% CI: 1.04, 1.13) for NO₃^-, and 1.14 (95% CI:1.04, 1.24) for SO₄^2-. The influence of BC on the prevalence of MetS was robust in both the multi-pollutant model and the PM_2.5-constituent joint model. The paper indicates long-term exposure to PM_2.5 mass and specific PM_2.5 constituents, particularly for BC, was significantly associated with a higher MetS prevalence among children and adolescents in China. Our results highlight the significance of establishing further regulations on PM_2.5 constituents.

Association of Neighborhood Child Opportunity Index with presenting visual acuity in amblyopic children

PURPOSE

To demonstrate the use of a novel measure of neighborhood quality, the Child Opportunity Index (COI), for investigating health disparities in pediatric ophthalmology.

METHODS

This study included children 2-12 years of age from a registry of patients diagnosed with amblyopia at an urban pediatric hospital between 2010 and 2014. Children previously treated for amblyopia were excluded. Patient demographics, residential addresses, and logMAR visual acuities were collected. The association between visual acuity at presentation and COI was examined using linear mixed-effects models adjusting for individual-level factors, including age, sex, race, ethnicity, and insurance type.

RESULTS

This study included 1,050 amblyopic children, of whom 317 (37%) were non-White and 149 (19%) were Hispanic; 461 (44%) had public insurance. Regarding residence, 129 (12%) lived in areas of very low opportunity (COI <20); 489 (47%) in areas of very high opportunity (COI ≥80). Children residing in the lowest opportunity neighborhoods correctly identified approximately two fewer letters at presentation with their better-seeing eye compared with children from the highest opportunity neighborhoods after adjusting for individual-level factors (-0.0090 logMAR per 20 unit increase in COI; 95% CI, -0.0172 to -0.0008; P = 0.031). No difference was appreciated in the worse-seeing eye.

CONCLUSIONS

Amblyopic children residing in communities with low neighborhood opportunity had slightly worse visual acuity in the better-seeing eye at presentation. Although statistically significant in the better-seeing eye, the two-letter difference attributable to neighborhood environment may not be clinically significant, and the impact of this disparity on treatment outcomes deserves further investigation.

Effects of Greenness on Myopia Risk and School-Level Myopia Prevalence Among High School-Aged Adolescents: Cross-sectional Study

BACKGROUND

Myopia is a serious public health issue. High school-aged adolescents in Beijing have an alarming prevalence of myopia. Therefore, determining myopia protective factors is essential. Green space has a certain association with myopia protective factors that can protect against myopia.

OBJECTIVE

This study aims to examine the effects of green space around schools on individual myopia risk in high school-aged adolescents and the school-level myopia prevalence.

METHODS

Green space was measured using the normalized difference vegetation index (NDVI). A total of 13,380 samples of 51 high schools were selected from a 2021 Beijing Municipal Health Commission survey. Adolescent myopia was defined as a spherical equivalent of ≤-1.00 diopters in the worse eye. Generalized linear mixed models with a binomial error structure were used to analyze the effects of the NDVI on personal myopia risk and adjust them by other factors, such as demographics, exposure time, and outdoor exercise. The effects of the NDVI on school-level myopia prevalence with adjusted demographics and the relative position factors of trees were analyzed through quasibinomial regression.

RESULTS

The overall prevalence of myopia was 80.61% (10,785/13,380, 95% CI 79.93%-81.27%). Although with a 0.1 increase in the 500 and 1000 m buffer NDVIs adjusted by demographic and other factors, the high school-aged personal myopia risk significantly dropped by 16% (odds ratio [OR] 0.84, 95% CI 0.73-0.97) and 12% (OR 0.88, 95% CI 0.79-0.99), respectively. However, only the adjusted 500 m buffer NDVI (by demographics and the position of trees) with a 0.1 increase significantly reduced the school-level myopia prevalence by 15% (OR 0.85, 95% CI 0.74-0.98). Subgroup analysis showed that the adjusted effects of the 500 m buffer NDVI are significant in schoolgirls (OR 0.82, 95% CI 0.72-0.93), juniors (OR 0.82, 95% CI 0.72-0.94), the Han nationality (OR 0.84, 95% CI 0.72-0.97), 1-year exposure (OR 0.84, 95% CI 0.71-0.99) and 3-year exposure (OR 0.78, 95% CI 0.65-0.94).

CONCLUSIONS

The greenness of a 500 m buffer around schools is associated with a lower personal myopia risk among adolescents and a lower prevalence of myopia in schools. With regard to prevention and control activities, green space within a 500 m buffer around schools is suggested as an independent protective factor for adolescent myopia.

Association between PM1 Exposure and Lung Function in Children and Adolescents: A Systematic Review and Meta-Analysis

The detrimental effects of PM_2.5 and PM₁₀ (particulate matter less than 2.5 or 10 μm) on human respiratory system, including lung function, have been widely assessed. However, the associations between PM₁ (particulate matter of less than 1 μm) and lung function in children and adolescents are less explored, and current evidence is inconsistent. We conducted a meta-analysis of the literature on the association between PM₁ and lung function in children and adolescents to fill this gap. With no date or language constraints, we used a combination of MeSH (Medical Subject Headings) terms and free text to search PubMed, EMBASE and Web of Science databases through, 1 October 2022 for "PM₁ exposure" and "lung function". A total of 6420 relevant studies were identified through our initial search, and seven studies were included in our study. In this meta-analysis, the fixed effect and random effects statistical models were used to estimate the synthesized effects of the seven included studies. For every 10 μg/m³ increase in short-term PM₁ exposure, forced vital capacity (FVC), forced expiratory volume in the first second (FEV₁), peak expiratory flow (PEF) and maximal mid-expiratory flow (MMEF) decreased by 31.82 mL (95% CI: 20.18, 43.45), 32.28 mL (95% CI: 16.73, 48.91), 36.85 mL/s (95% CI: 15.33, 58.38) and 34.51 mL/s (95% CI: 19.61, 49.41), respectively. For each 10 μg/m³ increase in long-term PM₁ exposure, FVC, FEV₁, PEF and MMEF decreased by 102.34 mL (95% CI: 49.30, 155.38), 75.17 mL (95% CI: 39.61, 110.73), 119.01 mL/s (95% CI: 72.14, 165.88) and 44.94 mL/s (95% CI: 4.70, 85.18), respectively. Our study provides further scientific evidence for the harmful effects of PM₁ exposure on lung function in children and adolescents, indicating that exposure to PM₁ is detrimental to pulmonary health. To reduce the adverse health effects of air pollution on children and adolescents, effective preventive measures should be taken.

Association between short-term exposure to ambient PM1 and PM2.5 and forced vital capacity in Chinese children and adolescents

This study aims to examine the association between short-term exposure to ambient PM₁, PM_1-2.5, and PM_2.5 and forced vital capacity (FVC). Population data were obtained from a school-based cross-sectional survey in Shandong in 2014. Distributed lag non-linear models were used to examine the association between exposure to PM₁, PM_1-2.5, and PM_2.5 and FVC at the day of FVC measurement and the previous 6 days (lag 0 to 6 days). A total of 35,334 students aged 9 to 18 years were included in the study, and the mean exposure concentrations of ambient PM₁, PM_1-2.5, and PM_2.5 for them were 47.4 (standard deviation [SD] = 21.3) μg/m³, 32.8 (SD = 32.2) μg/m³, and 80.1 (SD = 47.7) μg/m³, respectively. An inter-quartile range (IQR, 24 μg/m³) increment in exposure to PM₁ was significantly associated with a lower FVC at lag 0 and lag 1 day (β =  - 80 mL, 95% CI =  - 119, - 42, and β =  - 37 mL, 95% CI =  - 59, - 16, respectively), and an IQR (54 μg/m³) increment in exposure to PM_2.5 was significantly associated with a lower FVC at lag 0 and lag 1 day (β =  - 57 mL, 95% CI =  - 89, - 18, and β =  - 34 mL, 95% CI =  - 56, - 12, respectively) after adjustment for gender, age, body mass index category, residence, month of the survey, intake of eggs, intake of milk, physical activity, and screen time. No significant associations were observed for PM_1-2.5. The inverse associations of PM₁ and PM_2.5 with FVC were larger in males, younger children, those overweight or obese, and those with insufficient physical activity levels. Short-term exposure to ambient PM₁ and PM_2.5 was associated with decreased FVC, and PM₁ may be the primary fraction of PM_2.5 causing the adverse pulmonary effects. Our findings emphasize the need to address ambient PM, especially PM₁, pollution for affecting pulmonary health in children and adolescents.

Effects of air pollution on myopia: an update on clinical evidence and biological mechanisms

Myopia is one of the most common forms of refractive eye disease and considered as a worldwide pandemic experienced by half of the global population by 2050. During the past several decades, myopia has become a leading cause of visual impairment, whereas several factors are believed to be associated with its occurrence and development. In terms of environmental factors, air pollution has gained more attention in recent years, as exposure to ambient air pollution seems to increase peripheral hyperopia defocus, affect the dopamine pathways, and cause retinal ischemia. In this review, we highlight epidemiological evidence and potential biological mechanisms that may link exposure to air pollutants to myopia. A thorough understanding of these mechanisms is a key for establishing and implementing targeting strategies. Regulatory efforts to control air pollution through effective policies and limit individual exposure to preventable risks are required in reducing this global public health burden.

Use of unclean cooking fuels and visual impairment of older adults in India: A nationally representative population-based study

Despite widespread use of unclean cooking fuels (UCF) in India, evidence from nationally representative data on its association with visual impairment was lacking. We used a population-based nationwide survey of adults aged 45 years and older that included reported UCF and measured visual impairment. We estimated that 44.8% (95% CI: 42.6, 47.1) of older adults in India lived in households that used UCF. Age- and sex-adjusted prevalence of visual impairment was estimated to be 33.0% (95% CI: 31.0, 34.9) in the older population that did not use UCF and 9.0 percentage points (pp) (95% CI: 8.9, 9.1) higher among those who did. Among those who used UCF, age- and sex-adjusted prevalence of low distance vision was 4.3 pp (95% CI: 4.2, 4.4) higher, prevalence of low near vision was 8.0 pp (95% CI: 7.9, 8.1) higher, and prevalence of blindness was 1.0 pp (95% CI: 0.9, 1.0) higher. After controlling for a rich array of sociodemographic characteristics and state fixed effects, we estimated that use of UCF was associated with higher prevalence of visual impairment by 3.2 pp (95% CI: 1.4, 5.0), low distance vision by 1.8 pp (95% CI: 0.7, 2.9), and low near vision by 3.2 pp (95% CI: 1.3, 5.0). Doubly robust estimates of these differences were slightly larger. Blindness was not significantly partially associated with use of UCF (95% CI: -0.4, 0.6). We did not find support for the hypotheses that the visual impairment risk associated with use of UCF was even larger for females and in households without a separate kitchen or ventilation. The older population of India is highly reliant on UCF that is very strongly associated with visual impairment. Impaired vision should not be overlooked among the harms associated with UCF.

Magnetic resonance imaging investigations reveal that PM2.5 exposure triggers visual dysfunction in mice

OBJECTIVES

To investigate how PM_2.5 exposure affects the microstructure, metabolites or functions of the visual system.

METHODS

C57BL/6J mice were randomly assigned to groups exposed to the filtered air (the control group) or the concentrated ambient PM_2.5 (the PM_2.5 group). Visual evoked potentials (VEP), electroretinograms (ERG), diffusion tensor imaging (DTI), proton magnetic resonance spectroscopy (¹H-MRS) and resting-state functional MRI (rsfMRI) were performed. Parameters were obtained and compared between the two groups, including latencies and amplitudes of the P1 wave, N1 wave and P2 wave from VEP, latencies and amplitudes of the a wave and b wave from ERG, fractional anisotropy (FA), mean diffusion (MD), axial diffusivity (AD) and radial diffusivity (RD) from DTI, visual cortex (VC) metabolites from ¹H-MRS, and regional homogeneity (ReHo) from rsfMRI.

RESULTS

Compared with the values of the control group, the PM_2.5 group showed a prolonged N1 latency (43.11 ± 7.94 ms vs. 38.75 ± 4.60 ms) and lowered P1 amplitude (5.62 ± 4.38 μV vs. 8.56 ± 5.92 μV) on VEP (all p < 0.05). On ERG, the amplitude of the a wave was lowered (- 91.39 ± 56.29 μV vs. - 138.68 ± 89.05 μV), the amplitude of the b wave was lowered (194.38 ± 126.27 μV vs. 284.72 ± 170.99 μV), and the latency of the b wave was prolonged (37.78 ± 10.72 ms vs. 33.01 ± 4.34 ms) than the values of the control group (all p < 0.05). DTI indicated FA increase in the bilateral piriform cortex (Pir), FA decrease in the bilateral somatosensory cortex (S) and the bilateral striatum (Stri), AD decrease in the bilateral VC, the right S and the bilateral Pir, MD decrease in the bilateral Pir, and RD decrease in the bilateral Pir in the PM_2.5 mice (all p < 0.05, Alphasim corrected). ¹H-MRS showed Glutamate (Glu) increase and Phosphocholine (PCh) increase in the VC of the PM_2.5 group than those of the control group (PCh 1.63 ± 0.25 vs. 1.50 ± 0.25; PCh/total creatine(tCr) 0.19 ± 0.03 vs. 0.18 ± 0.03; Glu 10.46 ± 1.50 vs. 9.60 ± 1.19; Glu/tcr 1.23 ± 0.11 vs. 1.12 ± 0.11) (all p < 0.05). rsfMRI showed higher ReHo in the PM_2.5 mice in the left superior colliculus, the left motor cortex, the hippocampus, the periaqueductal gray and the right mesencephalic reticular formation (all p < 0.01, AlphaSim corrected).

CONCLUSIONS

This study revealed that PM_2.5 exposure triggered visual dysfunction, and altered microstructure, metabolite and function in the retina and visual brain areas along the visual system.

Fine Particulate Matter and Age-Related Eye Disease: The Canadian Longitudinal Study on Aging

Purpose

To determine the relationship between fine particulate matter (PM2.5) and ocular outcomes such as visual impairment and age-related eye disease.

Methods

Baseline data were used from the Canadian Longitudinal Study on Aging. The Comprehensive Cohort consisted of 30,097 adults ages 45 to 85 years. Annual mean PM2.5 levels (µg/m3) for each participant's postal code were estimated from satellite data. Ozone, sulfur dioxide, and nitrogen dioxide levels were also estimated. Binocular presenting visual acuity was measured using a visual acuity chart. Intraocular pressure (IOP) was measured in millimeters of mercury using the Reichart Ocular Response Analyzer. Participants were asked about a diagnosis of glaucoma, macular degeneration, or cataract. Logistic and linear regression models were used.

Results

The overall mean PM2.5 level was 6.5 µg/m3 (SD = 1.8). In the single pollutant models, increased PM2.5 levels (per interquartile range) were associated with visual impairment (odds ratio [OR] = 1.12; 95% confidence interval [CI], 1.02-1.24), glaucoma (OR = 1.14; 95% CI, 1.01-1.29), and visually impairing age-related macular degeneration (OR = 1.52; 95% CI, 1.10-2.09) after adjustment for sociodemographics and disease. PM2.5 had a borderline adjusted association with cataract (OR = 1.06; 95% CI, 0.99-1.14). In the multi-pollutant models, increased PM2.5 was associated with glaucoma and IOP only after adjustment for sociodemographics and disease (OR = 1.24; 95% CI, 1.05-1.46 and β = 0.24; 95% CI, 0.12-0.37).

Conclusions

Increased PM2.5 is associated with glaucoma and IOP. These associations should be confirmed using longitudinal data and potential mechanisms should be explored. If confirmed, this work may have relevance for revision of World Health Organization thresholds to protect human health.