Respiratory Filter Reduces the Cardiovascular Effects Associated With Diesel Exhaust Exposure: A Randomized, Prospective, Double-Blind, Controlled Study of Heart Failure: The FILTER-HF Trial

Ambient Air Pollution Exposure and Adverse Outcomes Among Medicare Beneficiaries With Heart Failure

BACKGROUND

Exposure to fine particulate matter (<2.5 um, particulate matter with an aerodynamic diameter <2.5 microns [PM2.5]) has been implicated in atherogenesis. Limited data in animal studies suggest that PM2.5 exposure leads to myocardial fibrosis and increased incidence of heart failure (HF). Whether PM2.5 is associated with adverse outcomes in patients with preexisting HF has not been widely studied.

METHODS AND RESULTS

In this retrospective cohort study, Medicare patients hospitalized with first HF between 2013 and 2020 were identified from the Medicare Provider Analysis and Review Part A 100% files. Patients were linked with integrated estimates of ambient PM2.5 obtained at 1×1 km using the zip code of participants' residence. The study outcomes were all-cause death, HF, and all-cause readmissions burden. A total of 2 599 525 patients were included in this study, with 6 321 731 person-years of follow-up. Mean PM2.5 was 7.3±1.7 μg/m3. Each interquartile range of PM2.5 was associated with 0.9% increased hazard of all-cause death, 4.5% increased hazard of first HF readmission, 3.1% increased risk of HF hospitalization burden, and 5.2% increase in all-cause readmission burden, after adjusting for 11 sociodemographic and medical factors. Subgroup analyses showed that the effects were more pronounced at levels <7 μg/m3 and in patients aged <75 years, Asians, and those residing in rural areas.

CONCLUSIONS

Ambient air pollution is associated with higher risk of adverse events in Medicare beneficiaries with established HF. These associations persist below the National Air Quality Standards (12 μg/m3), supporting that no threshold effect exists for health effects of air pollution exposure.

Joint Exposure to Ambient Air Pollutants, Genetic Risk, and Ischemic Stroke: A Prospective Analysis in UK Biobank

BACKGROUND

Our primary objective was to assess the association between joint exposure to various air pollutants and the risk of ischemic stroke (IS) and the modification of the genetic susceptibility.

METHODS

This observational cohort study included 307 304 British participants from the United Kingdom Biobank, who were stroke-free and possessed comprehensive baseline data on genetics, air pollutant exposure, alcohol consumption, and dietary habits. All participants were initially enrolled between 2006 and 2010 and were followed up until 2022. An air pollution score was calculated to assess joint exposure to 5 ambient air pollutants, namely particulate matter with diameters equal to or <2.5 µm, ranging from 2.5 to 10 µm, equal to or <10 µm, as well as nitrogen oxide and nitrogen dioxide. To evaluate individual genetic risk, a polygenic risk score for IS was calculated for each participant. We adjusted for demographic, social, economic, and health covariates. Cox regression models were utilized to estimate the associations between air pollution exposure, polygenic risk score, and the incidence of IS.

RESULTS

Over a median follow-up duration of 13.67 years, a total of 2476 initial IS events were detected. The hazard ratios (95% CI) of IS for per 10 µg/m3 increase in particulate matter with diameters equal to or <2.5 µm, ranging from 2.5 to 10 µm, equal to or <10 µm, nitrogen dioxide, and nitrogen oxide were 1.73 (1.33-2.14), 1.24 (0.88-1.70), 1.13 (0.89-1.33), 1.03 (0.98-1.08), and 1.04 (1.02-1.07), respectively. Furthermore, individuals in the highest quintile of the air pollution score exhibited a 29% to 66% higher risk of IS compared with those in the lowest quintile. Notably, participants with both high polygenic risk score and air pollution score had a 131% (95% CI, 85%-189%) greater risk of IS than participants with low polygenic risk score and air pollution score.

CONCLUSIONS

Our findings suggested that prolonged joint exposure to air pollutants may contribute to an increased risk of IS, particularly among individuals with elevated genetic susceptibility to IS.

Can individual protective measures safeguard cardiopulmonary health from air pollution? A systematic review and meta-analysis

Evidence supporting the effect of individual protective measures (IPMs) on air pollution is relatively scarce. In this study, we performed a systematic review and meta-analysis to investigate the effects of air purifiers, air-purifying respirators, and cookstove changes on cardiopulmonary health outcomes. We searched PubMed, Scopus, and Web of Science until December 31, 2022, 90 articles and 39,760 participants were included. Two authors independently searched and selected the studies, extracted information, and assessed each study's quality and risk of bias. We performed meta-analyses when three or more studies were available for each IPMs, with comparable intervention and health outcome. Systematic review showed that IPMs were beneficial in children and elderly with asthma along with healthy individuals. Meta-analysis results showed a reduction in cardiopulmonary inflammation using air purifiers than in control groups (with sham/no filter) with a decrease in interleukin 6 by -0.247 μg/mL (95% confidence intervals [CI] = -0.413, -0.082). A sub-group analysis for air purifier as an IPMs in developing counties reduced fractional exhaled nitric oxide by -0.208 ppb (95% confidence intervals [CI] = -0.394, -0.022). However, evidence describing the effects of air purifying respirator and cook stove changes on cardiopulmonary outcomes remained insufficient. Therefore, air purifiers can serve as efficient IPMs against air pollution. The beneficial effect of air purifiers is likely to have a greater effect in developing countries than in developed countries.

The Role of Fine Particles (PM 2.5) in the Genesis of Atherosclerosis and Myocardial Damage: Emphasis on Clinical and Epidemiological Data, and Pathophysiological Mechanisms

Due to the fact that atherosclerotic cardiovascular diseases (CVDs) dominate in the structure of morbidity, disability and mortality of the population, the study of the risk factors for the development of atherosclerotic CVDs, as well as the study of the underlying pathogenetic mechanisms thereof, is the most important area of scientific research in modern medicine. Understanding these aspects will allow to improve the set of treatment and preventive measures and activities. One of the important risk factors for the development of atherosclerosis, which has been actively studied recently, is air pollution with fine particulate matter (PM 2.5). According to clinical and epidemiological data, the level of air pollution with PM 2.5 exceeds the normative indicators in most regions of the world and is associated with subclinical markers of atherosclerosis and mortality from atherosclerotic CVDs. The aim of this article is to systematize and discuss in detail the role of PM 2.5 in the development of atherosclerosis and myocardial damage.

The Different Impact of PM2.5 on Atherogenesis in Overseas vs. Native Chinese in the CATHAY Study

Air pollution (PM2.5) has been associated with cardiovascular disease (CVD) globally and with early atherosclerosis surrogate markers in modernized China. A sizeable number of Chinese have migrated overseas, with an increase in their vulnerability to CVD. To evaluate the impact of PM2.5 air pollution on atherogenesis in native vs. overseas Chinese, we recruited 756 asymptomatic native Chinese and 507 age- and gender-matched overseas Chinese from Sydney and San Francisco. Their cardiovascular profiles were evaluated. PM2.5 was derived from remote sensing technology; atherosclerosis surrogate markers, flow-mediated dilation (FMD) and carotid intima-media thickness (IMT) were measured by ultrasound. The native Chinese had a higher proportion of smokers as well as higher blood pressure, glucose, metabolic syndrome and PM2.5 exposure (p < 0.001), but lower lipids and folate than the overseas Chinese (p < 0.0001). Carotid IMT was lower in the native Chinese (p < 0.0001), but the other vascular parameters were similar. A multivariate regression revealed that FMD in the native Chinese was related to the male gender, age and location; in the overseas Chinese, it was related to age, but not to PM2.5. Carotid IMT in the native Chinese was related to PM2.5, independent of atherosclerotic risk factors and location (R2 = 0.384, F = 34.5, p < 0.0001) whereas in the overseas Chinese, IMT was related to the male gender and age, but not to PM2.5 or overseas location (R2 = 0.282, F = 19.7, p < 0.0001). PM2.5 had a greater impact on atherogenesis in the native Chinese, independent of traditional risk factors, with implications for preventive strategies.

Relationship of arterial tonometry and exercise in patients with chronic heart failure: a systematic review with meta-analysis and trial sequential analysis

BACKGROUND

Arterial stiffness is a common characteristic in patients with chronic heart failure (CHF), and arterial tonometric technologies related to arterial stiffness are novel and effective methods and have an important value in the diagnosis and prognosis of CHF. In terms of ameliorating arterial stiffness in patients with CHF, exercise training is considered an adjuvant treatment and also an effective means in the diagnosis and judgment of prognosis. However, there are huge controversies and inconsistencies in these aspects. The objective of this meta-analysis was to systematically test the connection of arterial tonometry and exercise in patients with CHF.

METHODS

Databases, including MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, were accessed from inception to 7 March 2022. The meta-analysis was then conducted, and trial sequential analysis (TSA) was performed jointly to further verify our tests and reach more convincing conclusions by using RevMan version 5.4 software, STATA version 16.0 software, and TSA version 0.9.5.10 Beta software.

RESULTS

Eighteen articles were included, with a total of 876 participants satisfying the inclusion criteria. The pooling revealed that flow-mediated dilation (FMD) was lower in basal condition [standardized mean difference (SMD): - 2.28%, 95% confidence interval (CI) - 3.47 to - 1.08, P < 0.001] and improved significantly after exercise (SMD: 5.96%, 95% CI 2.81 to 9.05, P < 0.001) in patients with heart failure with reduced ejection fraction (HFrEF) compared with healthy participants. The high-intensity training exercise was more beneficial (SMD: 2.88%, 95% CI 1.78 to 3.97, P < 0.001) than the moderate-intensity training exercise to improve FMD in patients with CHF. For augmentation index (AIx), our study indicated no significant differences (SMD: 0.50%, 95% CI - 0.05 to 1.05, P = 0.074) in patients with heart failure with preserved ejection fraction (HFpEF) compared with healthy participants. However, other outcomes of our study were not identified after further verification using TSA, and more high-quality studies are needed to reach definitive conclusions in the future.

CONCLUSIONS

This review shows that FMD is lower in basal condition and improves significantly after exercise in patients with HFrEF compared with healthy population; high-intensity training exercise is more beneficial than moderate-intensity training exercise to improve FMD in patients with CHF; besides, there are no significant differences in AIx in patients with HFpEF compared with the healthy population. More high-quality studies on this topic are warranted.

Short-term exposure to traffic-related air pollution and STEMI events: Insights into STEMI onset and related cardiac impairment

AIMS

Evidence on the impacts of traffic-related air pollution (TRAP) on ST-segment elevation myocardial infarction (STEMI) events is limited. We aimed to assess the acute effects of TRAP exposure on the clinical onset of STEMI and related cardiac impairments.

METHODS AND RESULTS

We recruited patients who were admitted for STEMI and underwent primary percutaneous coronary intervention at Peking University Third Hospital between 2014 and 2020. Indicators relevant to cardiac impairments were measured. Concomitantly, hourly concentrations of traffic pollutants were monitored throughout the study period, including fine particulate matter, black carbon (BC), particles in size ranges of 5-560 nm, oxides of nitrogen (NO_X), nitrogen dioxide, and carbon monoxide. The mean (SD) age of participants was 62.4 (12.5) years. Daily average (range) concentrations of ambient BC and NO_X were 3.9 (0.1-25.0) μg/m³ and 90.8 (16.6-371.7) μg/m³. Significant increases in STEMI risks of 5.9% (95% CI: 0.1, 12.0) to 21.9% (95% CI: 6.0, 40.2) were associated with interquartile range increases in exposure to TRAP within a few hours. These changes were accompanied by significant elevations in cardiac troponin T levels of 6.9% (95% CI: 0.2, 14.1) to 41.7% (95% CI: 21.2, 65.6), as well as reductions in left ventricular ejection fraction of 1.5% (95% CI: 0.1, 2.9) to 3.7% (95% CI: 0.8, 6.4). Furthermore, the associations were attenuated in participants living in areas with higher residential greenness levels.

CONCLUSIONS

Our findings extend current understanding that short-term exposure to higher levels of traffic pollution was associated with increased STEMI risks and exacerbated cardiac impairments, and provide evidence on traffic pollution control priority for protecting vulnerable populations who are at greater risks of cardiovascular events.

Controlled human exposure to diesel exhaust: a method for understanding health effects of traffic-related air pollution

Diesel exhaust (DE) is a major component of air pollution in urban centers. Controlled human exposure (CHE) experiments are commonly used to investigate the acute effects of DE inhalation specifically and also as a paradigm for investigating responses to traffic-related air pollution (TRAP) more generally. Given the critical role this model plays in our understanding of TRAP's health effects mechanistically and in support of associated policy and regulation, we review the methodology of CHE to DE (CHE-DE) in detail to distill critical elements so that the results of these studies can be understood in context. From 104 eligible publications, we identified 79 CHE-DE studies and extracted information on DE generation, exposure session characteristics, pollutant and particulate composition of exposures, and participant demographics. Virtually all studies had a crossover design, and most studies involved a single DE exposure per participant. Exposure sessions were typically 1 or 2 h in duration, with participants alternating between exercise and rest. Most CHE-DE targeted a PM concentration of 300 μg/m3. There was a wide range in commonly measured co-pollutants including nitrogen oxides, carbon monoxide, and total organic compounds. Reporting of detailed parameters of aerosol composition, including particle diameter, was inconsistent between studies, and older studies from a given lab were often cited in lieu of repeating measurements for new experiments. There was a male predominance in participants, and over half of studies involved healthy participants only. Other populations studied include those with asthma, atopy, or metabolic syndrome. Standardization in reporting exposure conditions, potentially using current versions of engines with modern emissions control technology, will allow for more valid comparisons between studies of CHE-DE, while recognizing that diesel engines in much of the world remain old and heterogeneous. Inclusion of female participants as well as populations more susceptible to TRAP will broaden the applicability of results from CHE-DE studies.

Traffic-related air pollution associated pulmonary pathophysiologic changes and cardiac injury in elderly patients with COPD

Traffic-related air pollution (TRAP) has shown enormous environmental toxicity, but its cardiorespiratory health impact on chronic obstructive pulmonary disease (COPD) has been less studied. We followed a panel of 45 COPD patients with 4 repeated clinical visits across 14 months in a traffic-predominated urban area of Beijing, China, with concurrent measurements of TRAP metrics (fine particulate matter, black carbon, oxides of nitrogen and carbon monoxide). Linear mixed-effect models were performed to evaluate the associations and potential pathways linking traffic pollution to indicators of spirometry, cardiac injury, inflammation and oxidative stress. We observed that interquartile range increases in moving averages of TRAP exposures at prior up to 7 days were associated with significant reductions in large and small airway functions, namely decreases in forced vital capacity of 3.1-9.3% and forced expiratory flow 25-75% of 5.9-16.4%. Higher TRAP levels were also associated with worsening of biomarkers relevant to lung injury (hepatocyte growth factor and surfactant protein D) and cardiac injury (high-sensitivity cardiac troponin I, B-type natriuretic peptide and soluble ST2), as well as enhanced airway/systemic inflammation and oxidative stress. Mediation analyses showed that TRAP exposures may prompt cardiac injury, possibly via worsening pulmonary pathophysiology. These findings highlight the importance of traffic pollution control priority in urban areas.

Controlled human exposure to diesel exhaust: results illuminate health effects of traffic-related air pollution and inform future directions

Air pollution is an issue of increasing interest due to its globally relevant impacts on morbidity and mortality. Controlled human exposure (CHE) studies are often employed to investigate the impacts of pollution on human health, with diesel exhaust (DE) commonly used as a surrogate of traffic related air pollution (TRAP). This paper will review the results derived from 104 publications of CHE to DE (CHE-DE) with respect to health outcomes. CHE-DE studies have provided mechanistic evidence supporting TRAP’s detrimental effects on related to the cardiovascular system (e.g., vasomotor dysfunction, inhibition of fibrinolysis, and impaired cardiac function) and respiratory system (e.g., airway inflammation, increased airway responsiveness, and clinical symptoms of asthma). Oxidative stress is thought to be the primary mechanism of TRAP-induced effects and has been supported by several CHE-DE studies. A historical limitation of some air pollution research is consideration of TRAP (or its components) in isolation, limiting insight into the interactions between TRAP and other environmental factors often encountered in tandem. CHE-DE studies can help to shed light on complex conditions, and several have included co-exposure to common elements such as allergens, ozone, and activity level. The ability of filters to mitigate the adverse effects of DE, by limiting exposure to the particulate fraction of polluted aerosols, has also been examined. While various biomarkers of DE exposure have been evaluated in CHE-DE studies, a definitive such endpoint has yet to be identified. In spite of the above advantages, this paradigm for TRAP is constrained to acute exposures and can only be indirectly applied to chronic exposures, despite the critical real-world impact of living long-term with TRAP. Those with significant medical conditions are often excluded from CHE-DE studies and so results derived from healthy individuals may not apply to more susceptible populations whose further study is needed to avoid potentially misleading conclusions. In spite of limitations, the contributions of CHE-DE studies have greatly advanced current understanding of the health impacts associated with TRAP exposure, especially regarding mechanisms therein, with important implications for regulation and policy.

Joint exposure to various ambient air pollutants and incident heart failure: a prospective analysis in UK Biobank

AIMS

Little is known about the relation between the long-term joint exposure to various ambient air pollutants and the incidence of heart failure (HF). We aimed to assess the joint association of various air pollutants with HF risk and examine the modification effect of the genetic susceptibility.

METHODS AND RESULTS

This study included 432 530 participants free of HF, atrial fibrillation, or coronary heart disease in the UK Biobank study. All participants were enrolled from 2006 to 2010 and followed up to 2018. The information on particulate matter (PM) with diameters ≤2.5 µm (PM2.5), ≤10 µm (PM10), and between 2.5 and 10 µm (PM2.5-10) as well as nitrogen oxides (NO2 and NOx) was collected. We newly proposed an air pollution score to assess the joint exposure to the five air pollutants through summing each pollutant concentration weighted by the regression coefficients with HF from single-pollutant models. We also calculated the weighted genetic risk score of HF. During a median of 10.1 years (4 346 642 person-years) of follow-up, we documented 4201 incident HF. The hazard ratios (HRs) [95% confidence interval (CI)] of HF for a 10 µg/m3 increase in PM2.5, PM10, PM2.5-10, NO2, and NOx were 1.85 (1.34-2.55), 1.61 (1.30-2.00), 1.13 (0.80-1.59), 1.10 (1.04-1.15), and 1.04 (1.02-1.06), respectively. We found that the air pollution score was associated with an increased risk of incident HF in a dose-response fashion. The HRs (95% CI) of HF were 1.16 (1.05-1.28), 1.19 (1.08-1.32), 1.21 (1.09-1.35), and 1.31 (1.17-1.48) in higher quintile groups compared with the lowest quintile of the air pollution score (P trend <0.001). In addition, we observed that the elevated risk of HF associated with a higher air pollution score was strengthened by the genetic susceptibility to HF.

CONCLUSION

Our results indicate that the long-term joint exposure to various air pollutants including PM2.5, PM10, PM2.5-10, NO2, and NOx is associated with an elevated risk of incident HF in an additive manner. Our findings highlight the importance to comprehensively assess various air pollutants in relation to the HF risk.

Metabolomic Changes after Subacute Exposure to Polycyclic Aromatic Hydrocarbons: A Natural Experiment among Healthy Travelers from Los Angeles to Beijing

Emerging epidemiological evidence has associated exposure to polycyclic aromatic hydrocarbons (PAHs) with chronic diseases including cardiometabolic diseases and neurodegeneration. However, little information is available about their subacute effects, which may accumulate over years and contribute to chronic disease development. To fill this knowledge gap, we designed a natural experiment among 26 healthy young adults who were exposed to elevated PAHs for 10 weeks after traveling from Los Angeles to Beijing in 2014 and 2015. Serum was collected before, during, and after the trip for metabolomics analysis. We identified 50 metabolites that significantly changed 6-8 weeks after the travel to Beijing (FDR < 5%). The network analysis revealed two main independent modules. Module 1 was allocated to oxidative homeostasis-related response and module 2 to delayed enzymatic deinduction response. Remarkably, the module 1 metabolites were recovered 4-7 weeks after participants' return, while the module 2 metabolites were not. Urinary hydroxylated PAHs were significantly associated with metabolites from both modules, while PAH carboxylic acids, likely metabolites of alkylated PAHs, were only associated with antioxidation-related metabolites. These results suggested differential subacute effects of unsubstituted and alkylated PAHs. Further studies are warranted to elucidate the role of the reversibility of metabolite changes in adverse health effects of PAHs.

A systematic review of the health effects associated with the inhalation of particle-filtered and whole diesel exhaust

Background: Diesel exhaust is a complex mixture comprised of gases and particulate matter and is a contributor to ambient air pollution. To reduce health risks, recent changes in diesel engine technology have significantly altered the composition of diesel exhaust, primarily by lowering emissions of particulate matter. However, animal toxicological studies continue to report health effects following exposure to diesel exhaust from engines employing particulate filters. The cause of these effects remains unclear.Objective and methods: To gain an understanding of the role of both particle-filtered and whole diesel exhaust on specific health outcomes, we conducted a systematic review in which we examined animal toxicological and controlled human exposure studies that included a comparison between inhalation of particle-filtered and whole diesel exhaust on any health endpoint.Results: We identified 26 studies that met both the inclusion and study evaluation criteria. For most health outcomes, the particle filtration methods employed in the included studies did not appreciably attenuate the health effects associated with exposure to whole diesel exhaust. There were also several health endpoints for which significant effects were associated with exposure to either particle-filtered or whole diesel exhaust, but not to both.Conclusions: Overall, the results from this systematic review demonstrate that exposure to different components in diesel exhaust can have distinct and independent health effects. Thus, to better inform human health risk assessments, future studies aimed at elucidating the health effects from diesel exhaust should include exposure to both particle-filtered and whole diesel exhaust.

Short-term effects of ambient air pollution and outdoor temperature on biomarkers of myocardial damage, inflammation and oxidative stress in healthy adults

Supplemental Digital Content is available in the text.

The mechanisms whereby ambient air pollution and temperature changes promote cardiac events remain incompletely described. Seventy-three nonsmoking healthy adults (mean age 23.3, SD 5.4 years) were followed with up to four repeated visits across 15 months in Beijing in 2014–2016. Biomarkers relevant to myocardial damage (high-sensitivity cardiac troponin I [hs-cTnI]), inflammation (growth differentiation factor-15 [GDF-15]), and oxidative stress (8-hydroxy-2′-deoxyguanosine [8-OHdG]) were measured at each visit, while ambient air pollution and temperature were monitored throughout the study. Linear mixed-effects models coupled with distributed lag nonlinear models were used to assess the impacts of each exposure measure on study outcomes. During follow-up, average daily concentrations of fine particulate matter and outdoor temperature were 62.9 µg/m³ (8.1–331.0 µg/m³) and 10.1 °C (−6.5°C to 29.5°C). Serum hs-cTnI levels were detectable in 18.2% of blood samples, with 27.4% of individuals having ≥1 detectable values. Higher levels of ambient particulates and gaseous pollutants (per interquartile range) up to 14 days before clinical visits were associated with significant alterations in hs-cTnI levels of 22.9% (95% CI, 6.4, 39.4) to 154.7% (95% CI, 94.4, 215.1). These changes were accompanied by elevations of circulating GDF-15 and urinary 8-OHdG levels. Both low (5th percentile, −2.5 °C) and high (95th percentile, 24.8°C) outdoor temperatures, with breakpoint at ~13.0°C as the reference level, were also associated with elevations of hs-cTnI levels. Short-term exposure to ambient air pollution and temperature was associated with cardiac troponin, a biomarker of myocardial damage, along with increased inflammation and oxidative stress responses. These findings extend our understanding of the biological mechanisms linking pervasive environmental exposure to adverse cardiac events.

Health effects of exposure to diesel exhaust in diesel-powered trains

BACKGROUND

Short-term controlled exposure to diesel exhaust (DE) in chamber studies have shown mixed results on lung and systemic effects. There is a paucity of studies on well-characterized real-life DE exposure in humans. In the present study, 29 healthy volunteers were exposed to DE while sitting as passengers in diesel-powered trains. Exposure in electric trains was used as control scenario. Each train scenario consisted of three consecutive days (6 h/day) ending with biomarker samplings.

RESULTS

Combustion-derived air pollutants were considerably higher in the passenger carriages of diesel trains compared with electric trains. The concentrations of black carbon and ultrafine particles were 8.5 μg/m³ and 1.2-1.8 × 10⁵ particles/cm³ higher, respectively, in diesel as compared to electric trains. Net increases of NOx and NO₂ concentrations were 317 μg/m³ and 36 μg/m³. Exposure to DE was associated with reduced lung function and increased levels of DNA strand breaks in peripheral blood mononuclear cells (PBMCs), whereas there were unaltered levels of oxidatively damaged DNA, soluble cell adhesion molecules, acute phase proteins in blood and urinary excretion of metabolites of polycyclic aromatic hydrocarbons. Also the microvascular function was unaltered. An increase in the low frequency of heart rate variability measures was observed, whereas time-domain measures were unaltered.

CONCLUSION

Exposure to DE inside diesel-powered trains for 3 days was associated with reduced lung function and systemic effects in terms of altered heart rate variability and increased levels of DNA strand breaks in PBMCs compared with electric trains.

TRIAL REGISTRATION

ClinicalTrials.Gov ( NCT03104387 ). Registered on March 23rd 2017.

Traffic exposures, air pollution and outcomes in pulmonary arterial hypertension: a UK cohort study analysis

While traffic and air pollution exposure is associated with increased mortality in numerous diseases, its association with disease severity and outcomes in pulmonary arterial hypertension (PAH) remains unknown.Exposure to particulate matter with a 50% cut-off aerodynamic diameter ≤2.5 μm (PM_2.5), nitrogen dioxide (NO₂) and indirect measures of traffic-related air pollution (distance to main road and length of roads within buffer zones surrounding residential addresses) were estimated for 301 patients with idiopathic/heritable PAH recruited in the UK National Cohort Study of Idiopathic and Heritable PAH. Associations with transplant-free survival and pulmonary haemodynamic severity at baseline were assessed, adjusting for confounding variables defined a prioriHigher estimated exposure to PM_2.5 was associated with higher risk of death or lung transplant (unadjusted hazard ratio (HR) 2.68 (95% CI 1.11-6.47) per 3 μg·m^-3; p=0.028). This association remained similar when adjusted for potential confounding variables (HR 4.38 (95% CI 1.44-13.36) per 3 μg·m^-3; p=0.009). No associations were found between NO₂ exposure or other traffic pollution indicators and transplant-free survival. Conversely, indirect measures of exposure to traffic-related air pollution within the 500-1000 m buffer zones correlated with the European Society of Cardiology/European Respiratory Society risk categories as well as pulmonary haemodynamics at baseline. This association was strongest for pulmonary vascular resistance.In idiopathic/heritable PAH, indirect measures of exposure to traffic-related air pollution were associated with disease severity at baseline, whereas higher PM_2.5 exposure may independently predict shorter transplant-free survival.

Diesel exhaust exposure, its multi-system effects, and the effect of new technology diesel exhaust

Exposure to diesel exhaust (DE) from vehicles and industry is hazardous and affects proper function of organ systems. DE can interfere with normal physiology after acute and chronic exposure to particulate matter (PM). Exposure leads to potential systemic disease processes in the central nervous, visual, hematopoietic, respiratory, cardiovascular, and renal systems. In this review, we give an overview of the epidemiological evidence supporting the harmful effects of diesel exhaust, and the numerous animal studies conducted to investigate the specific pathophysiological mechanisms behind DE exposure. Additionally, this review includes a summary of studies that used biomarkers as an indication of biological plausibility, and also studies evaluating new technology diesel exhaust (NTDE) and its systemic effects. Lastly, this review includes new approaches to improving DE emissions, and emphasizes the importance of ongoing study in this field of environmental health.

Systemic effects of controlled exposure to diesel exhaust: a meta-analysis from randomized controlled trials

INTRODUCTION

Ambient air pollution is associated with adverse cardiovascular events. This meta-analysis aimed to investigate the short-term association between air pollution and cardiovascular effects on healthy volunteers.

METHODS

We searched databases to identify randomized trials with controlled human exposures to either of two models for studying ambient particulate matter: diesel-exhaust or concentrated ambient particles. Estimates of size effect were performed using standardized mean difference (SMD). Heterogeneity was assessed with I₂ statistics. Outcomes were vascular function estimated by forearm blood flow (FBF), blood pressure, heart rate, and blood analysis.

RESULTS

Database searches yielded 17 articles (n = 342) with sufficient information for meta-analyses. High levels of heterogeneity for the some outcomes were analyzed using random-effects model. The pooled effect estimate showed that short-term exposure to air pollution impaired FBF response from 2.7 to 2.5 mL/100 mL tissue/min (SMD 0.404; p = .006). There was an increase in 5000 platelet/mm³ following pollution exposure (SMD 0.390; p = .050) but no significant differences for other outcomes.

CONCLUSION

Controlled human exposures to air pollution are associated with the surrogates of vascular dysfunction and increase in platelet count, which might be related to adverse cardiovascular events. Given the worldwide prevalence of exposure to air pollution, these findings are relevant for public health. KEY MESSAGES Controlled exposure to air pollution impairs vasomotor response, which is a surrogate for adverse cardiovascular events. This is the first meta-analysis from randomized clinical trials showing short-term association between air pollution and cardiovascular effects on healthy volunteers. Given the worldwide prevalence of exposure to air pollution, this finding is important for public health.

Risk of Cardiovascular Hospitalizations from Exposure to Coarse Particulate Matter (PM10) Below the European Union Safety Threshold

The association between exposure to air pollution and acute cardiovascular (CV) events is well documented; however, limited data are available evaluating the public health safety of various "doses" of particular matter (PM) below currently accepted safety thresholds. We explored the cross-sectional association between PM with aerodynamic diameter <10 μm (PM10) and daily CV hospitalizations in Brescia, Italy, using Poisson regression models adjusted for age, gender, and meteorologic indices. Average daily exposure to PM10 obtained from arithmetic means of air pollution data were captured by 4 selected monitoring stations. PM10 data were expressed as daily means (lag 0-day) or 3-day moving averages (lag 3-day) and categorized according to the European Union daily limit value of 50 μg/m(3). From September 2004 to September 2007, data from 6,000 acute CV admissions to a tertiary referral center were collected. An increase of 1 μg/m(3) PM10 at lag 0-day was independently associated with higher rates of acute hospitalizations for composite CV-related events (relative risk [RR] 1.004, 95% confidence interval [CI] 1.002 to 1.006), acute heart failure (RR 1.004, 95% CI 1.001 to 1.008), acute coronary syndromes (RR 1.002, 95% CI 0.999 to 1.005), malignant ventricular arrhythmias (RR 1.004, 95% CI 0.999 to 1.010), and atrial fibrillation (RR 1.008, 95% CI 1.003 to 1.012). Similar results were obtained using PM10 lag 3-day data. The excess PM10 CV hospitalization risk (by lag 0-day and lag 3-day) did not vary significantly above and below the 50 μg/m(3) safety threshold or by age and gender. In conclusion, increased levels of PM10, even below the current limits set by the European Union, were associated with excess risk for admissions for acute CV events.