Associations between short-term changes in air pollution and correlates of arterial stiffness: The Veterans Affairs Normative Aging Study, 2007-2011

Association between exposure to air pollution and arterial stiffness in participants with and without atherosclerotic cardiovascular disease

AIMS

To assess the association of air pollution exposure at different time scales with arterial stiffness in participants with and without atherosclerotic cardiovascular disease (ASCVD).

METHODS

We measured participants' arterial stiffness with brachial-ankle pulse wave velocity (baPWV) from October 2016 to January 2020. Concentrations of air pollutants including fine particles < 2.5 μm aerodynamic diameter (PM2.5), inhalable particles < 10 μm aerodynamic diameter (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3) measured by fixed ambient air monitoring stations were collected for short- (7-day) and long-term (365-day) exposure assessment. We used generalized estimating equations (GEEs) to analyze and further explored the modification effects between ASCVD and air pollutants.

RESULTS

Seven hundred sixty-five participants were finally included and four hunderd sixty (60.1%) participants had a history of ASCVD. Based on the partial regression coefficients (β) and 95% confidence intervals (95% CI) calculated from GEEs using linear regression, each 10 μg/m3 increase in long-term exposure to PM2.5 and PM10 was associated with 31.85 cm/s (95% CI, 17.97 to 45.73) and 35.93 cm/s (95% CI, 21.01 to 50.84) increase in baPWV. There was no association between short-term exposure to air pollution and arterial stiffness. Although no significant interaction effect was observed between air pollution and ASCVD, baPWV showed a greater increment in the subgroup without ASCVD.

CONCLUSION

Long-term exposure to air pollution is closely associated with higher arterial stiffness in participants with and without ASCVD. Reducing air pollution exposure is essential in the primary and secondary prevention of ASCVD.

Impact of air pollution on cardiovascular aging

The world population is aging rapidly, and by some estimates, the number of people older than 60 will double in the next 30 years. With the increase in life expectancy, adverse effects of environmental exposures start playing a more prominent role in human health. Air pollution is now widely considered the most detrimental of all environmental risk factors, with some studies estimating that almost 20% of all deaths globally could be attributed to poor air quality. Cardiovascular diseases are the leading cause of death worldwide and will continue to account for the most significant percentage of non-communicable disease burden. Cardiovascular aging with defined pathomechanisms is a major trigger of cardiovascular disease in old age. Effects of environmental risk factors on cardiovascular aging should be considered in order to increase the health span and reduce the burden of cardiovascular disease in older populations. In this review, we explore the effects of air pollution on cardiovascular aging, from the molecular mechanisms to cardiovascular manifestations of aging and, finally, the age-related cardiovascular outcomes. We also explore the distinction between the effects of air pollution on healthy aging and disease progression. Future efforts should focus on extending the health span rather than the lifespan.

Air pollution exposure and vascular endothelial function: a systematic review and meta-analysis

Vascular endothelial dysfunction is an early stage to cardiovascular diseases (CVDs), but whether air pollution exposure has an effect on it remains unknown. We conducted a systematic review and meta-analysis to summarize epidemiological evidence between air pollution and endothelial dysfunction. We searched the database of PubMed, EMBASE, the Cochrane Library, and Web of Science up to November 10, 2022. Fixed and random effect models were used to pool the effect change or percent change (% change) and 95% confidence interval (95% CI) of vascular function associated with particulate matter (PM) and gaseous pollutants. I² statistics, funnel plot, and Egger's test were used to evaluate heterogeneity and publication bias. There were 34 articles included in systematic review, and 25 studies included in meta-analysis. For each 10 µg/m³ increment in short-term PM_2.5 exposure, augmentation index (AIx) and pulse wave velocity (PWV) increased by 2.73% (95% CI: 1.89%, 3.57%) and 0.56% (95% CI: 0.22%, 0.89%), and flow-mediated dilation (FMD) decreased by 0.17% (95% CI: - 0.33%, - 0.00%). For each 10 µg/m³ increment in long-term PM_2.5 exposure, FMD decreased by 0.99% (95% CI: - 1.41%, - 0.57%). The associations between remaining pollutants and outcomes were not statistically significant. The effect of short-term PM_2.5 exposure on FMD change was stronger in population with younger age, lower female proportion, higher mean body mass index and higher PM_2.5 exposure. Cardiac or vasoactive medication might attenuate this effect. Our study provides evidence that PM_2.5 exposure had adverse impact on vascular endothelial function, indicating the importance of air quality improvement for early CVD prevention.

The role of short-term air pollution and temperature on arterial stiffness in a longitudinal closed cohort of elderly individuals

BACKGROUND/AIMS

Our study adds to the sparse literature that examines whether arterial stiffness, related to cardiovascular risk, increases with exposure to air pollution. We assessed the associations between spatiotemporally resolved air pollutants and vascular and hemodynamic parameters in an elderly population-based in Eastern Massachusetts.

METHODS

Among 397 men living in Eastern Massachusetts between 2007 and 2013, we utilized time-varying linear mixed-effects regressions to examine associations between central augmentation index (%) and central pulse pressure (mmHg) and short-term (0-7 days) exposure to air pollution concentrations (fine particulate matter (PM2.5), nitrogen dioxide (NO2), ozone (O3)), and temperature adjusted for known cardiovascular risk factors. Central augmentation index (AIx) and pulse pressure (AP) were measured at each visit using radial artery applanation tonometry for pulse wave analysis. Each air pollutant and temperature were geocoded to the participant's residential address using validated ensemble and hybrid exposure models and gridMET predictions.

RESULTS

We found consistent results that higher short-term PM2.5 concentrations (0-7 day moving averages) were associated with significantly higher measures of arterial stiffness. Each 4.52 μg/m3 interquartile range (IQR) increase in daily PM2.5 for a 3-day moving average was associated with a 0.63% (95% confidence interval (CI): 0.11, 1.15) increase in AIx and a 1.65 mmHg (95% CI: 0.42, 2.88) increase in pulse pressure. Furthermore, each 3.83 μg/m3 IQR increase in daily PM2.5 for a 7-day moving average was associated with a 0.57% (95% CI: -0.01, 1.14) increase in AIx and a 1.91 mmHg (95% CI: 0.54, 3.28) increase in pulse pressure. Smaller increases in AIx and AP were observed for the other short-term moving averages of PM2.5 exposure apart from days zero and five for AIx. We found no clear association between O3, NO2, temperature, and the outcomes.

CONCLUSIONS

Short-term PM2.5 exposure was associated with markers of arterial stiffness and central hemodynamics.

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.

Glucose Metabolic Disorders Enhance Vascular Dysfunction Triggered by Particulate Air Pollution: a Panel Study

BACKGROUND

Vascular dysfunction is a biological pathway whereby particulate matter (PM) exerts deleterious cardiovascular effects. The effects of ambient PM on vascular function in prediabetic individuals are unclear.

METHODS

A panel study recruited 112 Beijing residents with and without prediabetes. Multiple vascular function indices were measured up to 7 times. The associations between vascular function indices and short-term exposure to ambient PM, including fine particulate matter (PM_2.5), ultrafine particles, accumulation mode particles, and black carbon, and the modification of these associations by glucose metabolic status were examined using linear mixed-effects models.

RESULTS

Increases in brachial artery pulse pressure, central aortic pulse pressure, and ejection duration, and decreases in subendocardial viability ratio and reactive hyperemia index were significantly associated with at least one PM pollutant in all participants, indicating increased vascular dysfunction. For example, for an interquartile range increment in 5-day moving average ultrafine particles, brachial artery pulse pressure, and central aortic pulse pressure increased 5.4% (0.8%-10.4%) and 6.2% (1.2%-11.5%), respectively. Additionally, PM-associated changes in vascular function differed according to glucose metabolic status. Among participants with high fasting blood glucose levels (≥6.1 mmol/L), PM exposure was significantly associated with increased brachial artery systolic blood pressure, central aortic systolic blood pressure, brachial artery pulse pressure, central aortic pulse pressure, and augmentation pressure normalized to a heart rate of 75 bpm and decreased subendocardial viability ratio and reactive hyperemia index. Weaker or null associations were observed in the low-fasting blood glucose group.

CONCLUSIONS

Glucose metabolic disorders may exacerbate vascular dysfunction associated with short-term ambient PM exposure.

Acute Cardiovascular Effects of Hydrotreated Vegetable Oil Exhaust

Ambient air pollution is recognized as a key risk factor for cardiovascular morbidity and mortality contributing to the global disease burden. The use of renewable diesel fuels, such as hydrotreated vegetable oil (HVO), have increased in recent years and its impact on human health are not completely known. The present study investigated changes in cardiovascular tone in response to exposure to diluted HVO exhaust. The study participants, 19 healthy volunteers, were exposed in a chamber on four separate occasions for 3 h and in a randomized order to: (1) HVO exhaust from a wheel loader without exhaust aftertreatment, (2) HVO exhaust from a wheel loader with an aftertreatment system, (3) clean air enriched with dry NaCl salt particles, and (4) clean air. Synchronized electrocardiogram (ECG) and photoplethysmogram (PPG) signals were recorded throughout the exposure sessions. Pulse decomposition analysis (PDA) was applied to characterize PPG pulse morphology, and heart rate variability (HRV) indexes as well as pulse transit time (PTT) indexes were computed. Relative changes of PDA features, HRV features and PTT features at 1, 2, and 3 h after onset of the exposure was obtained for each participant and exposure session. The PDA index A₁₃, reflecting vascular compliance, increased significantly in both HVO exposure sessions but not in the clean air or NaCl exposure sessions. However, the individual variation was large and the differences between exposure sessions were not statistically significant.

Solar Activity Is Associated With Diastolic and Systolic Blood Pressure in Elderly Adults

Background

Since solar activity and related geomagnetic disturbances modulate autonomic nervous system activity, we hypothesized that these events would be associated with blood pressure (BP).

Methods and Results

We studied 675 elderly men from the Normative Aging Study (Boston, MA) with 1949 BP measurements between 2000 and 2017. Mixed‐effects regression models were used to investigate the association of average 1‐day (ie, day of BP measurement) to 28‐day interplanetary magnetic field intensity, sunspot number, and a dichotomized measure of global geomagnetic activity (K_p index) in 4‐day increments with diastolic and systolic BP. We adjusted for meteorological conditions and other covariates associated with BP, and in additional models adjusted for ambient air pollutants (particulate matter with an aerodynamic diameter ≤2.5 µm, black carbon, and particle number) and ambient particle radioactivity. There were positive associations between interplanetary magnetic field, sunspot number, and K_p index and BP that were greatest with these exposures averaged over 16 through 28 days before BP measurement. An interquartile range increase of 16‐day interplanetary magnetic field and sunspot number and higher K_p index were associated with a 2.5 (95% CI, 1.7‒3.2), 2.8 (95% CI, 2.1‒3.4), and 1.7 (95% CI, 0.8‒2.5) mm Hg increase, respectively, for diastolic BP as well as a 2.1 (95% CI, 0.7‒3.6), 2.7 (95% CI, 1.5‒4.0), and 0.4 (95% CI, −1.2 to 2.1) mm Hg increase, respectively, for systolic BP. Associations remained after adjustment for ambient air pollutants and ambient particle radioactivity.

Conclusions

Solar activity and solar‐driven geomagnetic disturbances were positively associated with BP, suggesting that these natural phenomena influence BP in elderly men.

Arterial stiffness and carotid distensibility following acute formaldehyde exposure in female adults

Formaldehyde (FA) is a ubiquitous organic preservative used in several industries and represents an occupational health hazard. Short-term exposure to FA can increase oxidative stress and cause a decrease in conduit vessel function. These decrements in vascular function may extend to the arterial architecture, predisposing individuals to increased risk of cardiovascular disease. The purpose of this study was to investigate the impact of an acute 90-minute FA exposure period (259 ± 95 ppb) on indices of arterial architecture. Arterial stiffness and carotid distensibility as determined by central pressures, augmentation index (AIx), and carotid-femoral pulse wave velocity (cfPWV) (n=13F, 24 ± 1 year) as well as carotid stiffness and intima media thickness (IMT) (n = 9F, 23 ± 1 year) were assessed prior to (Pre-FA) and immediately following (Post-FA) exposure to FA in human cadaver dissection laboratories. Central pressures and cfPWV (Pre-FA: 5.2 ± 0.8 m.s^-1, Post-FA: 5.2 ± 1.1 m s^-1) were unchanged by acute FA exposure (p > 0.05). Carotid stiffness parameters and distension were unchanged by acute FA exposure (p > 0.05), although distensibility (Pre-FA: 33.9 ± 10.5[10-3*kPa^-1], Post-FA: 25.9 ± 5.5[10-3*kPa-1], p < 0.05), and IMT (Pre-FA: 0.42 ± 0.05 mm, Post-FA: 0.51 ± 0.11 mm, p < 0.05) decreased and increased, respectively. Individual Pre- to Post-FA changes in these markers of arterial architecture did not correlate with levels of FA exposure ([FA]: 20-473 ppb) (p > 0.05). Our group previously found vascular function decrements following acute FA exposure in human cadaver laboratories; here we found that carotid distensibility and intima media thickness are altered following FA exposure.

Short- and Long-Term Exposure to Particulate Matter and Pulse Wave Velocity

Background

In hemodialysis patients, brachial-ankle pulse wave velocity (baPWV) levels are affected by particulate matter with an aerodynamic diameter of 10 μm or less (PM₁₀). We conducted this study to determine whether there is an association between short- and long-term PM₁₀ exposure and baPWV in apparently healthy adults aged 40 years and older.

Methods

A total of 1,628 subjects who underwent health examinations between 2006 and 2009 were included in the study. On the basis of the day of medical screening, the 1–3-day and 365-day moving averages of PM₁₀ concentrations were used to evaluate the association between short- and long-term exposure to PM₁₀ and high baPWV (≥the third quartile of baPWV, 1,534 cm/s) using logistic regression models. Additional subgroup analyses were conducted according to age, sex, obesity (body mass index ≥25.0 kg/m²), and comorbidities such as metabolic syndrome.

Results

No statistically significant associations were identified between short-term and long-term exposure to PM₁₀ and baPWV in any of the subjects and subgroups. A 10-μg/m³ increase in the 2-day moving average of PM₁₀ exposure was marginally associated with high baPWV in non-obese subjects (odds ratio, 1.059; P=0.058). This association in non-obese subjects was significantly different from that in obese subjects (P=0.038).

Conclusion

This study did not show statistically significant associations between short-term and long-term exposure to PM₁₀ and baPWV in apparently healthy subjects. With short-term exposure to PM₁₀, non-obese subjects showed a marginally unfavorable association with baPWV. Further studies are necessary to validate and elucidate the mechanism underlying the effect of PM₁₀ on baPWV.

Calibration Method for Particulate Matter Low-Cost Sensors Used in Ambient Air Quality Monitoring and Research

Over the last decade, manufacturers have come forth with cost-effective sensors for measuring ambient and indoor particulate matter concentration. What these sensors make up for in cost efficiency, they lack in reliability of the measured data due to their sensitivities to temperature and relative humidity. These weaknesses are especially evident when it comes to portable or mobile measurement setups. In recent years many studies have been conducted to assess the possibilities and limitations of these sensors, however mostly restricted to stationary measurements. This study reviews the published literature until 2020 on cost-effective sensors, summarizes the recommendations of experts in the field based on their experiences, and outlines the quantile-mapping methodology to calibrate low-cost sensors in mobile applications. Compared to the commonly used linear regression method, quantile mapping retains the spatial characteristics of the measurements, although a common correction factor cannot be determined. We conclude that quantile mapping can be a useful calibration methodology for mobile measurements given a well-elaborated measurement plan assures providing the necessary data.

Residential proximity to greenness mitigates the hemodynamic effects of ambient air pollution

Residential proximity to greenness is associated with a lower risk of cardiovascular disease (CVD) and all-cause mortality. However, it is unclear whether the beneficial effects of greenness are linked to a reduction in the effects of ambient air pollutants. We measured arterial stiffness in 73 participants with moderate to high CVD risk. Average levels of ambient PM2.5 and ozone were calculated from local monitoring stations. Residential greenness was estimated using satellite-derived normalized difference vegetation index (NDVI) for a 200-m and 1-km radius around each participant's home. Participants were 51% female, average age of 52 yr, and 79% had diagnosed hypertension. In multiple linear regression models, residential NDVI was negatively associated with augmentation index (-3.8% per 0.1 NDVI). Ambient levels of PM2.5 [per interquartile range (IQR) of 6.9 μg/m3] were positively associated with augmentation pressure (3.1 mmHg), pulse pressure (5.9 mmHg), and aortic systolic pressure (8.1 mmHg). Ozone (per IQR of 0.03 ppm) was positively associated with augmentation index (5.5%), augmentation pressure (3.1 mmHg), and aortic systolic pressure (10 mmHg). In areas of low greenness, both PM2.5 and ozone were positively associated with pulse pressure. Additionally, ozone was positively associated with augmentation pressure and systolic blood pressure. However, in areas of high greenness, there was no significant association between indices of arterial stiffness with either PM2.5 or ozone. Residential proximity to greenness is associated with lower values of arterial stiffness. Residential greenness may mitigate the adverse effects of PM2.5 and ozone on arterial stiffness.NEW & NOTEWORTHY Previous studies have linked proximity to green spaces with lower cardiovascular disease risk. However, the mechanisms underlying the salutary effects of green areas are not known. In our study of participants at risk of cardiovascular disease, we found that arterial stiffness was positively associated with short-term exposure to PM2.5, PM10, and ozone and inversely associated with greenness. The association between pollution and arterial stiffness was attenuated in areas of high greenness, suggesting that living green neighborhoods can lessen the adverse cardiovascular effects of air pollution.

Commuter exposure to particulate matter in urban public transportation of Xi'an, China

PURPOSE

To investigate commuter exposures to particulate matter (PM) in urban public transportation buses and subways, PM concentrations were simultaneously monitored for these two modes, over the same routes, in Xi'an, China.

METHODS

The microenvironment variabilities in each stage of the total trip were analyzed. Exposure doses for the different commute processes were estimated based on the heart rates of volunteers. Experimental measurements were taken during peak traffic hours in July and October (summer and autumn) on two typical commute routes, for a total of 36 trips. One-way ANOVA was used to analyze the effects of different variables on commuter exposures.

RESULTS

On the same route, the average PM exposure concentration of bus commuters was higher than those of subway commuters. For example, on Route 1 in the case study, the average PM10, PM2.5, and PM1 exposure concentrations of bus commuters were 71.6%, 19%, and 10.4% higher, respectively, than those of subway commuters. In the ground transportation mode, the exposure concentration of bus commuters was affected by the type of vehicle. Particle concentrations were significantly higher inside compressed natural gas (CNG) buses, than in pure electric (PE) buses, and in summer, the PM10 concentration in a CNG bus was 4.3 times higher than that in a PE bus. In a CNG bus, commuters in the back door area suffered the highest PM10 exposure concentration (179.6 μg/m3), followed by those in the rear of the carriage (142.8 μg/m3), and then those in the front door area (105.4 μg/m3).

CONCLUSION

Commuters' avoidance of ground traffic sources, effective ventilation systems in buses, and the use of screens in subway systems can all help to lower the PM exposure of commuters. For all the modes of transportation in our study, the hottest spots for PM exposure appeared in the period when commuters were waiting for transit vehicles to arrive.

Air pollution and cardiovascular disease: car sick

The cardiovascular effects of inhaled particle matter (PM) are responsible for a substantial morbidity and mortality attributed to air pollution. Ultrafine particles, like those in diesel exhaust emissions, are a major source of nanoparticles in urban environments, and it is these particles that have the capacity to induce the most significant health effects. Research has shown that diesel exhaust exposure can have many detrimental effects on the cardiovascular system both acutely and chronically. This review provides an overview of the cardiovascular effects on PM in air pollution, with an emphasis on ultrafine particles in vehicle exhaust. We consider the biological mechanisms underlying these cardiovascular effects of PM and postulate that cardiovascular dysfunction may be implicated in the effects of PM in other organ systems. The employment of multiple strategies to tackle air pollution, and especially ultrafine particles from vehicles, is likely to be accompanied by improvements in cardiovascular health.

Acute Effects of High-Level PM2.5 Exposure on Central Blood Pressure

Central aortic blood pressure (BP) has been increasingly recognized as having a closer relationship with cardiovascular risks than peripheral BP. However, the effects of particulate matter pollution on central aortic BP have not been clearly demonstrated. In this study, we assessed the association between short-term ambient fine particulate matter (with an aerodynamic diameter ≤2.5 μm; PM_2.5) exposure and central aortic BP in a Chinese community-based population. A total of 4715 visits were in our final analysis, including 2151 visits at the baseline and 2564 visits at the follow-up. Central aortic systolic BP (cSBP) was measured noninvasively using the method of radial artery tonometry with Omron HEM-9000AI machine. Data from air pollution monitoring stations were used to estimate daily PM_2.5 exposure. Generalized additive mixed models with clinical and meteorologic covariates adjusted were used to examine the association between PM_2.5 exposure and cSBP. The relationships between PM_2.5 exposure and cSBP were nonlinear, and significant increments of cSBP were observed when the PM_2.5 exposure concentration was above 100 μg/cm³. An interquartile range increase (80.25 μg/m³) in daily PM_2.5 on the day of cSBP measurement (lag 0 day) was associated with 2.54 mm Hg (95% CI, 0.92-4.16) elevation in cSBP. The associations of PM_2.5 with cSBP were not modified by age, sex, body mass index, medications, and comorbid diseases except for cardiovascular disease. Our findings demonstrated that short-term exposure to high concentration of ambient PM_2.5 above 100 μg/cm³ was associated with significant increases in central aortic BP in a Chinese community-based population.

Associations Between Sub-Clinical Markers of Cardiometabolic Risk and Exposure to Residential Indoor Air Pollutants in Healthy Adults in Perth, Western Australia: A Study Protocol

BACKGROUND

A growing body of epidemiological and clinical evidence has implicated air pollution as an emerging risk factor for cardiometabolic disease. Whilst individuals spend up to two-thirds of daily time in their domestic residential environment, very few studies have been designed to objectively measure the sub-clinical markers of cardiometabolic risk with exposure to domestic indoor air pollutants. This cross-sectional study aims to investigate associations between the components of domestic indoor air quality and selected sub-clinical cardiometabolic risk factors in a cohort of healthy adults living in Perth, Western Australia.

METHODS

One hundred and eleven non-smoking adults (65% female) living in non-smoking households who were aged between 35-69 years were recruited for the project. Study subjects were invited to participate in all sections of the study, which included: Domestic indoor air monitoring along with the concurrent 24 h ambulatory monitoring of peripheral and central blood pressure and measures of central hemodynamic indices, standardized questionnaires on aspects relating to current health status and the domestic environment, a 24 h time-activity diary during the monitoring period, and clinic-based health assessment involving collection of blood and urine biomarkers for lipid and glucose profiles, as well as measures of renal function and an analysis of central pulse wave and pulse wave velocity.

RESULTS

This study provides a standardized approach to the study of sub-clinical cardiometabolic health effects that are related to the exposure to indoor air pollution.

CONCLUSION

The findings of this study may provide direction for future research that will further contribute to our understanding of the relationship that exists between indoor air pollution and sub-clinical markers of cardiometabolic risk.

Short-term exposure to ambient air pollution and circulating biomarkers of endothelial cell activation: The Framingham Heart Study

BACKGROUND

Short-term exposure to air pollution has been associated with cardiovascular events, potentially by promoting endothelial cell activation and inflammation. A few large-scale studies have examined the associations and have had mixed results.

METHODS

We included 3820 non-current smoking participants (mean age 56 years, 54% women) from the Framingham Offspring cohort examinations 7 (1998-2001) and 8 (2005-2008), and Third Generation cohort examination 1 (2002-2005), who lived within 50 km of a central monitoring station. We calculated the 1- to 7-day moving averages of fine particulate matter (PM_2.5), black carbon (BC), sulfate (SO₄^2-), nitrogen oxides (NO_x), and ozone before examination visits. We used linear mixed effect models for P-selectin, monocyte chemoattractant protein 1 (MCP-1), intercellular adhesion molecule 1, lipoprotein-associated phospholipase A2 activity and mass, and osteoprotegerin that were measured up to twice, and linear regression models for CD40 ligand and interleukin-18 that were measured once, adjusting for demographics, life style and clinical factors, socioeconomic position, time, and meteorology.

RESULTS

We found negative associations of PM_2.5 and BC with P-selectin, of ozone with MCP-1, and of SO₄^2- and NO_x with osteoprotegerin. At the 5-day moving average, a 5 µg/m³ higher PM_2.5 was associated with 1.6% (95% CI: - 2.8, - 0.3) lower levels of P-selectin; a 10 ppb higher ozone was associated with 1.7% (95% CI: - 3.2, - 0.1) lower levels of MCP-1; and a 20 ppb higher NO_x was associated with 2.0% (95% CI: - 3.6, - 0.4) lower levels of osteoprotegerin.

CONCLUSIONS

We did not find evidence of positive associations between short-term air pollution exposure and endothelial cell activation. On the contrary, short-term exposure to higher levels of ambient pollutants were associated with lower levels of P-selectin, MCP-1, and osteoprotegerin in the Framingham Heart Study.

Responses of healthy young males to fine-particle exposure are modified by exercise habits: a panel study

BACKGROUND

Aerobic exercise benefits health but increases inhalation of fine particles (PM2.5) in ambient air. Acute cardiopulmonary responses to PM2.5 exposure in individuals with different exercise habits, especially in areas with severe air pollution, are not well understood.

METHODS

To examine acute cardiopulmonary responses to PM2.5 exposure modified by exercise habits, a panel of 20 healthy non-smoking male subjects, recruited in Beijing, China, completed seven visits. The exercise frequency per week and preferred exercise place were recorded using a baseline questionnaire to describe exercise habits. Fractional exhaled nitric oxide (FeNO), cytokines in exhaled breath condensate, blood pressure, and pulse-wave analysis (PWA) indices were measured during each visit as biomarkers of acute cardiopulmonary responses. The hourly average mass concentration of PM2.5 and black carbon (BC), and the number concentrations of ultrafine particles (UFP) and accumulation mode particles (AMP) were monitored throughout the follow-up period at an outdoor fixed monitoring station beginning 14 days prior to each visit. Linear mixed-effects models were used to evaluate the associations between acute changes in biomarker levels and exposure to PM2.5 and its constituents. The primary aim was to assess the modification of long-term exercise habits on these associations.

RESULTS

FeNO concentration, systolic blood pressure, ejection duration, aortic augmentation pressure, and aortic pressure index were positively associated with exposure to PM2.5 and its constituents. However, no associations with cytokine levels or diastolic blood pressure were observed. In a stratified analysis, we found that acute cardiopulmonary responses were modified by exercise habit. Specifically, the interquartile ranges (IQR) of increases in the 6-12-h moving average (MA) PM2.5 and AMP exposure were associated with 19-21% and 24-26% increases in FeNO, respectively, in subjects with high exercise frequency; these associations were significantly stronger than those in subjects with low exercise frequency. An IQR increase in 3-11-d MA AMP exposure was associated with a 10-26% increase in aortic augmentation pressure in subjects with low exercise frequency; this association was significantly stronger than that in subjects with high exercise frequency. An IQR increase in 9-13-d MA UFP exposure was associated with a 13-17% increase in aortic augmentation pressure in subjects who preferred outdoor exercise; this association was stronger than that in subjects who preferred indoor exercise.

CONCLUSIONS

In highly polluted areas, frequent exercise might protect against PM2.5-associated arterial stiffness but exacerbate airway inflammation.

Long- and short-term air pollution exposure and measures of arterial stiffness in the Framingham Heart Study

BACKGROUND

Studies of air pollution exposure and arterial stiffness have reported inconsistent results and large studies employing the reference standard of arterial stiffness, carotid-femoral pulse-wave velocity (CFPWV), have not been conducted.

AIM

To study long-term exposure to ambient fine particles (PM2.5), proximity to roadway, and short-term air pollution exposures in relation to multiple measures of arterial stiffness in the Framingham Heart Study.

METHODS

We assessed central arterial stiffness using CFPWV, forward pressure wave amplitude, mean arterial pressure and augmentation index. We investigated long-and short-term air pollution exposure associations with arterial stiffness with linear regressions using long-term residential PM2.5 (2003 average from a spatiotemporal model using satellite data) and proximity to roadway in addition to short-term averages of PM2.5, black carbon, particle number, sulfate, nitrogen oxides, and ozone from stationary monitors.

RESULTS

We examined 5842 participants (mean age 51 ± 16, 54% women). Living closer to a major roadway was associated with higher arterial stiffness (0.11 m/s higher CFPWV [95% CI: 0.01, 0.22] living <50 m vs 400 ≤ 1000 m). We did not observe association between arterial stiffness measures and long-term PM2.5 or short-term levels of PM2.5, particle number, sulfate or ozone. Higher levels of black carbon and nitrogen oxides in the previous days were unexpectedly associated with lower arterial stiffness.

CONCLUSIONS

Long-term exposure to PM2.5 was not associated with arterial stiffness but positive associations with living close to a major road may suggest that pollutant mixtures very nearby major roads, rather than PM2.5, may affect arterial stiffness. Furthermore, short-term air pollution exposures were not associated with higher arterial stiffness.

Longitudinal Analysis of Long-Term Air Pollution Levels and Blood Pressure: A Cautionary Tale from the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Air pollution exposures are hypothesized to impact blood pressure, yet few longitudinal studies exist, their findings are inconsistent, and different adjustments have been made for potentially distinct confounding by calendar time and age.

OBJECTIVE

We aimed to investigate the associations of long- and short-term [Formula: see text] and [Formula: see text] concentrations with systolic and diastolic blood pressures and incident hypertension while also accounting for potential confounding by age and time.

METHODS

Between 2000 and 2012, Multi-Ethnic Study of Atherosclerosis participants were measured for systolic and diastolic blood pressure at five exams. We estimated annual average and daily [Formula: see text] and [Formula: see text] concentrations for 6,569 participants using spatiotemporal models and measurements, respectively. Associations of exposures with blood pressure corrected for medication were studied using mixed-effects models. Incident hypertension was examined with Cox regression. We adjusted all models for sex, race/ethnicity, socioeconomic status, smoking, physical activity, diet, season, and site. We compared associations from models adjusting for time-varying age with those that adjusted for both time-varying age and calendar time.

RESULTS

We observed decreases in pollution and blood pressures (adjusted for age and medication) over time. Strong, positive associations of long- and short-term exposures with blood pressure were found only in models with adjustment for time-varying age but not adjustment for both time-varying age and calendar time. For example, [Formula: see text] higher annual average [Formula: see text] concentrations were associated with 2.7 (95% CI: 1.5, 4.0) and [Formula: see text] (95% CI: [Formula: see text] 1.0) mmHg in systolic blood pressure with and without additional adjustment for time, respectively. Associations with incident hypertension were similarly weakened by additional adjustment for time. Sensitivity analyses indicated that air pollution did not likely cause the temporal trends in blood pressure.

CONCLUSIONS

In contrast to experimental evidence, we found no associations between long- or short-term exposures to air pollution and blood pressure after accounting for both time-varying age and calendar time. This research suggests that careful consideration of both age and time is needed in longitudinal studies with trending exposures. https://doi.org/10.1289/EHP2966.

Air Pollution and Cardiovascular Disease: A Focus on Vulnerable Populations Worldwide

Purpose of review

Certain subgroups defined by sociodemographics (race/ethnicity, age, sex and socioeconomic status [SES]), geographic location (rural vs. urban), comorbid conditions and country economic conditions (developed vs. developing) may disproportionately suffer the adverse cardiovascular effects of exposure to ambient air pollution. Yet, previous reviews have had a broad focus on the general population without consideration of these potentially vulnerable populations.

Recent findings

Over the past decade, a wealth of epidemiologic studies have linked air pollutants including particulate matter, oxides of nitrogen, and carbon monoxide to cardiovascular disease (CVD) risk factors, subclinical CVD, clinical cardiovascular outcomes and cardiovascular mortality in certain susceptible populations. Highest risk for poor CVD outcomes from air pollution exist in racial/ethnic minorities, especially in blacks compared to whites in the U.S, those at low SES, elderly populations, women, those with certain comorbid conditions and developing countries compared to developed countries. However, findings are less consistent for urban compared to rural populations.

Summary

Vulnerable subgroups including racial/ethnic minorities, women, the elderly, smokers, diabetics and those with prior heart disease had higher risk for adverse cardiovascular outcomes from exposure to air pollution. There is limited data from developing countries where concentrations of air pollutants are more extreme and cardiovascular event rates are higher than that of developed countries. Further epidemiologic studies are needed to understand and address the marked disparities in CVD risk conferred by air pollution globally, particularly among these vulnerable subgroups.

Long-term effects of air pollution on ankle-brachial index

BACKGROUND

Ankle-brachial index (ABI) has been linked to the risk of cardiovascular events. However, the association between long-term exposure to air pollution and abnormal ABI has not been fully investigated.

METHODS

This cross-sectional study involved 4544 participants from the KORA Study (2004-2008) in the region of Augsburg, Germany. Participants' residential annual mean concentrations of particulate matter (PM) and nitrogen dioxide (NO₂) were predicted with land-use regression models, and the traffic information was collected from geographic information systems. We applied multinomial logistic regression models to assess the effects of air pollution on the prevalence of low and high ABI, and quantile regression models to explore the non-monotonic relationship between air pollution and ABI. We also examined effect modification by individual characteristics.

RESULTS

Long-term exposure to PM with an aerodynamic diameter ≤ 10 μm (PM₁₀) and ≤ 2.5 μm (PM_2.5) was significantly associated with a higher prevalence of low ABI, with the respective odds ratios (ORs) of 1.82 (95%CI: 1.11-2.97) and 1.59 (95%CI: 1.01-2.51) for a 5th to 95th percentile increment in pollutants. Positive associations with the prevalence of high ABI were observed for PM (e.g., PM₁₀: OR = 1.63, 95%CI: 1.07-2.50) and NO₂ (OR = 1.84, 95%CI: 1.15-2.94). Quantile regression analyses revealed similar non-monotonic results. The effects of air pollution on having abnormal ABI were stronger in physically inactive, hypertensive, or non-diabetic participants.

CONCLUSIONS

Long-term exposure to PM and NO₂ was associated with a higher prevalence of both low and high ABI, indicating the adverse effects of air pollution on atherosclerosis and arterial stiffness in the lower extremities.

The effects of facemasks on airway inflammation and endothelial dysfunction in healthy young adults: a double-blind, randomized, controlled crossover study

Background

Facemasks are increasingly worn during air pollution episodes in China, but their protective effects are poorly understood. We aimed to evaluate the filtration efficiencies of N95 facemasks and the cardiopulmonary benefits associated with wearing facemasks during episodes of pollution.

Results

We measured the filtration efficiencies of particles in ambient air of six types of N95 facemasks with a manikin headform. The most effective one was used in a double-blind, randomized, controlled crossover study, involving 15 healthy young adults, conducted during 2 days of severe pollution in Beijing, China. Subjects were asked to walk along a busy-traffic road for 2 h wearing authentic or sham N95 facemasks. Clinical tests were performed four times to determine changes in the levels of biomarkers of airway inflammation, endothelial dysfunction, and oxidative stress within 24 h after exposure.

The facemasks removed 48–75% of number concentrations of ambient air particles between 5.6 and 560 nm in diameter. After adjustments for multiple comparison, the exhaled nitric oxide level and the levels of interleukin-1α, interleukin-1β, and interleukin-6 in exhaled breath condensate increased significantly in all subjects; however, the increases in those wearing authentic facemasks were statistically significantly lower than in the sham group. No significant between-group difference was evident in the urinary creatinine-corrected malondialdehyde level. In arterial stiffness indicators, the ejection duration of subjects wearing authentic facemasks was higher after exposure compared to the sham group; no significant between-group difference was found in augmentation pressure or the augmentation index.

Conclusions

In young healthy adults, N95 facemasks partially reduced acute particle-associated airway inflammation, but neither systemic oxidative stress nor endothelial dysfunction improved significantly. The clinical significance of these findings long-term remains to be determined.

Trial registration

The trial registration number (TRN) for this study is ChiCTR1800016099, which was retrospectively registered on May 11, 2018.

Electronic supplementary material

The online version of this article (10.1186/s12989-018-0266-0) contains supplementary material, which is available to authorized users.

Air Pollution and Successful Aging: Recent Evidence and New Perspectives

PURPOSE OF REVIEW

Worldwide demographic changes occurring in a relatively short period have led to a growing interest in the determinants of aging "successfully" and how to promote a healthier old age. As environmental exposures such as ambient air pollution are believed to play a role in the process of aging, they might represent one of the pathways turning potential successful agers to unsuccessful agers. We aimed to critically review the current epidemiological evidence of the associations between chronic exposure to ambient air pollution and several key determinants of unsuccessful aging and to identify specific populations of unsuccessful agers that are potentially more vulnerable to air pollution's health effects.

RECENT FINDINGS

Epidemiologic evidence supports the association between air pollution and increased risk for several major chronic diseases, cognitive impairment, frailty, and decreased longevity-all important determinants of unsuccessful aging-as well as evidence for higher vulnerability among frail populations. However, several methodological shortcomings, including possible publication bias, lack of use of an adequate indicator of unsuccessful aging, limitations in exposure assessment, and residual confounding particularly due to socioeconomic status, hinder inference of causal relationship at this stage. Future studies should use constructs such as frailty index to estimate successful aging, as well as integrate time activity patterns into the exposure assessment metric. Additionally, studies in low- and middle-income countries are needed.

Ambient air pollution, adipokines, and glucose homeostasis: The Framingham Heart Study

OBJECTIVE

To examine associations of proximity to major roadways, sustained exposure to fine particulate matter (PM2.5), and acute exposure to ambient air pollutants with adipokines and measures of glucose homeostasis among participants living in the northeastern United States.

METHODS

We included 5958 participants from the Framingham Offspring cohort examination cycle 7 (1998-2001) and 8 (2005-2008) and Third Generation cohort examination cycle 1 (2002-2005) and 2 (2008-2011), who did not have type 2 diabetes at the time of examination visit. We calculated 2003 annual average PM2.5 at participants' home address, residential distance to the nearest major roadway, and daily PM2.5, black carbon (BC), sulfate, nitrogen oxides (NOx), and ozone concentrations. We used linear mixed effects models for fasting glucose, insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) which were measured up to twice, and used linear regression models for adiponectin, resistin, leptin, and hemoglobin A1c (HbA1c) which were measured only once, adjusting for demographics, socioeconomic position, lifestyle, time, and seasonality.

RESULTS

The mean age was 51years and 55% were women. Participants who lived 64m (25th percentile) from a major roadway had 0.28% (95% CI: 0.05%, 0.51%) higher fasting plasma glucose than participants who lived 413m (75th percentile) away, and the association appeared to be driven by participants who lived within 50m from a major roadway. Higher exposures to 3- to 7-day moving averages of BC and NOx were associated with higher glucose whereas the associations for ozone were negative. The associations otherwise were generally null and did not differ by median age, sex, educational attainment, obesity status, or prediabetes status.

CONCLUSIONS

Living closer to a major roadway or acute exposure to traffic-related air pollutants were associated with dysregulated glucose homeostasis but not with adipokines among participants from the Framingham Offspring and Third Generation cohorts.

Ozone exposure is associated with acute changes in inflammation, fibrinolysis, and endothelial cell function in coronary artery disease patients

BACKGROUND

Air pollution is a major risk factor for cardiovascular disease, of which ozone is a major contributor. Several studies have found associations between ozone and cardiovascular morbidity, but the results have been inconclusive. We investigated associations between ozone and changes across biological pathways associated with cardiovascular disease.

METHODS

Using a panel study design, 13 participants with coronary artery disease were assessed for markers of systemic inflammation, heart rate variability and repolarization, lipids, blood pressure, and endothelial function. Daily measurements of ozone and particulate matter (PM2.5) were obtained from central monitoring stations. Single (ozone) and two-pollutant (ozone and PM2.5) models were used to assess percent changes in measurements per interquartile ranges of pollutants.

RESULTS

Per interquartile increase in ozone, changes in tissue plasminogen factor (6.6%, 95% confidence intervals (CI) = 0.4, 13.2), plasminogen activator inhibitor-1 (40.5%, 95% CI = 8.7, 81.6), neutrophils (8.7% 95% CI = 1.5, 16.4), monocytes (10.2%, 95% CI = 1.0, 20.1), interleukin-6 (15.9%, 95% CI = 3.6, 29.6), large-artery elasticity index (-19.5%, 95% CI = -34.0, -1.7), and the baseline diameter of the brachial artery (-2.5%, 95% CI = -5.0, 0.1) were observed. These associations were robust in the two-pollutant model.

CONCLUSIONS

We observed alterations across several pathways associated with cardiovascular disease in 13 coronary artery disease patients following ozone exposures, independent of PM2.5. The results support the biological plausibility of ozone-induced cardiovascular effects. The effects were found at concentrations below the EPA National Ambient Air Quality Standards for both ozone and PM2.5.

Extreme levels of ambient air pollution adversely impact cardiac and central aortic hemodynamics: the AIRCMD-China study

Ambient air pollution is an independent risk factor for cardiovascular diseases. However, the underlying mechanisms have yet to be fully elucidated. We performed a panel study on 65 nonsmoking patients with metabolic syndrome, with four repeated clinical visits between 2012 and 2013 in Beijing, China. Cardiac and central aortic hemodynamic parameters were measured by pulse wave analyses as subendocardial viability ratio, ejection duration, and central aortic pressure. We also calculated rate-pressure product parameter and collected peripheral blood for analyses. High levels of ambient particulate matter with diameter ≤10 and 2.5 μm (PM₁₀ and PM_2.5), black carbon, sulfur dioxide, and nitrogen dioxide were 121.3, 99.5, 6.5, 24.5, and 59.2 μg/m³, respectively. Short- to medium-term exposures to high levels of ambient air pollution adversely impacted central hemodynamics-derived surrogates of myocardial perfusion and oxygen demand. Each 10 μg/m³ increase in PM_2.5 was associated with significant decreases of 0.67% (95% confidence interval: -2.84, -0.22) in subendocardial viability ratio at moving average 35 days (MA35) and an increase of 0.31 in rate-pressure product (95% confidence interval: 0.03, 0.59) at MA5. In conclusion, our results suggest that impaired myocardial perfusion and increased myocardial oxygen demand may play importantly mechanistic roles in air pollution-attributed cardiovascular diseases.

Oxidative Stress and Cardiovascular Risk: Obesity, Diabetes, Smoking, and Pollution: Part 3 of a 3-Part Series

Oxidative stress occurs whenever the release of reactive oxygen species (ROS) exceeds endogenous antioxidant capacity. In this paper, we review the specific role of several cardiovascular risk factors in promoting oxidative stress: diabetes, obesity, smoking, and excessive pollution. Specifically, the risk of developing heart failure is higher in patients with diabetes or obesity, even with optimal medical treatment, and the increased release of ROS from cardiac mitochondria and other sources likely contributes to the development of cardiac dysfunction in this setting. Here, we explore the role of different ROS sources arising in obesity and diabetes, and the effect of excessive ROS production on the development of cardiac lipotoxicity. In parallel, contaminants in the air that we breathe pose a significant threat to human health. This paper provides an overview of cigarette smoke and urban air pollution, considering how their composition and biological effects have detrimental effects on cardiovascular health.

Is physical activity a modifier of the association between air pollution and arterial stiffness in older adults: The SAPALDIA cohort study

INTRODUCTION AND OBJECTIVES

Air pollution and insufficient physical activity have been associated with inflammation and oxidative stress, molecular mechanisms linked to arterial stiffness and cardiovascular disease. There are no studies on how physical activity modifies the association between air pollution and arterial stiffness. We examined whether the adverse cardiovascular effects of air pollution were modified by individual physical activity levels in 2823 adults aged 50-81 years from the well-characterized Swiss Cohort Study on Air Pollution and Lung and Heart Diseases (SAPALDIA).

METHODS

We assessed arterial stiffness as the brachial-ankle pulse wave velocity (baPWV [m/s]) with an oscillometric device. We administered a self-reported physical activity questionnaire to classify each subject's physical activity level. Air pollution exposure was estimated by the annual average individual home outdoor PM₁₀ and PM_2.5 (particulate matter <10μm and <2.5μm in diameter, respectively) and NO₂ (nitrogen dioxide) exposure estimated for the year preceding the survey. Exposure estimates for ultrafine particles calculated as particle number concentration (PNC) and lung deposited surface area (LDSA) were available for a subsample (N=1353). We used mixed effects logistic regression models to regress increased arterial stiffness (baPWV≥14.4m/s) on air pollution exposure and physical activity while adjusting for relevant confounders.

RESULTS

We found evidence that the association of air pollution exposure with baPWV was different between inactive and active participants. The probability of having increased baPWV was significantly higher with higher PM₁₀, PM_2.5, NO₂, PNC and LDSA exposure in inactive, but not in physically active participants. We found some evidence of an interaction between physical activity and ambient air pollution exposure for PM₁₀, PM_2.5 and NO₂ (p_interaction=0.06, 0.09, and 0.04, respectively), but not PNC and LDSA (p_interaction=0.32 and 0.35).

CONCLUSIONS

Our study provides some indication that physical activity may protect against the adverse vascular effects of air pollution in low pollution settings. Additional research in large prospective cohorts is needed to assess whether the observed effect modification translates to high pollution settings in mega-cities of middle and low-income countries.

A systematic review of arterial stiffness, wave reflection and air pollution

Arterial stiffening is associated with increased cardiovascular risk. Whether exposure to relatively high levels of air pollution is associated with arterial stiffening is unclear. We aimed to assess the association between exposure to major air pollutants and arterial stiffening. PubMed, SCOPUS and Web of Science databases (through 31 January 2017) were searched using a combination of terms related to exposure to gaseous [nitrogen dioxide (NO2), nitrogen oxides (NOx) and sulphur dioxide (SO2)] or particulate matter pollutants (PM2.5, PM10 and PM10-2.5), arterial stiffness (pulse wave velocity) and reflected waves (augmentation index, augmentation pressure). Pertinent information were extracted from selected studies. In this systematic review were included 8 studies with available data on air pollution and arterial stiffness/reflected waves parameters (8 studies explored the effects of exposure to particulate matter pollutants, 3 studies the effects of exposure to gaseous pollutants); seven of them reported increased arterial stiffness/reflected waves after exposure to air pollution (6 of 8 studies after particulate matter pollutants; 2 of 3 studies after gaseous pollutants). Arterial stiffness and reflected waves were increased in the majority of the studies after both short- and long-term exposure to air pollutants. In conclusion, available evidence supports an association of main air pollutants with increased arterial stiffness and reflected waves. This finding may have implications for population-based strategies for the reduction of arterial stiffness, a vascular biomarker and an intermediate endpoint for cardiovascular disease.

Impact of seasonality and air pollutants on carotid-femoral pulse wave velocity and wave reflection in hypertensive patients

Objective

The effects of seasonality on blood pressure (BP) and cardiovascular (CV) events are well established, while the influence of seasonality and other environmental factors on arterial stiffness and wave reflection has never been analyzed. This study evaluated whether seasonality (daily number of hours of light) and acute variations in outdoor temperature and air pollutants may affect carotid-femoral pulse wave velocity (PWV) and pressure augmentation.

Design and method

731 hypertensive patients (30–88 years, 417 treated) were enrolled in a cross-sectional study during a 5-year period. PWV, central BP, Augmentation Index (AIx) and Augmentation Pressure (AP) were measured in a temperature-controlled (22–24°C) room. Data of the local office of the National Climatic Data Observatory were used to estimate meteorological conditions and air pollutants (PM₁₀, O₃, CO, N₂O) exposure on the same day.

Results

PWV (mean value 8.5±1.8 m/s) was related to age (r = 0.467, p<0.001), body mass index (r = 0.132, p<0.001), central systolic (r = 0.414, p<0.001) and diastolic BP (r = 0.093, p = 0.013), daylight hours (r = -0.176, p<0.001), mean outdoor temperature (r = -0.082, p = 0.027), O₃ (r = -0.135, p<0.001), CO (r = 0.096, p = 0.012), N₂O (r = 0.087, p = 0.022). In multiple linear regression analysis, adjusted for confounders, PWV remained independently associated only with daylight hours (β = -0.170; 95% CI: -0.273 to -0.067, p = 0.001). No significant correlation was found between pressure augmentation and daylight hours, mean temperature or air pollutants. The relationship was stronger in untreated patients and women. Furthermore, a positive, independent association between O₃ levels and PWV emerged in untreated patients (β: 0.018; p = 0.029; CI: 0.002 to 0.034) and in women (β: 0.027; p = 0.004; CI: 0.009 to 0.045).

Conclusions

PWV showed a marked seasonality in hypertensive patients. Environmental O₃ levels may acutely reduce arterial stiffness in hypertensive women and in untreated patients.

Association of short-term exposure to fine particulate matter and nitrogen dioxide with acute cardiovascular effects

This study evaluated whether exposure to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) is associated with cardiovascular effects by examining a panel of 89 healthy subjects in Taipei, Taiwan. The subjects received two health examinations approximately 8months apart in 2013. Brachial-ankle pulse wave velocity (baPWV), a physiological indicator of arterial stiffness, and high-sensitivity C-reactive protein (hsCRP), a biomarker of vascular inflammations, were measured during each examination. Two exposure assessment methods were used for estimating the subjects' exposure to PM2.5 and NO2. The first method involved constructing daily land use regression (LUR) models according to measurements collected at ambient air quality monitoring stations. The second method required combining the LUR estimates with indoor monitoring data at the workplace of the subjects. Linear mixed models were used to examine the association between the exposure estimates and health outcomes. The results showed that a 10-μg/m(3) increase in PM2.5 concentration at a 1-day lag was associated with 2.1% (95% confidence interval: 0.7%-3.6%) and 2.4% (0.8%-4.0%) increases in baPWV based on the two exposure assessment methods, whereas no significant association was observed for NO2. The significant effects of PM2.5 remained in the two-pollutant models. By contrast, NO2, but not PM2.5, was significantly associated with increased hsCRP levels (16.0%-37.3% in single-pollutant models and 26.4%-44.6% in two-pollutant models, per 10-ppb increase in NO2). In conclusion, arterial stiffness might be more sensitive to short-term PM2.5 exposure than is inflammation.

Prenatal Air Pollution Exposure and Early Cardiovascular Phenotypes in Young Adults

Exposure to ambient air pollutants increases risk for adverse cardiovascular health outcomes in adults. We aimed to evaluate the contribution of prenatal air pollutant exposure to cardiovascular health, which has not been thoroughly evaluated. The Testing Responses on Youth (TROY) study consists of 768 college students recruited from the University of Southern California in 2007–2009. Participants attended one study visit during which blood pressure, heart rate and carotid artery arterial stiffness (CAS) and carotid artery intima-media thickness (CIMT) were assessed. Prenatal residential addresses were geocoded and used to assign prenatal and postnatal air pollutant exposure estimates using the U.S. Environmental Protection Agency’s Air Quality System (AQS) database. The associations between CAS, CIMT and air pollutants were assessed using linear regression analysis. Prenatal PM₁₀ and PM_2.5 exposures were associated with increased CAS. For example, a 2 SD increase in prenatal PM_2.5 was associated with CAS indices, including a 5% increase (β = 1.05, 95% CI 1.00–1.10) in carotid stiffness index beta, a 5% increase (β = 1.05, 95% CI 1.01–1.10) in Young’s elastic modulus and a 5% decrease (β = 0.95, 95% CI 0.91–0.99) in distensibility. Mutually adjusted models of pre- and postnatal PM_2.5 further suggested the prenatal exposure was most relevant exposure period for CAS. No associations were observed for CIMT. In conclusion, prenatal exposure to elevated air pollutants may increase carotid arterial stiffness in a young adult population of college students. Efforts aimed at limiting prenatal exposures are important public health goals.

Short-term fluctuations in personal black carbon exposure are associated with rapid changes in carotid arterial stiffening

BACKGROUND

Vascular changes may underpin the association between airborne black carbon (BC) and cardiovascular events. Accurate assessment of personal exposure is a major challenge in epidemiological research. BC concentrations are strongly related to time-activity patterns, which is particularly relevant when investigating short-term effects. We investigated associations between arterial stiffness and personal short-term BC exposure.

METHODS

This panel study included 54 healthy adults (92% women, mean age 40.7years). BC exposure was monitored individually with a micro-aethalometer during one workweek. Functional and structural properties of the carotid artery were examined ultrasonographically on two separate days. The effect of different short-term personal BC exposure windows (1, 2, 4, 6, 8, 24 and 48h before the ultrasound examination) on carotid artery stiffness was estimated using mixed models while adjusting for other known correlates of arterial stiffness.

RESULTS

Median personal BC exposures within the same day ranged from 599.8 to 728.9ng/m(3) and were associated with carotid arterial stiffness measures. Young's elastic modulus and pulse wave velocity, both measures of stiffness, were positively associated with BC exposure, while the distensibility and compliance coefficient, measures of elasticity, were negatively associated with BC exposure. The strongest associations were observed with BC exposure 8h before the clinical examination. For each 100ng/m(3) increase in exposure within this time window, Young's elastic modulus increased by 2.38% (95% CI: 0.81 to 3.97; P=0.0033), while the distensibility coefficient decreased by 2.27% (95% CI: -3.62 to -0.92; P=0.0008).

CONCLUSIONS

Short-term elevations in personal BC exposure, even within hours, are associated with increased arterial stiffness. This response may reflect a pathway by which air pollution triggers cardiovascular events.

Air pollution and risk of type 2 diabetes mellitus: a systematic review and meta-analysis

AIM

Whether exposure to relatively high levels of air pollution is associated with diabetes occurrence remains unclear. We sought to assess and quantify the association between exposure to major air pollutants and risk of type 2 diabetes.

METHODS

PubMed and EMBASE databases (through September 2013) were searched using a combination of terms related to exposure to gaseous (NO2 and NOx) or particulate matter pollutants (PM2.5, PM10 and PM10-2.5) and type 2 diabetes. Descriptive and quantitative information were extracted from selected studies. We used random-effects models meta-analysis to derive overall risk estimates per type of pollutant.

RESULTS

We included ten studies (five cross-sectional and five prospective), assessing the effects of air pollutants on the occurrence of diabetes. In prospective investigations, the overall effect on diabetes occurrence was significant for both NO2 (adjusted hazard ratio [HR], 1.13; 95% confidence interval [95%CI], 1.01-1.22; p < 0.001; I(2) = 36.4%, pheterogeneity = 0.208) and PM2.5 (HR, 1.11; 95%CI, 1.03-1.20; p < 0.001; I(2) = 0.0%, pheterogeneity = 0.827). Odds ratios were reported by two cross-sectional studies which revealed similar associations between both NO2 and PM2.5 with type 2 diabetes. Across studies, risk estimates were generally adjusted for age, gender, body mass index and cigarette smoking.

CONCLUSIONS

Available evidence supports a prospective association of main air pollutants with an increased risk for type 2 diabetes. This finding may have implications for population-based strategies to reduce diabetes risk.

A feasibility study of the association of exposure to biomass smoke with vascular function, inflammation, and cellular aging

BACKGROUND

Biomass smoke at higher concentrations is associated with respiratory symptoms and, after years of exposure, increased risk of respiratory disorders in adults, but its effects on cardiovascular diseases are not well characterized, particularly compared with other pollution sources like tobacco smoke or traffic.

METHODS

We conducted a cross-sectional study and enrolled 25 women living in rural Sichuan, China. We measured integrated 24-h personal exposure to fine particulate matter (PM2.5) and black carbon, and measured PM2.5 and black carbon in their kitchens. We assessed participants' brachial and central blood pressure and arterial stiffness using pulse wave analysis, and analyzed dried blood spot and buccal cell samples for C-reactive protein and relative telomere length. We also evaluated the difference in these physiological and biomarker measures between individuals with high (≥median) versus low (<median) PM2.5 exposure using multivariate regression.

RESULTS

Geometric mean 24-h PM2.5 and black carbon exposures were 61 µg/m(3) (95% CI: 48, 78) and 3.2 µg/m(3) (95% CI: 2.3, 4.5), respectively. Average kitchen PM2.5 and black carbon concentrations were only moderately correlated with personal exposures (PM2.5: r=0.41; black carbon: r=0.63), although they had similar means. Women in the high and low exposure groups were similar in age, obesity, socioeconomic status, salt intake, and physical activity. Women in the high PM2.5 exposure group had higher mean brachial systolic blood pressure (SBP; difference=4.6 mmHg, 95% CI -7.8, 16.9), central SBP (difference=3.1 mmHg, 95% CI: -8.4, 14.5), central pulse pressure (difference=4.1 mmHg; 95% CI: -4.2, 12.4), and augmentation index (difference=2.8%, 95% CI: -1.6, 7.2). High exposed women had 43% shorter telomere length (95% CI: -113, 28) than that of women in the low exposure group. There were no differences in pulse wave velocity or C-reactive protein between the two exposure groups. None of the results was statistically significant.

CONCLUSIONS

Our results suggest that it is feasible to measure markers of vascular function and biomarkers of inflammation and oxidative stress in field studies of biomass smoke. Although many of the associations were in the expected direction, larger studies would be needed to establish the effects.

A national case-crossover analysis of the short-term effect of PM2.5 on hospitalizations and mortality in subjects with diabetes and neurological disorders

BACKGROUND

Diabetes and neurological disorders are a growing burden among the elderly, and may also make them more susceptible to particulate air matter with aerodynamic diameter less than 2.5 μg (PM2.5). The same biological responses thought to effect cardiovascular disease through air pollution-mediated systemic oxidative stress, inflammation and cerebrovascular dysfunction could also be relevant for diabetes and neurodegenerative diseases.

METHODS

We conducted multi-site case-crossover analyses of all-cause deaths and of hospitalizations for diabetes or neurological disorders among Medicare enrollees (>65 years) during the period 1999 to 2010 in 121 US communities. We examined whether 1) short-term exposure to PM2.5 increases the risk of hospitalization for diabetes or neurological disorders, and 2) the association between short-term exposure to PM2.5 and all-cause mortality is modified by having a previous hospitalization of diabetes or neurological disorders.

RESULTS

We found that short term exposure to PM2.5 is significantly associated with an increase in hospitalization risks for diabetes (1.14% increase, 95% CI: 0.56, 1.73 for a 10 μg/m3 increase in the 2 days average), and for Parkinson's disease (3.23%, 1.08, 5.43); we also found an increase in all-cause mortality risks (0.64%, 95% CI: 0.42, 0.85), but we didn't find that hospitalization for diabetes and neurodegenerative diseases modifies the association between short term exposure to PM2.5 and all-cause mortality.

CONCLUSION

We found that short-term exposure to fine particles increased the risk of hospitalizations for Parkinson's disease and diabetes, and of all-cause mortality. While the association between short term exposure to PM2.5 and mortality was higher among Medicare enrollees that had a previous admission for diabetes and neurological disorders than among Medicare enrollees that did not had a prior admission for these diseases, the effect modification was not statistically significant. We believe that these results provide useful insights regarding the mechanisms by which particles may affect the brain. A better understanding of the mechanisms will enable the development of new strategies to protect individuals at risk and to reduce detrimental effects of air pollution on the nervous system.