Rural-urban differences in associations between air pollution and cardiovascular hospital admissions in Guangxi, southwest China

Long-term exposure to low-level ozone and the risk of hypertension: A prospective cohort study conducted in a low-pollution region of southwestern China

BACKGROUND

The current evidence regarding the association between long-term exposure to ozone (O3) and hypertension incidence is limited and inconclusive, particularly at low O3 concentrations. Therefore, our research aims to investigate the potential link between long-term O3 exposure and hypertension in a region with low pollution levels.

METHODS

From 2010 to 2012, we conducted a cohort prospective study by recruiting nearly 10,000 attendees through multistage cluster random sampling in Guizhou Province, China. These individuals were followed up from 2016 to 2020, and 5563 cases were finally included in the analysis. We employed a high-resolution model with both temporal and spatial accuracy to estimate the maximum daily 8-h average O3 and utilized annual average O3 concentrations for three exposure periods (2009_10, 2007_10, 2005_10) as the exposure indicator. Time-dependent covariates Cox regression model was exerted to estimate the hazard ratios (HRs) of hypertension incidence. Generalized linear model was employed to assess the association between O3 and systolic, diastolic, pulse, and mean arterial pressure. The dose-response curve was explored using a restricted cubic spline function.

RESULTS

1213 hypertension incidents occurred during 39,001.80 person-years, with an incidence density of 31.10/1000 Person Years (PYs). The average O3 concentrations during the three exposure periods were 66.76 μg/m3, 67.85 μg/m3, and 67.21 μg/m3, respectively. Per 1 μg/m3 increase in O3 exposure was associated with 11 % increase in the incidence of hypertension in the single-pollution model, and the association was more pronounced in Han, urban, and higher altitude areas. SBP, PP, and MAP were increased by 0.619 (95 % CI, 0.361-0.877) mm Hg, 0.477 (95 % CI, 0.275-0.679) mm Hg, 0.301 (95 % CI, 0.127-0.475) mm Hg, respectively. Furthermore, we observed a nonlinear exposure-response relationship between O3 and hypertension incidence.

CONCLUSIONS

Long-term exposure to low-level O3 exposure is associated with an increased risk of hypertension.

Long-term exposure to ambient ozone and cardiovascular diseases: Evidence from two national cohort studies in China

INTRODUCTION

The health effects of ambient ozone have been investigated in many previous studies. However, the effects of long-term exposure to ambient ozone on the incidence of cardiovascular disease (CVD) remain inconclusive.

OBJECTIVES

To estimate the associations of long-term exposure to maximum daily 8-hours average ozone (MDA8 O3) with the incidence of total CVD, heart disease, hypertension, and stroke.

METHODS

This was a prospective cohort study, and the data was obtained from the China Health and Retirement Longitudinal Survey (CHARLS) implemented during 2011-2018 and the China Family Panel Studies (CFPS) implemented during 2010-2018. We applied a Cox proportional hazards regression model to evaluate the associations of MDA8 O3 with total CVD, heart disease, hypertension, and stroke risks, and the corresponding population-attributable fractions (PAF) attributable to MDA8 O3 were also calculated. All analyses were conducted by R software.

RESULTS

The mean MDA8 O3 concertation of all included participants in the CHARLS and CFPS were 51.03 part per billion (ppb) and 51.15 ppb, respectively. In the CHARLS including 18,177 participants, each 10 ppb increment in MDA8 O3 concentration was associated with a 31% increase [hazard ratio (HR) = 1.31, 95% confidence interval (CI): 1.22-1.42] in the risk of incident heart disease, and the corresponding population-attributable fractions (PAF) was 13.79% [10.12%-17.32%]. In the CFPS including 30,226 participants, each 10 ppb increment in MDA8 O3 concentration was associated with an increase in the risk of incident total CVD (1.07 [1.02-1.13]), and hypertension (1.10 [1.03-1.18]). The PAFs of total CVD, and hypertension attributable to MDA8 O3 were 3.53% [0.82%-6.16%], and 5.11% [1.73%-8.38%], respectively. Stratified analyses showed greater associations in males, urban areas, and Southern China.

CONCLUSIONS

Long-term exposure to MDA8 O3 may increase the incidence of CVD. Therefore, the policies that control O3 and related precursors are persistently needed.

Exploring cardiovascular health in children: the influence of Hemoglobin-to-Platelet ratio in contrasting rural and urban communities

Understanding the associations and possible mechanisms between Cardiorespiratory Fitness (CRF) and residential location is an important focus of public health research. This is a cross-sectional study carried out with 2250 students (6-17 years), from southern Brazil. In addition to age, sex, and body size measurements, we also recorded hemoglobin and platelet count measurements using venous blood samples (10 ml). The CRF was measured using the 6-minute run/walk test, with predictors explored via allometry. Results identified a novel and independent association between the hemoglobin-to-platelet count ratio and children's CRF, after controlling for confounders. We also provide evidence of a possible mechanism for this association, having identified reduced measures of hemoglobin and increased platelet counts observed in children living in urban (vs rural) areas. These results suggest the need for more effective public health practices and policies addressing the built enviroment´s health effects in Brazil and potentially other congested ciries.

Urban-rural disparities in the association of nitrogen dioxide exposure with cardiovascular disease risk in China: effect size and economic burden

BACKGROUND

Together with rapid urbanization, ambient nitrogen dioxide (NO2) exposure has become a growing health threat. However, little is known about the urban-rural disparities in the health implications of short-term NO2 exposure. This study aimed to compare the association between short-term NO2 exposure and hospitalization for cardiovascular disease (CVD) among urban and rural residents in Shandong Province, China. Then, this study further explored the urban-rural disparities in the economic burden attributed to NO2 and the explanation for the disparities.

METHODS

Daily hospitalization data were obtained from an electronic medical records dataset covering a population of 5 million. In total, 303,217 hospital admissions for CVD were analyzed. A three-stage time-series analytic approach was used to estimate the county-level association and the attributed economic burden.

RESULTS

For every 10-μg/m3 increase in NO2 concentrations, this study observed a significant percentage increase in hospital admissions on the day of exposure of 1.42% (95% CI 0.92 to 1.92%) for CVD. The effect size was slightly higher in urban areas, while the urban-rural difference was not significant. However, a more pronounced displacement phenomenon was found in rural areas, and the economic burden attributed to NO2 was significantly higher in urban areas. At an annual average NO2 concentration of 10 μg/m3, total hospital days and expenses in urban areas were reduced by 81,801 (44,831 to 118,191) days and 60,121 (33,002 to 86,729) thousand CNY, respectively, almost twice as much as in rural areas. Due to disadvantages in socioeconomic status and medical resources, despite similar air pollution levels in the urban and rural areas of our sample sites, the rural population tended to spend less on hospitalization services.

CONCLUSIONS

Short-term exposure to ambient NO2 could lead to considerable health impacts in either urban or rural areas of Shandong Province, China. Moreover, urban-rural differences in socioeconomic status and medical resources contributed to the urban-rural disparities in the economic burden attributed to NO2 exposure. The health implications of NO2 exposure are a social problem in addition to an environmental problem. Thus, this study suggests a coordinated intervention system that targets environmental and social inequality factors simultaneously.

The mediation role of blood lipids on the path from air pollution exposure to MAFLD: A longitudinal cohort study

BACKGROUND & AIMS

Recent cross-sectional studies found that exposure to ambient air pollution (AP) was associated with an increased risk of metabolic dysfunction-associated fatty liver disease (MAFLD). The alternation of blood lipids may explain the association, but epidemiological evidence is lacking. We aimed to examine whether and to what extent the association between long-term exposure to AP and incident MAFLD is mediated by blood lipids and dyslipidemia in a prospective cohort.

METHODS

We included 6350 participants from the China Multi-Ethnic Cohort (CMEC, baseline 2018-2019, follow-up 2020-2021). Three-year average (2016-2018) of AP (PM1, PM2.5, PM10, NO2), blood lipids (TC, LDL-C, HDL-C, TG with their combinations) and incident MAFLD for each individual were assessed chronologically. Linear and logistic regression was used to assess the associations among AP, blood lipids, and MAFLD, and the potential mediation effects of blood lipids were evaluated using causal mediation analysis.

RESULTS

A total of 744 participants were newly diagnosed with MAFLD at follow-up. The odds ratios of MAFLD associated with a 10 μm increase in PM1, PM2.5, and NO2 were 1.35 (95 % CI: 1.14, 1.58), 1.34 (1.10, 1.65) and 1.28 (1.14, 1.44), respectively. Blood lipids are important mediators between AP and incident MAFLD. LDL-C (Proportion Mediated: 6.9 %), non-HDL (13.4 %), HDL-C (20.7 %), LDL/HDL (30.1 %), and dyslipidemia (6.5 %) significantly mediated the association between PM2.5 and MAFLD. For PM1, the indirect effects were similar to those for PM2.5, with a larger value for the direct effect, and the mediation proportion by blood lipids was less for NO2.

CONCLUSION

Blood lipids are important mediators between AP and MAFLD, and can explain 5 %-30 % of the association between AP and incident MAFLD, particularly cholesterol-related variables, indicating that AP could lead to MAFLD through the alternation of blood lipids. These findings provided mechanical evidence of AP leading to MAFLD in epidemiological studies.

Association of air pollution and green space with all-cause general practitioner and emergency room visits: A cross-sectional study of young people and adults living in Belgium

BACKGROUND

Residing in areas with lower levels of air pollution and higher green space is beneficial to physical and mental health. We investigated associations of PM2.5, tree cover and grass cover with in-hours and out-of-hours GP visits and ER visits, for young people and adults. We estimated potential cost savings of GP visits attributable to high PM2.5.

METHODS

We linked individual-level health insurance claims data of 315,123 young people (10-24 years) and 885,988 adults (25-64 years) with census tract-level PM2.5, tree cover and grass cover. Deploying negative binomial generalized linear mixed models, we estimated associations between quartile exposures and the three outcome measures.

RESULTS

For in-hours and out-of-hours GP visits, among young people as well as adults, statistically significant pairwise differences between quartiles suggested increasing beneficial effects with lower PM2.5. The same outcomes were statistically significantly less frequent in quartiles with highest tree cover (>30.00%) compared to quartiles with lower tree cover, but otherwise pairwise differences were not statistically significant. These associations largely persisted in rural and urban areas. Among adults living in urban areas lower grass cover was associated with increased in-hours GP visits and ER visits. Assuming causality, reducing PM2.5 levels to the lowest quartile (4.91-7.49 μg/m³), among adults, 195,964 in-hours and 74,042 out-of-hours GP visits could be avoided annually. Among young people, 27,457 in-hours and 22,423 out-of-hours GP visits could be avoided annually. Nationally, this amounts to an annual potential cost saving of €43 million (€5.7 million in out-of-pocket payments and €37.2 million in compulsory health insurance).

CONCLUSION

Higher ambient PM2.5 and lower tree cover show associations with higher non-urgent and urgent medical care utilization. These findings confirm the importance of reducing air pollution and fostering green zones, and that such policies may contribute positively to economic growth.

Short-term exposure to air pollution and outpatient visits for conjunctivitis: a time-series analysis in Urumqi, China

Conjunctivitis is an inflammatory disease of the conjunctival tissue caused by a variety of causes; despite the conjunctiva being directly exposed to the external atmospheric environment, the important role of air pollution is not fully evaluated, especially in areas with poor air quality undergoing rapid economic and industrial development. Information on 59,731 outpatient conjunctivitis visits from 1 January 2013 to 31 December 2020 was obtained from the Ophthalmology Department of the First Affiliated Hospital of Xinjiang Medical University (Urumqi, Xinjiang, China), and data on six air pollutants including particulate matter with a median aerometric diameter of less than 10 and 2.5 mm (PM₁₀ and PM_2.5, respectively), carbon monoxide (CO), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and ozone (O₃) from eleven standard urban background fixed air quality monitors were also recorded. 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 effect of exposure to air pollutants on the risk of conjunctivitis outpatient visits. Further subgroup analyses were conducted for gender, age, and season, as well as the type of conjunctivitis. Single and multi-pollutant models showed that exposure to PM_2.5, PM₁₀, NO₂, CO, and O₃ was associated with increased risk of outpatient conjunctivitis visits on the lag 0 day and various other lag days. Variations in the effect estimates on direction and magnitude were found in different subgroup analyses. We conducted the first time-series analysis with the longest duration as well as the largest sample size in Northwest China, which provides evidence that outpatient conjunctivitis visits is significantly associated with air pollution in Urumqi, China. Meanwhile, our results demonstrate the effectiveness of SO₂ reduction in reducing the risk of outpatient conjunctivitis visits in the Urumqi region and reaffirm the need to implement special air pollution control measures.

Ambient nitrogen dioxide and cardiovascular diseases in rural regions: a time-series analyses using data from the new rural cooperative medical scheme in Fuyang, East China

Most of studies relating ambient nitrogen dioxide (NO₂) exposure to hospital admissions for cardiovascular diseases (CVDs) were conducted among urban population. Whether and to what extent these results could be generalizable to rural population remains unknown. We addressed this question using data from the New Rural Cooperative Medical Scheme (NRCMS) in Fuyang, Anhui, China. Daily hospital admissions for total CVDs, ischaemic heart disease, heart failure, heart rhythm disturbances, ischaemic stroke, and haemorrhagic stroke in rural regions of Fuyang, China, were extracted from NRCMS between January 2015 and June 2017. A two-stage time-series analysis method was used to assess the associations between NO₂ and CVD hospital admissions and the disease burden fractions attributable to NO₂. In our study period, the average number (standard deviation) of hospital admissions per day were 488.2 (117.1) for total CVDs, 179.8 (45.6) for ischaemic heart disease, 7.0 (3.3) for heart rhythm disturbances, 13.2 (7.2) for heart failure, 267.9 (67.7) for ischaemic stroke, and 20.2 (6.4) for haemorrhagic stroke. The 10-μg/m³ increase of NO₂ was related to an elevated risk of 1.9% (RR: 1.019, 95% CI: 1.005 to 1.032) for hospital admissions of total CVDs at lag0-2 days, 2.1% (1.021, 1.006 to 1.036) for ischaemic heart disease, and 2.1% (1.021, 1.006 to 1.035) for ischaemic stroke, respectively, while no significant association was observed between NO₂ and hospital admissions for heart rhythm disturbances, heart failure, and haemorrhagic stroke. The attributable fractions of total CVDs, ischaemic heart disease, and ischaemic stroke to NO₂ were 6.52% (1.87 to 10.94%), 7.31% (2.19 to 12.17%), and 7.12% (2.14 to 11.85%), respectively. Our findings suggest that CVD burdens in rural population are also partly attributed to short-term exposure to NO₂. More studies across rural regions are required to replicate our findings.

Associations between seasonal ambient air pollution and adverse perinatal outcomes: a retrospective cohort study in Wenzhou, China

Prenatal exposure to ambient air pollution has been associated with adverse perinatal outcomes in previous studies. However, few studies have examined the interaction between air pollution and the season of conception on term low birth weight (TLBW) or macrosomia. Birth registry data of singleton live births in Wenzhou, China, between January 2015 and December 2016 were accessed from the Wenzhou Maternal and Child Health Information Management platform, and data on the ambient air pollutants in Wenzhou were obtained from the Chinese Air Quality Online Monitoring and Analysis Platform. Single-/two-pollutant binary logistic regression models were used to assess the associations between ambient air pollutants (PM_2.5, PM₁₀, NO₂, SO₂, and O₃) and TLBW/macrosomia, further exploring whether the season of conception interacts with air pollution to impact birth weight. Finally, 213,959 term newborns were selected, including 2452 (1.1%) infants with TLBW and 13,173 (6.1%) infants with macrosomia. In the single-/two-pollutant models, we observed an increased risk of TLBW associated with maternal exposure to PM_2.5, PM₁₀, SO₂, and NO₂ during the entire pregnancy, especially in the 2nd trimester. Maternal exposure to O₃ during the 1st trimester was associated with increased macrosomia risk, and O₃ exposure during the 3rd trimester was associated with increased TLBW risk. Pregnant women who conceive in the warm season may experience a more adverse ambient air environment that is related to the risks of TLBW. These findings add to the evidence suggesting that air pollution and the season of conception may have synergistic effects on adverse perinatal outcomes, especially TLBW. Further prospective cohort studies are needed to validate our results.

Full-Coverage PM2.5 Mapping and Variation Assessment during the Three-Year Blue-Sky Action Plan Based on a Daily Adaptive Modeling Approach

Owing to a series of air pollution prevention and control policies, China’s PM2.5 pollution has greatly improved; however, the long-term spatial contiguous products that facilitate the analysis of the distribution and variation of PM2.5 pollution are insufficient. Due to the limitations of missing values in aerosol optical depth (AOD) products, the reconstruction of full-coverage PM2.5 concentration remains challenging. In this study, we present a two-stage daily adaptive modeling framework, based on machine learning, to solve this problem. We built the annual models in the first stage, then daily models were constructed in the second stage based on the output of the annual models, which incorporated the parameter and feature adaptive tuning strategy. Within this study, PM2.5 concentrations were adaptively modeled and reconstructed daily based on the multi-angle implementation of atmospheric correction (MAIAC) AOD products and other ancillary data, such as meteorological factors, population, and elevation. Our model validation showed excellent performance with an overall R2 = 0.91 and RMSE = 9.91 μg/m3 for the daily models, along with the site-based cross-validation R2s and RMSEs of 0.86–0.87 and 12–12.33 μg/m3; these results indicated the reliability and feasibility of the proposed approach. The daily full-coverage PM2.5 concentrations at 1 km resolution across China during the Three-Year Blue-Sky Action Plan were reconstructed in this study. We analyzed the distribution and variations of reconstructed PM2.5 at three different time scales. Overall, national PM2.5 pollution has significantly improved with the annual average concentration dropping from 33.67–28.03 μg/m3, which demonstrated that air pollution control policies are effective and beneficial. However, some areas still have severe PM2.5 pollution problems that cannot be ignored. In conclusion, the approach proposed in this study can accurately present daily full-coverage PM2.5 concentrations and the research outcomes could provide a reference for subsequent air pollution prevention and control decision-making.