Sex disparity in cognitive aging related to later-life exposure to ambient air pollution.

BACKGROUND: Sex difference in the association between ambient air pollution and cognitive aging remained unclear. This current study aimed to assess the impacts of long-term exposure to major air pollutants on cognitive performance among Chinese middle-aged and older adults, and explore whether these associations could be modified by sex. METHODS: By deriving longitudinal data from four waves of the China Health and Retirement Longitudinal Study, we included 13,507 participants aged 45+ years who had at least two cognitive tests recorded from 2011 to 2018. We used a standardized questionnaire consisting of five domain-specific functions to measure global cognitive score. Based on well-validated spatiotemporal datasets, annual average concentrations of ambient fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone (O3) were assigned to each enrollee at prefectural city level and at the simulated residential addresses through Monte Carlo simulation approach. Linear mixed-effects models were applied to assess the impacts of major air pollutants on cognitive function with multiple adjustments. Sex-stratified analyses were performed to examine the potential effect modification on these associations. To enhance the interpretability of our results, we also compared the estimated effects of air pollutants with the effect of aging on cognitive function. RESULTS: We evaluated 38,950 records of cognitive function tests, of which 44.0% were from women. An increase of 10-µg/m3 in PM2.5, NO2 and O3 exposure were associated with 0.36 (95% confidence interval: -0.40, -0.31), 0.51 (-0.60, -0.43) and 0.26 (-0.47, -0.06) points decline in global cognitive score, respectively, equivalent to the effect of aging by 2.8-5.0 years. Sex-stratified analyses suggested significantly greater cognitive impairment associated with air pollutants in women than men. We found reversely J-shaped concentration-response relationships between ambient air pollutants and cognitive decline in both sexes. Main findings on sex-specific associations were robust to the adjustments for covariates, inclusion criteria, and co-pollutant analyses, as well as sensitivity analyses based on simulation-based exposure for PM2.5 and NO2. CONCLUSIONS: Later-life exposure to ambient air pollution may accelerate cognitive aging of middle-aged and older adults, suggesting significant sex disparity with higher vulnerability in women.

Long-term exposure to ambient NO2 and adult mortality: A nationwide cohort study in China.

INTRODUCTION: A number of population-based studies have investigated long-term effects of nitrogen dioxide (NO2) on mortality, while great heterogeneities exist between studies. In highly populated countries in Asia, cohort evidence for NO2-mortality association was extensively sparse. OBJECTIVES: This study aimed to quantify longitudinal association of ambient NO2 exposure with all-cause mortality in Chinese adults. METHODS: A national cohort of 30,843 adults were drawn from 25 provincial regions across mainland China, and followed up from 2010 through 2018. Participants' exposures to ambient air pollutants were assigned according to their residential counties at baseline, through deriving monthly estimates from high-quality gridded datasets developed by machine learning methods. Cox proportional hazards models with time-varying exposures were utilized to assess the association of all-cause mortality with long-term exposure to ambient NO2. NO2-attributable deaths in China were estimated by province and county for years 2010 and 2018, with reference to the counterfactual exposure of 6.9 µg/m3 (the lowest county-level average in this cohort). RESULTS: We observed a total of 1662 deaths during 224020 person-years of follow-up (median 8.1 year). An approximately linear NO2-mortality relation (p = 0.273 for nonlinearity) was identified across a broad exposure range of 6.9-57.4 µg/m3. Per 10-µg/m3 increase in annual NO2 exposure was associated with an hazard ratio of 1.127 (95% confidence interval: 1.042-1.219, p = 0.003) for all-cause mortality. Risk estimates remained robust after additionally adjusting for the confounding effects of co-pollutants (i.e., PM2.5 or/and O3). In 2018, 1.65 million deaths could be attributed to ambient NO2 exposure (national average 17.3 µg/m3) in China, representing a decrease of 4.3% compared with the estimate of 1.72 million in 2010 (20.5 µg/m3). CONCLUSION: This cohort study provided national evidence for elevated risk of all-cause mortality associated with long-term exposure to ambient NO2 in Chinese adults.

Association between residential greenness and obstructive sleep apnoea among adults in Southern China.

BACKGROUND: No previous study has explored the association of residential greenness with obstructive sleep apnoea (OSA) indexes. OBJECTIVE: To investigate the association of exposure to residential greenness with OSA indexes in adults in Guangdong Province, Southern China. METHODS: From January 1, 2005 to December 31, 2015, a total of 3925 participants were recruited from the Sleep Center of Guangdong Provincial People's Hospital. Apnea-hypopnea index (AHI) and oxygen desaturation index (ODI) were measured by polysomnography or home sleep test (HST). Participants' daytime sleepiness scores were evaluated using The Epworth Sleeping Scale (ESS). The normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI) were used to assess residential greenness levels. Generalized linear regression models were used to assess the associations of residential greenness with OSA indexes after adjusting for multiple covariates. RESULTS: The mean (standard deviation) age of the participants was 63.3 (14.4) years. In adjusted models, an interquartile range (IQR) increase in 3-year average NDVI was significantly associated with 9.8 % (95 % confidence interval [95 % CI]: 17.5 %, 2.1 %); 14.5 % (95 % CI: 24.5 %, 4.4 %) and 6.9 % (95 % CI: 13.7 %, 0.0 %) decreases in AHI, ODI and ESS scores, respectively. Furthermore, an IQR increase in 3-year average EVI was significantly associated with 7.8 % (95 % CI: 13.7 %, 1.9 %); 10.8 % (95 % CI: 18.3 %, 3.2 %) and 7.2 % (95 % CI: 12.5 %, 2.0 %) declines in AHI, ODI and ESS scores, respectively. Significant associations were only observed among males, adults aged ≥65 years old, and in the warm season. CONCLUSIONS: Our study indicates that higher residential greenness was significantly associated with lower OSA indexes in adult population in South China, especially in males, in the elderly, and in the warm season.

Longitudinal association of egg intake frequency with cardiovascular disease in Chinese adults.

BACKGROUND AND AIMS: Reducing dietary cholesterol is generally acceptable for the prevention of cardiovascular disease (CVD). Eggs are nutrient-dense and common food items across the world, while rich in cholesterol. The potential effects of egg intake on cardiovascular health remain uncertainty and have been under debate in past decades. METHODS AND RESULTS: A nationwide cohort of 20,688 participants aged 16-110 years without CVD at baseline were derived from the China Family Panel Studies. Egg consumption was assessed by a semi-quantitative food frequency questionnaire. We adopted stratified Cox proportional hazards model with random intercepts for provinces to evaluate associations of egg intake with CVD incidence. During a median follow-up of 6.0 years, we identified 2395 total CVD incidence and mean egg consumption was 3 times/week. Egg intakes were associated lower risks of CVD incidence in the multivariate-adjusted model. Compared with the non-consumers, the corresponding HRs (95% confidence interval) for total CVD events were 0.84 (0.74-0.94) for 1-2 times per week, 0.78 (0.69-0.88) for 3-6/week, and 0.83 (0.72-0.95) for ≥7/week. Similar relationships were found in hypertension. Approximately non-linear relationships were observed between egg consumption with total CVD and hypertension incidence, identifying the lowest risk in 3-6 times/week. Subgroup analyses estimated lower risks of total CVD and hypertension in females only, with significant effect modification by sex (P for interaction = 0.008 and 0.020). CONCLUSION: Egg consumption may be associated with lower risks of CVD incidence among Chinese adults. Our findings could have implications in CVD prevention and might be considered in the development of dietary guidelines.

Reduction in daily ambient PM2.5 pollution and potential life gain by attaining WHO air quality guidelines in Tehran.

BACKGROUND: Fine particulate matter pollution (PM2.5) is widely considered to be a top-ranked risk factor for premature mortality and years of life lost (YLL). However, evidence regarding the effect of daily air quality improvement on life expectancy is scarce, especially in the Middle East such as Iran. This study aimed to investigate the potential benefits in life expectancy at concentrations meeting the daily PM2.5 standards during 2012-2016 in Tehran, Iran. METHODS: We collected daily non-accidental mortality and data on air pollutants and weather conditions from Tehran, Iran, 2012-2016. A quasi-Poisson or Gaussian time-series regression was employed to fit the associations between ambient PM2.5 and mortality or YLL. Potential gains in life expectancy (PGLE) and attributable fraction (AF) were estimated by assuming that daily PM2.5 concentrations attained the World Health Organization air quality guidelines (WHO AQG) 2005 (25 µg/m3) and 2021 (15 µg/m3). RESULTS: During the study period, a total of 221,231 non-accidental deaths were recorded in Tehran, resulting in 3.6 million YLL. The mean concentration of ambient PM2.5 was 34.7 µg/m3 (standard deviation: 15.3 µg/m3). For a 10-µg/m3 rise in 4-day moving average (lag 03-day) in PM2.5 concentration, non-accidental mortality and YLL increased by 1.12% (95% confidence interval: 0.60, 1.65) and 20.73 (7.08, 34.39) person years, respectively. A relatively higher effect was observed in males and young adults aged 18-64 years. We estimated that 39830 [AF = 1.1%] and 74284 [AF = 2.1%] YLL could potentially be avoided if daily PM2.5 concentrations attained the WHO AQG 2005 and 2021, respectively, which corresponded to potential gains in life expectancy of 0.18 (0.06, 0.30) and 0.34 (0.11, 0.56) years for each deceased person. PM2.5-associated PGLE estimates were largely robust when performing sensitivity analyses. CONCLUSIONS: Our findings indicated that short-term exposure to PM2.5 is associated with increased non-accidental YLL and mortality. Prolonged life expectancy could be achieved if the particulate matter air pollution level were kept under a stricter standard.

Longitudinal Impacts of PM2.5 Constituents on Adult Mortality in China.

Limited evidence exists for long-term effects of PM2.5 constituents on mortality. Hence, we aimed to assess associations between all-cause mortality and long-term exposure to PM2.5 constituents in China. We designed a nationwide cohort study of 30524 adults from 162 prefectural areas across mainland China with follow-ups through years 2010-2017. Cox proportional hazards models with time-varying exposures were employed to quantify associations between all-cause mortality and long-term exposure to PM2.5 and constituents. A total of 1210 deaths occurred during 172297.7 person-years. A multiadjusted Cox model estimated an hazard ratio (HR) of 1.125 (95% confidence interval: 1.058-1.197) for all-cause mortality, associated with an interquartile range (IQR = 26.7 µg/m3) rise in exposure to PM2.5. Comparable or stronger associations were found among PM2.5 constituents with the mortality risk increased by 11.3-14.1% per IQR increase in exposure concentrations. After adjustment for the collinearity between total PM2.5 and constituents, effect estimates for nitrate, ammonium, and sulfate remained significant and became larger. Urban residents, alcohol drinkers, smokers, and men were more susceptible to chronic impacts from ambient PM2.5 constituents. This cohort study added the novel longitudinal evidence for elevated mortality linked with long-term exposure to PM2.5 constituents among Chinese adults.

Assessing short-term impacts of PM2.5 constituents on cardiorespiratory hospitalizations: Multi-city evidence from China.

Apart from concentrations of particulate mass, PM2.5-associated effects on health may largely depend on its chemical components. However, little is known regarding the underlying effects of specific PM2.5 constituents. The study included nearly 1 million hospital admissions from five Chinese cities during 2015-2017. Based on the modified Community Multiscale Air Quality model, our study simulated daily concentrations of PM2.5 and five main components. We used a time-stratified case-crossover design with conditional logistic regression models to estimate short-term effects of PM2.5 constituents on cause-specific hospital admissions. Per interquartile range increase in exposure to PM2.5, elemental carbon, organic carbon, nitrate, sulfate and ammonium at lag 04-day was related to an excess risk (ER%) for non-accidental admissions of 1.6% [95% confidence interval: 1.1-2.0], 1.9% [1.3-2.4], 1.0% [0.5-1.6], 1.2% [0.4-2.0], 1.2% [0.9-1.5] and 1.4% [0.9-1.9], respectively. Great heterogeneities of constituents-admission associations existed in diverse causes and constituents. This study provided multi-center high-quality evidence that hospital admissions, particularly those for ischemic heart disease (ER% ranging from 2.3 to 5.4% at lag 04-day) and pneumonia (1.9-5.1% at lag 4-day), could be triggered by short-term exposures to ambient PM2.5 constituents. Relatively stronger constituents-admission associations were found among females for respiratory causes and the elderly for cardiovascular causes.

Comparative analysis of daily and hourly temperature variability in association with all-cause and cardiorespiratory mortality in 45 US cities.

Temperature variability (TV) has been widely associated with increased mortality risk and burden. Extensive researches have used the standard deviations of several days' daily maximum and minimum temperatures or hourly mean temperatures as daily and hourly TV measures (TVdaily and TVhourly). However, comparative analysis of daily and hourly TV related to cardiorespiratory mortality is still limited. We collected daily mortality and meteorological data in 45 US metropolises, 1987-2000. A three-stage analysis was adopted to investigate TV-mortality associations using TVdaily and TVhourly as exposure metrics. We first applied a time-series quasi-Poisson regression to estimate location-specific TV-mortality relationships, which were then pooled using random-effects meta-analysis with maximum likelihood estimation. We additionally calculated attributable fraction (AF) as a reflection of mortality burden associated with TV. Stratified analyses by age were also performed to identify the susceptible group to TV-related risks. There were a total of 15.4 million all-cause deaths, of which 6.1 million were from cardiovascular causes and 1.2 million were from respiratory causes. Per 1 °C increase in TVdaily and TVhourly was associated with an increase of 0.53% (95% confidence interval: 0.31-0.76%) and 0.52% (0.26-0.79%) in cardiovascular mortality risks, 0.62% (0.26-0.98%) and 0.53% (0.13-0.94%) in respiratory mortality risks. Estimates of cardiovascular AF for TVdaily and TVhourly were 2.43% (1.42-3.43%) vs. 1.63% (0.82-2.43%), whereas estimates of respiratory AF were 3.07% (1.11-4.99%) vs. 1.89% (0.43-3.34%). Both daily and hourly TV indexes showed approximately linear relationships with different mortality categories and similar lag patterns, but greater fractions were estimated using TVdaily than those using TVhourly. People over 75 years old were relatively more vulnerable to TV-induced risks of mortality. In conclusion, both TVdaily and TVhourly significantly increased all-cause and cardiorespiratory mortality risks and burden. Daily and hourly TV metrics exhibited comparable effects of mortality risk, while greater mortality burden was estimated using TVdaily than TVhourly. Our findings may add significance to TV-mortality research and help to promote optimal health management strategies to better mitigate TV-related health effects.

Long-term exposure to fine particulate constituents and cardiovascular diseases in Chinese adults.

BACKGROUND: Ambient fine particulate matter (PM2.5) has been linked to various cardiovascular disease (CVD) endpoints. However, little is known regarding the health effects of PM2.5 constituents. This study aimed to assess the associations of CVD incidence with long-term exposures to PM2.5 constituents in China, including black carbon (BC), organic matter (OM), sulfate (SO42-), nitrate (NO3-) and ammonium (NH4+). METHODS: A nationwide cohort of 14,331 adults were drawn from the China Family Panel Study, a high-quality longitudinal survey initiated from 2010 over 25 provincial regions in China. We used the baseline survey and the ensuing three waves of follow-up data during 2010-2017 to conceive our study cohort. Annual county-level exposures of PM2.5 and its constituents for each participant were assessed by aggregating satellite-derived estimates at a monthly time-scale and 1 km-resolution. A directed acyclic graph (DAG) was developed to identify confounding variables. Cox proportional hazards models with time-varying exposures and province-level random intercepts were employed to quantify associations of CVD incidence with long-term exposures to PM2.5 and its constituents. RESULTS: During 84,162.4 person-years' follow-up, a total of 1575 CVD, 953 hypertension and 342 stroke incidents occurred. DAG-based Cox model estimated an hazard ratio (HR) of 1.291 (95% confidence interval: 1.147-1.454) for total CVD and 1.326 (1.151-1.528) for hypertension, associated with per interquartile range (IQR=27.9 µg/m3) increase in exposure to PM2.5 mass. Elevated CVD risks were also significantly related to several PM2.5 constituents, with the largest HRs observed in SO42- (1.721 [1.517-1.951], IQR = 5.67 µg/m3), followed by NH4+ (1.537 [1.341-1.762], IQR = 4.44 µg/m3), NO3- (1.311 [1.128-1.523], IQR = 8.92 µg/m3) and BC (1.294 [1.158-1.446], IQR = 2.28 µg/m3). No associations were identified between long-term exposures to particulate constituents and incidence of stroke. Associations with PM2.5 and constituents (BC, NO3-, NH4+ and SO42-) were more pronounced among adults aged over 50 years, and residents in southern region. CONCLUSIONS: Long-term exposures to PM2.5 mass and specific constituents (i.e., BC, NO3-, NH4+ and SO42-) were associated with increased risks of total CVD and hypertension incidence in Chinese adults. Findings may have implications for in-depth understandings of biological mechanisms in chronic impacts of ambient PM2.5 on cardiovascular health.

Assessing PM2.5-associated risk of hospitalization for COPD: an application of daily excessive concentration hours.

Existing PM2.5-morbidity studies using daily mean concentration as exposure metric may fail to capture intra-day variations of PM2.5 concentrations, resulting in underestimated health impacts to some extent. This study introduced a novel indicator, daily excessive concentration hours (DECH), defined as sums of per-hourly excessive concentrations of PM2.5 against a specific threshold within a day. PM2.5 DECHs were separately calculated as daily concentration-hours >8, 10, 15, 20, and 25 µg/m3 (abbreviations: DECH-8, DECH-10, DECH-15, DECH-20, and DECH-25). We adopted a time-stratified case-crossover design with conditional logistic regression models to compare risks of hospitalizations for chronic obstructive pulmonary disease (COPD) associated with PM2.5 mean and DECHs in Shenzhen, China. We observed highly comparable PM2.5-COPD associations using exposure metrics of daily mean and DECHs with above-defined thresholds. For instance, PM2.5 mean and DECHs showed similar increases in risks of COPD hospitalization for an interquartile range rise in exposure, with odds ratio estimates of 1.26 (95% confidence interval: 1.06-1.50) for PM2.5 mean, 1.24 (1.05-1.46) for DECH-10 and 1.21 (1.06-1.39) for DECH-25, respectively. Findings remained robust after further adjusting for gaseous pollutants (e.g., SO2, NO2, CO, and O3) and meteorologic factors (e.g., wind speed and air pressure). Our study strengthened the evidence that DECHs could come be as a novel exposure metric in health risk assessments associated with short-term exposure to ambient PM2.5.

Intraday effects of ambient PM1 on emergency department visits in Guangzhou, China: A case-crossover study.

BACKGROUND: Short-term exposure to PM2.5 has been widely associated with human morbidity and mortality. However, most up-to-date research was conducted at a daily timescale, neglecting the intra-day variations in both exposure and outcome. As an important fraction in PM2.5, PM1 has not been investigated about the very acute effects within a few hours. METHODS: Hourly data for size-specific PMs (i.e., PM1, PM2.5, and PM10), all-cause emergency department (ED) visits and meteorological factors were collected from Guangzhou, China, 2015-2016. A time-stratified case-crossover design with conditional logistic regression analysis was performed to evaluate the hourly association between size-specific PMs and ED visits, adjusting for hourly mean temperature and relative humidity. Subgroup analyses stratified by age, sex and season were conducted to identify potential effect modifiers. RESULTS: A total of 292,743 cases of ED visits were included. The effects of size-specific PMs exhibited highly similar lag patterns, wherein estimated odds ratio (OR) experienced a slight rise from lag 0-3 to 4-6 h and subsequently attenuated to null along with the extension of lag periods. In comparison with PM2.5 and PM10, PM1 induced slightly larger effects on ED visits. At lag 0-3 h, for instance, ED visits increased by 1.49% (95% confidence interval: 1.18-1.79%), 1.39% (1.12-1.66%) and 1.18% (0.97-1.40%) associated with a 10-µg/m3 rise, respectively, in PM1, PM2.5 and PM10. We have detected a significant effect modification by season, with larger PM1-associated OR during the cold months (1.017, 1.013 to 1.021) compared with the warm months (1.010, 1.005 to 1.015). CONCLUSIONS: Our study provided brand-new evidence regarding the adverse impact of PM1 exposure on human health within several hours. PM-associated effects were significantly more potent during the cold months. These findings may aid health policy-makers in establishing hourly air quality standards and optimizing the allocation of emergency medical resources.