Long-Term Effects of Ambient PM2.5 on Hypertension and Blood Pressure and Attributable Risk Among Older Chinese Adults

PM2.5-mediated cardiovascular disease in aging: Cardiometabolic risks, molecular mechanisms and potential interventions

Air pollution, particularly fine particulate matter (PM2.5) with <2.5 μm in diameter, is a major public health concern. Studies have consistently linked PM2.5 exposure to a heightened risk of cardiovascular diseases (CVDs) such as ischemic heart disease (IHD), heart failure (HF), and cardiac arrhythmias. Notably, individuals with pre-existing age-related cardiometabolic conditions appear more susceptible. However, the specific impact of PM2.5 on CVDs susceptibility in older adults remains unclear. Therefore, this review addresses this gap by discussing the factors that make the elderly more vulnerable to PM2.5-induced CVDs. Accordingly, we focused on physiological aging, increased susceptibility, cardiometabolic risk factors, CVDs, and biological mechanisms. This review concludes by examining potential interventions to reduce exposure and the adverse health effects of PM2.5 in the elderly population. The latter includes dietary modifications, medications, and exploration of the potential benefits of supplements. By comprehensively analyzing these factors, this review aims to provide a deeper understanding of the detrimental effects of PM2.5 on cardiovascular health in older adults. This knowledge can inform future research and guide strategies to protect vulnerable populations from the adverse effects of air pollution.

Associations between PM 2.5 and its chemical constituents and blood pressure: a cross-sectional study

OBJECTIVES

To investigate the associations between PM 2.5 and its chemical constituents with blood pressure (BP), assess effects across BP quantiles, and identify the key constituent elevating BP.

METHODS

A total of 36 792 adults were included in the cross-sectional study, representing 25 districts/counties of southeast China. Quantile regression models were applied to estimate the associations of PM 2.5 and its chemical constituents (ammonium [NH 4+ ], nitrate [NO 3- ], sulfate [SO 42- ], black carbon [BC], organic matter [OM]) with systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean artery pressure (MAP). A weighted quantile sum (WQS) index was used to estimate the relative importance of each PM 2.5 chemical constituent to the joint effect on BP.

RESULTS

The adverse effects of each interquartile range (IQR) increase in PM 2.5 , NH 4+ , NO 3- , SO 42- , and BC on BP were found to be greater with elevated BP, especially when SBP exceeded 133 mmHg and DBP exceeded 82 mmHg. Each IQR increase in all five PM 2.5 chemical constituents was associated with elevated SBP ( β [95% CI]: 0.90 [0.75, 1.05]), DBP ( β : 0.44 [0.34, 0.53]), and MAP ( β : 0.57 [0.45, 0.69]), NH 4+ (for SBP: weight = 99.43%; for DBP: 12.78%; for MAP: 60.73%) and BC (for DBP: 87.06%; for MAP: 39.07%) predominantly influencing these effects. The joint effect of PM 2.5 chemical constituents on risks for elevated SBP and DBP exhibited an upward trend from the 70 th quantile (SBP exceeded 133 mmHg, DBP exceeded 82 mmHg).

CONCLUSION

Long-term exposure to PM 2.5 and its chemical constituents was associated with increased risk for elevated BP, with NH 4+ and BC being the main contributors, and such associations were significantly stronger at 70th to 90th quantiles (SBP exceeded 133 mmHg, DBP exceeded 82 mmHg).

A pilot study of the cardiopulmonary effects in healthy volunteers after exposure to high levels of PM2.5 in a New York City subway station

BACKGROUND

Subway systems are becoming increasingly common worldwide transporting large populations in major cities. PM2.5 concentrations have been demonstrated to be exceptionally high when underground, however. Studies on the impact of subway PM exposure on cardiopulmonary health in the United States are limited.

METHODS

Healthy volunteers in New York City were exposed to a 2-h visit on the 9th Street Station platform on the Port Authority Trans-Hudson train system. Blood pressure, heart rate variability (HRV), spirometry, and forced impulse oscillometry were measured, and urine, blood spot, and nasal swab biosamples were collected for cytokine analysis at the end of the 2-h exposure period. These endpoints were compared against individual control measurements collected after 2-h in a "clean" control space. In addition to paired comparisons, mixed effects models with subject as a random effect were employed to investigate the effect of the PM2.5 concentrations and visit type (i.e., subway vs. control).

RESULTS

Mean PM2.5 concentrations on the platform and during the control visit were 293.6 ± 65.7 (SD) and 4.6 ± 1.9 µg/m3, respectively. There was no change in any of the health metrics, but there was a non-significant trend for SDNN to be lower after subway exposure compared to control exposure. Total symptomatic scores did increase post-subway exposure compared to reported values prior to exposure or after the control visit. No significant changes in cytokine concentrations in any specimen type were observed. Mixed-effects models mostly corroborated these paired comparisons.

CONCLUSIONS

Acute exposures to PM on a subway platform do not cause measurable cardiopulmonary effects apart from reductions in HRV and increases in symptoms in healthy volunteers. These findings match other studies that found little to no changes in lung function and blood pressure after exposure in underground subway stations. Future work should still target potentially more vulnerable populations, such as individuals with asthma or those who spend increased time underground on the subway such as transit workers.

Relationships between sensory processing patterns and metabolic risk factors among community dwelling people with metabolic syndrome: A cross-sectional and correlational research design

BACKGROUND

Metabolic Syndrome (MetS) increases the risk of other serious health problems, particularly cardiovascular diseases and stroke. Sensory processing patterns (SPPs) are internal factors shaping behaviors and emotions, both healthy and unhealthy. There is a lack of studies directly examining the relationship between the SPPs and metabolic risk factors.

METHOD

This study aimed to investigate SPPs and their association with metabolic risk factors in individuals with metabolic syndrome (MetS). One hundred and seventeen individuals with MetS completed questionnaires on demographic characteristics and the Thai Sensory Patterns Assessment-adult version. Data on metabolic risk factors, including fasting blood glucose, blood pressure, and waist circumference, were collected.

RESULTS

The findings revealed high arousal levels in proprioceptive and auditory senses among the participants. The fasting blood glucose was significantly correlated with a preference in the tactile sense (r = -0.150, P<0.05), while waist circumference was associated with arousal level in the auditory and smell-taste senses (r = 0.140, -0.160, P<0.05). Moreover, the GLMM revealed that fasting blood glucose was associated with preferences in tactile, vestibular, and proprioceptive senses (r = -0.481, 0.726, -0.386, P<0.05). Furthermore, diastolic blood pressure was associated with preferences in vestibular sense (r = 0.099; P<0.05).

CONCLUSION

The SPPs might be related to metabolic risk factors, so it is important to recognize how individual SPPs relate to metabolic risk factors. However, further studies using a larger sample may be needed to deeply explore the mechanisms underlying these associations.

Plasma irisin associations with executive function among children in a prospective cohort

OBJECTIVE

To examine the longitudinal associations between irisin and executive function among children, as well as the sex difference in this correlation.

METHODS

The study involving 330 children aged 6-10 years conducted in Guangzhou, China. Baseline surveys and fasting blood samples were collected in 2017. Plasma irisin concentration was measured using Enzyme-Linked Immunosorbent Assay (ELISA). Executive function was assessed by the Behavior Rating Inventory of Executive Function (BRIEF) scale in 2017 and followed up after 2 years. Multivariable linear regression was used for association analysis.

RESULTS

The plasma irisin concentration was 9.04±2.18 ng/mL. There was no statistical difference in plasma irisin and change values of BRIEF T-scores between boys and girls. No significant associations were found between plasma irisin and change values of BRIEF T-scores (P > 0.05) in the overall sample. Further subgroup analyses according to sex revealed that plasma irisin was negatively associated with change values of behavior regulation index (BRI, β=-0.521, 95 %CI: -1.036 ∼ -0.006), emotional control (β=-0.649, 95 %CI: -1.249 ∼ -0.049), working memory T-scores (β=-0.774, 95 %CI: -1.350 ∼ -0.199) in girls. Moreover, we firstly identified a sex effect modification in the association of plasma irisin with change values of working memory T-score (Pinterference=0.012).

CONCLUSIONS

Higher irisin concentration was associated with better executive function performance in girls. Further studies that included populations in other regions or countries are needed to confirm these findings.

Examining Relationships between Perceptions of Air Quality-Objectively Assessed Particulate Matter-And Health-Related Attributions among Midlife and Older Adults from the San Francisco Bay Area, California, USA

This investigation explored (1) correlations between midlife and older adults' air quality perceptions with objective particulate matter 2.5 (PM2.5) and diesel PM, and (2) correlations between air quality perceptions with health-related attributions among a sample of midlife and older adults (n = 66) living in or around senior affordable public housing sites in California's San Francisco Bay Area. The adapted air quality perception scale was used to measure perceptions of air quality, while health-related attributions were obtained from the vitality plus scale (VPS), with higher values indicating worse perceptions of air quality and poorer responses to health-related attributions, respectively. Self-reported data were linked to zip code level PM2.5 and diesel PM obtained from the CalEnviroScreen 4.0. All correlations were evaluated using Spearman's rank correlations. The mean (SD) age was 70.6 (9.1) years, and 75.7% were female. We observed moderate, positive correlations between both PM2.5 and diesel PM with three domains: perceptions related to protection measures against air quality, emotional/mental perceptions, and sensorial perceptions. We also found evidence of moderate, positive correlations between the domains of physical symptoms, perceptions related to protection measures against air quality, and emotional/mental perceptions with health-related attributions, such as sleep-related items and feelings of restlessness or agitation. Results from this exploratory study suggest that midlife and older adults' perceptions of air quality may be moderately related to both objective air quality data and certain health behaviors and symptoms. Findings underscore the importance of considering individual perceptions as an additional area in public health strategies aimed at protecting midlife and older adults from the impacts of air pollution.

Association between residential air pollution exposure and cardiovascular risk factors in adults living in northern France

Air pollution is associated with elevated cardiovascular mortality and an increase in cardiovascular risk factors. However, the literature data on associations between air pollution and cardiovascular risk factors are contradictory. To explore the relationship between residential exposure to atmospheric pollutants and cardiovascular risk factors (lipid biomarker and blood pressure levels). We studied a sample of 2339 adult participants in the ELISABET study from the Dunkirk and Lille urban areas of France. The mean annual exposure to atmospheric pollutants (PM10, NO2 and SO2) at the home address was estimated via an air dispersion model. The associations were probed in multivariate linear regression models. The mean NO2 level was 26.05 μg/m3 in Lille and 19.96 µg/m3 in Dunkirk. The mean PM10 level was 27.02 μg/m3 in Lille and 26.53 μg/m3 in Dunkirk. We detected a significant association between exposure to air pollutants and the high-density lipoprotein (HDL) (which is a protective factor against cardiovascular diseases) level: for a 2 µg/m3 increment in PM10, the HDL level decreased by 1.72% (p = 0.0037). None of the associations with other lipid variables or with blood pressure were significant. We didn't find evidence significant associations for most of the risk factors but, long-term exposure of adults to moderate levels of ambient air pollution was associated with a decrement in HDL.

Associations between long-term exposure to air pollution, diabetes, and hypertension in metropolitan Iran: an ecologic study

Epidemiological studies on air pollution, diabetes, and hypertension conflict. This study examined air pollution, diabetes, and hypertension in adults in 11 metropolitan areas of Iran (2012-2016). Local environment departments and the Tehran Air Quality Control Company provided air quality data. The VIZIT website and Stepwise Approach to Chronic Disease Risk Factor Surveillance study delivered chronic disease data. Multiple logistic regression and generalized estimating equations evaluated air pollution-related diabetes and hypertension. In Isfahan, Ahvaz, and Tehran, PM2.5 was linked to diabetes. In all cities except Urmia, Yasuj, and Yazd, PM2.5 was statistically related to hypertension. O3 was connected to hypertension in Ahvaz, Tehran, and Shiraz, whereas NO2 was not. BMI and gender predict hypertension and diabetes. Diabetes, SBP, and total cholesterol were correlated. Iran's largest cities' poor air quality may promote diabetes and hypertension. PM2.5 impacts many cities' outcomes. Therefore, politicians and specialists have to control air pollution.

The impact of co-exposure to air and noise pollution on the incidence of metabolic syndrome from a health checkup cohort

Previous studies have found associations between the incidence of metabolic syndrome (MetS) and exposure to air pollution or road traffic noise. However, investigations on environmental co-exposures are limited. This study aimed to investigate the association between co-exposure to air pollution and road traffic noise and MetS and its subcomponents. Participants living in Taipei City who underwent at least two health checkups between 2010 and 2016 were included in the study. Data were sourced from the MJ Health database, a longitudinal, large-scale cohort in Taiwan. The monthly traffic noise exposure (Lden and Lnight) was computed using a dynamic noise map. Monthly fine particulate data at one kilometer resolution were computed from satellite imagery data. Cox proportional hazards regression models with month as the underlying time scale were used to estimate hazard ratios (HRs) for the impact of PM2.5 and road traffic noise exposure on the risk of developing MetS or its subcomponents. Data from 10,773 participants were included. We found significant positive associations between incident MetS and PM2.5 (HR: 1.88; 95% CI 1.67, 2.12), Lden (HR: 1.10; 95% CI 1.06, 1.15), and Lnight (HR: 1.07; 95% CI 1.02, 1.13) in single exposure models. Results further showed significant associations with an elevated risk of incident MetS in co-exposure models, with HRs of 1.91 (95% CI 1.69, 2.16) and 1.11 (95% CI 1.06, 1.16) for co-exposure to PM2.5 and Lden, and 1.90 (95% CI 1.68, 2.14) and 1.08 (95% CI 1.02, 1.13) for co-exposure to PM2.5 and Lnight. The HRs for the co-exposure models were higher than those for models with only a single exposure. This study provides evidence that PM2.5 and noise exposure may elevate the risk of incident MetS and its components in both single and co-exposure models. Therefore, preventive approaches to mitigate the risk of MetS and its subcomponents should consider reducing exposure to PM2.5 and noise pollution.

Effects of long-term exposure to ambient fine particulate matter and its specific components on blood pressure and hypertension incidence

BACKGROUND

Epidemiological evidence on the association of PM2.5 (particulate matter with aerodynamic diameter ≤ 2.5 μm) and its specific components with hypertension and blood pressure is limited.

METHODS

We applied information of participants from the World Health Organization's (WHO) Study on Global Ageing and Adult Health (SAGE) to estimate the associations of long-term PM2.5 mass and its chemical components exposure with blood pressure (BP) and hypertension incidence in Chinese adults ≥ 50 years during 2007-2018. Generalized linear mixed model and Cox proportional hazard model were applied to investigate the effects of PM2.5 mass and its chemical components on the incidence of hypertension and BP, respectively.

RESULTS

Each interquartile range (IQR = 16.80 μg/m3) increase in the one-year average of PM2.5 mass concentration was associated with a 17 % increase in the risk of hypertension (HR = 1.17, 95 % CI: 1.10, 1.24), and the population attributable fraction (PAF) was 23.44 % (95 % CI: 14.69 %, 31.55 %). Each IQR μg/m3 increase in PM2.5 exposure was also related to increases of systolic blood pressure (SBP) by 2.54 mmHg (95 % CI:1.99, 3.10), and of diastolic blood pressure (DBP) by 1.36 mmHg (95 % CI: 1.04, 1.68). Additionally, the chemical components of SO42-, NO3-, NH4+, OM, and BC were also positively associated with an increased risk of hypertension incidence and elevated blood pressure.

CONCLUSIONS

These results indicate that long-term exposure to PM2.5 mass and its specific components may be major drivers of escalation in hypertension diseases.

Association of fine particulate matter (PM2.5) exposure and chronic kidney disease outcomes: a systematic review and meta-analysis

Several studies have reported an increased risk of chronic kidney disease (CKD) outcomes after long-term exposure (more than 1 year) to particulate matter with an aerodynamic diameter of ≤ 2.5 µm (PM2.5). However, the conclusions remain inconsistent. Therefore, we conducted this meta-analysis to examine the association between long-term PM2.5 exposure and CKD outcomes. A literature search was conducted in PubMed, Scopus, Cochrane Central Register of Controlled trials, and Embase for relevant studies published until August 10, 2023. The main outcomes were incidence and prevalence of CKD as well as incidence of end-stage kidney disease (ESKD). The random-effect model meta-analyses were used to estimate the risk of each outcome among studies. Twenty two studies were identified, including 14 cohort studies, and 8 cross-sectional studies, with a total of 7,967,388 participants. This meta-analysis revealed that each 10 μg/m3 increment in PM2.5 was significantly associated with increased risks of both incidence and prevalence of CKD [adjusted odds ratio (OR) 1.31 (95% confidence interval (CI) 1.24 to 1.40), adjusted OR 1.31 (95% CI 1.03 to 1.67), respectively]. In addition, the relationship with ESKD incidence is suggestive of increased risk but not conclusive (adjusted OR 1.16; 95% CI 1.00 to 1.36). The incidence and prevalence of CKD outcomes had a consistent association across all subgroups and adjustment variables. Our study observed an association between long-term PM2.5 exposure and the risks of CKD. However, more dedicated studies are required to show causation that warrants urgent action on PM2.5 to mitigate the global burden of CKD.

Mediating effect of body fat percentage in the association between ambient particulate matter exposure and hypertension: a subset analysis of China hypertension survey

BACKGROUND

Hypertension caused by air pollution exposure is a growing concern in China. The association between air pollutant exposure and hypertension has been found to be potentiated by obesity, however, little is known about the processes mediating this association. This study investigated the association between fine particulate matter (aerodynamic equivalent diameter ≤ 2.5 microns, PM2.5) exposure and the prevalence of hypertension in a representative population in southern China and tested whether obesity mediated this association.

METHODS

A total of 14,308 adults from 48 communities/villages in southern China were selected from January 2015 to December 2015 using a stratified multistage random sampling method. Hourly PM2.5 measurements were collected from the China National Environmental Monitoring Centre. Restricted cubic splines were used to analyze the nonlinear dose-response relationship between PM2.5 exposure and hypertension risk. The mediating effect mechanism of obesity on PM2.5-associated hypertension was tested in a causal inference framework following the approach proposed by Imai and Keele.

RESULTS

A total of 20.7% (2966/14,308) of participants in the present study were diagnosed with hypertension. Nonlinear exposure-response analysis revealed that exposure to an annual mean PM2.5 concentration above 41.8 µg/m3 was associated with increased hypertension risk at an incremental gradient. 9.1% of the hypertension burden could be attributed to exposure to elevated annual average concentrations of PM2.5. It is noteworthy that an increased body fat percentage positively mediated 59.3% of the association between PM2.5 exposure and hypertension risk, whereas body mass index mediated 34.3% of this association.

CONCLUSIONS

This study suggests that a significant portion of the estimated effect of exposure to PM2.5 on the risk of hypertension appears to be attributed to its effect on alterations in body composition and the development of obesity. These findings could inform intersectoral actions in future studies to protect populations with excessive fine particle exposure from developing hypertension.

PM2.5 promotes apoptosis of alveolar epithelial cells via targeting ROS/p38 signaling pathway and thus leads to emphysema in mice

BACKGROUND

The aim of this study was to uncover the ability of PM2.5 exposure to induce apoptosis in alveolar epithelial cells by stimulating excessive production of reactive oxygen species (ROS), thus activating p38 to result in emphysema in mice.

METHODS

Male BALB/c mice with 6-8-week-old were exposed to 200 TPM mg/L PM2.5 for 12 weeks. Lung tissues of mice were harvested after sacrifice. Hematoxylin and eosin staining was conducted for observing alveolar structure change. Protein levels of p-p38 and p38, as well as ROS level in mouse liver tissues were determined. A549 cells were exposed to different doses of PM2.5, followed by ROS detection, protein level detection of p-p38 and p38, and apoptosis determination. After transfection of si-p38, protein level of clv-caspase3 and apoptotic rate in PM2.5-exposed A549 cells were assessed.

RESULTS

After 12-week exposure to PM2.5, enlarged alveolar space, elevated ROS level in lung tissues and activated p38 were observed in mice. In PM2.5-exposed A549 cells, ROS level, p-p38 expression and apoptotic rate were dose-dependently enhanced. The antioxidant NAC reversed the above changes in PM2.5-exposed A549 cells. Silence of p38 reversed the enhanced clv-claspase3 level and apoptotic rate in PM2.5-exposed A549 cells.

CONCLUSIONS

PM2.5 exposure elevates ROS level in lung tissues, and activates p38, thus leading to apoptosis of alveolar epithelial cells. PM2.5 finally results in the development of emphysema in mice.

Association of fine particulate matter and its constituents with hypertension: the modifying effect of dietary patterns

BACKGROUND

Studies have shown that nutritional supplements could reduce the adverse effects induced by air pollution. However, whether dietary patterns can modify the association of long-term exposure to fine particulate matter (PM2.5) and its constituents with hypertension defined by the 2017 ACC/AHA guideline has not been evaluated.

METHODS

We included 47,501 Chinese adults from a nationwide cross-sectional study. PM2.5 and five constituents were estimated by satellite-based random forest models. Dietary approaches to stop hypertension (DASH) and alternative Mediterranean diet (AMED) scores were calculated for each participant. Interactions between dietary patterns and air pollution were examined by adding a multiplicative interaction term to logistic models.

RESULTS

Long-term exposure to PM2.5 and its constituents was associated with an increased risk of hypertension and stage 1-2 hypertension. The DASH and AMED scores significantly modified these associations, as individuals with higher scores had a significantly lower risk of air pollution-related hypertension and stage 1-2 hypertension (P-interaction < 0.05), except for interaction between PM2.5, sulfate, nitrate, ammonium, and AMED score on stage 1 hypertension. For each IQR increase in PM2.5, participants with the lowest DASH and AMED quintiles had hypertension risk with ORs (95%CI) of 1.20 (1.10, 1.30) and 1.19 (1.09, 1.29), whereas those with the highest DASH and AMED quintiles had lower risks with 0.98 (0.91, 1.05) and 1.04 (0.97, 1.11). The stratified analysis found modification effect was more prominent in the < 65 years age group. Consuming more fresh vegetables, fruits, whole grains, and dairy would reduce the risk of hypertension caused by PM2.5 and its constituents.

CONCLUSIONS

Dietary patterns rich in antioxidants can reduce long-term exposure to PM2.5 and its constituents-induced hypertension defined by the 2017 ACC/AHA guideline, especially in young and middle-aged individuals. Compared to the Mediterranean diet, the DASH diet offers superior dietary guidance to prevent stage 1 hypertension caused by air pollution.

Association of joint exposure to various ambient air pollutants during adolescence with blood pressure in young adulthood

The association of various air pollutants exposure during adolescence with blood pressure (BP) in young adulthood is uncertain. We intended to evaluate the long-term association of individual and joint air pollutants exposure during adolescence with BP in young adulthood. This cross-sectional study of incoming students was conducted in five geographically disperse universities in China during September and October 2018. Mean concentrations of particulate matter with diameters ≤2.5 μm (PM2.5 ), ≤10 μm (PM10 ), nitrogen dioxides (NO2 ), carbon monoxide (CO), sulfur dioxide (SO2 ), and ozone (O3 ) at participants' residential addresses during 2013-2018 were collected from the Chinese Air Quality Reanalysis dataset. Generalized linear mixed models (GLM) and quantile g-computation (QgC) models were utilized to estimate the association between individual and joint air pollutants exposure and systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure (PP). A total of 16,242 participants were included in the analysis. The GLM analyses showed that PM2.5 , PM10 , NO2 , CO, and SO2 were significantly positively associated with SBP and PP, while O3 was positively associated with DBP. The QgC analyses indicated that long-term exposure to a mixture of the six air pollutants had a significant positive joint association with SBP and PP. In conclusion, air pollutant co-exposure during adolescence may influence BP in young adulthood. The findings of this study emphasized the impacts of multiple air pollutants interactions on potential health and the need of minimizing pollution exposures in the environment.

Long-term exposure to PM2.5 and O3 with cardiometabolic multimorbidity: Evidence among Chinese elderly population from 462 cities

Cardiometabolic multimorbidity (CMM) refers to the presence of multiple cardiovascular and metabolic diseases (CMDs), such as hypertension, diabetes, and cardio-cerebrovascular diseases (CCVD), in the same individual, and has emerge as a significant global health concern due to population aging. Although previous research has demonstrated the association between cardiovascular and metabolic diseases and air pollutants, evidence on the link between CMM and air pollution exposure among Chinese older adults is limited. To address this research gap, we conducted a national representative survey of 222,179 adults aged 60 and older to investigate the epidemiology of CMM and its association with long-term exposure to PM_2.5 and O₃ in China's elderly population. We found that the prevalence of CMM among Chinese older adults was 16.9%, and hypertension and CCVD were the most common CMM cluster (10.8%). After adjusting for confounding variables, we observed a significant positive association between PM_2.5 exposure and the prevalence of hypertension, diabetes, and CCVD, with a respective excess risk increase of 3.2%, 3.6%, and 5.5% for every 10-unit increase. Moreover, every 10-unit increase in PM_2.5 was linked to a higher risk of hypertension and diabetes (2.2%), hypertension and CCVD (5.4%), diabetes and CCVD (5.6%), and hypertension, diabetes, and CCVD combined (7.6%). We also found a U-shaped curve relationship between O₃ exposure and the occurrence of hypertension, diabetes, and CCVD, as well as different subtypes of CMM, with the lowest risk of O₃ exposure was observed near 75-80 μg/m³. Furthermore, we identified that female and rural residents are more vulnerable to the health risks of air pollution than male and urban residents. Given the increasing aging of the population and rising prevalence of multimorbidity, policymakers should focus more attention on the female and rural elderly population to prevent and control CMM. This study provides compelling evidence that reducing air pollution levels can be an effective strategy to prevent and manage CMM among older adults.

Combined effects of heatwaves and air pollution, green space and blue space on the incidence of hypertension: A national cohort study

Extreme heat exposure has been associated with hypertension. However, its interactive influences with air pollution, green and blue spaces are unclear. This study aimed to explore the interaction between heatwaves, air pollution, green and blue spaces on hypertension. Cohort data enrolled 6448 Chinese older adults aged 65 years and over were derived from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) between 2008 and 2018. Nine heatwave definitions, combining three heat thresholds (92.5th, 95th, and 97.5th percentiles of daily maximum temperature) and three durations (≥2, 3 and 4 days) were used as time-varying variables in the analysis and were the one-year exposure before survival events. Fine particulate matter (PM ≤2.5 μm in aerodynamic diameter (PM_2.5)), the Normalized Difference Vegetation Index (NDVI) and the average proportion of open water bodies were used to reflect the air pollution, green and blue space exposures, respectively. PM_2.5, green and blue space exposures were time-varying indicators and contemporaneous with heatwaves. Mixed Cox models with time-varying variables were fitted to assess the multiplicative and additive interaction of heatwaves, PM_2.5, and green and blue spaces on hypertension, measured by a traditional product term with the ratio of hazard ratio (HR) and relative risk due to interaction (RERI), respectively. A positive multiplicative (HRs >1) and additive interaction (RERIs >0) between heatwaves and higher PM_2.5 levels was observed. There was a synergistic effect between heatwaves and decreasing greenness levels on hypertension incidence on additive and multiplicative scales. No significant interaction between heatwaves and blue space was observed in the analysis. The combined effects of heatwaves, air pollution, green and blue space exposures on the risk of hypertension varied with age, gender, and educational attainment. This study's findings complemented the existing evidence and revealed synergistic harmful impacts for heatwaves with air pollution and lack of green space on hypertension incidence.

Association between long-term exposure to ambient particulate matter and blood pressure, hypertension: an updated systematic review and meta-analysis

Evidence of more recent studies should be updated to evaluate the effect of long-term exposure to particulate matter (PM) on blood pressure and hypertension.        Studies of long-term effects of PM₁, PM_2.5 and PM₁₀ on blood pressure (SBP, DBP, MAP), hypertension were searched in Pubmed, Web of Science and Embase before May, 2021. Meta-analysis of 41 studies showed that exposure to PM₁, PM_2.5 was associated with SBP (1.76 mmHg (95%CI:0.71, 2.80) and 0.63 mmHg (95%CI:0.40, 0.85), per 10 μg/m³ increase in PM), all three air pollutants (PM₁, PM_2.5, PM₁₀) was associated with DBP (1.16 mmHg (95%CI:0.34, 1.99), 0.31 mmHg (95%CI:0.16, 0.47), 1.17 mmHg (95%CI:0.24, 2.09), respectively. As for hypertension, PM₁, PM_2.5 and PM₁₀ were all significantly associated with higher risk of hypertension (OR=1.27 (95%CI:1.06, 1.52), 1.15 (95%CI:1.10, 1.20) and 1.11 (95%CI:1.07, 1.16). In conclusion, our study indicated a positive association between long-term exposure to particulate matter and increased blood pressure, hypertension.

Long-term exposure to fine particulate matter modifies the association between physical activity and the risk of hypertension

The trade-off between the potentially detrimental effects of fine particulate matter (PM_2.5) and the benefits of physical activity (PA) is unclear. We aimed to explore the independent and interaction effects between long-term PM_2.5 exposure and PA on blood pressure (BP) and hypertension. A total of 8704 adults (≥45 years) without hypertension at baseline in a nationwide cohort of the China Health and Retirement Longitudinal Study (CHARLS) were followed from 2011 to 2015. The participants were selected using a four-stage, stratified, and cluster sampling procedure. The annual PM_2.5 concentrations at the residential address were estimated from a two-stage machine learning model with a 10 km × 10 km resolution. A standard questionnaire collected information on PA and potential confounders, and metabolic equivalents (MET·h/wk), which combined frequency, intensity, and duration information, were used to assess PA levels. We adopted mixed-effects regression models to explore the independent and interaction effects between long-term PM_2.5 exposure and PA on BP and risk of hypertension. Systolic blood pressure (SBP) decreased by -0.84 mmHg (95% CI: -1.34, -0.34) per an IQR (interquartile range, 175.5 MET·h/wk) increase in PA, and diastolic blood pressure (DBP) decreased by -0.42 mmHg (95% CI: -0.76, -0.07). Each IQR (36.1 μg/m³) increment in PM_2.5 was associated with 0.48 mmHg (95% CI: -0.24, 1.20) in SBP and -0.02 mmHg (95% CI: -0.44, 0.39) in DBP. PM_2.5 showed an elevated effect with risks of hypertension (odds ratio, OR = 1.01; 95% CI: 1.00, 1.03), while PA showed the inverse result (OR = 0.98; 95% CI: 0.97, 0.99). Interaction analyses indicated PA maintained the beneficial effects on BP, but the negative association was attenuated, accompanied by the increase of PM_2.5. PA decreased the BP and hypertension risks, while PM_2.5 showed the opposite results. PM_2.5 attenuated the beneficial effects of PA on BP and modified the association between PA and the risk of hypertension.

PM2.5 and Cardiovascular Health Risks

PM2.5 is a frequently studied particulate matter metric, due to its wide range of identified overall adverse health effects, particularly cardiovascular health risks. However, there are no clear clinical practice guidelines for air pollution in regard to the prevention of cardiovascular health risks, since most of the current medical guidelines for CVD focus on metabolic risk factors such as hyperlipidemia or diabetes. We sought to determine the relationship between PM2.5 and cardiovascular disease, cardiovascular events, and all-cause mortality by performing a systematic review and meta-analysis. We searched Ovid MEDLINE, Ovid Embase, Ovid Cochrane Database of Systematic Reviews, Scopus, and Web of Science from the database inception to December 2022 for studies that reported an association between PM2.5 and cardiovascular disease, cardiovascular events, and all-cause mortality. We used the DerSimonian & Laird random-effects method to pool hazard ratios or risk ratios separately from the included studies. Of the total 18 prospective studies, 7,300,591 individuals were followed for a median follow-up of 9 years. Compared to low long-term exposure to PM 2.5 levels, an increase in exposure to PM 2.5 levels resulted in an increase in all-cause mortality (HR 1.08 95% CI of 1.05-1.11, P < 0.05). Similarly, when compared to a low long-term exposure to PM 2.5 levels, an increase in exposure to PM 2.5 levels resulted in an increase in cardiovascular disease (HR 1.09, 95% CI of 1.00-1.18, P < 0.05) and an increase in cardiovascular disease mortality (HR 1.12, 95% CI of 1.07-1.18, P < 0.05). Increased exposure to PM 2.5 levels is significantly associated with an increased risk of all-cause mortality, cardiovascular disease, and cardiovascular disease mortality. Although federal primary and secondary standards are in place, those standards are not low enough to prevent CVD health effects. Clinicians should emphasize PM2.5 as a modifiable CV risk factors for their patients to potentially reduce the development of CV complications. A clinical action guideline is needed specifically for air pollution effects on CVD, and how to mitigate them.

Burden of cardiovascular disease attributable to particulate matter pollution in the eastern Mediterranean region: analysis of the 1990-2019 global burden of disease

AIMS

Particulate matter pollution is the most important environmental mediator of global cardiovascular morbidity and mortality. Air pollution evidence from the Eastern Mediterranean Region (EMR) is limited, owing to scarce local studies, and the omission from multinational studies. We sought to investigate trends of particulate matter (PM2.5)-related cardiovascular disease (CVD) burden in the EMR from 1990 to 2019.

METHODS AND RESULTS

We used the 1990-2019 global burden of disease methodology to investigate total PM2.5, ambient PM2.5, and household PM2.5-related CVD deaths and disability-adjusted life years (DALYs) and cause-specific CVD mortality in the EMR. The average annual population-weighted PM2.5 exposure in EMR region was 50.3 μg/m3 [95% confidence interval (CI):42.7-59.0] in 2019, which was comparable with 199 048.1 μg/m3 (95% CI: 36.5-65.3). This was despite an 80% reduction in household air pollution (HAP) sources since 1990. In 2019, particulate matter pollution contributed to 25.67% (95% CI: 23.55-27.90%) of total CVD deaths and 28.10% (95% CI: 25.75-30.37%) of DALYs in the region, most of which were due to ischaemic heart disease and stroke. We estimated that 353 071 (95% CI: 304 299-404 591) CVD deaths in EMR were attributable to particulate matter in 2019, including 264 877 (95% CI: 218 472-314 057) and 88 194.07 (95% CI: 60 149-119 949) CVD deaths from ambient PM2.5 pollution and HAP from solid fuels, respectively. DALY's in 2019 from CVD attributable to particulate matter was 28.1% when compared with 26.69% in 1990. The age-standardized death and DALY rates attributable to air pollution was 2122 per 100 000 in EMR in 2019 and was higher in males (2340 per 100 000) than in females (1882 per 100 000).

CONCLUSION

The EMR region experiences high PM2.5 levels with high regional heterogeneity and attributable burden of CVD due to air pollution. Despite significant reductions of overall HAP in the past 3 decades, there is continued HAP exposure in this region with rising trend in CVD mortality and DALYs attributable to ambient sources. Given the substantial contrast in disease burden, exposures, socio-economic and geo-political constraints in the EMR region, our analysis suggests substantial opportunities for PM2.5 attributable CVD burden mitigation.

Effects of fine ambient particulate matters on de novo hypertensive disorders of pregnancy and blood pressure before 20 weeks

The effects of fine particulate matter (PM) on de novo hypertensive disorders of pregnancy (HDP) were inconsistent during the first and second trimesters. This study aimed to assess the trimester-specific effects of PM_2.5 and PM₁ prior to diagnosis of de novo HDP. The exposure of fine PM was predicted by satellite remote sensing data according to maternal residential addresses. De novo HDP was defined as gestational hypertension and preeclampsia during the current pregnancy. A logistic regression model was performed to assess the association of PM_2.5 and PM₁ with HDP during the first and early second trimesters (0-13 weeks and 14-20 weeks). The generalized estimating equation model was conducted to assess the effect of PM_2.5 and PM₁ on blood pressure. The present study included 22,821 pregnant women (mean age, 29.1 years) from 2013 to 2017. PM_2.5 and PM₁ were significantly associated with an increased risk of de novo HDP during the first trimester (OR = 1.070, 95% CI: 1.013-1.130; OR = 1.264, 95% CI: 1.058-1.511 for per 10 μg/m³) and early second trimester (OR = 1.045, 95% CI: 1.003-1.088; OR = 1.170, 95% CI: 1.002-1.366 for per 10 μg/m³). Significant trends of increased de novo HDP risk was also observed with the increment of PM (all P for trend <0.05). The stratified analyses demonstrated that the associations between exposure to fine PM and the risk of HDP were more pronounced among the pregnant women with maternal age above 35 and low maternal education level (all OR >1.047). Each 10 μg/m³ increase of PM₁ and PM_2.5 before diagnosis of de novo HDP elevated 0.204 (95% CI: 0.098-0.310) and 0.058 (95%CI: 0.033-0.083) mmHg of systolic blood pressure. Exposure to PM_2.5 and PM₁ during the first and early second trimester were positively associated with the risk of de novo HDP. The fine PM before diagnosis of de novo HDP elevated the systolic blood pressure.

Short-term effect of ambient air pollution on outpatient visits for children in Guangzhou, China

This study examined the short-term relationship between ambient air pollutants and children's outpatient visits, and identified the effect of modifications by season. Daily recordings of air pollutants (CO, NO₂, O₃, SO₂, PM₁₀, and PM_2.5) and children's outpatient visit data were collected in Guangzhou from 2015 to 2019. A generalized additive model adjusted for potential confounding was introduced to verify the association between ambient air pollution and outpatient visits for children. Subgroup analysis by season was performed to evaluate the potential effects. A total of 5,483,014 children's outpatient visits were recorded. The results showed that a 10 μg/m³ increase in CO, NO₂, O₃, SO₂, PM₁₀, and PM_2.5 corresponded with a 0.19% (95% CI: 0.15-0.24%), 2.46% (2.00-2.92%), 0.27% (0.07-0.46%), 7.16% (4.80-9.57%), 1.16% (0.83-1.49%), and 1.35% (0.88-1.82%) increase in children's outpatient visits on the lag0 of exposure, respectively. The relationships were stronger for O₃, PM₁₀, and PM_2.5 in the warm seasons, and for CO, NO₂, and SO₂ in the cool seasons. When adjusting for the co-pollutants, the effects of CO, NO₂, and PM₁₀ were robust. The results of this study indicate that six air pollutants might increase the risk of children's outpatient visits in Guangzhou, China, especially in the cool season.

Association between polycyclic aromatic hydrocarbon exposure and hypertension among the U.S. adults in the NHANES 2003-2016: A cross-sectional study

The global burden of hypertension, the major cause of cardiovascular disease (CVD) globally, remains unresolved. Exposure to PM2.5 has been linked to hypertension (HTN) in adults and the elderly globally according to previous studies. Nonetheless, evidence on the association of polycyclic aromatic hydrocarbon (PAH) exposure and HTN risk in the general adult population in the United States was limited. To investigate the relationship between PAH exposure and HTN in adults in the United States, cross-sectional data during 2003 and 2016 from the National Health and Nutrition Examination Survey (NHANES) on a stratified multistage random sample of the civilian non-institutionalized population were utilized. After eliminating individuals with incomplete information of interest, the final analysis contained 8951 subjects aged ≥20. In the multivariate logistic regression model, 1-hydroxynaphthalene and 2-hydroxyfluorene were found positively associated with increased risk of HTN among overall participants after adjusting for the covariates. 1-hydroxynaphthalene and 2-hydroxynaphthalene showed positive associations with HTN risk among overweight participants. In the Bayesian kernel machine regression (BKMR) model, 1-hydroxynaphthalene and 2-hydroxyfluorene presented great importance to HTN risk among overall individuals. In the male subgroup analyses by BKMR, 2-hydroxyfluorene presented a positive effect on HTN risk when the remaining OH-PAHs were set at their 25th, 50th, and 75th percentile. Our findings highlight the complexities of estimating the risk of HTN associated with mixed PAH exposure, and additional longitudinal studies are required to determine the exact link between PAH exposure and HTN risk, as well as the underlying mechanisms.

Maternal fasting glucose levels throughout the pregnancy and risk of adverse birth outcomes in newborns: a birth cohort study in Foshan city, Southern China

OBJECTIVE

We aimed to investigate the associations between maternal fasting plasma glucose (FPG) levels and glycemic fluctuations during different trimesters and adverse birth outcomes among newborns.

METHODS

This cohort study used data from 63 213 pregnant women and their offspring in Foshan city from November 2015 to January 2019. Associations between maternal FPG and glycemic fluctuations during different trimesters and adverse birth outcomes [congenital heart defect (CHD), macrosomia, small/large for gestational age (SGA/LGA), and preterm birth (PTB)] in newborns were estimated using mixed-effects logistic regression models.

RESULTS

A total of 45 516 participants accepted at least one FPG test throughout pregnancy, and 7852 of whom had glycemic trajectory data. In the adjusted model, higher maternal FPG throughout the pregnancy was associated with an increased risk of adverse birth outcomes (except for SGA). Each 1 mmol/L increase in maternal FPG during trimester 1 was associated with higher odds of CHD (OR = 1.14 (95% CI: 1.02, 1.26)). The same increase in maternal FPG during trimester 3 was associated with a higher risk of PTB (OR = 1.05 (95% CI: 1.01, 1.10)). Increment of maternal FPG during trimester 2 and trimester 3 was associated with a higher risk of macrosomia and LGA. Increase in FPG throughout the pregnancy was associated with slightly lower odds of SGA. Similar results were observed when analyzing the associations between glycemic fluctuations during different trimesters and adverse birth outcomes.

CONCLUSIONS

Our findings indicate higher maternal FPG levels during different trimesters were associated with different adverse birth outcomes, which suggests the importance of glycemic management throughout the pregnancy.

The association of long-term ambient fine particulate matter exposure with blood pressure among Chinese adults

Previous studies indicated that long-term exposure to high level of fine particulate matter (PM_2.5) was associated with elevated blood pressure (BP) and hypertension, but most of them were conducted in high-income countries with low PM_2.5 level. Therefore, we aimed to evaluate the adverse impacts of long-term exposure to PM_2.5 on BP and hypertension in China with high concentration. A total of 99,084 adults aged ≥18 years old were included from three cohorts among the project of Prediction for Atherosclerotic Cardiovascular Disease Risk in China. PM_2.5 concentrations during 2000-2015 at 1 × 1 km spatial resolution were evaluated using satellite-based spatiotemporal models. Generalized estimating equation was applied to assess the impact of three-year average PM_2.5 concentrations on BP level and hypertension. We also examined whether health status and lifestyles modified the effects of PM_2.5 on BP and hypertension. Generally, high concentration of PM_2.5 was associated with increased BP level and higher risk of hypertension. With each 10 μg/m³ increment in PM_2.5 concentration, systolic BP (SBP) and diastolic BP (DBP) increased by 1.67 [95% confidence interval (CI): 1.48, 1.86] mmHg and 0.45 (95% CI: 0.35, 0.56) mmHg, and the prevalence of hypertension increased by 29% [odds ratio (OR): 1.29, 95% CI: 1.26, 1.32]. In comparison with the first quartile of PM_2.5 concentration, SBP, DBP and prevalence of hypertension in the fourth quartile were increased by 8.26 (95% CI: 7.73, 8.80) mmHg, 2.85 (95% CI: 2.55, 3.15) mmHg, and 133% (OR: 2.33, 95% CI: 2.21, 2.47), respectively, in the fully adjusted model. However, the relationships of PM_2.5 with BP might be non-linear, as BP level started to decline when PM_2.5 exceeded 75 μg/m³. In conclusion, long-term PM_2.5 exposure could elevate BP level and prevalence of hypertension. People living in high-polluted areas should strengthen their awareness of prevention.

The pathophysiological and molecular mechanisms of atmospheric PM2.5 affecting cardiovascular health: A review

BACKGROUND

Exposure to ambient fine particulate matter (PM2.5, with aerodynamic diameter less than 2.5 µm) is a leading environmental risk factor for global cardiovascular health concern.

OBJECTIVE

To provide a roadmap for those new to this field, we reviewed the new insights into the pathophysiological and cellular/molecular mechanisms of PM2.5 responsible for cardiovascular health.

MAIN FINDINGS

PM2.5 is able to disrupt multiple physiological barriers integrity and translocate into the systemic circulation and get access to a range of secondary target organs. An ever-growing body of epidemiological and controlled exposure studies has evidenced a causal relationship between PM2.5 exposure and cardiovascular morbidity and mortality. A variety of cellular and molecular biology mechanisms responsible for the detrimental cardiovascular outcomes attributable to PM2.5 exposure have been described, including metabolic activation, oxidative stress, genotoxicity, inflammation, dysregulation of Ca2+ signaling, disturbance of autophagy, and induction of apoptosis, by which PM2.5 exposure impacts the functions and fates of multiple target cells in cardiovascular system or related organs and further alters a series of pathophysiological processes, such as cardiac autonomic nervous system imbalance, increasing blood pressure, metabolic disorder, accelerated atherosclerosis and plaque vulnerability, platelet aggregation and thrombosis, and disruption in cardiac structure and function, ultimately leading to cardiovascular events and death. Therein, oxidative stress and inflammation were suggested to play pivotal roles in those pathophysiological processes.

CONCLUSION

Those biology mechanisms have deepen insights into the etiology, course, prevention and treatment of this public health concern, although the underlying mechanisms have not yet been entirely clarified.

Associations between conjunctivitis and ambient PM2.5 and physical activity: A nationwide prospective cohort study

BACKGROUND

Currently, there is no evidence of fine particulate matter pollution (PM_2.5) altering the relationship between physical activity (PA) and the risk of conjunctivitis.

METHODS

Based on the UK Biobank study, we included 308,507 participants aged 40-69 years at baseline (2006 to 2010) and prospectively followed up for conjunctivitis diagnosis till 2020. Annual concentrations of PM_2.5 in 2010 were estimated for each participant using Land Use Regression models. PA levels during work and leisure time were reported via the International Physical Activity Questionnaire at baseline. We used Cox proportional hazards models to examine the associations of PM_2.5 and PA with incident conjunctivitis, as well as their interaction at both multiplicative and additive scales.

RESULTS

During the 11.6 years of follow up, we identified 4002 incident conjunctivitis cases. High-PA (≥3000 metabolic equivalent of task [MET]-mins/week) was associated with lower risk of conjunctivitis (hazard ratio [HR]: 0.79, 95% confidence interval [CI]: 0.73-0.86) compared to low-PA (0 to <600 MET-mins/week), while every 1 μg/m³ increment in PM_2.5 was associated with a 16% higher risk of conjunctivitis (HR = 1.16, 95% CI: 1.09-1.23). We did not observe statistically significant interactions between PM_2.5 and PA on their associations with conjunctivitis.

CONCLUSION

Habitual PA and PM_2.5 exposure were oppositely related to incident conjunctivitis. The benefits of PA remain in people irrespective of exposure to air pollution.

Association between smoking and hypertension under different PM2.5 and green space exposure: A nationwide cross-sectional study

Background

Smoking has been widely reported to have a significant relationship with hypertension, but the past description of this relationship has not been uniform. In addition, there has been a lack of research to discuss the impact of environmental exposure on the relationship between smoking and hypertension. Therefore, this study estimates the association between smoking and hypertension in middle aged and elderly people in China under different PM_2.5 (fine particulate matter) concentrations and the green space exposure conditions.

Methods

Individual sample data from the China Health and Retirement Longitudinal Study in 2018 and the long-term average exposure concentration of fine particles and green space exposure for all participants were used with a multilevel binary logistic mixed effects model. Adjustments were made for sociodemographic characteristics and other health behaviors including drinking, physical activity, and social activity. The normalized difference vegetation index (NDVI) and PM_2.5 concentration stratification were assigned with the median of the population exposure concentration as the dividing line, and the dual environmental factor stratification was assigned in combination with the two types of environmental exposure. The analysis was also stratified using age groups.

Results

A total of 10,600 participants over the age of 45 were included in the study. The effects of smoking on hypertension were diverse under different environmental exposure conditions. There was a significant relationship between smoking behavior and hypertension in the Low-NDVI group, and the effect value of this relationship was significantly different from that in the High-NDVI group. Furthermore, for respondents exposed to low green spaces and high PM_2.5 environments at the same time (Low-NDVI/High-PM_2.5 group), their smoking behavior may lead to an increase in the risk of hypertension. In addition, the risk of hypertension caused by smoking in the middle-aged (45-64) was significant under low green space exposure, but the effect difference between the different age groups was not significant.

Conclusions

The relationship between smoking and hypertension was different under different environmental exposure conditions. Exposure to low green spaces may strengthen the association between smoking and hypertension risk. When participants were exposed to both low green spaces and high PM_2.5 concentrations, the risk of hypertension caused by smoking was significantly higher than that of those who were exposed to high green spaces and low PM_2.5 concentrations.

Acute ambulatory blood pressure response to short-term black carbon exposure: The MobiliSense sensor-based study

Documented relationships between black carbon (BC) exposure and blood pressure (BP) have been inconsistent. Very few studies measured both BC exposure and ambulatory BP across the multiple daily environments visited in the general population, and none adjusted for personal noise exposure, a major confounder. Our study addresses these gaps by considering 245 adults living in the Grand Paris region. Personal exposure to BC was monitored for 2 days using AE51 microaethalometers. Ambulatory BP was measured every 30 min after waking up using Arteriograph 24 monitors (n = 6772). Mixed effect models with a random intercept at the individual level and time-autocorrelation structure adjusted for personal noise exposure were used to evaluate the associations between BC exposure (averaged from 5 min to 1 h before each BP measurement) and BP. To increase the robustness of findings, we eliminated confounding by unmeasured time-invariant personal variables, by modelling the associations with fixed-effect models. All models were adjusted for potential confounders and short-term time trends. Results from mixed models show that a 1-μg/m³ increase in 5-minute averaged BC exposure was associated with an increase of 0.57 mmHg in ambulatory systolic blood pressure (SBP) (95 % CI: 0.30, 0.83) and with an increase of 0.36 mmHg in diastolic blood pressure (DBP) (95 % CI: 0.14, 0.58). The slope of the exposure-response relationship gradually decreased for both SBP and DBP with the increase in the averaging period of BC exposure from 5 min to 1 h preceding each BP measurement. Findings from the fixed-effect models were consistent with these results. There was no effect modification by noise in the associations, across all exposure windows. We found evidence of a relationship between BC exposure and acute increase in ambulatory SBP and DBP after adjustment for personal noise exposure, with potential implications for the development of adverse cardiovascular outcomes.

Overview of particulate air pollution and human health in China: Evidence, challenges, and opportunities

Ambient particulate matter (PM) pollution in China continues to be a major public health challenge. With the release of the new WHO air quality guidelines in 2021, there is an urgent need for China to contemplate a revision of air quality standards (AQS). In the recent decade, there has been an increase in epidemiological studies on PM in China. A comprehensive evaluation of such epidemiological evidence among the Chinese population is central for revision of the AQS in China and in other developing countries with similar air pollution problems. We thus conducted a systematic review on the epidemiological literature of PM published in the recent decade. In summary, we identified the following: (1) short-term and long-term PM exposure increase mortality and morbidity risk without a discernible threshold, suggesting the necessity for continuous improvement in air quality; (2) the magnitude of long-term associations with mortality observed in China are comparable with those in developed countries, whereas the magnitude of short-term associations are appreciably smaller; (3) governmental clean air policies and personalized mitigation measures are potentially effective in protecting public and individual health, but need to be validated using mortality or morbidity outcomes; (4) particles of smaller size range and those originating from fossil fuel combustion appear to show larger relative health risks; and (5) molecular epidemiological studies provide evidence for the biological plausibility and mechanisms underlying the hazardous effects of PM. This updated review may serve as an epidemiological basis for China’s AQS revision and proposes several perspectives in designing future health studies.

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Acute effects of PM are smaller in China compared with developed countries

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Health effects caused by PM depend on particle composition, source, and size

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There are no thresholds for the health effects of PM

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Mechanistic studies support the biological plausibility of PM’s health effects

Association between Fine Particulate Air Pollution and the Onset of Uveitis in Mainland China

PURPOSE

Although it has long been recognized that air pollution can affect the immune system and human ocular symptoms, it is uncertain whether air pollutants may also contribute to the development of uveitis. This study aimed to quantify the association of particulate matters less than 2.5 μm (PM2.5) with uveitis onset.

METHODS

We combined monthly averages of PM2.5 concentrations, with data from the largest database of uveitis cases to assess the association between PM2.5 and uveitis onset. We further estimated the uveitis burden that was attributed to PM2.5 exposure and used choropleth maps to precisely characterize geographical variations.

RESULTS

We found that a 10 μg/m3 increase in PM2.5 concentration was associated with a one-case per 10 individuals increase in uveitis onset across the dataset. Our results further suggest that PM2.5 concentrations above the level of the minimum exposure are responsible for 13% of novel uveitis cases in our cohort. Conclusion: These findings provide evidence supporting the association between fine particulate air pollution and uveitis onset.

Residential greenness attenuated association of long-term air pollution exposure with elevated blood pressure: Findings from polluted areas in Northern China

Background

Evidence on the hypertensive effects of long-term air pollutants exposure are mixed, and the joint hypertensive effects of air pollutants are also unclear. Sparse evidence exists regarding the modifying role of residential greenness in such effects.

Methods

A cross-sectional study was conducted in typically air-polluted areas in northern China. Particulate matter with diameter < 1 μm (PM₁), particulate matter with diameter < 2.5 μm (PM_2.5), particulate matter with diameter < 10 μm (PM₁₀), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and ozone (O₃) were predicted by space-time extremely randomized trees model. We used the Normalized Difference Vegetation Index (NDVI) to reflect residential green space. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were examined. We also calculated the pulse pressure (PP) and mean arterial pressure (MAP). Generalized additive model and quantile g-computation were, respectively, conducted to investigate individual and joint effects of air pollutants on blood pressure. Furthermore, beneficial effect of NDVI and its modification effect were explored.

Results

Long-term air pollutants exposure was associated with elevated DBP and MAP. Specifically, we found a 10-μg/m³ increase in PM_2.5, PM₁₀, and SO₂ were associated with 2.36% (95% CI: 0.97, 3.76), 1.51% (95% CI: 0.70, 2.34), and 3.54% (95% CI: 1.55, 5.56) increase in DBP; a 10-μg/m³ increase in PM_2.5, PM₁₀, and SO₂ were associated with 1.84% (95% CI: 0.74, 2.96), 1.17% (95% CI: 0.52, 1.83), and 2.43% (95% CI: 0.71, 4.18) increase in MAP. Air pollutants mixture (one quantile increase) was positively associated with increased values of DBP (8.22%, 95% CI: 5.49, 11.02) and MAP (4.15%, 95% CI: 2.05, 6.30), respectively. These identified harmful effect of air pollutants mainly occurred among these lived with low NDVI values. And participants aged ≥50 years were more susceptible to the harmful effect of PM_2.5 and PM₁₀ compared to younger adults.

Conclusions

Our study indicated the harmful effect of long-term exposure to air pollutants and these effects may be modified by living within higher green space place. These evidence suggest increasing residential greenness and air pollution control may have simultaneous effect on decreasing the risk of hypertension.

Air pollution and blood pressure in the elderly: evidence from a panel study in Nanjing, China

Background

Air pollution is known to have notable negative effects on human health. Recently, the effect of air pollution on blood pressure among the elderly has attracted researchers’ attention. However, the existing evidence is not consistent, given that positive, null, and negative outcomes are presented in the literature. In this study, we investigated the relationship between blood pressure (BP) and indices of air pollutants (PM_2.5, PM₁₀, and air quality index) in a specific elderly population through a panel study to address this knowledge gap.

Methods

We obtained repeated BP measurements from January 2017 to May 2019 in a panel of 619 elderly with a total of 5106 records in Nanjing, China. Data on daily indices of ambient air pollutants, including fine particulate matter with an aerodynamic diameter of ≤ 2.5μ m (PM_2.5), ≤ 10μ m (PM₁₀), and air quality index (AQI) of the same period were obtained. We evaluated the association between BP and average concentrations of air pollutants in the past one-week, two-week, and four-week lags before measuring the BP. The non-linear panel regression models were used with fixed- and mixed-effects to control age, gender, and temperature.

Results

In the non-linear panel fixed-effects model, the average concentration of PM_2.5 is significantly associated with systolic BP (SBP) at all lags but is only significantly correlated with diastolic BP (DBP) at a one-week lag. An interquartile range (IQR) increase of one-week average moving PM_2.5 (38.86 μg/m³) of our sample increases the SBP and DBP by 7.68% and 6.9%, respectively. PM₁₀ shows the same pattern of effect on BP as PM_2.5. AQI shows less significant associations with BP. In the non-linear mixed-effects model, the average concentrations of PM_2.5 and PM₁₀ are significantly associated with SBP at all lags but have no significant effect on DBP at one- and two-week lags. AQI is only significantly associated with DBP at a one-week lag.

Conclusions

Exposures to ambient particulate matter (PM_2.5 and PM₁₀) were associated with increased BP among older people, indicating a potential link between air pollution and the high prevalence of hypertension. Air pollution is a well-recognized risk factor for future cardiovascular diseases and should be reduced to prevent hypertension among the elderly.

The Impact of Fine Particulate Matter 2.5 on the Cardiovascular System: A Review of the Invisible Killer

Air pollution exerts several deleterious effects on the cardiovascular system, with cardiovascular disease (CVD) accounting for 80% of all premature deaths caused by air pollution. Short-term exposure to particulate matter 2.5 (PM_2.5) leads to acute CVD-associated deaths and nonfatal events, whereas long-term exposure increases CVD-associated risk of death and reduces longevity. Here, we summarize published data illustrating how PM_2.5 may impact the cardiovascular system to provide information on the mechanisms by which it may contribute to CVDs. We provide an overview of PM_2.5, its associated health risks, global statistics, mechanistic underpinnings related to mitochondria, and hazardous biological effects. We elaborate on the association between PM_2.5 exposure and CVD development and examine preventive PM_2.5 exposure measures and future strategies for combating PM_2.5-related adverse health effects. The insights gained can provide critical guidelines for preventing pollution-related CVDs through governmental, societal, and personal measures, thereby benefitting humanity and slowing climate change.

The effects of greenness exposure on hypertension incidence among Chinese oldest-old: a prospective cohort study

BACKGROUND

Although the oldest-old (those aged over 80 years) are vulnerable to environmental factors and have the highest prevalence of hypertension, studies focusing on greenness exposure and the development of hypertension among them are insufficient. The aim of this study was to explore the association between residential greenness and hypertension in the oldest-old population.

METHODS

This cohort study included data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS). The oldest-old were free of hypertension at baseline (2008), and hypertension events were assessed by follow-up surveys in 2011, 2014, and 2018. The one-year averages of the normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI) at 500-m buffer before the interview year of incident hypertension or last censoring interview were collected at the level of 652 residential units (district or county). The linear or nonlinear association between greenness and hypertension incidence was analyzed using the Cox proportional hazards model with penalized splines. The linear links between greenness and hypertension incidence were determined using the Cox proportional hazards model included a random effect term.

RESULTS

Among 5253 participants, the incidence rate of hypertension was 7.25 (95% confidence interval [CI]: 6.83-7.67) per 100 person-years. We found a nonlinear association between greenness exposure and hypertension risk, and the exposure-response curve showed that 1 change point existed. We examined the linear effect of greenness on hypertension by categorizing the NDVI/EVI into low and high-level exposure areas according to the change point. We found more notable protective effects of each 0.1-unit increase in greenness on hypertension incidence for participants living in the high-level greenness areas (hazard ratio (HR) = 0.60; 95% CI: 0.53-0.70 for NDVI; HR = 0.46; 95% CI: 0.37-0.57 for EVI). In contrast, no significant influence of greenness exposure on hypertension risk was found for participants living in the low-level greenness areas (HR = 0.77; 95% CI: 0.38-1.55 for NDVI; HR = 0.73; 95% CI: 0.33-1.63 for EVI).

CONCLUSIONS

Greenness exposure is nonlinearly associated with hypertension risk among the oldest-old, presenting its relationship in an inverse "U-shaped" curve. Greenness is a protective factor that decreases the risk of hypertension.

Associations of genetic risk factors and air pollution with incident hypertension among participants in the UK Biobank study

The purposes of this study were to quantify the association of the combination of air pollution and genetic risk factors with hypertension and explore the interactions between air pollution and genetic risk. This study included 391,366 participants of European ancestry initially free from pre-existing hypertension in the UK Biobank. Exposure to ambient air pollutants, including particulate matter (PM_2.5 PM_2.5-10, and PM₁₀), nitrogen dioxide (NO₂) and nitrogen oxides (NO_X), was estimated through land use regression modelling, and the associations between air pollutants and the incidence of hypertension were investigated using a Cox proportional hazards model adjusted for covariates. Furthermore, we established a polygenic risk score for hypertension and assessed the combined effect of genetic susceptibility and air pollution on incident hypertension. The results showed significant associations between the risk of hypertension and exposure to PM_2.5 (hazard ratio [HR]: 1.41, 95% confidence interval [CI]: 1.29-1.53; per 10 μg/m³), PM₁₀ (1.05, 1.00-1.09; per 10 μg/m³), and NO_X (1.01, 1.01-1.02 per 10 μg/m³). Additive effects of PM_2.5 and NO_X exposure and genetic risk were observed. Compared to individuals with a low genetic risk and low air pollution exposure, participants with high air pollution exposure and a high genetic risk had a significantly increased risk of hypertension (PM_2.5: 71% (66%-76%), PM₁₀: 59% (55%-64%), NO_X: 65% (60%-70%)). Our results indicate that long-term exposure to air pollution is associated with an increased risk of hypertension, especially in individuals with a high genetic risk.

Evaluation of associations between estimates of particulate matter exposure and new onset type 2 diabetes in the REGARDS cohort

BACKGROUND

Studies of PM_2.5 and type 2 diabetes employ differing methods for exposure assignment, which could explain inconsistencies in this growing literature. We hypothesized associations between PM_2.5 and new onset type 2 diabetes would differ by PM_2.5 exposure data source, duration, and community type.

METHODS

We identified participants of the US-based REasons for Geographic and Racial Differences in Stroke (REGARDS) cohort who were free of diabetes at baseline (2003-2007); were geocoded at their residence; and had follow-up diabetes information. We assigned PM_2.5 exposure estimates to participants for periods of 1 year prior to baseline using three data sources, and 2 years prior to baseline for two of these data sources. We evaluated adjusted odds of new onset diabetes per 5 µg/m³ increases in PM_2.5 using generalized estimating equations with a binomial distribution and logit link, stratified by community type.

RESULTS

Among 11,208 participants, 1,409 (12.6%) had diabetes at follow-up. We observed no associations between PM_2.5 and diabetes in higher and lower density urban communities, but within suburban/small town and rural communities, increases of 5 µg/m³ PM_2.5 for 2 years (Downscaler model) were associated with diabetes (OR [95% CI] = 1.65 [1.09, 2.51], 1.56 [1.03, 2.36], respectively). Associations were consistent in direction and magnitude for all three PM_2.5 sources evaluated.

SIGNIFICANCE

1- and 2-year durations of PM_2.5 exposure estimates were associated with higher odds of incident diabetes in suburban/small town and rural communities, regardless of exposure data source. Associations within urban communities might be obfuscated by place-based confounding.

Air Pollution and Cardiorespiratory Changes in Older Adults Living in a Polluted Area in Central Chile

One recognized cause of cardiorespiratory diseases is air pollution. Older adults (OA) are one of the most vulnerable groups that suffer from its adverse effects. The objective of the study was to analyze the association between exposure to air pollution and changes in cardiorespiratory variables in OA. Observational prospective cohort study. Health questionnaires, blood pressure (BP) measurements, lung functions, respiratory symptoms, physical activity levels, and physical fitness in high and low exposure to air pollution were all methods used in evaluating OAs in communes with high contamination rates. Linear and logistic models were created to adjust for variables of interest. A total of 92 OA participated in this study. 73.9% of the subjects were women with 72.3 ± 5.6 years. 46.7% were obese, while 12.1% consumed tobacco. The most prevalent diseases found were hypertension, diabetes, and cardiovascular disease. Adjusted linear models maintained an increase for systolic BP of 6.77 mmHg (95% CI: 1.04-12.51), and diastolic of 3.51 mmHg (95% CI: 0.72-6.29), during the period of high exposure to air pollution. The adjusted logistic regression model indicated that, during the period of high exposure to air pollution increase the respiratory symptoms 4 times more (OR: 4.43, 95% CI: 2.07-10.04) in the OA. The results are consistent with an adverse effect on cardiorespiratory variables in periods of high exposure to air pollution in the OA population.

The association of hypertension and prehypertension with greenness and PM2.5 in urban environment

BACKGROUND

The interplay of air pollution and urban greenness on hypertension (HTN) is not fully understood.

METHODS

We conducted a cross-sectional study to explore the role of greenness and PM_2.5 on HTN for 40,375 adult residents in the New Taipei City, Taiwan. Normalized Difference Vegetation Index (NDVI) defined greenness and land use regression derived exposures of PM_2.5 were used to calculate odds ratios (ORs) of HTN in logistic regression models and common OR of normal to stage 3 HTN in ordinal logistic regression models. Linear regression model was used to evaluate the association between NDVI and blood pressures, including systolic (SBP), diastolic (DBP) and mean (MBP) pressures. The mediation and moderation analysis were used to assess the mediation and moderation effect of PM_2.5 on the association between greenness and SBP.

RESULTS

We found 37.3%, 21.4%, 8.2% and 2.7% of prehypertension and stage 1-3 hypertensions, respectively, for our study participants with annual PM_2.5 exposures of 10.96-43.59 μg/m³ living in an urban environment with NDVI within 500 m buffer ranging from -0.22 to 0.26. The ORs of HTN were 0.744 (95% CI: 0.698-0.793) for NDVI (quartile 4 vs. quartile 1) and 1.048 (1.012-1.085) for each IQR (8.69 μg/m³) increase in PM_2.5, respectively. The common OR of the higher level of 5 categories of BP was 1.1310 (1.241-1.383). With each IQR increase of NDVI (0.03), we found SBP, DBP and MBP were decreased by 0.78 mm Hg (-0.93-0.64), 0.52 mm Hg (-0.62-0.43) and 0.61 mm Hg (-0.71-0.51), respectively, in linear regression models. Stratified analysis found greenness effect was more prominent for people who are younger, female, never smoking, and without chronic diseases. PM_2.5 is moderated rather than mediated the association between greenness and SBP.

CONCLUSIONS

Greenness was associated with lower prevalence of prehypertension and all stages of HTN and this relationship was moderated by PM_2.5.

Frailty Risk in Older Adults Associated With Long-Term Exposure to Ambient PM2.5 in 6 Middle-Income Countries

BACKGROUND

A series of studies have explored the health effects of long-term exposure to ambient PM2.5 among older adults. However, few studies have investigated the adverse effect of long-term exposure to ambient PM2.5 on frailty, and the results are inconclusive. This study sought to investigate the associations between long-term exposure to ambient PM2.5 and frailty in 6 low- and middle-income countries.

METHODS

We included an analytical sample of 34 138 individuals aged 50 and older from the Study on global AGEing and adult health Wave 1 (2007/2010). Air pollution estimates were generated using a standard methodology derived from Moderate Resolution Imaging Spectroradiometer observations and Multiangle Imaging Spectroradiometer instruments from the Terra satellite, along with simulations from the GEOS-Chem chemical transport model. A 3-level hierarchical logistic model was used to evaluate the association between frailty index and long-term PM2.5 exposure at 3 levels (individual, province, and country).

RESULTS

In rural areas, each 10 μg/m3 increase in ambient PM2.5 was associated with a 30% increase in the odds of frailty (OR = 1.30, 95% CI: 1.21-1.39) after adjusting for various potential confounding factors. The gender-stratified analysis showed that the association seemed to be slightly stronger in men (OR = 1.31, 95% CI: 1.18-1.46) than in women (OR = 1.21, 95% CI: 1.07-1.36) in rural areas.

CONCLUSION

In a large sample of community-based older adults from 6 middle-income countries, we found evidence that long-term PM2.5 exposure was associated with frailty in rural areas.

Estimation and Analysis of PM2.5 Concentrations with NPP-VIIRS Nighttime Light Images: A Case Study in the Chang-Zhu-Tan Urban Agglomeration of China

Rapid economic and social development has caused serious atmospheric environmental problems. The temporal and spatial distribution characteristics of PM_2.5 concentrations have become an important research topic for sustainable social development monitoring. Based on NPP-VIIRS nighttime light images, meteorological data, and SRTM DEM data, this article builds a PM_2.5 concentration estimation model for the Chang-Zhu-Tan urban agglomeration. First, the partial least squares method is used to calculate the nighttime light radiance, meteorological elements (temperature, relative humidity, and wind speed), and topographic elements (elevation, slope, and topographic undulation) for correlation analysis. Second, we construct seasonal and annual PM_2.5 concentration estimation models, including multiple linear regression, support random forest, vector regression, Gaussian process regression, etc., with different factor sets. Finally, the accuracy of the PM_2.5 concentration estimation model that results in the Chang-Zhu-Tan urban agglomeration is analyzed, and the spatial distribution of the PM_2.5 concentration is inverted. The results show that the PM_2.5 concentration correlation of meteorological elements is the strongest, and the topographic elements are the weakest. In terms of seasonal estimation, the spring estimation results of multiple linear regression and machine learning estimation models are the worst, the winter estimation results of multiple linear regression estimation models are the best, and the annual estimation results of machine learning estimation models are the best. At the same time, the study found that there is a significant difference in the temporal and spatial distribution of PM_2.5 concentrations. The methods in this article overcome the high cost and spatial resolution limitations of traditional large-scale PM_2.5 concentration monitoring, to a certain extent, and can provide a reference for the study of PM_2.5 concentration estimation and prediction based on satellite remote sensing technology.

Adverse effects of PM2.5 on cardiovascular diseases

As an air pollutant, fine particulate matter with a diameter  ≤ 2.5 μm (PM_2.5) can enter the body through the respiratory tract and cause adverse cardiovascular effects. Here, the effects of PM_2.5 on atherosclerosis, hypertension, arrhythmia, myocardial infarction are summarized from the perspective researches of human epidemiology, animal, cell and molecule. The results of this review should be proved useful as a scientific basis for the prevention and treatment of cardiovascular disease caused by PM_2.5.

Long-term effects of PM2.5 components on blood pressure and hypertension in Chinese children and adolescents

Growing evidence has linked fine particulate matter (PM_2.5) exposure to elevated blood pressure, but the effects of PM_2.5 components are unclear, particularly in children and adolescents. Based on a cross-sectional investigation in China, we analyzed the associations between long-term exposure to PM_2.5 and its major components with elevated blood pressure in children and adolescents. A representative sample (N = 37,610) of children and adolescents with age 7-18 years was collected in seven Chinese provinces. Exposures to PM_2.5 and five of its major components, including black carbon (BC), organic matter (OM), inorganic nitrate (NO₃^-), sulfate (SO₄^2-), and soil particles (SOIL), were estimated using satellite-based spatiotemporal models. The associations between long-term exposures to PM_2.5 and its components and diastolic blood pressure (DBP), systolic blood pressure (SBP), and hypertension were investigated using mixed-effects logistic and linear regression models. Within the populations, 11.5 % were classified as hypertension. After adjusting for a variety of covariates, per interquartile range (IQR) increment in PM_2.5 mass and BC levels were significantly associated with a higher hypertension prevalence with odds ratios (ORs) of 1.56 (95% confidence interval (CI): 1.08, 2.25) for PM_2.5 and 1.19 (95% CI: 1.04, 1.35) for BC. Long-term exposures to PM_2.5 and BC have also been associated with elevated SBP and DBP. Additionally, OM and NO₃^- were significantly associated with increased SBP, while SOIL was significantly associated with increased DBP. In the subgroup analysis, the associations between long-term exposures to BC and blood pressure vary significantly by urbanicity of residential area and diet habits. Our study suggests that long-term exposure to PM_2.5 mass and specific PM_2.5 components, especially for BC, are significantly associated with elevated blood pressure and a higher hypertension prevalence in Chinese children and adolescents.

Association between long-term exposure to PM2.5 and hypertension: A systematic review and meta-analysis of observational studies

BACKGROUND

Numerous studies have examined the association between long-term exposure to particulate matter with an aerodynamic diameter of ≤2.5 μm (PM_2.5) and hypertension. However, the results are inconsistent.

OBJECTIVES

Considering the limitations of previous meta-analyses and the publication of many new studies in recent years, we conducted this meta-analysis to assess the relationship between long-term PM_2.5 exposure and the incidence and prevalence of hypertension in a healthy population.

METHODS

We searched PubMed, Web of Science, Embase, and Scopus for relevant studies published until April 2, 2021 and reviewed the reference lists of previous reviews. A total of 28 observational studies reporting RR or OR with 95% CI for the association between long-term PM_2.5 exposure and the risk of hypertension were included.

RESULTS

After the sensitivity analysis, we excluded one study with a high degree of heterogeneity, resulting in 27 studies and 28 independent reports. Approximately 42 million participants were involved, and the cases of hypertension in cohort and cross-sectional studies were 508,749 and 1,793,003, respectively. The meta-analysis showed that each 10 μg/m³ increment in PM_2.5 was significantly associated with the risks of hypertension incidence (RR = 1.21, 95% CI: 1.07, 1.35) and prevalence (OR = 1.06, 95% CI: 1.03, 1.09). Subgroup analyses showed that occupational exposure had a significant effect on the association of PM_2.5 and hypertension incidence (p for interaction = 0.042) and that the PM_2.5 concentration level and physical activity had a noticeable effect on the association of PM_2.5 and hypertension prevalence (p for interaction = 0.005; p for interaction = 0.022).

CONCLUSIONS

A significantly positive correlation was observed between long-term PM_2.5 exposure and risks of hypertension incidence and prevalence, and a high PM_2.5 concentration resulted in an increased risk of hypertension.

The Association Between Long-Term Exposure to Particulate Matter and Incidence of Hypertension Among Chinese Elderly: A Retrospective Cohort Study

Background and Objectives: Studies that investigate the links between particulate matter ≤2. 5 μm (PM_2.5) and hypertension among the elderly population, especially those including aged over 80 years, are limited. Therefore, we aimed to examine the association between PM_2.5 exposure and the risk of hypertension incidence among Chinese elderly. Methods: This prospective cohort study used 2008, 2011, 2014, and 2018 wave data from a public database, the Chinese Longitudinal Healthy Longevity Survey, a national survey investigating the health of those aged over 65 years in China. We enrolled cohort participants who were free of hypertension at baseline (2008) from 706 counties (districts) and followed up in the 2011, 2014, and 2018 survey waves. The annual PM_2.5 concentration of 706 counties (districts) units was derived from the Atmospheric Composition Analysis Group database as the exposure variable, and exposure to PM_2.5 was defined as 1-year average of PM_2.5 concentration before hypertension event occurrence or last interview (only for censoring). A Cox proportional hazards model with penalized spline was used to examine the non-linear association between PM_2.5 concentration and hypertension risk. A random-effects Cox proportional hazards model was built to explore the relationship between each 1 μg/m³, 10 μg/m³ and quartile increment in PM_2.5 concentration and hypertension incidence after adjusting for confounding variables. The modification effects of the different characteristics of the respondents were also explored. Results: A total of 7,432 participants aged 65-116 years were enrolled at baseline. The median of PM_2.5 exposure concentration of all the participants was 52.7 (inter-quartile range, IQR = 29.1) μg/m³. Overall, the non-linear association between PM_2.5 and hypertension incidence risk indicated that there was no safe threshold for PM_2.5 exposure. The higher PM_2.5 exposure, the greater risk for hypertension incidence. Each 1 μg/m³ [adjusted hazard ratio (AHR): 1.01; 95% CI: 1.01-1.02] and 10 μg/m³ (AHR: 1.12; 95% CI: 1.09-1.16) increments in PM_2.5, were associated with the incidence of hypertension after adjusting for potential confounding variables. Compared to first quartile (Q1) exposure, the adjusted HRs of hypertension incidence for the Q2, Q3 and Q4 exposure of PM_2.5 were 1.31 (95% CI: 1.13-1.51), 1.35 (95% CI: 1.15-1.60), and 1.83 (95% CI: 1.53-2.17), respectively. The effects appear to be stronger among those without a pension, living in a rural setting, and located in central/western regions. Conclusion: We found no safe threshold for PM_2.5 exposure related to hypertension risk, and more rigorous approaches for PM_2.5 control were needed. The elderly without a pension, living in rural and setting in the central/western regions may be more vulnerable to the effects of PM_2.5 exposure.

The impact of PM2.5 on children's blood pressure growth curves: A prospective cohort study

OBJECTIVE

The aim of this study was to explore the association between exposure to particulate matter with an aerodynamic diameter of 2.5 mm or less (PM2.5) and blood pressure (BP) levels in children and adolescents and to illustrate the impact of PM2.5 levels on BP growth curves in a cohort study.

METHODS

A longitudinal study was designed and included 4303 children (7617 BP measurements) living in the selected areas, and evaluations were conducted in 2014-2015 (visit 1) and followed up in 2019 (visit 2). Two-stage stratified cluster sampling was used to include urban-rural areas. A mixed linear regression model and mixed logistic regression model were used to analyze the effect of PM2.5 exposure on BP and the incidence of prehypertension and hypertension in children.

RESULTS

After adjusting for covariates, systolic blood pressure (SBP) (2.21 (95% CIs: 0. 81, 3.62), mmHg), diastolic blood pressure (DBP) (1.92 (95% CIs: 0.74, 3.11), mmHg), mean arterial pressure (MAP) (2.03 (95% CIs: 0.89, 3.17), mmHg) and heart rate (HR) (2.24 (95% CIs: 0.11, 4.37), beats/min) increased significantly in the fourth quartile of PM2.5 exposure levels compared with the first quartile (all P < 0.01). In addition, long-term exposure to PM2.5 was significantly positively correlated with SBP, DBP and MAP, and the effect was more notable in urban areas than that in rural areas. Moreover, the risk of prehypertension and hypertension incidence increased by 1.17 (95% CIs: 1.03, 1.33) fold with a one-quartile increase in PM2.5 exposure. The long-term effects of annual mean PM2.5 exposure on SBP, DBP and MAP were significant from pregnancy to 7, 3 and 4 years of age, respectively.

CONCLUSION

Long-term exposure to PM2.5 was positively associated with growth curves of hemodynamics indexed from pregnancy to childhood and adolescence, and the effect was more significant in urban areas than in rural areas.

Constituents of fine particulate matter and asthma in six low- and middle-income countries

BACKGROUND

Evidence concerning the effects of different chemical components of PM_2.5 on asthma is limited, and the methodology to compare the relative importance of different PM_2.5 components is lacking.

OBJECTIVES

To examine the associations between PM_2.5 components and asthma, and investigate which constituent of PM_2.5 possessed the most harmful effect on asthma.

METHODS

A total of 45,690 subjects were surveyed in six countries from 2007 to 2010. We geo-coded the residential community address of the participants, and used satellite remote sensing and chemical transport modeling to estimate their annual average concentrations. Mixed-effects generalized additive models were utilized to examine the associations between PM_2.5 constituents and prevalence of asthma. We further used counterfactual analyses to determine the potential number of asthma cases.

RESULTS

We identified 6,178 asthma cases among the participants, producing a prevalence of 13.5%. The odds ratio (OR) for asthma associated with per standard deviation (SD) increment was 1.12 for PM_2.5 mass, 1.12 for organic carbon (OC), 1.18 for black carbon (BC), 1.19 for sulfate, 1.28 for ammonium, and 1.21 for nitrate after controlling for potential confounders. Our counterfactual analyses suggested that ammonium was responsible for a substantial decline in asthma cases (1382, corresponding to 22.37% of overall cases) if the concentration was reduced to the 5th percentile of the current level.

CONCLUSIONS

Our study suggests that some chemical components (including BC, OC, sulfate, ammonium, and nitrate) of PM_2.5 might be hazardous constituents contributing to the prevalence of asthma, among them, ammonium might be responsible for substantial proportion of asthma cases if reduced to a certain level.

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

Apart from concentrations of particulate mass, PM_2.5-associated effects on health may largely depend on its chemical components. However, little is known regarding the underlying effects of specific PM_2.5 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 PM_2.5 and five main components. We used a time-stratified case-crossover design with conditional logistic regression models to estimate short-term effects of PM_2.5 constituents on cause-specific hospital admissions. Per interquartile range increase in exposure to PM_2.5, 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 PM_2.5 constituents. Relatively stronger constituents-admission associations were found among females for respiratory causes and the elderly for cardiovascular causes.