Fine particulate matter exposure and lipid levels among children in Mexico city

Windows of susceptibility and joint effects of prenatal and postnatal ambient air pollution and temperature exposure on asthma and wheeze in Mexican children

INTRODUCTION

Prenatal and early-life exposure to air pollution and extreme temperatures are associated with childhood asthma and wheeze. However, potential windows of susceptibility and their sex-specific and interactive effects have not been fully elucidated. We aimed to identify critical windows of susceptibility and evaluate sex-specific effects in these associations, and evaluate exposure interactions.

METHODS

We analyzed data from 468 mother-child pairs enrolled in the PROGRESS birth cohort in Mexico City. Daily residential levels of PM2.5, NO2, and temperature were generated from our validated spatiotemporally resolved models from conception to age 4 years. Childhood asthma and wheeze outcomes were collected at 4-6 and 7-8 years. Distributed lag nonlinear models (DLNMs) were used to identify susceptible windows for prenatal weekly-specific and postnatal monthly-specific associations of air pollution and temperature with respiratory outcomes adjusting for covariates. To evaluate sex-specific effects, DLNMs were stratified. Joint effects were assessed using relative excess risk due to interaction and attributable proportion.

RESULTS

Mid-gestation was a critical window for both PM2.5 (weeks 20-28, cumulative OR: 1.18 [95% CI: 1.01, 1.37]; weeks 19-26, cumulative OR: 1.18 [95% CI: 1.02, 1.36]) and NO2 (weeks 18-25, cumulative OR: 1.16 [95% CI: 1.02, 1.31]) exposure, associated with higher odds of wheeze. Postnatal exposure to PM2.5 and NO2 during the first year of life was also linked to higher odds of wheeze. The warmer and colder temperatures showed mixed effects on respiratory outcomes. We observed a synergistic interaction between high PM2.5 and high temperature exposure during the first year of life, associated with higher odds of current wheeze. The associations of prenatal air pollution and temperature exposure with respiratory outcomes were more pronounced in males.

CONCLUSIONS

Early-life air pollution exposure contributes to the development of childhood asthma and wheeze, while exposure to temperature showed mixed associations with respiratory outcomes.

Increased vascular stiffness in children exposed in utero but not children exposed postnatally to emissions from a coal mine fire

Background

Chronic, low-intensity air pollution exposure has been consistently associated with increased atherosclerosis in adults. However, there was limited research regarding the implications of acute, high-intensity air pollution exposure during childhood. We aimed to determine whether there were any associations between early-life exposure to such an episode and early-life vascular function changes.

Methods

We conducted a prospective cohort study of children (<9 years old) who lived in the vicinity of the Hazelwood coal mine fire (n = 206). Vascular function was measured using noninvasive diagnostic methods including carotid intima-media thickness and pulse wave velocity (PWV). Exposure estimates were calculated from prognostic models and location diaries during the exposure period completed by each participant's parent. Linear mixed-effects models were used to determine whether there were any associations between exposure and changes in vascular outcomes at the 3- and 7-year follow-ups and over time.

Results

At the 7-year follow-up, each 10 μg/m3 increase in daily PM2.5 in utero was associated with increased PWV (β = 0.13 m/s; 95% confidence interval [CI] = 0.02, 0.24; P = 0.02). The association between in utero exposure to daily PM2.5 was not altered by adjustment for covariates, body mass index, and maternal fire stress. Each 1 µg/m3 increase in background PM2.5 was associated with increased PWV (β = 0.68 m/s; 95% CI = 0.10, 1.26; P = 0.025), in children from the in utero exposure group. There was a trend toward smaller PWV (β = -0.17 m/s; 95% CI = -0.366, 0.02) from the 3- to 7-year follow-up clinic suggesting that the deficits observed previously in children exposed postnatally did not persist.

Conclusion

There was a moderate improvement in vascular stiffness of children exposed to PM2.5 from a local coal mine fire in infancy. There was a mild increase in vascular stiffness in children exposed to PM2.5 from a local coal mine fire while their mothers were pregnant.

Early-life exposure to ambient air pollution with cardiovascular risk factors in adolescents: Findings from the "Children of 1997" Hong Kong birth cohort

BACKGROUND

Long-term exposure to ambient air pollution is associated with cardiovascular disease (CVD) risk. Little is known about the impact of early-life exposure to air pollutants on CVD risk factors in late adolescence, which may track into adulthood. To clarify, we examined this question in a unique setting with high air pollution and a high level of economic development.

METHODS

This study leveraged the "Children of 1997" Hong Kong birth cohort (N = 8327), including here 3350 participants. We estimated ambient air pollutant exposure including inhalable particulate matter (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2) and nitrogen monoxide (NO) by growth phase (in utero, infancy, childhood) and overall based on residential address. Generalized linear regression was used to assess the associations of air pollutants exposure by growth phase and sex with CVD risk factors (fasting blood glucose, glycosylated hemoglobin, lipid profile, blood pressure, and body mass index) at 17.6 years. We also assessed whether associations varied by sex.

RESULTS

Early life exposed had little association with glucose metabolism, blood pressure or body mass index, but after considering multiple comparisons early exposure to PM10 was associated with low density lipoprotein (LDL) in boys, with β and 95 % confidence intervals (95 % CI) of 0.184 (0.069 to 0.298) mmol/l, 0.151 (0.056 to 0.248) mmol/l, and 0.157 (0.063 to 0.252) mmol/l by per interquartile range (IQR) increment of PM10 for in utero, infancy, and overall, respectively. No such associations were evident for girls, differences by sex were evident.

CONCLUSIONS

Our study suggested sex-specific associations of early-life PM10 exposure with elevated LDL in adolescence, especially exposure in utero and infancy.

The association of in-utero exposure to air pollution and atherogenic index of plasma in newborns

BACKGROUND

Prenatal exposure to particulate matter (PM) and traffic was associated with the programming of cardiovascular diseases (CVDs) in early life. However, the exact underlying mechanisms are not fully understood. Therefore, we aimed to evaluate the association between in-utero exposure to PMs and traffic indicators with the atherogenic index of plasma (AIP) in newborns, which is a precise index reflecting an enhancement of lipid risk factors for CVDs.

METHODS

In this cross-sectional study, a total of 300 mother-newborn pairs were enrolled in Sabzevar, Iran. Spatiotemporal land-use regression models were used to estimate the level of PM1, PM2.5 and PM10 at the mother's residential address. The total length of streets in different buffers (100,300 and 500m) and proximity to major roads were calculated as indicators of traffic. The AIP of cord blood samples was calculated using an AIP calculator. Multiple linear regression models were used to examine the association of PM concentrations as well as traffic indicators with AIP controlled for relevant covariates.

RESULTS

PM2.5 exposure was significantly associated with higher levels of AIP in newborns. Each interquartile range (IQR) increment of PM2.5 concentration at the mothers' residential addresses was associated with a 5.3% (95% confidence interval (CI): 0.0, 10.6%, P = 0.04) increase in the AIP. Associations between PM1, PM10 and traffic indicators with cord blood level of AIP were positive but not statistically significant.

CONCLUSION

Our findings showed that in utero exposure to PM2.5 may be associated with CVDs programming through the increase of atherogenic lipids.

Association between Air Pollution and Lipid Profiles

Dyslipidemia is a critical factor in the development of atherosclerosis and consequent cardiovascular disease. Numerous pieces of evidence demonstrate the association between air pollution and abnormal blood lipids. Although the results of epidemiological studies on the link between air pollution and blood lipids are unsettled due to different research methods and conditions, most of them corroborate the harmful effects of air pollution on blood lipids. Mechanism studies have revealed that air pollution may affect blood lipids via oxidative stress, inflammation, insulin resistance, mitochondrial dysfunction, and hypothalamic hormone and epigenetic changes. Moreover, there is a risk of metabolic diseases associated with air pollution, including fatty liver disease, diabetes mellitus, and obesity, which are often accompanied by dyslipidemia. Therefore, it is biologically plausible that air pollution affects blood lipids. The overall evidence supports that air pollution has a deleterious effect on blood lipid health. However, further research into susceptibility, indoor air pollution, and gaseous pollutants is required, and the issue of assessing the effects of mixtures of air pollutants remains an obstacle for the future.

Association between ambient air pollutants and lipid profile: A systematic review and meta-analysis

BACKGROUND

Studies of the effects of atmospheric pollutants on lipid profiles remain inconsistent and controversial.

AIM

The study was aimed to investigate the relationship between the exposure to ambient air pollutants and variations in the blood lipid profiles in the population.

METHODS

A comprehensive search of three different databases (PubMed, Web of Science, and the Cochrane Library) until December 17, 2022, yielded 17 origional studies fulfilling the inclusion criteria for a meta-analysis. Aggregate effect measures and 95% confidence intervals (95% CI) for the relevant ambient air pollutants were deduced employing random effects models.

RESULTS

The collective meta-analysis indicated that long-term exposure to PM₁, PM_2.5, PM₁₀ and CO showed a substantial correlation with TC (PM₁: β = 2.04, 95%CI = 0.15-3.94; PM_2.5: β = 1.11, 95%CI = 0.39-1.84; PM₁₀: β = 1.70, 95%CI = 0.67-2.73; CO: β = 0.08, 95%CI = 0.06-0.10), PM₁₀ exhibited a significant association with TG (β = 0. 537,95% CI = 0.09-0.97), whereas HDL-C demonstrated notable relationships with PM₁, PM₁₀, SO₂ and CO (PM₁: β = -2.38, 95%CI = -4.00 to -2.76; PM₁₀: β = -0.77, 95%CI = -1.33 to -0.21; SO₂: β = -0.91, 95%CI = -1.73 to -0.10; CO: β = -0.03, 95%CI = -0.05 to 0.00). PM_2.5, PM₁₀ also showed significant associations with LDL-C (PM_2.5: β = 1.44 95%CI = 0.48-2.40; PM₁₀: β = 1.62 95%CI = 0.90-2.34). Subgroup analysis revealed significant or stronger correlations predominantly in cohort study designs, with higher male comparisons, and in regions exhibiting elevated contaminant levels.

CONCLUSION

In summary, the analysis substantiates that ambient air pollutants can be recognized as potent contributors to alterations in lipid profiles, particularly particulate pollutants which exert more obvious effects on lipid profiles.

Air Pollution, Built Environment, and Early Cardiovascular Disease

As the world's population becomes increasingly urbanized, there is growing concern about the impact of urban environments on cardiovascular health. Urban residents are exposed to a variety of adverse environmental exposures throughout their lives, including air pollution, built environment, and lack of green space, which may contribute to the development of early cardiovascular disease and related risk factors. While epidemiological studies have examined the role of a few environmental factors with early cardiovascular disease, the relationship with the broader environment remains poorly defined. In this article, we provide a brief overview of studies that have examined the impact of the environment including the built physical environment, discuss current challenges in the field, and suggest potential directions for future research. Additionally, we highlight the clinical implications of these findings and propose multilevel interventions to promote cardiovascular health among children and young adults.

Effects of short-term PM2.5 exposure on blood lipids among 197,957 people in eastern China

Globally, air pollution is amongst the most significant causes of premature death. Nevertheless, studies on the relationship between fine particulate matter (PM_2.5) exposure and blood lipids have typically not been population-based. In a large, community-based sample of residents in Yixing city, we assessed the relationship between short-term outdoor PM_2.5 exposure and blood lipid concentrations. Participants who attended the physical examination were enrolled from Yixing People's hospital from 2015 to 2020. We collected general characteristics of participants, including gender and age, as well as test results of indicators of blood lipids. Data on daily meteorological factors were collected from the National Meteorological Data Sharing Center ( http://data.cma.cn/ ) and air pollutant concentrations were collected from the China Air Quality Online Monitoring and Analysis Platform ( https://www.aqistudy.cn/ ) during this period. We applied generalized additive models to estimate short-term effects of ambient PM_2.5 exposure on each measured blood lipid-related indicators and converted these indicators into dichotomous variables (non- hyperlipidemia and hyperlipidemia) to calculate risks of hyperlipidemia associated with PM_2.5 exposure. A total of 197,957 participants were included in the analysis with mean age 47.90 years (± SD, 14.28). The increase in PM_2.5 was significantly associated with hyperlipidemia (odds ratio (OR) 1.003, 95% CI 1.001-1.004), and it was still significant in subgroups of males and age < 60 years. For every 10 μg/m³ increase in PM_2.5, triglyceride levels decreased by 0.5447% (95% CI - 0.7873, - 0.3015), the low-density lipoprotein cholesterol concentration increased by 0.0127 mmol/L (95% CI 0.0099, 0.0156), the total cholesterol concentration increased by 0.0095 mmol/L (95% CI 0.0053, 0.0136), and no significant association was observed between PM_2.5 and the high-density lipoprotein cholesterol concentration. After excluding people with abnormal blood lipid concentrations, the associations remained significant except for the high-density lipoprotein cholesterol concentration. PM_2.5 was positively correlated with low-density lipoprotein cholesterol and total cholesterol, and negatively correlated with triglyceride, indicating PM_2.5 can potentially affect health through blood lipid levels.

Respiratory mechanics following chronic cigarette smoke exposure in the Apoe − / − mouse model

Even though cigarette smoking (CS) has been on the decline over the past 50 years, it is still the leading cause of preventable premature death in the United States. Preclinical models have investigated the cardiopulmonary effects of CS exposure (CSE), but the structure-function relationship in the respiratory system has not yet been fully explored. To evaluate these relationships, we exposed female apolipoprotein E-deficient (Apoe− / − ) mice to mainstream CS (n = 8 ) for 5 days/week over 24 weeks with room air as a control (AE,n = 8 ). To contextualize the impact of CSE, we also assessed the natural aging effects over 24 weeks of air exposure (baseline,n = 8 ). Functional assessments were performed on a small animal mechanical ventilator (flexiVent, SCIREQ), where pressure-volume curves and impedance data at four levels of positive end-expiratory pressure (P peep and with increasing doses of methacholine were collected. Constant phase model parameters (R N : Newtonian resistance, H: coefficient of tissue elastance, and G: coefficient of tissue resistance) were calculated from the impedance data. Perfusion fixed-left lung tissue was utilized for quantification of parenchyma airspace size and tissue thickness, airway wall thickness, and measurements of elastin, cytoplasm + nucleus, fibrin, and collagen content for the parenchyma and airways. Aging caused the lung to become more compliant, with an upward-leftward shift of the pressure-volume curve and a reduction in all constant phase model parameters. This was supported by larger parenchyma airspace sizes, with a reduction in cell cytoplasm + nucleus area. Airway walls became thinner, even though low-density collagen content increased. In contrast, CSE caused a downward-rightward shift of the pressure-volume curve along with an increase in H, G, and hysteresivity (η = G / H ). Organ stiffening was accompanied by enhanced airway hyper-responsiveness following methacholine challenge. Structurally, parenchyma airspaces enlarged, as indicated by an increase in equivalent airspace diameter (D 0 ), and the septum thickened with significant deposition of low-density collagen along with an influx of cells. Airway walls thickened due to deposition of both high and low-density collagen, infiltration of cells, and epithelial cell elongation. In all, our data suggest that CSE in female Apoe− / − mice reduces respiratory functionality and causes morphological alterations in both central and peripheral airways that results in lung stiffening, compared to AE controls.

Ambient Air Pollution and Atherosclerosis: A Potential Mediating Role of Sphingolipids

BACKGROUND

The pathophysiological mechanisms of air pollution-induced atherosclerosis are incompletely understood. Sphingolipids serve as biological intermediates during atherosclerosis development by facilitating production of proatherogenic apoB (apolipoprotein B)-containing lipoproteins. We explored whether sphingolipids mediate the proatherogenic effects of air pollution.

METHODS

This was a prospective panel study of 110 participants (mean age 56.5 years) followed from 2013 to 2015 in Beijing, China. Targeted lipidomic analyses were used to quantify 24 sphingolipids in 579 plasma samples. The mass concentrations of ambient particulate matter ≤2.5 μm in diameter (PM_2.5) were continuously monitored by a fixed station. We evaluated the associations between sphingolipid levels and average PM_2.5 concentrations 1-30 days before clinic visits using linear mixed-effects models and explored whether sphingolipids mediate PM_2.5-associated changes in the levels of proatherogenic apoB-containing lipoproteins (LDL-C [low-density lipoprotein cholesterol] and non-HDL-C [nonhigh-density lipoprotein cholesterol]) using mediation analyses.

RESULTS

We observed significant increases in the levels of non-HDL-C and fourteen sphingolipids associated with PM_2.5 exposure, from short- (14 days) to medium-term (30 days) exposure time windows. The associations exhibited near-monotonic increases and peaked in 30-day time window. Increased levels of the sphingolipids, namely, sphinganine, ceramide C24:0, sphingomyelins C16:0/C18:0/C18:1/C20:0/C22:0/C24:0, and hexosylceramides C16:0/C18:0/C20:0/C22:0/C24:0/C24:1 significantly mediated 32%, 58%, 35% to 93%, and 23% to 86%, respectively, of the positive association between 14-day PM_2.5 average and the non-HDL-C level, but not the LDL-C level. Similar mediation effects (19%-91%) of the sphingolipids were also observed in 30-day time window.

CONCLUSIONS

Our results suggest that sphingolipids may mediate the proatherogenic effects of short- and medium-term PM_2.5 exposure.

Ambient air pollution during pregnancy and cardiometabolic biomarkers in cord blood

Prenatal air pollution exposure has been associated with adverse childhood cardiometabolic outcomes. It is unknown whether evidence of metabolic disruption associated with air pollution is identifiable at birth. We examined exposure to prenatal ambient air pollution and cord blood cardiometabolic biomarkers among 812 mother-infant pairs in the Healthy Start study.

Particulate matter air pollutants and cardiovascular disease: Strategies for intervention

Air pollution is consistently linked with elevations in cardiovascular disease (CVD) and CVD-related mortality. Particulate matter (PM) is a critical factor in air pollution-associated CVD. PM forms in the air during the combustion of fuels as solid particles and liquid droplets and the sources of airborne PM range from dust and dirt to soot and smoke. The health impacts of PM inhalation are well documented. In the US, where CVD is already the leading cause of death, it is estimated that PM2.5 (PM < 2.5 μm in size) is responsible for nearly 200,000 premature deaths annually. Despite the public health data, definitive mechanisms underlying PM-associated CVD are elusive. However, evidence to-date implicates mechanisms involving oxidative stress, inflammation, metabolic dysfunction and dyslipidemia, contributing to vascular dysfunction and atherosclerosis, along with autonomic dysfunction and hypertension. For the benefit of susceptible individuals and individuals who live in areas where PM levels exceed the National Ambient Air Quality Standard, interventional strategies for mitigating PM-associated CVD are necessary. This review will highlight current state of knowledge with respect to mechanisms for PM-dependent CVD. Based upon these mechanisms, strategies for intervention will be outlined. Citing data from animal models and human subjects, these highlighted strategies include: 1) antioxidants, such as vitamins E and C, carnosine, sulforaphane and resveratrol, to reduce oxidative stress and systemic inflammation; 2) omega-3 fatty acids, to inhibit inflammation and autonomic dysfunction; 3) statins, to decrease cholesterol accumulation and inflammation; 4) melatonin, to regulate the immune-pineal axis and 5) metformin, to address PM-associated metabolic dysfunction. Each of these will be discussed with respect to its potential role in limiting PM-associated CVD.

Association of long-term exposure to PM2.5 with blood lipids in the Chinese population: Findings from a longitudinal quasi-experiment

BACKGROUND

Although epidemiological studies on the effect of chronic fine particulate matter (PM_2.5) exposure on lipid disorders have been conducted, it is unclear if improved air quality is associated with beneficial changes in the blood lipid profile. In China, clean air actions introduced in 2013 have rapidly reduced the concentration of ambient PM_2.5.

METHODS

We conducted a change-by-change study, based on two waves (2011 and 2015) of a national survey of the same 5111 Chinese adults before and after implementation of the clean air actions. Long-term PM_2.5 exposure was assessed using a state-of-the-art estimator at the city level. Based on the within-individual differences between the two waves, we associated PM_2.5 changes with the variations of four lipid biomarkers-triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C)-using a mixed-effects regression model. The robustness and homogeneity of the association were tested via sensitivity analyses.

RESULTS

For each 10 μg/m³ reduction in PM_2.5, LDL-C, and TC decreased by 2.71 (95% confidence interval [CI] 0.10-5.32) and 4.16 (95% CI 1.24-7.08)mg/dL, respectively. There was no significant association with HDL-C or TG. The results were robust among models adjusted for different covariates. PM_2.5 was a significant risk factor for dyslipidemia with an adjusted relative risk of 1.21 (95% CI 1.09-1.34). The association between PM_2.5 and LDL-C was stronger in the elderly or adults who did not take medications.

CONCLUSIONS

The results suggest that PM_2.5 exert a cardiotoxic effect by increasing the risk of lipid disorders. Improvement of air quality could prevent dyslipidemia by reducing LDL-C and TC levels. Clean air policies should be implemented as public health measures in countries with aging societies, especially developing ones with a high air pollution burden.

Peat smoke inhalation alters blood pressure, baroreflex sensitivity, and cardiac arrhythmia risk in rats

Wildland fires (WF) are linked to adverse health impacts related to poor air quality. The cardiovascular impacts of emissions from specific biomass sources are however unknown. The purpose of this study was to assess the cardiovascular impacts of a single exposure to peat smoke, a key regional WF air pollution source, and relate these to baroreceptor sensitivity and inflammation. Three-month-old male Wistar-Kyoto rats, implanted with radiotelemeters for continuous monitoring of heart rate (HR), blood pressure (BP), and spontaneous baroreflex sensitivity (BRS), were exposed once, for 1-hr, to filtered air or low (0.38 mg/m³ PM) or high (4.04 mg/m³) concentrations of peat smoke. Systemic markers of inflammation and sensitivity to aconitine-induced cardiac arrhythmias, a measure of latent myocardial vulnerability, were assessed in separate cohorts of rats 24 hr after exposure. PM size (low peat = 0.4-0.5 microns vs. high peat = 0.8-1.2 microns) and proportion of organic carbon (low peat = 77% vs. high peat = 65%) varied with exposure level. Exposure to high peat and to a lesser extent low peat increased systolic and diastolic BP relative to filtered air. In contrast, only exposure to low peat elevated BRS and aconitine-induced arrhythmogenesis relative to filtered air and increased circulating levels of low-density lipoprotein cholesterol, complement components C3 and C4, angiotensin-converting enzyme (ACE), and white blood cells. Taken together, exposure to peat smoke produced overt and latent cardiovascular consequences that were likely influenced by physicochemical characteristics of the smoke and associated adaptive homeostatic mechanisms.

Cardiovascular adaptations to particle inhalation exposure: molecular mechanisms of the toxicology

Ambient air, occupational settings, and the use and distribution of consumer products all serve as conduits for toxicant exposure through inhalation. While the pulmonary system remains a primary target following inhalation exposure, cardiovascular implications are exceptionally culpable for increased morbidity and mortality. The epidemiological evidence for cardiovascular dysfunction resulting from acute or chronic inhalation exposure to particulate matter has been well documented, but the mechanisms driving the resulting disturbances remain elusive. In the current review, we aim to summarize the cellular and molecular mechanisms that are directly linked to cardiovascular health following exposure to a variety of inhaled toxicants. The purpose of this review is to provide a comprehensive overview of the biochemical changes in the cardiovascular system following particle inhalation exposure and to highlight potential biomarkers that exist across multiple exposure paradigms. We attempt to integrate these molecular signatures in an effort to provide direction for future investigations. This review also characterizes how molecular responses are modified in at-risk populations, specifically the impact of environmental exposure during critical windows of development. Maternal exposure to particulate matter during gestation can lead to fetal epigenetic reprogramming, resulting in long-term deficits to the cardiovascular system. In both direct and indirect (gestational) exposures, connecting the biochemical mechanisms with functional deficits outlines pathways that can be targeted for future therapeutic intervention. Ultimately, future investigations integrating "omics"-based approaches will better elucidate the mechanisms that are altered by xenobiotic inhalation exposure, identify biomarkers, and guide in clinical decision making.