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

Could the association between ozone and arterial stiffness be modified by fish oil supplementation?

BACKGROUND

Arterial stiffness (AS) is an important predicting factor for cardiovascular disease. However, no epidemiological studies have ever explored the mediating role of biomarkers in the association between ozone and AS, nor weather fish oil modified such association.

METHODS

Study participants were drawn from the UK biobank, and a total of 95,699 middle-aged and older adults were included in this study. Ozone was obtained from Community Multiscale Air Quality (CMAQ) model matched to residential addresses, fish oil from self-reported intake, and arterial stiffness was based on device measurements. First, we applied a double robust approach to explore the association between ozone or fish oil intake and arterial stiffness, adjusting for potential confounders at the individual and regional levels. Then, how triglycerides, apolipoprotein B (Apo B)/apolipoprotein A (ApoA) and non-high-density lipoprotein cholesterol (Non-HDL-C) mediate the relationship between ozone and AS. Last, the modifying role of fish oil was further explored by stratified analysis.

RESULTS

The mean age of participants was 55 years; annual average ozone exposure was associated with ASI (beta:0.189 [95%CI: 0.146 to 0.233], P < 0.001), and compared to participants who did not consume fish oil, fish oil users had a lower ASI (beta: 0.061 [95%CI: -0.111 to -0.010], P = 0.016). The relationship between ozone exposure and AS was mediated by triglycerides, ApoB/ApoA, and Non-HDL-C with mediation proportions ranging from 10.90% to 18.30%. Stratified analysis showed lower estimates on the ozone-AS relationship in fish oil users (P = 0.011).

CONCLUSION

Ozone exposure was associated with higher levels of arterial stiffness, in contrast to fish oil consumption, which showed a protective association. The association between ozone exposure and arterial stiffness was partially mediated by some biomarkers. In the general population, fish oil consumption might provide protection against ozone-related AS.

Long-Term Exposure to Fine Particulate Constituents and Vascular Damage in a Population with Metabolic Abnormality in China

AIM

To date, PM2.5-associated vascular damage in metabolic abnormalities has remained controversial. We knew little about the vascular damage of PM2.5 constituents. Thus, this study aimed to investigate the relationship between long-term exposure to PM2.5 and its constituents and vascular damage in metabolic abnormalities.

METHODS

A total of 124,387 participants with metabolic abnormalities (defined as at least one metabolic disorder, such as obesity, elevated blood pressure, elevated triglyceride level, elevated fasting glucose level, or low HDL cholesterol level) were recruited in this study from 11 representative centers in China between January 2011 and December 2017. PM2.5 and its constituents (black carbon [BC], organic matter [OM], sulfate [SO42-], nitrate [NO3-], and ammonium salts [NH4＋]) were extracted. Elevated brachial-ankle pulse wave velocity (baPWV) (≥ 1,400 cm/s) and declined ankle-brachial index (ABI) (＜0.9) indicated vascular damage. Multivariable logistic regression and Quantile g-Computation models were utilized to explore the impact on outcomes.

RESULTS

Of the 124,387 participants (median age, 49 years), 87,870 (70.64%) were men. One-year lag exposure to PM2.5 and its constituents was significantly associated with vascular damage in single pollutant models. The adjusted odds ratios (OR) for each 1-µg/m3 increase in PM2.5 was 1.013 (95% CI, 1.012-1.015) and 1.031 (95% CI, 1.025-1.037) for elevated baPWV and decreased ABI, respectively. PM2.5 constituents were also associated with vascular damage in multi-pollutant models. Among the PM2.5 constituents, BC (47.17%), SO42- (33.59%), and NH4＋ (19.23%) have the highest contribution to elevated baPWV and NO3- (47.89%) and BC (23.50%) to declined ABI.

CONCLUSION

Chronic exposure to PM2.5 and PM2.5 constituents was related to vascular damage in the abnormal metabolic population in China. The heterogeneous contribution of different PM2.5 constituents to vessel bed damage is worthy of attention when developing targeted strategies.

Assessment of black carbon exposure level and health economic loss in China

Based on the geographic information system (GIS) software and the application of the black carbon (BC) and fine particulate matter ([Formula: see text]) ratio method, this paper analyzed and calculated the national BC distribution from 2015 to 2017 and evaluated the national human exposure to BC. The results showed that from 2015 to 2017, 2/3 of the national land area and nearly half of the population were exposed to 1-3 [Formula: see text], and the area and population exposed to a concentration less than 2 [Formula: see text] increased yearly, while the area and population exposed to a concentration higher than 9 [Formula: see text] decreased yearly. The estimated economic loss showed that 77.3% of the targeted districts or counties claimed a loss per square kilometer of 50 million Chinese Yuan (CNY) or less from the perspective of annual changes, and districts and counties in Beijing-Tianjin-Hebei and Hunan with annual losses between 50 and 500 million CNY showed an increasing trend. The BC ratio (the proportion of BC economic loss to GDP) of Beijing-Tianjin-Hebei and Hunan also showed an increasing trend yearly.

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.

Low-cost air pollution monitoring system-an opportunity for reducing the health risk associated with physical activity in polluted air

The issue of air pollution by particulate matter (PM) concerns many places in the world. At the same time, many residents undertake physical activity (recreation, rehabilitation, sport) in the open air. Generally, the amount of dust concentration depends on both the place (center or periphery of the city) and the time of day. In the present study we describe the outcome of monitoring of the state of air pollution by particle matter (PM₁₀) in the Kraków agglomeration area in order to show that it can provide information concerning air quality in the area where people practice varied kinds of sports in the open air. The measurements of PM₁₀ have been made by a few stations with identical construction working as one network. The details of the air pollution monitoring system and its data quality verification have been described. The network stations made multipoint observations across the Kraków Metropolitan Area during the year 2017 in eight locations. The locations selected represent a diverse spectrum of terrain conditions in which the Kraków agglomeration community undertakes physical activity. For most months of 2017, the minimum monthly average 4-hour PM₁₀ concentrations were recorded between 10–14 h, regardless of location, whereas the maximum was between 18–22. We also noticed a huge differences in the average monthly value of PM₁₀ in some locations within the Kraków agglomeration—ranging between 4.9–339.0 µg m⁻³. This indicates that some regions of the city are more suitable for performance of physical activity in the open air than others. In conclusion, we postulate that a low-cost air pollution monitoring system is capable of providing valuable information concerning air quality in a given region, which seems to be of importance also to people who practice varied sports activities in the open air.

Bus commuter exposure and the impact of switching from diesel to biodiesel for routes of complex urban geometry

We report on commuters' exposure to black carbon (BC), PM_2.5 and particle number (PN, with aerodynamic diameter, d_a, in the range 0.01 <d_a< 1.0 μm) collected on-board diesel- and biodiesel-fuelled buses of the Bus Rapid Transit (BRT) system of the city of Curitiba, Brazil. Particulate concentrations measured at high sampling rates allowed the capture of fine gradients along the route and the comparison of in-cabin air pollution on buses of different technologies. Of all metrics, BC showed the largest discrepancies, with mean concentrations of 20.1 ± 20.0 μg m^-3 and 3.9 ± 26.0 μg m^-3 on diesel- and biodiesel-fuelled buses, respectively. Mean PM_2.5 concentrations were similar (31.6 ± 28.5 μg m^-3 and 29.0 ± 17.8 μg m^-3), whilst mean PN concentrations were larger on the biodiesel buses (56,697 ± 26,800 # cm^-3vs. 43,322 ± 32,243 # cm^-3). The results are in line with studies on biodiesel emission factors that reported lower BC mass but more particles with smaller diameters. Our hypothesis is that different emission factors of diesel and biodiesel engines reflected in differences of in-cabin particulate concentrations. We found that the passenger exposure during the bus commutes was affected not only by the fuel used but also by the street geometry along the route, with segments with canyon configurations resulting in peak exposure to particulates. The results suggest that i) switching from diesel to biodiesel may help abate commuters' exposure to BC particles on-board buses of the BRT system, whilst it would need to be complemented with after-treatment technologies to reduce emissions; ii) further reductions in exposure (to peaks in particular) could be achieved by changing bus routes to ones that avoid passing through narrow urban street canyons.

Personal exposure to particulate air pollution and vascular damage in peri-urban South India

OBJECTIVE

Air pollution is a leading preventable risk factor for cardiovascular diseases. Previous studies mostly relied on concentrations at residence, which might not represent personal exposure. Personal air pollution exposure has a greater variability compared with levels of ambient air pollution, facilitating evaluation of exposure-response functions and vascular pathophysiology. We aimed to evaluate the association between predicted annual personal exposure to PM2.5 and black carbon (BC) and three vascular damage markers in peri-urban South India.

METHODS

We analyzed the third wave of the APCAPS cohort (2010-2012), which recruited participants from 28 villages. We used predicted personal exposure to PM2.5 and BC derived from 610 participant-days of 24 h average gravimetric PM2.5 and BC measurements and predictors related to usual time-activity. Outcomes included carotid intima-media thickness (CIMT), carotid-femoral pulse wave velocity (cf-PWV) and augmentation index (AIx). We fit linear mixed models, adjusting for potential confounders and accounting for the clustered data structure. We evaluated nonlinear associations using generalized additive mixed models.

RESULTS

Of the 3017 participants (mean age 38 years), 1453 (48%) were women. The average PM2.5 exposure was 51 µg/m3 (range 13-85) for men, and 61 µg/m3 (range 40-120) for women, while the average BC was 4 µg/m3 (range 3-7) for men and 8 µg/m3 (range 3-22) for women. A 10 μg/m3 increase of PM2.5 was positively associated with CIMT (0.026 mm, 95% CI 0.014, 0.037), cf-PWV (0.069 m/s, 95% CI 0.008, 0.131) and AIx (0.8%, 95% CI 0.3, 1.3) among men. The exposure-response function for PM2.5 and AIx among men showed non-linearity, particularly within the exposure range dominated by tobacco smoking and occupational exposures. Both PM2.5 and BC were positively associated with AIx among women (0.6%, 95% CI 0.2, 1.0, per 10 μg/m3 PM2.5; 0.5%, 95% CI 0.1, 0.8, per 2 μg/m3 BC).

CONCLUSIONS

Personal exposure to particulate matter was associated with vascular damage in a peri-urban population in South India. Personal exposure to particulate matter appears to have gender-specific effects on the type of vascular damage, potentially reflecting differences in sources of personal exposure by gender.

Association between microenvironment air quality and cardiovascular health outcomes

Exposure to fine particulate matter (PM_2.5) is associated with cardiovascular disease risk. To date, there are few studies on short-term PM_2.5 exposure in different microenvironments and its impact on immediate health effects, particularly in the Southeast Asia region. This study assessed PM_2.5 concentrations in different microenvironments in a densely populated city in the tropics using low-cost personal PM_2.5 sensors as well as their associations with acute cardiovascular health outcomes. A total of 49 adult participants affiliated with the National University of Singapore (NUS) community were recruited. Personal low-cost sensors were used to measure PM_2.5 concentrations between September 2017 and March 2019. Demographic information and time-activity patterns were collected using questionnaires. Wilcoxon pairwise comparisons were used to determine statistical differences between PM_2.5 exposures at 18 different microenvironments. Generalized Estimating Equations (GEE) models were used to assess the association between PM_2.5 exposure and blood pressure as well as heart rate. All models were adjusted for age, sex, body mass index, physical activity, temperature, duration of exposure, and baseline cardiovascular parameters. Significant differences in PM_2.5 concentrations were observed across different microenvironments. Air-conditioned offices and tertiary teaching spaces had the lowest (median = 13.1 μg/m³) and hawker centres had the highest (median = 32.0 μg/m³) PM_2.5 concentrations. Significant positive associations between PM_2.5 exposure and heart rate (β = 0.40, p = 4.6 × 10^-5) as well as diastolic blood pressure (β = 0.16, p = 0.0077) were also observed. Short-term exposure to PM_2.5 was significantly associated with higher heart rate and blood pressure. Further work is needed to investigate the variations within each type of microenvironment and expand the study to other sub-populations such as the elderly and children.

Development of a land use regression model for black carbon using mobile monitoring data and its application to pollution-avoiding routing

Black carbon is often used as an indicator for combustion-related air pollution. In urban environments, on-road black carbon concentrations have a large spatial variability, suggesting that the personal exposure of a cyclist to black carbon can heavily depend on the route that is chosen to reach a destination. In this paper, we describe the development of a cyclist routing procedure that minimizes personal exposure to black carbon. Firstly, a land use regression model for predicting black carbon concentrations in an urban environment is developed using mobile monitoring data, collected by cyclists. The optimal model is selected and validated using a spatially stratified cross-validation scheme. The resulting model is integrated in a dedicated routing procedure that minimizes personal exposure to black carbon during cycling. The best model obtains a coefficient of multiple correlation of R=0.520. Simulations with the black carbon exposure minimizing routing procedure indicate that the inhaled amount of black carbon is reduced by 1.58% on average as compared to the shortest-path route, with extreme cases where a reduction of up to 13.35% is obtained. Moreover, we observed that the average exposure to black carbon and the exposure to local peak concentrations on a route are competing objectives, and propose a parametrized cost function for the routing problem that allows for a gradual transition from routes that minimize average exposure to routes that minimize peak exposure.

The application of Raman spectroscopy combined with multivariable analysis on source apportionment of atmospheric black carbon aerosols

Source apportionment studies become increasingly crucial for black carbon (BC) in atmospheric particulate matters given its linkage with adverse public health and climate impacts. In this work, a facile and rapid method using Raman spectra combined with stepwise discriminant analysis (SDA) was proposed to identify and quantify the contributions of atmospheric BC sources. Four BC samples from biomass burning, coal combustion, gasoline and diesel vehicle emission were characterized by Raman spectra. The SDA model was established based on 10 parameters with significant differences (p < 0.05), giving an accuracy of 83% with a cross-validation rate of 80%. Utilizing four suggested discriminant variables from SDA model, vehicle emission was predicted as the dominant contributor to ambient BC particles, among which gasoline contributed much higher than diesel at an urban road intersection in Shanghai, China. This new method shows great potential to classify and investigate the sources of atmospheric BC aerosols and provide more effective information on air pollution control measures.

Modelling urban cyclists' exposure to black carbon particles using high spatiotemporal data: A statistical approach

This is a pioneering work in South America to model the exposure of cyclists to black carbon (BC) while riding in an urban area with high spatiotemporal variability of BC concentrations. We report on mobile BC concentrations sampled on 10 biking sessions in the city of Curitiba (Brazil), during rush hours of weekdays, covering four routes and totaling 178 km. Moreover, simultaneous BC measurements were conducted within a street canyon (street and rooftop levels) and at a site located 13 km from the city center. We used two statistical approaches to model the BC concentrations: multiple linear regression (MLR) and a machine-learning technique called random forests (RF). A pool of 25 candidate variables was created, including pollution measurements, traffic characteristics, street geometry and meteorology. The aggregated mean BC concentration within 30-m buffers along the four routes was 7.09 μg m^-3, with large spatial variability (5th and 95th percentiles of 1.75 and 16.83 μg m^-3, respectively). On average, the concentrations at the street canyon façade (5 m height) were lower than the mobile data but higher than the urban background levels. The MLR model explained a low percentage of variance (24%), but was within the values found in the literature for on-road BC mobile data. RF explained a larger variance (54%) with the additional advantage of having lower requirements for the target and predictor variables. The most impactful predictor for both models was the traffic rate of heavy-duty vehicles. Thus, to reduce the BC exposure of cyclists and residents living close to busy streets, we emphasize the importance of renewing and/or retrofitting the diesel-powered fleet, particularly public buses with old vehicle technologies. Urban planners could also use this valuable information to project bicycle lanes with greater separation from the circulation of heavy-duty diesel vehicles.

Acute Effects of Air Pollution and Noise from Road Traffic in a Panel of Young Healthy Adults

Panel studies are an efficient means to assess short-term effects of air pollution and other time-varying environmental exposures. Repeated examinations of volunteers allow for an in-depth analysis of physiological responses supporting the biological interpretation of environmental impacts. Twenty-four healthy students walked for 1 h at a minimum of four separate occasions under each of the following four settings: along a busy road, along a busy road wearing ear plugs, in a park, and in a park but exposed to traffic noise (65 dB) through headphones. Particle mass (PM_2.5, PM₁), particle number, and noise levels were measured throughout each walk. Lung function and exhaled nitrogen oxide (NO) were measured before, immediately after, 1 h after, and approximately 24 h after each walk. Blood pressure and heart rate variability were measured every 15 min during each walk. Recorded air pollution levels were found to correlate with reduced lung function. The effects were clearly significant for end-expiratory flows and remained visible up to 24 h after exposure. While immediate increases in airway resistance could be interpreted as protective (muscular) responses to particulate air pollution, the persisting effects indicate an induced inflammatory reaction. Noise levels reduced systolic blood pressure and heart rate variability. Maybe due to the small sample size, no effects were visible per specific setting (road vs. park).

Personal exposure to traffic-related air pollutants and relationships with respiratory symptoms and oxidative stress: A pilot cross-sectional study among urban green space workers

Exposure to ambient air pollution has been associated with various adverse health effects including respiratory, cardiovascular and neurological diseases. Exposure data for some specific pollutants and settings are however still insufficient and mechanisms underlying negative health outcomes are not fully elucidated. This pilot study aimed to assess individual exposure to three traffic-related air pollutants, black carbon (BC), polycyclic aromatic hydrocarbons (PAHs) and benzene, and the relationship with respiratory and oxidative stress outcomes in a cross-sectional sample of 48 green space workers in Brussels, Belgium. Participants were followed during four consecutive working days in 2016-2017 during which their individual exposure to BC, PAHs, benzene and more generally air pollution was measured using aethalometers, urinary biomarkers (1-hydroxypyrene, 1-naphthol, 2-naphthol, S-phenylmercapturic acid) and questionnaires. Data on respiratory health and oxidative stress were collected using questionnaires and respiratory/urinary biomarkers (exhaled nitric oxide [NO], 8-hydroxydeoxyguanosine [8-OHdG]). Associations between exposure and health outcomes were investigated using comparison tests and linear regression models, after stratification by present-day smoking status. Spatial variation in BC exposure was high, with concentrations varying between 0.26 and 5.69 μg/m³. The highest levels were recorded during transport and, to a lesser extent, in green spaces located in the vicinity of roads with high traffic intensity. Concentrations of PAHs and benzene biomarkers did not systematically exceed the limits of detection. Among smokers, respiratory inflammation increased linearly with exposure to BC measured over the four days of follow-up (β = 8.73, 95% CI: 4.04, 13.41). Among non-smokers, oxidative stress increased linearly with BC measured on the fourth day (β = 2.88, 95% CI: 1.52, 4.24). Despite some limitations, this work supports the hypothesis that BC induces respiratory inflammation and oxidative stress. It also highlights the value of this compound as well as exhaled NO and urinary 8-OHdG biomarkers to detect early/mild effects of air pollution.

Air pollution and telomere length in adults: A systematic review and meta-analysis of observational studies

Telomere length (TL) has been suggested to be a surrogate for cellular ageing, and a record of cumulative inflammation and oxidative stress over life. An emerging body of evidence has associated exposure to air pollution to changes in TL. To date there is no available systematic review of literature on this association. We aimed to systematically review and conduct meta-analysis of published studies on the relationship between air pollution and TL in adults. Electronic databases were systematically searched for available English language studies on the association between air pollution and TL published up to 1 July 2018. Meta-analyses were conducted following MOOSE guidelines. The heterogeneity in the reported associations was assessed using Cochran's Q test and quantified as I² index. Publication bias was assessed using Egger's regression. Our search identified 19 eligible studies including 11 retrospective and eight prospective studies of which, four had excellent quality, ten had good quality and five had fair quality. Meta-analysis result of two studies on long-term exposure to PM_2.5 showed an inverse association between these exposures and TL (for 5 μg/m³ PM_2.5-0.03 95% CI; -0.05, -0.01). Meta-analysis of short-term exposure to PM_2.5 with three studies and Polychlorinated Biphenyls (PCBs) with two studies revealed a direct association between these exposures and TL (0.03 95% CI; 0.02, 0.04 and 0.10 95% CI; 0.06, 0.15 respectively). No statistically significant relationship between exposure to PM₁₀ and polycyclic aromatic hydrocarbons (PAHs) exposure and TL were observed. We observed suggestive evidence for associations between air pollution and TL with potentially different direction of associations for short- and long-term exposures.

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.

Changing places to study short-term effects of air pollution on cardiovascular health: a panel study

BACKGROUND

Short-term exposure to ambient air pollution triggers acute cardiovascular events. Here, we evaluate the association of exposure to ambient air pollution with two intermediate cardiovascular endpoints: blood pressure and carotid stiffness.

METHODS

In a one-year panel study, we included 20 healthy volunteers (10 male-female couples aged 59-75 years) with air pollution and health parameters measured every two months at their region of residence (Leuven, Belgium) and twice during two ten-day periods in two locations, one with higher (Milan, Italy) and one with lower (Vindeln, Sweden) air pollution levels (220 observations). We measured blood pressure, carotid arterial stiffness, personal exposure to NO₂, and ambient concentrations of PM₁₀, PM_2.5, and NO₂. We used linear mixed models to evaluate the associations between the health outcomes and the air pollutants.

RESULTS

Compared with Leuven, exposure to pollutants was higher in Milan and lower in Vindeln, with the highest contrast for NO₂ (median 20.7 μg/m³ (IQR:7.4) vs 65.1 μg/m³ (9.0) and 4.5 mg/m³ (0.8), respectively). We did not observe significant associations between either systolic or diastolic blood pressure and variations in air pollution. However, we found significant associations between arterial stiffness and 5 day average exposure to the studied pollutants. The strongest associations were observed for PM₁₀ with carotid distensibility (DC) and compliance (CC) coefficients, and the young elastic modulus (YEM): 4.3% (95%CI:7.0;1.5) increase in DC, 4.7% (95%CI:7.1;2.3) increase in CC and 4.2% (95%CI:1.1;7.3) decrease in YEM for each 10 μg/m³ decreases in PM₁₀.

CONCLUSIONS

Our study suggests that short-term exposure to air pollution results in reductions in carotid elasticity among elderly population.

Prolonged exposure to carbon nanoparticles induced methylome remodeling and gene expression in zebrafish heart

Growing black carbon (BC) emission has become one of the major urgent environmental issues facing human beings. Usually, BC or BC-containing carbon nanoparticles (CNPs) were recognized as non-directly toxic components of atmospheric particulate matter. However, epidemiology studies have provided much evidence of the associations of exposure of particulate-containing carbon particles with cardiovascular diseases. There are still no related studies to support the epidemiological conclusions. Hence, in this article we exposed adult zebrafish to CNPs for 60 days, and then explored the heart location and potential adverse effects on cardiac tissues of these nanosized carbon particles. Our results first showed direct visualization of cardiac endothelial uptake and heart deposition of CNPs in zebrafish. In addition, CNPs caused significant ultrastructural alterations in myocardial tissue and induced the expression of inflammatory cytokines in a dose-dependent manner, resulting in sub-endocardial inflammation and cell apoptosis. Moreover, our data demonstrated the perturbations caused by CNPs on DNA methylation, suggesting that DNA methylome remodeling might play a critical role in CNP-induced cardiotoxicity in zebrafish heart. Therefore, this study not only proved a laboratory link between CNP exposure and cardiotoxicity in vivo, but also indicated a possible toxicity mechanism involved.

Characteristics of peak concentrations of black carbon encountered by elementary school children

The objectives of this study were to examine characteristics of peak concentrations, including frequency, duration, and relative magnitude, and estimate its contributions to overall daily exposure to BC by activity and microenvironment. We assessed daily personal exposures from August 2015 to January 2016 (75.2% of weekdays and 24.8% of weekend days; 64.1% of school days and 35.9% of holidays) among forty 10-12 years old children living in the Seoul metropolitan area. These children were equipped with a microaethalometer (BC monitor) and recorded a time-activity diary. Pre-administrated questionnaires and follow-up interviews also provided information on children's time-activity patterns. Owing to the absence of a generally accepted threshold, peaks were alternatively defined as BC concentrations higher TWA, the 95th percentile, and the 99th percentile. Peak concentrations made substantial contributions to total daily exposure to BC (peaks ≥ TWA: 60%, peaks ≥95th-percentile: 19%, and peaks ≥99th-percentile: 6%). Average peak levels higher than TWA and the 95th percentile differed significantly by activity and ME. Transportation and cooking led to frequent peak occurrences which disproportionately contributed to daily integrated exposure relative to time spent in these activities. Walking was characterized by occasional brief but high-magnitude peaks exceeding the 99th percentile, which produced the most intense potential dose (0.09% of daily time spent on walking accounted for 1.6% of daily potential dose). It might be attributed to encounters with high emissions sources such as passing/idling vehicles and environmental tobacco smoke. Trips by diesel vehicle produced frequently occurring and long-duration peaks above the 95th percentile that contributed 2% to total daily exposure (corresponding time: 0.3%). Charbroiling meat incurred sustained peaks as intense as those in trips by diesel vehicles. Peaks during commuting showed relatively high exposure intensity on weekdays, possibly because of increased surrounding traffic volume on these days, while those during cooking accounted for a more elevated residential contribution to daily integrated exposure.

Cyclist exposure to black carbon, ultrafine particles and heavy metals: An experimental study along two commuting routes near Antwerp, Belgium

Urban environments typically exhibit large atmospheric pollution variation, in both space and time. In contrast to traditional monitoring networks suffering from a limited spatial coverage, mobile platforms enable personalized high-resolution monitoring, providing valuable insights into personal atmospheric pollution exposure, and the identification of potential pollution hotspots. This study evaluated personal cyclist exposure to UFPs, BC and heavy metals whilst commuting near Antwerp, Belgium, by performing mobile measurements with wearable black carbon (BC) and ultrafine particle (UFP) instruments. Loaded micro-aethalometer filterstrips were chemically analysed and the inhaled pollutant dose determined from the exhibited heart rate. Considerable spatial pollutant variation was observed along the travelled routes, with distinct contributions from spatial factors (e.g. traffic intersections, urban park and market) and temporary events. On average 300% higher BC, 20% higher UFP and changing elemental concentrations are observed along the road traffic route (RT), when compared to the bicycle highway route (BH). Although the overall background pollution determines a large portion of the experienced personal exposure (in this case 53% for BC and 40% for UFP), cyclists can influence their personal atmospheric pollution exposure, by selecting less exposed commuting routes. Our results, hereby, strengthen the body of evidence in favour of further policy investments in isolated bicycle infrastructure.

Air Pollution Stress and the Aging Phenotype: The Telomere Connection

Aging is a complex physiological phenomenon. The question why some subjects grow old while remaining free from disease whereas others prematurely die remains largely unanswered. We focus here on the role of air pollution in biological aging. Hallmarks of aging can be grouped into three main categories: genomic instability, telomere attrition, and epigenetic alterations leading to altered mitochondrial function and cellular senescence. At birth, the initial telomere length of a person is largely determined by environmental factors. Telomere length shortens with each cell division and exposure to air pollution as well as low residential greens space exposure is associated with shorter telomere length. Recent studies show that the estimated effects of particulate air pollution exposure on the telomere mitochondrial axis of aging may play an important role in chronic health effects of air pollution. The exposome encompasses all exposures over an entire life. As telomeres can be considered as the cellular memories of exposure to oxidative stress and inflammation, telomere maintenance may be a proxy for assessing the "exposome". If telomeres are causally related to the aging phenotype and environmental air pollution is an important determinant of telomere length, this might provide new avenues for future preventive strategies.

Clinical effects of air pollution on the central nervous system; a review

The purpose of this review is to describe recent clinical and epidemiological studies examining the adverse effects of urban air pollution on the central nervous system (CNS). Air pollution and particulate matter (PM) are associated with neuroinflammation and reactive oxygen species (ROS). These processes affect multiple CNS pathways. The conceptual framework of this review focuses on adverse effects of air pollution with respect to neurocognition, white matter disease, stroke, and carotid artery disease. Both children and older individuals exposed to air pollution exhibit signs of cognitive dysfunction. However, evidence on middle-aged cohorts is lacking. White matter injury secondary to air pollution exposure is a putative mechanism for neurocognitive decline. Air pollution is associated with exacerbations of neurodegenerative conditions such as Alzheimer's and Parkinson's diseases. Increases in stroke incidences and mortalities are seen in the setting of air pollution exposure and CNS pathology is robust. Large populations living in highly polluted environments are at risk. This review aims to outline current knowledge of air pollution exposure effects on neurological health.

Comparison of ultrasound-measured properties of the common carotid artery to tobacco smoke exposure in a cohort of Indonesian patients

BACKGROUND

The purpose of this study was to use point-of-care ultrasound (POCUS) to investigate the relationship between tobacco smoke exposure and the characteristics of the common carotid artery (CCA). The effect of both primary and secondary smoking on CCA properties was evaluated.

METHODS

We performed a prospective cross-sectional study across 20 primary care clinics in Bandung, West Java, Indonesia in July 2016. Point of care ultrasound was performed on a convenience sample of Indonesian patients presenting to clinic. The CCA wall stiffness and carotid intima-media thickness (CIMT) were measured during diastole and systole. These measurements were correlated with smoke exposure and cardiovascular disease.

RESULTS

We enrolled 663 patients in the study, with 426 patients enrolled in the smoking category and 237 patients enrolled in the second-hand smoke category. There was an overall positive correlation with the measured lifestyle factors and the ultrasound-measured variables in the group of individuals who smoked. For all variables, age seemed to contribute the most out of all of the lifestyle factors for the positive changes in CIMT and CCA wall stiffness.

CONCLUSION

Our data yielded correlations between CCA properties and cardiovascular risk, as well as between CIMT and arterial stiffness. We were also able to demonstrate an increase in thickness of the CIMT in patients who have been exposed by tobacco through the use of ultrasound. Further large scale studies comparing patients with multiple cardiac risk factors need to be performed to confirm the utility of ultrasound findings of cardiovascular disease and stroke.

Associations of oxidative stress and inflammatory biomarkers with chemically-characterized air pollutant exposures in an elderly cohort

BACKGROUND

Exposure to air pollution has been associated with cardiorespiratory morbidity and mortality. However, the chemical constituents and pollution sources underlying these associations remain unclear.

METHOD

We conducted a cohort panel study involving 97 elderly subjects living in the Los Angeles metropolitan area. Airway and circulating biomarkers of oxidative stress and inflammation were measured weekly over 12 weeks and included, exhaled breath condensate malondialdehyde (EBC MDA), fractional exhaled nitric oxide (FeNO), plasma oxidized low-density lipoprotein (oxLDL), and plasma interleukin-6 (IL-6). Exposures included 7-day personal nitrogen oxides (NOx), daily criteria-pollutant data, five-day average particulate matter (PM) measured in three size-fractions and characterized by chemical components including transition metals, and in vitro PM oxidative potential (dithiothreitol and macrophage reactive oxygen species). Associations between biomarkers and pollutants were assessed using linear mixed effects regression models.

RESULTS

We found significant positive associations of airway oxidative stress and inflammation with traffic-related air pollutants, ultrafine particles and transition metals. Positive but nonsignificant associations were observed with PM oxidative potential. The strongest associations were observed among PM variables in the ultrafine range (PM <0.18µm). It was estimated that an interquartile increase in 5-day average ultrafine polycyclic aromatic hydrocarbons was associated with a 6.3% (95% CI: 1.1%, 11.6%) increase in EBC MDA and 6.7% (95% CI: 3.4%, 10.2%) increase in FeNO. In addition, positive but nonsignificant associations were observed between oxLDL and traffic-related pollutants, ultrafine particles and transition metals while plasma IL-6 was positively associated with 1-day average traffic-related pollutants.

CONCLUSION

Our results suggest that exposure to pollutants with high oxidative potential (traffic-related pollutants, ultrafine particles, and transition metals) may lead to increased airway oxidative stress and inflammation in elderly adults. This observation was less clear with circulating biomarkers.

Inflammation and Vascular Effects after Repeated Intratracheal Instillations of Carbon Black and Lipopolysaccharide

Inflammation and oxidative stress are considered the main drivers of vasomotor dysfunction and progression of atherosclerosis after inhalation of particulate matter. In addition, new studies have shown that particle exposure can induce the level of bioactive mediators in serum, driving vascular- and systemic toxicity. We aimed to investigate if pulmonary inflammation would accelerate nanoparticle-induced atherosclerotic plaque progression in Apolipoprotein E knockout (ApoE^-/-) mice. ApoE^-/- mice were exposed to vehicle, 8.53 or 25.6 μg nanosized carbon black (CB) alone or spiked with LPS (0.2 μg/mouse/exposure; once a week for 10 weeks). Inflammation was determined by counting cells in bronchoalveolar lavage fluid. Serum Amyloid A3 (Saa3) expression and glutathione status were determined in lung tissue. Plaque progression was assessed in the aorta and the brachiocephalic artery. The effect of vasoactive mediators in plasma of exposed ApoE^-/- mice was assessed in aorta rings isolated from naïve C57BL/6 mice. Pulmonary exposure to CB and/or LPS resulted in pulmonary inflammation with a robust influx of neutrophils. The CB exposure did not promote plaque progression in aorta or BCA. Incubation with 0.5% plasma extracted from CB-exposed ApoE^-/- mice caused vasoconstriction in aorta rings isolated from naïve mice; this effect was abolished by the treatment with the serotonin receptor antagonist Ketanserin. In conclusion, repeated pulmonary exposure to nanosized CB and LPS caused lung inflammation without progression of atherosclerosis in ApoE^-/- mice. Nevertheless, plasma extracted from mice exposed to nanosized CB induced vasoconstriction in aortas of naïve wild-type mice, an effect possibly related to increased plasma serotonin.