Ambient fine particulate matter pollution and years of life lost from cardiovascular diseases in 48 large Chinese cities: Association, effect modification, and additional life gain

Interaction between walkability and fine particulate matter on ischemic heart disease: A prospective cohort study in China

BACKGROUND

Previous studies have suggested that neighborhoods characterized by higher walkability are related to a reduced risk of ischemic heart disease (IHD), whereas exposure to PM2.5 is positively associated with risk of IHD. Nevertheless, their joint impact on IHD warrants further investigation.

METHODS

This prospective cohort study was performed in Yinzhou, Ningbo, China, comprising 47,516 participants. Individual-level walkability and PM2.5 were evaluated using a commercial walkability database and a land use regression (LUR) model, respectively. Hazard ratios (HRs) and 95 % confidence intervals (95 % CIs) were calculated using two Cox proportional hazards models: one based on two-year average PM2.5 levels prior to baseline, and the other incorporating time-varying PM2.5 assessed on a monthly scale. Dose-response relationships were explored using restricted cubic spline (RCS) functions. Interactions on both additive and multiplicative scales were assessed via relative excess risk due to interaction (RERI) and likelihood-ratio tests. Joint effects were explored and visualized using a 3D wireframe plot.

RESULTS

Over a median follow-up of 5.14 years, 1735 incident cases of IHD were identified. Adjusted HRs (95 % CIs) were 1.56 (1.34-1.81) per 10 μg/m3 increase in PM2.5 and 0.96 (0.94-0.98) per 10-unit increase in walkability, with both exposures exhibiting non-linear dose-response relationships. Walkability and PM2.5 were positively correlated (rs = 0.12, P < 0.001), and a multiplicative interaction was detected (Pinteraction = 0.019).

CONCLUSION

Walkability was inversely associated with risk of IHD, whereas exposure to PM2.5 was positively associated with IHD. Notably, the pernicious effects of PM2.5 could be attenuated in areas with higher levels of walkability. Our findings underscore the significance of walkable urban design, air quality improvement, as preventive strategies for IHD.

Enhancing the health benefits of air quality improvement: a comparative study across diverse scenarios

In many studies, linear methods were used to calculate health benefits of air quality improvement, but the relationship between air pollutants and diseases may be complex and nonlinear. In addition, previous studies using reference number as average number of diseases may overestimate the health benefits. Therefore, the nonlinear model estimation and resetting of the reference number were very important. Hospital admission data for coronary heart disease (CHD), meteorological data, and air pollutant data of Zibo City from 2015 to 2019 were collected. The generalized additive model (GAM) was used to explore the association between air pollutants and hospital admission for CHD, and to evaluate the effects on health benefits under different reference number settings. A total of 21,105 hospitalized cases for CHD were reported in Zibo during the study period. The results of the GAM showed there was a log-linear exposure-response relationship between O3 and hospital admissions for CHD, with RR (relative risk) of 1.0143 (95% CI: 1.0047 ~ 1.0239). There were log-nonlinear exposure-response relationships between PM10, PM2.5, SO2, and hospital admissions for CHD. With the increase of pollutants concentrations, the risk for hospital admission showed a trend of increasing first and then decreasing. Compared with the average hospital admissions as the reference number, health benefits calculated by hospital admissions predicted by the GAM model yielded lower. Using the World Health Organization air quality guidelines as reference, attributable fractions of O3, PM10, and PM2.5 were 1.97% (95% CI: 0.63 ~ 3.40%), 11.82% (95% CI: 8.60 ~ 15.24%), and 11.82% (95% CI: 8.79 ~ 15.04%), respectively. When quantifying health benefits brought by improving air quality, corresponding calculation methods should first be determined according to the exposure-response relationships between air pollutants and outcomes. Then, applying the average hospital admissions as reference number may overestimate health benefits resulting from improved air quality.

Cumulative and lagged effects of varying-sized particulate matter exposure associates with toddlers' gut microbiota

Particulate matter (PM) is an important component of air pollutants and is associated with various health risks. However, the impact of PM on toddlers' gut microbiota is rarely investigated. This study aimed to assess the cumulative and lagged effects of varying-sized PMs on toddlers' gut microbiota. We collected demographic information, stool samples, and exposure to PM from 36 toddlers aged 2-3 years. The toddlers were divided into warm season group and cooler season group according to the collection time of stool samples. The gut microbiota was processed and analyzed using 16S rRNA V3-V4 gene regions. The concentration of PM was calculated using China High Air Pollutants (CHAP) database. To assess the mixed effects of varying-sized PM, multiple-PM models were utilized. There were significant differences between the community composition, α- and β-diversity between two groups. In multiple-PM models, there was a significant effect of weight quantile sum (PM1, PM2.5, and PM10) on α-diversity indices. In weight quantile sum models, after adjusting for a priori confounders, we found a negative effect of weight quantile sum on Enterococcus (β = -0.134, 95% CI -0.263 to -0.006), positive effects of weight quantile sum on unclassified_f__Ruminococcaceae (β = 0.247, 95% CI 0.102 to 0.393), Ruminococcus_1 (β = 0.444, 95% CI 0.238 to 0.650), unclassified_f__Lachnospiraceae (β = 0.278, 95% CI 0.099 to 0.458), and Family_XIII_AD_3011_group (β = 0.254, 95% CI 0.086 to 0.422) in WSG and CSG. In lagged weight quantile sum models, the correlation between lag time PM levels and the gut microbiota showed seasonal trends, and weights of PM changed with lag periods. This is the first study to highlight that cumulative and lagged effects of PMs synergistically affect the diversities (α- and β-diversity) and abundance of the gut microbiota in toddlers. Further research is needed to explore the mediating mechanism of varying-sized PMs exposure on the gut microbiota in toddlers.

Effect of Air Pollution Particulate Matter on Ischemic and Hemorrhagic Stroke: A Scoping Review

Air pollution particulate matter (PM) exposure has been established as a risk factor for stroke. However, few studies have investigated the effects of PM exposure on stroke subtypes (ischemic and hemorrhagic stroke). Ischemic (IS) and hemorrhagic strokes (HS) involve distinctive pathophysiological pathways and may be differentially influenced by PM exposure. This review aims to characterize the effects of PM exposure on ischemic and hemorrhagic strokes. It also identifies subpopulations that may be uniquely vulnerable to PM toxicity. Pubmed was queried from 2000 to 2023 to identify clinical and epidemiological studies examining the association between PM exposure and stroke subtypes (ischemic and hemorrhagic stroke). Inclusion criteria were: 1) articles written in English 2) clinical and epidemiological studies 3) studies with a clear definition of stroke, IS, HS, and air pollution 4) studies reporting the effects of PM and 5) studies that included distinct analyses per stroke subtype. Two independent reviewers screened the literature for applicable studies. A total of 50 articles were included in this review. Overall, PM exposure increases ischemic stroke risk in both lightly and heavily polluted countries. The association between PM exposure and hemorrhagic stroke is variable and may be influenced by a country's ambient air pollution levels. A stronger association between PM exposure and stroke is demonstrated in older individuals and those with pre-existing diabetes. There is no clear effect of sex or hypertension on PM-associated stroke risk. Current literature suggests PM exposure increases ischemic stroke risk, with an unclear effect on hemorrhagic stroke risk. Older patients and those with pre-existing diabetes may be the most vulnerable to PM toxicity. Future investigations are needed to characterize the influence of sex and hypertension on PM-associated stroke risk.

The effect of ambient temperature and risk of cardiovascular disease hospitalization in China: a meta-analysis

The effect of ambient temperature on relative risk (RR) of cardiovascular disease (CVD) is different in China than in other countries due to the different geographical environment, climate the different inter- and intra-individual characteristics of the population within China. It is therefore important to integrate information to evaluate the impact of temperature on RR of CVD in China. We performed a meta-analysis to evaluate the effect of temperature on RR of CVD. The Web of Science, Google Scholar, and China National Knowledge Infrastructure databases were searched back to 2022 and nine studies were included in the study. The Cochran Q test and I2 statistics were used to assess heterogeneity, while Egger's test was used to assess publication bias. The pooled estimated size of the relationship between ambient temperature and CVD hospitalization in the random effect model was 1.2044 (95%CI: 1.0610-1.3671) for the cold effect and 1.1982 (95%CI: 1.0166-1.4122) for the heat effect. The Egger's test showed a potential publication bias for the cold effect, whereas there was no apparent publication bias for the heat effect. There is a significant effect of ambient temperature on RR of CVD for both the cold effect and heat effect. The effect of socioeconomic factors should be considered more thoroughly in future studies.

Time trends in the burden of stroke and subtypes attributable to PM2.5 in China from 1990 to 2019

Background

Increasing studies have found that PM2.5 has large adverse effects on stroke mortality. We want to investigate the long-term trends in the mortality of stroke attributable to ambient particulate matter pollution and household air pollution to provide evidence facilitating the design of policy.

Methods

The deaths data of stroke and its subtypes attributable to PM2.5 were obtained from the Global Burden of Disease (GBD) 2019, analyzed by Joinpoint regression software and the age-period-cohort (APC) method to assess the magnitude of the trends in mortality and the temporal trends in the mortality rate by age, period, and cohort.

Results

From 1990 to 2019, the age-standardized mortality rate (ASMR) attributable to PM2.5 exposure trended downwards, but the trends of ambient particulate matter pollution and household air pollution were opposite. The trends varied among subtypes, the AAPC of intracerebral hemorrhage, ischemic stroke, and subarachnoid hemorrhage attributable to PM2.5 were 0.7, 2.5, and-3.3%, respectively. The longitudinal age curve of the APC model showed that the mortality rates due to PM2.5 exposure increased with age. The period RRs of ischemic stroke due to ambient particulate matter pollution increased significantly. The cohort RRs of ambient particulate matter pollution increased among those born from 1905 to 1990. The net drifts of all subtypes attributable to PM2.5 were below 0, but owing to the increase of ambient particulate matter pollution, the range of the decline was small. Males had higher net drift values, compared with females.

Conclusions

Ambient particulate matter pollution has become the main type of PM2.5 leading to stroke in China. PM2.5 exposure is more harmful to ischemic stroke, males, and elderly. Chinese government should pay attention to the long-term impact of ambient air pollution on stroke and take effective public health policies and interventions.

Differentiating the effects of air pollution on daily mortality counts and years of life lost in six Chinese megacities

BACKGROUND

Ambient air pollution has been widely associated with increased mortality and years of life lost (YLL) from various diseases. However, no study has assessed that the effects of air pollution on overall YLL were due to increased number of mortalities or average YLL per death.

METHODS

We first conducted a time-series study from 2013 to 2016, covering six Chinese megacities. Generalized additive models with a Gaussian link were utilized to estimate the associations of fine particulate matter (PM_2.5) and nitrogen dioxide (NO₂) with daily overall YLL and average YLL per death from various causes, including non-accidental causes, cardiovascular diseases (CVD), respiratory diseases (RD), ischemic heart disease (IHD), chronic obstructive pulmonary diseases (COPD), stroke and acute myocardial infraction (AMI). The city-specific estimates were then pooled by random-effects meta-analysis.

RESULTS

A total of 1,586,741 deaths from non-accidental causes and 21,916,857 YLLs were recorded in the six cities, providing an average of 13.81 daily YLLs per death. Significant effects of PM_2.5 and NO₂ on daily overall YLL and daily mortality count were observed, but there were no significant effects on average YLL per death. At the pooled level, each 10 μg/m³ increase in PM_2.5 and NO₂ was associated with increased YLL and higher mortality due to non-accidental causes [PM_2.5: 5.45 years, 95% CI: 1.47, 9.42 and ERR (excess relative risk) = 0.25%, 95% CI: 0.14%, 0.35%; NO₂: 20.46 years, 95% CI: 10.77, 30.15 and ERR = 1.13%, 95% CI: 0.63%, 1.63%]. Consistent results and patterns were observed for other cause-specific diseases, including IHD, COPD, stroke and AMI.

CONCLUSIONS

Our study indicates observed associations between air pollution and YLL might be mainly induced by increasing mortality count, rather than increasing average life lost for each death. More relevant intervention should be performed to reduce the number of deaths due to air pollution.

Evaluation of life expectancy loss associated with submicron and fine particulate matter (PM1 and PM2.5) air pollution in Nanjing, China

Particulate matters with an aerodynamic diameter ≤1 μm (PM₁) significantly increased mortality risk, and the effect of PM₁ was even greater than that of PM_2.5 (aerodynamic diameter ≤2.5 μm). But the quantitative impact of PM₁ on life expectancy was unknown. We aim to examine the extent to which that people's life expectancy was shortened by PM₁ and PM_2.5. We obtained daily data on deaths, PM₁ and PM_2.5 records, and weather variables during 2016-2017 in Nanjing, China. Years of life lost (YLLs) were calculated by matching each decedent's age and sex to the Chinese life table. The fitted nonlinear dose-response associations of YLLs with PM₁ and PM_2.5 were estimated by utilizing a generalized additive model with a Gaussian link that controlled for confounding factors including meteorological variables, day of week, and long-term trend and seasonality. The effect estimates were presented as the YLLs when PM₁ and PM_2.5 concentrations fell in different ranges. Life expectancy losses attributable to PM₁ and PM_2.5 were calculated. Stratified analyses were also performed by age, sex, and death causes. Significant PM-YLL associations were observed, with greater increases in YLLs associated with PM₁ (68.9 thousand). PM₁ was estimated to reduce life expectancy, which was greater than PM_2.5 (PM₁: 1.67 years; PM_2.5: 1.55 years). For PM₁, greater years of loss in PM-related life expectancy were found in the female group, ≥65 years group, and cardiovascular disease group. Exposure to PM₁ had a greater impact on life expectancy loss than did PM_2.5. Constant efforts are urgently needed to control PM₁ air pollution to improve people's longevity.

Air pollution and life expectancy in Europe: Does investment in renewable energy matter?

This study examines the relationship between health and air pollution using a novel approach that allows differentiation between potential and observed health. It also permits an analysis of those factors that may contribute towards reducing any differences between the latter concepts. To this end, a panel data from 29 European countries for the periods 2005 and 2018 is used. Results indicate that the main pollutants affecting European countries, namely NOx, PM10 and PM2.5 have a negative impact on life expectancy at birth, while investment in renewable energies has a positive effect. Several conclusions can be drawn from these results. Firstly, if the aim is to minimize the detrimental effects of the global production of goods and services on air quality, a greater investment in renewable energies as compared to other more polluting ones, is called for. In turn, this would contribute to an improvement in the general health of citizens and the planet thereby increasing overall potential life expectancy. Secondly, NOx gases seem to be the ones that most affect the population's mean potential life expectancy. Results indicate that with regard to particulate matters, those with a diameter of less than 2.5 μm, are the ones that have the greatest impact on the health of European citizens, more so than larger particles (with a diameter between 10 and 2.5 μm).

Inequality amplifies the negative association between life expectancy and air pollution: A cross-national longitudinal study

Ambient air pollution, in the form of fine particulate matter (PM_2.5), poses serious population health risks. We estimate cross-national longitudinal models to test whether the negative relationship between life expectancy and PM_2.5 concentration is larger in nations with higher levels of income inequality. The dependent variable is average life expectancy at birth, and the focal predictor variables include PM_2.5 concentration, income inequality, and the two-way interaction between them. We also estimate the average marginal effects of PM_2.5 concentration from low to high values of income inequality, and the predicted values of life expectancy from low to high values of PM_2.5 concentration and income inequality. Results indicate that the negative relationship between life expectancy and PM_2.5 concentration is larger in nations with higher levels of income inequality, and the reductions in predicted life expectancy are substantial when both PM_2.5 concentration and income inequality are high. We suggest that the theoretical principles of Power, Proximity, and Physiology help explain our findings. This study underscores the importance in considering the multiplicative impacts of environmental conditions and socioeconomic factors in the modeling of population health.

Ambient sulfur dioxide and years of life lost from stroke in China: a time-series analysis in 48 cities

BACKGROUND AND OBJECTIVES

Sulfur dioxide (SO₂) is a ubiquitous air pollutant and its concentration in China remains at a higher level in the world. However, evidence regarding short-term effect of SO₂ on years of life lost (YLL) from stroke is scarce. We aim to estimate the short-term association between SO₂ pollution and YLL for stroke and the related excess life years and economic loss.

METHODS

A national time-series study was conducted in 48 Chinese cities from 2013 to 2017. Generalized additive model coupled with random-effects model were used to explore the effects of SO₂ on YLL from stroke. Stratified analyses were performed by demographical and geographical factors, and the effect modification of city-level factors was estimated. In addition, the related economic loss was calculated using the method of the value per statistical life year (VSLY).

RESULTS

Averaged daily mean SO₂ concentration was 27.1 μg/m³ in 48 Chinese cities from 2013 to 2017. Per 10 μg/m³ increase in the concentration of SO₂ (lag03) was associated with an increment of 0.70% (95% confidence interval: 0.27%,1.13%), 0.51% (-0.01%,1.04%), 0.71% (0.14%,1.28%) increase in YLL from total stroke, hemorrhagic and ischemic stroke, respectively. The effect of short-term ambient SO₂ exposure on YLL from stroke was more pronounced in the less-educated population and those living in the south. The corresponding excess economic loss during the study period due to SO₂-related YLL from stroke accounted for 0.08% (0.03%, 0.13%) of the GDP in China.

CONCLUSIONS

Our results provide evidence from China that short-term exposure to SO₂ is positively associated with YLL from stroke and its major subtypes in certain subgroups of population. This study calls for greater awareness of the adverse health effect due to SO₂ in China and other developing countries, as well as local-specific implementation of air pollution mitigation measures.

Short-term effects of ambient nitrogen dioxide on years of life lost in 48 major Chinese cities, 2013-2017

BACKGROUND

Evidence on the acute effect of short-term exposure to nitrogen dioxide (NO₂) on years of life lost (YLL) is rare, especially in multicity setting.

METHODS

We conducted a time series study among 48 major Chinese cities covering more than 403 million people from 2013 to 2017. The relative percentage changes of NO₂-YLL were estimated by generalized additive models in each city, then were pooled to generate average effects using random-effect models. In addition, stratified analyses by individual demographic factors and temperature as well as meta-regression analyses incorporating city-specific air pollutant concentrations, meteorological conditions, and socioeconomic indicators were performed to explore potential effect modification.

RESULTS

A 10 μg/m³ increase in two-day moving average (lag01) NO₂ concentration was associated with 0.64% (95% CI: 0.47%, 0.81%), 0.47% (95% CI: 0.27%, 0.68%), and 0.68% (95% CI: 0.34%, 1.02%) relative increments in YLL due to nonaccidental causes, cardiovascular diseases (CVD), and respiratory diseases (RD), respectively. These associations were generally robust to the adjustment of co-pollutants, except for NO₂-CVD that might be confounded by fine particulate matter. The increased YLL induced by NO₂ were more pronounced in elderly people, hotter days, and cities characterized by less severe air pollution or higher temperature.

CONCLUSIONS

Our results demonstrated robust evidence on the associations between NO₂ exposure and YLL due to nonaccidental causes, CVD, and RD, which provided novel evidence to better understand the disease burden related to NO₂ pollution and to facilitate allocation of health resources targeting high-risk subpopulation.