Exploration of the composition and sources of urban fine particulate matter associated with same-day cardiovascular health effects in Dearborn, Michigan

The association between PM2.5 components and blood pressure changes in late pregnancy: A combined analysis of traditional and machine learning models

BACKGROUND

PM2.5 is a harmful mixture of various chemical components that pose a challenge in determining their individual and combined health effects due to multicollinearity issues with traditional linear regression models. This study aimed to develop an analytical methodology combining traditional and novel machine learning models to evaluate PM2.5's combined effects on blood pressure (BP) and identify the most toxic components.

METHODS

We measured late-pregnancy BP of 1138 women from the Heshan cohort while simultaneously analyzing 31 PM2.5 components. We utilized multiple linear regression modeling to establish the relationship between PM2.5 components and late-pregnancy BP and applied Random Forest (RF) and generalized Weighted Quantile Sum (gWQS) regression to identify the most toxic components contributing to elevated BP and to quantitatively evaluate the cumulative effect of the PM2.5 component mixtures.

RESULTS

The results revealed that 16 PM2.5 components, such as EC, OC, Ti, Fe, Mn, Cu, Cd, Mg, K, Pb, Se, Na+, K+, Cl-, NO3-, and F-, contributed to elevated systolic blood pressure (SBP), while 26 components, including two carbon components (EC, OC), fourteen metallics (Ti, Fe, Mn, Cr, Mo, Co, Cu, Zn, Cd, Na, Mg, Al, K, Pb), one metalloid (Se), and nine water-soluble ions (Na+, K+, Mg2+, Ca2+, NH4+, Cl-, NO3-, SO42-, F-), contributed to elevated diastolic blood pressure (DBP). Mn and Cr were the most toxic components for elevated SBP and DBP, respectively, as analyzed by RF and gWQS models and verified against each other. Exposure to PM2.5 component mixtures increased SBP by 1.04 mmHg (95% CI: 0.33-1.76) and DBP by 1.13 mmHg (95% CI: 0.47-1.78).

CONCLUSIONS

Our study highlights the effectiveness of combining traditional and novel models as an analytical strategy to quantify the health effects of PM2.5 constituent mixtures.

The effect of short-term remote ischemic preconditioning on endothelial function of patients with chronic kidney disease: A randomized pilot study

AIM

Patients with chronic kidney disease (CKD) are more susceptible to endothelial dysfunction and cardiovascular disease (CV). Remote ischemic preconditioning (rIPC) has been proven efficient in improving endothelial function and lowering the risk of CV. However, the safety and effect of rIPC on endothelial function in patients with CKD have not been effectively assessed.

METHODS

45 patients with CKD (average estimated glomerular filtration rate: 48.4 mL/min/1.73 m2) were randomly allocated to either 7-day daily upper-arm rIPC (4 × 5 min 200 mmHg, interspaced by 5-min reperfusion) or control (4 × 5 min 60 mmHg, interspaced by 5-min reperfusion). Vascular endothelial function was assessed by natural log-transformed reactive hyperemia index (LnRHI) before and after a 7-day intervention. Arterial elasticity was assessed by augmentation index (AI).

RESULTS

The results showed that LnRHI could be improved by rIPC treatment (Pre = 0.57 ± 0.04 vs. Post = 0.67 ± 0.04, p = .001) with no changes relative to control (Pre = 0.68 ± 0.06 vs. Post = 0.64 ± 0.05, p = .470). Compared with the control group, the improvement of LnRHI was greater after rIPC treatment (rIPC vs. Control: 0.10 ± 0.03 vs. -0.04 ± 0.06, between-group mean difference, -0.15 [95% CI, -0.27 to -0.02], p = .027), while there was no significant difference in the change of AI@75 bpm (p = .312) between the two groups.

CONCLUSION

RIPC is safe and well tolerated in patients with CKD. This pilot study suggests that rIPC seems to have the potential therapeutic effect to improve endothelial function. Of note, further larger trials are still warranted to confirm the efficacy of rIPC in improving endothelial function in CKD patients.

Environmental Exposome and Atrial Fibrillation: Emerging Evidence and Future Directions

There has been increased awareness of the linkage between environmental exposures and cardiovascular health and disease. Atrial fibrillation is the most common sustained cardiac arrhythmia, affecting millions of people worldwide and contributing to substantial morbidity and mortality. Although numerous studies have explored the role of genetic and lifestyle factors in the development and progression of atrial fibrillation, the potential impact of environmental determinants on this prevalent condition has received comparatively less attention. This review aims to provide a comprehensive overview of the current evidence on environmental determinants of atrial fibrillation, encompassing factors such as air pollution, temperature, humidity, and other meteorologic conditions, noise pollution, greenspace, and the social environment. We discuss the existing evidence from epidemiological and mechanistic studies, critically evaluating the strengths and limitations of these investigations and the potential underlying biological mechanisms through which environmental exposures may affect atrial fibrillation risk. Furthermore, we address the potential implications of these findings for public health and clinical practice and identify knowledge gaps and future research directions in this emerging field.

Reduction of Outdoor and Indoor PM2.5 Source Contributions via Portable Air Filtration Systems in a Senior Residential Facility in Detroit, Michigan

Background: The Reducing Air Pollution in Detroit Intervention Study (RAPIDS) was designed to evaluate cardiovascular health benefits and personal fine particulate matter (particulate matter < 2.5 μm in diameter, PM2.5) exposure reductions via portable air filtration units (PAFs) among older adults in Detroit, Michigan. This double-blind randomized crossover intervention study has shown that, compared to sham, air filtration for 3 days decreased 3-day average brachial systolic blood pressure by 3.2 mmHg. The results also showed that commercially available HEPA-type and true HEPA PAFs mitigated median indoor PM2.5 concentrations by 58% and 65%, respectively. However, to our knowledge, no health intervention study in which a significant positive health effect was observed has also evaluated how outdoor and indoor PM2.5 sources impacted the subjects. With that in mind, detailed characterization of outdoor and indoor PM2.5 samples collected during this study and a source apportionment analysis of those samples using a positive matrix factorization model were completed. The aims of this most recent work were to characterize the indoor and outdoor sources of the PM2.5 this community was exposed to and to assess how effectively commercially available HEPA-type and true HEPA PAFs were able to reduce indoor and outdoor PM2.5 source contributions. Methods: Approximately 24 h daily indoor and outdoor PM2.5 samples were collected on Teflon and Quartz filters from the apartments of 40 study subjects during each 3-day intervention period. These filters were analyzed for mass, carbon, and trace elements. Environmental Protection Agency Positive Matrix Factorization (PMF) 5.0 was utilized to determine major emission sources that contributed to the outdoor and indoor PM2.5 levels during this study. Results: The major sources of outdoor PM2.5 were secondary aerosols (28%), traffic/urban dust (24%), iron/steel industries (15%), sewage/municipal incineration (10%), and oil combustion/refinery (6%). The major sources of indoor PM2.5 were organic compounds (45%), traffic + sewage/municipal incineration (14%), secondary aerosols (13%), smoking (7%), and urban dust (2%). Infiltration of outdoor PM2.5 for sham, HEPA-type, and true HEPA air filtration was 79 ± 24%, 61 ± 32%, and 51 ± 34%, respectively. Conclusions: The results from our study showed that intervention with PAFs was able to significantly decrease indoor PM2.5 derived from outdoor and indoor PM2.5 sources. The PAFs were also able to significantly reduce the infiltration of outdoor PM2.5. The results of this study provide insights into what types of major PM2.5 sources this community is exposed to and what degree of air quality and systolic blood pressure improvements are possible through the use of commercially available PAFs in a real-world setting.

Pre- and postnatal particulate matter exposure and blood pressure in children and adolescents: A systematic review and meta-analysis

BACKGROUND

Early life is a susceptible period of air pollution-related adverse health effects. Hypertension in children might be life-threatening without prevention or treatment. Nevertheless, the causative association between environmental factors and childhood hypertension was limited. In the light of particulate matter (PM) as an environmental risk factor for cardiovascular diseases, this study investigated the association of pre- and postnatal PM exposure with blood pressure (BP) and hypertension among children and adolescents.

METHOD

Four electronic databases were searched for related epidemiological studies published up to September 13, 2022. Stata 14.0 was applied to examine the heterogeneity among the studies and evaluate the combined effect sizes per 10 μg/m³ increase of PM by selecting the corresponding models. Besides, subgroup analysis, sensitivity analysis, and publication bias test were also conducted.

RESULTS

Prenatal PM_2.5 exposure was correlated with increased diastolic blood pressure (DBP) in offspring [1.14 mmHg (95% CI: 0.12, 2.17)]. For short-term postnatal exposure effects, PM_2.5 (7-day average) was significantly associated with systolic blood pressure (SBP) [0.20 mmHg (95% CI: 0.16, 0.23)] and DBP [0.49 mmHg (95% CI: 0.45, 0.53)]; and also, PM₁₀ (7-day average) was significantly associated with SBP [0.14 mmHg (95% CI: 0.12, 0.16)]. For long-term postnatal exposure effects, positive associations were manifested in SBP with PM_2.5 [β = 0.44, 95% CI: 0.40, 0.48] and PM₁₀ [β = 0.35, 95% CI: 0.19, 0.51]; DBP with PM₁ [β = 0.45, 95% CI: 0.42, 0.49], PM_2.5 [β = 0.31, 95% CI: 0.27, 0.35] and PM₁₀ [β = 0.32, 95% CI: 0.19, 0.45]; and hypertension with PM₁ [OR = 1.43, 95% CI: 1.40, 1.46], PM_2.5 [OR = 1.65, 95% CI: 1.29, 2.11] and PM₁₀ [OR = 1.26, 95% CI: 1.09, 1.45].

CONCLUSION

Both prenatal and postnatal exposure to PM can increase BP, contributing to a higher prevalence of hypertension in children and adolescents.

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

BACKGROUND

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

OBJECTIVE

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

MAIN FINDINGS

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

CONCLUSION

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

The influences of ambient fine particulate matter constituents on plasma hormones, circulating TMAO levels and blood pressure: A panel study in China

Considerable investigations have been carried out to address the relationship between ambient fine particulate matter (PM_2.5) and blood pressure (BP) in patients with hypertension. However, few studies have explored the influence of PM_2.5 and its constituents on Trimethylamine N-oxide (TMAO), an established risk factor for hypertension and cardiovascular disease (CVD), particularly in severely air-polluted areas. To explore the potential impact of PM_2.5 constituents on BP, plasma hormones, and TMAO, a panel study was conducted to investigate changes in BP, plasma hormones, and TMAO in response to ambient air pollution exposure in stage 1 hypertensive young adults. Linear mixed effect models were used to estimate the cumulative effects of fine particulate matters (PM_2.5) and its constituents on BP, plasma hormones and TMAO. We found that one interquartile range (IQR) (35 μg/m³) increase in 0-1 day moving-average PM_2.5 concentrations was statistically significantly associated with elevated systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) with estimated values of 0.13 (95% confidence interval (CI): 0.03 to 0.23) mmHg, 0.18 (95% CI: 0.08 to 0.28) mmHg, and 0.17 (95% CI: 0.09 to 0.26) mmHg, respectively. Hormone disturbance in the renin-angiotensin-aldosterone system was also associated with PM_2.5 exposure. Elevated TMAO levels with an IQR increase for 0-4, 0-5, 0-6 moving-average concentrations of PM_2.5 were found, and the increased values ranged from 26.28 (95% CI: 2.92 to 49.64) to 60.78 (31.95-89.61) ng/ml. More importantly, the PM_2.5-bound metal constituents, such as manganese (Mn), titanium (Ti), and selenium (Se) showed robust associations with elevated BP and plasma TMAO levels. This study demonstrates associations between PM_2.5 metal constituents and increased BP, changes in plasma hormones and TMAO, in stage 1 hypertensive young adults. Source control, aiming to reduce the emission of PM_2.5-bound metals should be implemented to reduce the risk of hypertension and CVD.

Susceptibility of patients with chronic obstructive pulmonary disease to heart rate difference associated with the short-term exposure to metals in ambient fine particles: A panel study in Beijing, China

Susceptibility of patients with chronic obstructive pulmonary disease (COPD) to cardiovascular autonomic dysfunction associated with exposure to metals in ambient fine particles (PM_2.5, particulate matter with aerodynamic diameter ≤2.5 µm) remains poorly evidenced. Based on the COPDB (COPD in Beijing) panel study, we aimed to compare the associations of heart rate (HR, an indicator of cardiovascular autonomic function) and exposure to metals in PM_2.5 between 53 patients with COPD and 82 healthy controls by using linear mixed-effects models. In all participants, the HR levels were significantly associated with interquartile range increases in the average concentrations of Cr, Zn, and Pb, but the strength of the associations differed by exposure time (from 1.4% for an average 9 days (d) Cr exposure to 3.5% for an average 9 d Zn exposure). HR was positively associated with the average concentrations of PM_2.5 and certain metals only in patients with COPD. Associations between HR and exposure to PM_2.5, K, Cr, Mn, Ni, Cu, Zn, As, and Se in patients with COPD significantly differed from those in health controls. Furthermore, association between HR and Cr exposure was robust in COPD patients. In conclusion, our findings indicate that COPD could exacerbate difference in HR following exposure to metals in PM_2.5.

Chemical content and source apportionment of 36 heavy metal analysis and health risk assessment in aerosol of Beijing

The concentration levels of 36 airborne heavy metals and atmospheric radioactivity in total suspended particulate (TSP) samples were measured to investigate the chemical characteristics, potential sources of aerosols, and health risk in Beijing, China, from September 2016 to September 2017. The TSP concentrations varied from 6.93 to 469.18 μg/m³, with a median of 133.97 μg/m³. The order for the mean concentrations of heavy metals, known as hazardous air pollutants (HAPs), was as follows: Mn > Pb > As > Cr > Ni > Se > Cd > Co > Sb > Hg > Be; Non-Designated HAPs Metals: Ca > Fe > Mg > Al > K > Na > Zn > P > Ba > Ti > Cu > Sr > B > Sn > I > V > Rb > Ce > Mo > Cs > Th > Ag > U > Pt. The median concentration of As was higher than China air quality standard (6 ng/m³). The gross α and β concentration levels in aerosols were (1.84 ± 1.59) mBg/m³ and (1.15 ± 0.85) mBg/m³, respectively. The enrichment factor values of Cu, Ba, B, Ce, Tl, Cs, Pb, As, Cd, Sb, Hg, Fe, Zn, Sn, I, Mo, and Ag were higher than 10, which indicated enriched results from anthropogenic sources. Pb, As, and Cd are considered to originate from multiple sources; fireworks released Ba during China spring festival; Fe, Ce, and Cs may come from stable emissions such as industrial gases. The health risks from anthropogenic metals via inhalation, ingestion, and dermal pathway were estimated on the basis of health quotient as well as the results indicated that children faced the higher risk than adults during the research period. For adults, the health risk posed by heavy metals in atmospheric particles was below the acceptable level.

PM2.5 upregulates rat mesenteric arteries 5-HT2A receptor via inflammatory-mediated mitogen-activated protein kinases signaling pathway

Fine particulate matter (PM_2.5 ) is an important environmental risk factor for cardiovascular diseases. However, little is known about the effects of PM_2.5 on arteries. The present study investigated whether PM_2.5 alters 5-hydroxytryptamine (5-HT) receptor expression and inflammatory mediators on rat mesenteric arteries, and examined the underlying mechanisms. Isolated rat mesenteric arteries segments were cultured with PM_2.5 in the presence or absence of ERK1/2, JNK, and p38 pathway inhibitors. Contractile reactivity was monitored by a sensitive myograph. The expression of 5-HT_2A/1B receptors and inflammatory mediators were studied by a real-time polymerase chain reaction and/or by immunohistochemistry. The phosphorylation of mitogen-activated protein kinases (MAPK) pathway was detected by Western blot. Compared with the fresh or culture alone groups, 1.0 μg/mL PM_2.5 cultured for 16 hours significantly enhanced contractile response induced by 5-HT and increased 5-HT_2A receptor mRNA and protein expressions, indicating PM_2.5 upregulates 5-HT_2A receptor. SB203580 (p38 inhibitor) and U0126 (ERK1/2 inhibitor) significantly decreased PM_2.5 -induced elevated contraction and mRNA and protein expression of 5-HT_2A receptor. Cultured with PM_2.5 significantly increased the mRNA expression of inflammatory mediators (NOS2, IL-1β, and TNF-α), while SB203580 decreased mRNA expression level of NOS2, IL-1β, and TNF-α. SP600125 (JNK inhibitor) decreased mRNA expression level of TNF-α and IL-1β. After PM_2.5 exposure, the phosphorylation of p38 and ERK1/2 protein were increased. SB203580 and U0126 inhibited the PM_2.5 caused increased phosphorylation protein of p38 and ERK1/2. In conclusion, PM_2.5 induces inflammatory-mediated MAPK pathway in artery which subsequently results in enhanced vascular contraction responding to 5-HT via the upregulated 5-HT_2A receptors.

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).

Mean platelet volume mediated the relationships between heavy metals exposure and atherosclerotic cardiovascular disease risk: A community-based study

BACKGROUND

Heavy metals were related to increased risk of atherosclerotic cardiovascular disease (ASCVD). However, potential mechanisms under such associations remain unclear. We aimed to investigate the mediating role of mean platelet volume in the associations between heavy metals exposure and 10-year ASCVD risk.

METHOD

Urinary heavy metals and mean platelet volume were measured in 3081 adults from the Wuhan-Zhuhai cohort in China. The associations between urinary heavy metals, mean platelet volume and 10-year ASCVD risk were separately analyzed through generalized linear models and logistic regression models. Mediation analyses were conducted to assess the role of mean platelet volume in the associations between urinary heavy metals and 10-year ASCVD risk.

RESULTS

After adjusting for potential confounders, 10-year ASCVD risk was positively associated with urinary iron (odds ratio (OR) = 1.142, 95% confidence interval (1.038-1.256)), copper (OR = 1.384 (1.197-1.601)), zinc (OR = 1.520 (1.296-1.783)), cadmium (OR = 1.153 (0.990, 1.342)) and antimony (OR = 1.452 (1.237-1.704)), and negatively related with urinary barium (OR = 0.905 (0.831-0.985)). Also, we found significant dose-response relationships between urinary iron, zinc, antimony and mean platelet volume, as well as between mean platelet volume and 10-year ASCVD risk (all pfor trends < 0.05). Furthermore, mediation analyses indicated that mean platelet volume mediated 17.55%, 6.15% and 7.38% of the associations between urinary iron, zinc, antimony and 10-year ASCVD risk, respectively (all pvalue < 0.05).

CONCLUSIONS

Elevated concentrations of urinary iron, copper, zinc, cadmium and antimony were associated with increased risk of 10-year ASCVD. Mean platelet volume partially mediated the associations of urinary iron, zinc and antimony with 10-year ASCVD risk.

Long-term exposure to fine particulate matter and tachycardia and heart rate: Results from 10 million reproductive-age adults in China

BACKGROUND

Epidemiological evidence of the association of long-term ambient fine particulate matter (aerodynamic diameter ≤2.5 μm; PM_2.5) exposure with resting heart rate is limited. We explored the association of long-term (3-year average) ambient PM_2.5 exposure with tachycardia and resting heart rate.

METHODS

This cross-sectional study surveyed 10,427,948 reproductive-age (20-49 years) adults across China in 2015. Tachycardia was classified as a resting heart rate of >80 beats per minute (bpm). The annual average ambient PM_2.5 concentrations were obtained from a hybrid satellite-based geophysical statistical model. Linear mixed models and mixed effects logistic regressions adjusted for potential confounding were performed to explore the associations of PM_2.5 with resting heart rate and PM_2.5 with tachycardia, respectively. The effect modifiers by sex, age, body mass index, urbanity, race, region, smoking status, and drinking status were also assessed. Attributable cases and population fraction were estimated according to the PM_2.5- tachycardia relationship.

RESULTS

The mean age was 28 years, and 16.3% of the participants had tachycardia. The odds ratio for tachycardia was 1.018 (95% confidence intervals [CI]: 1.017, 1.020) per 10 μg/m³ increase in the 3-year average PM_2.5 exposure. A 10 μg/m³ increase in the 3-year average ambient PM_2.5 level was associated with a 0.076 (95% CI: 0.073, 0.079) bpm elevation in the resting heart rate. Of the tachycardia burden, 4.0% (95% CI: 3.8%, 4.3%) could be attributed to ambient PM_2.5 exposure in Chinese reproductive-age adults.

CONCLUSIONS

Exposures to ambient PM_2.5 were associated with elevated resting heart rate. It might be possible to decrease China's avoidable tachycardia burden in reproductive-age adults through decreasing PM_2.5 levels.

Estimating Acute Cardiovascular Effects of Ambient PM2.5 Metals

BACKGROUND

Few epidemiologic studies have investigated health effects of water-soluble fractions of PM_2.5 metals, the more biologically accessible fractions of metals, in their attempt to identify health-relevant components of ambient PM_2.5.

OBJECTIVES

In this study, we estimated acute cardiovascular effects of PM_2.5 components in an urban population, including a suite of water-soluble metals that are not routinely measured at the ambient level.

METHODS

Ambient concentrations of criteria gases, PM_2.5, and PM_2.5 components were measured at a central monitor in Atlanta, Georgia, during 1998-2013, with some PM_2.5 components only measured during 2008-2013. In a time-series framework using Poisson regression, we estimated associations between these pollutants and daily counts of emergency department (ED) visits for cardiovascular diseases in the five-county Atlanta area.

RESULTS

Among the PM_2.5 components we examined during 1998-2013, water-soluble iron had the strongest estimated effect on cardiovascular outcomes [R͡R=1.012 (95% CI: 1.005, 1.019), per interquartile range increase (20.46ng/m³)]. The associations for PM_2.5 and other PM_2.5 components were consistent with the null when controlling for water-soluble iron. Among PM_2.5 components that were only measured during 2008-2013, water-soluble vanadium was associated with cardiovascular ED visits [R͡R=1.012 (95% CI: 1.000, 1.025), per interquartile range increase (0.19ng/m³)].

CONCLUSIONS

Our study suggests cardiovascular effects of certain water-soluble metals, particularly water-soluble iron. The observed associations with water-soluble iron may also point to certain aspects of traffic pollution, when processed by acidifying sulfate, as a mixture harmful for cardiovascular health. https://doi.org/10.1289/EHP2182.

Combustion-Related Organic Species in Temporally Resolved Urban Airborne Particulate Matter

Accurate characterization of the chemical composition of particulate matter (PM) is essential for improved understanding of source attribution and resultant health impacts. To explore this we conducted ambient monitoring of a suite of 15 combustion-related organic species in temporally resolved PM 2.5 samples during an ongoing animal exposure study in a near source environment in Detroit, MI. All of the 15 species detected were above the method detection limit in 8 hour samples. This study focused on two molecular classes: Polycyclic Aromatic Hydrocarbons (PAHs) and Hopanes measured in samples. Of the 12 PAHs studied, benzo[b]fluoranthene (169 pg m-3), benzo[g,h,i]perylene (124 pg m-3), and benzo[e]pyrene (118, pg m-3) exhibited the three highest mean concentrations while 17α(H),21β(H)-Hopane (189 pg m-3) and 17α(H),21β(H)-30-Norhopane (145 pg m-3) had the highest mean concentrations of the 3 Hopanes analyzed in samples. Ratios of individual compound concentrations to total compound concentrations (∑ 15 compounds) showed the greatest daily variation for 17α(H),21β(H)-Hopane (11-28%) and 17α(H),21β(H)-30-Norhopane (8-20%). Diagnostic PAH concentration ratios ([IP]/[IP + BP] (range 0.30 - 0.45), [BaP]/[BaP+BeP] (range 0.26 - 0.44), [BaP]/[BP] (range 0.41 - 0.82), [Bb]/[Bk] (range 2.07 - 2.66), in samples reflected impacts froma mixture of combustion sources consistent with greater prevalence of petroleum combustion source emissions (gasoline, diesel, kerosene, and crude oil) compared to coal or wood combustion emissions impacts at this urban site. Results from this study demonstrate that short duration sampling for organic speciation provides temporally relevant exposure information.

Analysis of Temporal Variability in the Short-term Effects of Ambient Air Pollutants on Nonaccidental Mortality in Rome, Italy (1998-2014)

OBJECTIVES

The association between short-term air pollution exposure and daily mortality has been widely investigated, but little is known about the temporal variability of the effect estimates. We examined the temporal relationship between exposure to particulate matter (PM) (PM₁₀, PM_2.5) and gases (NO₂, SO₂, and CO) with mortality in a large metropolitan area over the last 17 y.

METHODS

Our analysis included 359,447 nonaccidental deaths among ≥35-y-old individuals in Rome, Italy, over the study period 1998–2014. We related daily concentrations to mortality counts with a time-series Poisson regression analysis adjusted for long-term trends, meteorology, and population dynamics.

RESULTS

Annual average concentrations decreased over the study period for all pollutants (e.g., from 42.9 to 26.6 μg/m³ for PM₁₀). Each pollutant was positively associated with mortality, with estimated percentage increases over the entire study period ranging from 0.19% (95% CI: 0.13, 0.26) for a 1-Mg/m³ increase in CO (0–1 d lag) to 3.03% (95% CI: 2.44, 3.63) for a 10-μg/m³ increase in NO₂ (0–5 d lag). We did not observe clear temporal patterns in year- or period-specific effect estimates for any pollutant. For example, we estimated that a 10-μg/m³ increase in PM₁₀ was associated with 1.16% (95% CI: 0.53, 1.79), 0.99% (95% CI: 0.23, 1.77), and 1.87% (95% CI: 1.00, 2.74) increases in mortality for the periods 2001–2005, 2006–2010, and 2011–2014, respectively, and corresponding estimates for a 10-μg/m³ increase in NO₂ were 4.20% (95% CI: 3.15, 5.25), 1.78% (95% CI: 0.73, 2.85), and 3.32% (95% CI: 2.03, 4.63).

CONCLUSIONS

Mean concentrations of air pollutants have decreased over the last two decades in Rome, but effect estimates for a fixed increment in each exposure were generally consistent. These findings suggest that there has been little or no change in the overall toxicity of the air pollution mixture over time. https://doi.org/10.1289/EHP19.

Airborne fine particulate matter alters the expression of endothelin receptors in rat coronary arteries

Exposure to airborne fine particulate matter (PM_2.5) is associated with cardiovascular diseases. However, a comprehensive understanding of the underlying mechanisms by which PM_2.5 induces or aggravates these diseases is still insufficiently clear. The present study investigated whether PM_2.5 alters the expression of the endothelin subtype B (ET_B) and endothelin subtype A (ET_A) receptors in the coronary artery and examined the underlying mechanisms. Rat coronary artery segments were cultured with PM_2.5 in the presence or absence of MEK/ERK1/2, JNK, and p38 pathway inhibitors. Contractile reactivity was measured by myography. ET_B and ET_A receptor expression was evaluated using RT-PCR, western blot and immunohistochemistry. Compared with fresh arteries, the cultured coronary arteries showed a significantly enhanced contraction mediated by the ET_B receptor and an unaltered contraction mediated by the ET_A receptor. Culture with PM_2.5 significantly enhanced the contraction and the mRNA and protein expression levels of the ET_B and ET_A receptors in the coronary arteries, suggesting that PM_2.5 induces an upregulation of ET_A and ET_B receptors. In addition, the PM_2.5-induced increases in ET_B- and ET_A-mediated vasoconstriction and receptor expressions could be notably decreased by MEK1/2 inhibitor, U0126 and Raf inhibitor, SB386023, suggesting that the upregulation of ET_B and ET_A receptors is related with MEK/ERK1/2 pathway. In conclusion, PM_2.5 induces the ET_B and ET_A receptor upregulation in rat coronary arteries, and the MEK/ERK1/2 pathway may be involved in this process.

PM2.5-induced cardiovascular dysregulation in rats is associated with elemental carbon and temperature-resolved carbon subfractions

Background

We tested the hypothesis that cardiovascular responses to PM_2.5 exposure will be enhanced in hypertensive rats and linked to specific carbonaceous pollutants in an urban industrial setting.

Methods

Spontaneously hypertensive rats were exposed by inhalation to concentrated PM_2.5 in an industrial area of Dearborn, Michigan, for four consecutive summer days. Blood pressure (BP), heart rate (HR) and HR variability (HRV) metrics (SDNN, RMSSD) were assessed by radiotelemetry and compared to 1 h- and 8 h-averaged fluctuations in PM_2.5 composition, with a focus on elemental and organic carbon (EC and OC, respectively), and temperature-resolved subfractions (EC1-EC5, PC (pyrolized carbon), and OC1-OC4), as well as other major and minor PM components.

Results

Mean HR and BP were increased, while HRV was decreased over 4 days of exposure. Using 1 h averages, EC (1 μg/m³ increase) was associated with increased HR of 11-32 bpm (4-11% increase), 1.2-1.5 ms (22-27%) decreases in SDNN, 3-14 mmHg (1.5-8%) increases in systolic BP, and 5-12 mmHg (4-9%) increases in diastolic BP. By comparison, associations with OC were negligible. Using 8 h averages, EC subfractions were linked with increased heart rate (EC1: 13 bpm; EC2, EC3, PC: <5 bpm) and SDNN (EC1> > EC2 > EC3, EC4, PC), but with decreased RMSSD (EC2, EC5 > EC3, EC4). Minimal effects were associated with OC and OC1. Associations between carbon subfractions and BP were negligible. Associations with non-carbonaceous components and trace elements were generally non-significant or of negligible effect size.

Conclusions

These findings are the first to describe associations between acute cardiovascular responses and thermally resolved carbon subfractions. We report that cardiovascular responses to PM_2.5 carbonaceous materials appear to be driven by EC and its EC1 fraction.