Cardiovascular and inflammatory mechanisms in healthy humans exposed to air pollution in the vicinity of a steel mill

Co-exposure of ferruginous components of subway particles with lipopolysaccharide impairs vascular function: A comparative study with ambient particulate matter

Several empirical studies have linked subway and ambient particle exposure to toxicity, pro-inflammatory responses, and vascular dysfunction. However, the health effects of pollutants generated from varying sources, particularly when combined with lipopolysaccharide (LPS), are still unexplored. Therefore, the aim of this study was to investigate the characteristic health effects of iron oxide particles (the main components of subway particles) in comparison with urban aerosols (UA) and vehicle exhaust particles (VEP), alone and in combination with LPS. This study revealed that iron oxides caused a more significant reduction in human umbilical vein endothelial cell viability, increased lactate dehydrogenase release, and decreased the production of plasminogen activator inhibitor-1, a fibrinolytic modulator, and endothelin-1, a vasoconstrictor, compared to those by VEP and UA at marginally toxic and toxic concentrations. While VEP and UA induced an increase in interleukin (IL)-6 production, iron oxides, particularly Fe3O4, increased IL-8 production at slightly toxic and non-cytotoxic concentrations. In addition, co-exposure of all particles and LPS at non-cytotoxic concentrations promoted pro-inflammatory cytokine (IL-6 and IL-8) production relative to exposure to the particles alone. Interestingly, the tendency towards either coagulation or fibrinolytic conditions was dependent on the concentration of exposed particles at the same LPS concentration. Furthermore, increases in inflammation, neutrophil and lymphocyte recruitment around blood vessels, and edema were observed in murine lungs exposed to a combination of iron oxides and LPS compared to those in mice exposed to iron oxide alone. Thus, iron oxide-rich subway particulate poses more health risks than outdoor ambient particles since they can significantly impair endothelial function, particularly through gross cellular and vascular homeostatic protein damage, and induce exacerbated inflammatory responses during co-exposure. These findings provide novel empirical evidence for epidemiological studies seeking mechanisms responsible for the observed health impact of transport- and occupational-related exposures on vascular dysfunction.

Dysregulated blood biomarkers in women with acute and chronic respiratory conditions due to air pollutant exposure: An exploratory systematic review

Background

Air pollution exposure poses significant health risks for the general population, but particularly for women with acute and chronic respiratory conditions. Given the increasing global burden of air pollution-related illnesses, understanding these biomarkers is crucial for developing targeted interventions and improving respiratory health outcomes in vulnerable populations. In this systematic review, we aimed to determine potential dysregulated respiratory inflammatory blood biomarker candidates in adult female patients who experience varying levels and sources of inhaled pollutant exposure.

Methods

We searched the Cochrane Library, PubMed, and Web of Science with nuanced search terms to retrieve articles published in English between 1 January 2000 and 12 June 2023, to ensure relevancy. We filtered our findings to generate a focussed narrative analysis and used the Risk of Bias In Non-randomized Studies-of Exposures (ROBINS-E) and Risk-of-bias VISualization (robVIS) tools to ensure the validity of the data and the quality of the conclusions being made.

Results

We identified 916 articles from the databases used in our search, 16 of which met the criteria of our focussed narrative analysis. Among blood biomarkers, platelet-activating factor and eosinophilia could be used to assess the severity of asthma conditions, as a lack or reduction thereof indicates specific conditions. Pro-inflammatory cytokines require further validation, as some studies with a high risk of bias have reported conflicting results compared to more recent research on whether these markers are up-regulated or down-regulated. We found one study to be at a very high risk of bias, two had a high risk of bias, one had some concerns of confounding factors which may not have affected their results, and 12 studies had a low risk of bias.

Conclusions

There were narrowed-down blood biomarker candidates that could be used in future research and avenues of research like generating specific microRNA sequences to test for prognostic/diagnostic tests.

Registration

PROSPERO: 42023435721.

Cytotoxic Potencies of Zinc Oxide Nanoforms in A549 and J774 Cells

Zinc oxide nanoparticles (NPs) are used in a wide range of consumer products and in biomedical applications, resulting in an increased production of these materials with potential for exposure, thus causing human health concerns. Although there are many reports on the size-related toxicity of ZnO NPs, the toxicity of different nanoforms of this chemical, toxicity mechanisms, and potency determinants need clarification to support health risk characterization. A set of well-characterized ZnO nanoforms (e.g., uncoated ca. 30, 45, and 53 nm; coated with silicon oil, stearic acid, and (3-aminopropyl) triethoxysilane) were screened for in vitro cytotoxicity in two cell types, human lung epithelial cells (A549), and mouse monocyte/macrophage (J774) cells. ZnO (bulk) and ZnCl2 served as reference particles. Cytotoxicity was examined 24 h post-exposure by measuring CTB (viability), ATP (energy metabolism), and %LDH released (membrane integrity). Cellular oxidative stress (GSH-GSSG) and secreted proteins (targeted multiplex assay) were analyzed. Zinc oxide nanoform type-, dose-, and cell type-specific cytotoxic responses were seen, along with cellular oxidative stress. Cell-secreted protein profiles suggested ZnO NP exposure-related perturbations in signaling pathways relevant to inflammation/cell injury and corresponding biological processes, namely reactive oxygen species generation and apoptosis/necrosis, for some nanoforms, consistent with cellular oxidative stress and ATP status. The size, surface area, agglomeration state and metal contents of these ZnO nanoforms appeared to be physicochemical determinants of particle potencies. These findings warrant further research on high-content "OMICs" to validate and resolve toxicity pathways related to exposure to nanoforms to advance health risk-assessment efforts and to inform on safer materials.

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSION

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

Age and sex differences in the effects of short- and long-term exposure to air pollution on endothelial dysfunction

BACKGROUND

The effects of air pollution on endothelial function remain unclear across populations. We aimed to use brachial artery flow-mediated dilatation (FMD) to identify demographic differences in the effects of air pollution exposure on endothelial dysfunction.

METHODS

We measured FMD in 850 participants from October 2016 to January 2020. Location-specific concentrations of fine particulate matter < 2.5 μm aerodynamic diameter (PM2.5), inhalable particulate matter < 10 μm aerodynamic diameter (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3) measured by fixed ambient air monitoring stations were collected for short- and long-term exposure assessment. Multiple linear regression models and restricted cubic splines were used to assess the associations before and after stratification by age and sex.

RESULTS

This study eventually included 828 participants [551 (66.5%) younger than 65 years and 553 (66.8%) men]. Each 10 µg/m3 increase in 7-day exposure to PM2.5 and PM10 was significantly linearly associated with a 0.07% (β = -0.07, 95% CI: -0.13 to -0.004) and 0.05% (β = -0.05, 95% CI: -0.10 to -0.004) decrease in FMD in the fully adjusted model. After full adjustment, long-term exposure to all air pollutants was significantly associated with impaired FMD. Each 10 µg/m3 increase in long-term exposure to PM2.5 and PM10 was significantly associated with a -0.18% (95% CI: -0.34 to -0.03) and - 0.23% (95% CI: -0.40 to -0.06) change in FMD, respectively. After stratification, the associations of lower FMD with long-term exposure to PM2.5, PM10, SO2, NO2, and CO significantly persisted in men and participants younger than 65 years instead of women or older participants. For short-term exposure, we observed differences consistent with long-term exposure and a stronger effect of 7-day exposure to SO2 in men due to a significant interaction effect.

CONCLUSION

Short- and long-term exposure to different air pollutants are strongly associated with decreased endothelial function, and susceptibility to air pollution varies significantly with age and sex.

Source apportionment of ambient PM10 collected at three sites in an urban-industrial area with multi-time resolution factor analyses

Chemical speciation data for PM₁₀, collected for annual trend analyses of health-relevant species, at three receptor sites in a highly industrialized area (IJmond) in the Netherlands were used in a multi-time resolution receptor model (ME-2) to identify the PM₁₀ sources in this area. Despite the available data not being optimized for receptor modelling, five-factor solutions were obtained for all sites based on independent PMF analysis on PM₁₀ data from the three sites (IJM, WAZ and BEV). Four factors were common to all three sites: nitrate-sulphate (average percentage contributions to PM₁₀: IJM: 35.3 %, WAZ: 37.7 %, and BEV: 36.3 %); sea salt (20.2 %, 23.7 %, 15.2 %); industrial (8.1 %, 11.0 %, 18.1 %) and brake wear/traffic (31.4 %, 21.2 %, 20.6 %). At WAZ, a local/site-specific factor containing most of the PAH measurements was found (6.4 %) while a crustal matter factor was resolved at IJM (7.6 %) and BEV (9.8 %). Additionally, sludge-drying was a potential source of the marker species in the industrial factor at WAZ. Bootstrapping (BS) and factor displacement (DISP) were applied to the factor profiles in this work for error estimation. In general, the factor profiles at all three sites had very small intervals from both BS and DISP methods. To our knowledge, this is the first time DISP was applied in a complex model such as the multi-time resolution model. Most of the measured metal and PAH concentrations found in the IJmond area during the 2017-2019 period had local sources, with significant contributions from several processes related to the steel industry. This study shows that available detailed PM₁₀ chemical speciation data, although primarily collected for annual trend analyses of health-relevant species, could also be used in receptor modelling by applying a multi-time framework. We propose general recommendations for the optimization of the measurement strategy for source apportionment of PM in areas with similar urban-industrial land use.

Cardiopulmonary benefits of respirator intervention against near road ambient particulate matters in healthy young adults: A randomized, blinded, crossover, multi-city study

Wearing a respirator is generally the most convenient individual intervention against ambient particulate matter (PM), and therefore there has been considerable research into its effectiveness. However, the effects of respirator intervention under different PM concentration settings have been insufficiently elucidated. We conducted a randomized, blinded, crossover intervention study in four representative cities in China in which 128 healthy university students spent 2-h walking along a busy road wearing either a real or a sham respirator and then spent the next 5-h indoors away from traffic pollution. Lung function, blood pressure, and heart rate variability were continuously measured throughout the visit. Linear mixed-effect models were fitted to evaluate the protective effects of respirator intervention on the cardiopulmonary indicators. Results showed that the beneficial effects of respirator intervention were only occasionally significant at specific time points or in specific cities or in selected parameters. Overall, respirator intervention was associated with reduced SBP (6.2 vs. 11.5 mmHg compared to baseline, p < 0.05) and increased LF (44 vs. 35 ms² compared to baseline, p < 0.05) over the 2-h walk, but no significant effects were found over the 7-h period. Respirators have significant effect modifications on the associations between PM_2.5/PM₁₀ and the cardiopulmonary indicators, but the directions of effects were inconsistent. The intercity difference in the effects of respirator intervention was found significant, with Taiyuan and Shanghai to be the two cities with lower personal PM concentrations but more pronounced benefits. In conclusion, reducing personal exposure to PM can have some beneficial effects in some scenarios. However, respirators may not provide sufficient protection from air pollution overall, and we should avoid over-reliance on respirators and accelerate efforts to reduce emissions of pollutants in the first place. Despite standardized procedures, we found inconsistency in results across cities, consistent with the previous literature.

Alterations of IL-1beta and TNF-alpha expression in RAW264.7 cell damage induced by two samples of PM2.5 with different compositions

Fine particulate matter 2.5 (PM2.5) has been demonstrated by previous studies to be associated with cell damage. To explore the impact of the composition of PM2.5 on PM2.5-mediated inflammation, this study investigated the composition of PM2.5 collected during the wintertime indoor heating season and observed its inflammatory effect. Samples were collected during the heating season from December 5, 2017, to January 8, 2018, in Xi'an. Compositions of organic carbon (OC), elemental carbon (EC), and water-soluble ions were analysed. Two representative samples (sample 1 and 2) were selected with significant differences in compositions. They were configured into four concentrations (0.1 μg/mL, 1 μg/mL, 10 μg/mL, 20 μg/mL) and used as interventions on RAW264.7 cells for 4 h and 24 h separately. Cell viability was detected by CCK-8. Tumour necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) gene and protein expression levels were detected by real-time quantitative real-time polymerase chain reaction (RT-qPCR) and western blotting. The results showed that the cell viability of sample 1 intervened cells at 4 h and 24 h was lower than that of sample 2. IL-1β gene in most PM2.5 intervention groups was lower than in the control group. Protein expression was higher at 4 h than at 24 h. In conclusion, PM2.5 components influence cell viability and expression of IL-1β and TNF-α, while high concentrations of NO3-, Cl-, Na+, K+, Mg2+, Ca2+, and others in the PM2.5 composition have a significant harmful effect.

Acute cardiovascular effects of inhaled ambient particulate matter: Chemical composition-related oxidative stress, endothelin-1, blood pressure, and ST-segment changes in Wistar rats

Short-term increases in particulate matter (PM) are associated with heightened morbidity and mortality from cardiovascular causes. Inhalation of PM is known to increase endothelin (ET)-1 levels. Yet, less is known about particle composition-related changes at the molecular level including the endothelinergic system and relationship with cardiovascular function changes. In this work, adult Wistar male rats were exposed for 4 h by nose-only inhalation to clean air, Ottawa urban particles (EHC-93, 48 mg/m³) and water-leached (EHC-93L, 49 mg/m³) particles, to examine the effect of particle compositional changes on oxidative stress, circulating ETs, blood pressure, and heart electrophysiology. Particle deposition in the respiratory compartment was estimated at 85 μg (25 ng/cm²). Lung cell proliferation was low in both treatment groups, indicating absence of acute injury. Inhalation of EHC-93 caused statistically significant elevations (p < 0.05) of oxidative stress markers, ET-1, ET-3, blood pressure, and a decrease of ST-segment duration in the ECG at 1.5 days post-exposure. Leached particles (EHC-93L) caused rapid but transient elevation (p < 0.05) of oxidative stress, ET-1, ET-2, and ET-3 at earlier time points, with no changes in blood pressure or ST-segment. These results demonstrate that inhalation of urban particles at an internal dose inadequate to cause acute lung injury can induce oxidative stress, enhance vasoactive endothelins, leading to vasopressor response, affecting cardiac electrophysiology in Wistar rats, consistent with the cardiovascular impacts of ambient particles in human populations. Change in particle potency after removal of soluble species, notably cadmium, zinc and polar organics suggests that the toxicodynamics of cardiovascular effects can be modified by physicochemical properties of particles.

Health Endpoint of Exposure to Criteria Air Pollutants in Ambient Air of on a Populated in Ahvaz City, Iran

The presence of criteria air pollutants (CAP) in the ambient air of a populated inhalation region is one of the main serious public health concerns. The present study evaluated the number of cardiovascular mortalities (CM), hospital admissions with cardiovascular disease (HACD), and hospital admissions for respiratory disease (HARD) due to CAP exposure between 2010 and 2014. The study used the Air Q model and descriptive analysis to investigate the health endpoint attributed to the ground level of ozone (O₃), nitrogen dioxide (NO₂), sulfide dioxide (SO₂), and particle matter (PM₁₀). Baseline incidence (BI) and relative risk (RR) are the most important factors in the evaluation of health outcomes from exposure to CAP in the ambient air of a populated area according to EPA and the World Health Organization (WHO) guidelines. Our study showed that annual cases of cardiovascular mortality during the period 2010–2014 relating to particle mater were 478, 506, 469, 427, and 371; ozone was 19, 24, 43, 56, and 49; nitrogen dioxide was 18, 20, 23, 27, and 21; and sulfide dioxide was 26, 31, 37, 43 and 11, in the years 2010 to 2014, respectively. These results indicate that the number of hospital admissions for respiratory disease attributed to PM were 2054, 2277, 2675, 2042, and 1895; O₃ was 27, 35, 58, 73, and 63; NO₂ was 23, 24, 15, 25, and 18; and SO₂ was 23, 24, 25, 30, and 20, in the years from 2010 to 2014, respectively. The results also showed that the number of hospital admissions for cardiovascular disease related to particle mater was 560, 586, 529, 503, and 472; ozone was 22, 32, 38, 55, and 51; nitrogen dioxide was 19, 18, 13, 21, and 14; and sulfide dioxide was 12, 14, 16, 22, and 9, in the same period, respectively. Observations showed that most of the pollution was from outdoor air and in the human respiratory tract. Increased levels of sulfide dioxide, particle matter, nitrogen dioxide, and ozone can cause additional morbidity and mortality for exposed populations. According to the results, it is possible to help increase the level of public health. The use of these findings could also be of great help to health professionals and facilitators at regional and national levels.

The effect of using personal-level indoor air cleaners and respirators on biomarkers of cardiorespiratory health: a systematic review

BACKGROUND

Emerging studies have investigated potential cardiovascular and respiratory health impacts from the use of personal-level intervention equipment against air pollution exposure. The objective of this systematic review is to assess the efficacy of personal-level air pollution intervention on mitigating adverse health effects from air pollution exposure by using portable air cleaner or wearing respirator.

METHODS

In this systematic review, we searched PubMed and Web of Science for published literatures up to May 31, 2020, focusing on personal-level air pollution intervention studies. Among these studies, we investigated the impacts on cardio-respiratory responses to the use of these interventions. The intervention of review interest was the use of personal-level equipment against air pollution, including using portable air cleaner indoors or wearing respirator outdoors. The outcome of review interest was impacts on cardio-respiratory health endpoints following interventions, including level changes in blood pressure, heart rate variability (HRV), lung function, and biomarkers of inflammation and oxidative stress. Weighted mean differences or percent changes were pooled in meta-analyses for these health endpoints. The heterogeneity across studies was assessed using the Cochran's Q-statistic test, and the individual study quality was assessed using the Cochrane risk of bias tool version 2 (RoB 2). We further applied the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) method to evaluate the certainty of evidence.

RESULTS

From systematic literature search and screening, we identified 29 related eligible intervention studies, including 21 studies on indoor portable air cleaner use and 8 studies on respirator use. For portable air cleaner intervention, we observed suggestive evidence of beneficial changes on cardio-respiratory health endpoints. Collectively in these studies, we found significantly beneficial changes of 2.01% decreases (95% CI: 0.50%, 3.52%) in systolic blood pressure, as well as non-significantly beneficial changes of 3.04% increases (95% CI: -2.65%, 8.74%) in reactive hyperemia index and 0.24% increases (95% CI: -0.82%, 1.31%) in forced expiratory volume in 1 s. We also observed non-significant reductions in levels of inflammation and oxidative stress biomarkers, including C-reactive protein, interleukin-6, fibrinogen, fractional exhaled nitric oxide and malondialdehyde. For respirator intervention, we observed some beneficial changes on cardiovascular health endpoints, such as significant increases in HRV parameters [SDNN (2.20%, 95% CI: 0.54%, 3.86%)], as well as non-significant decreases in blood pressure [SBP (0.63 mmHg, 95% CI: -0.39, 1.66)]; however, no sufficient data were available for meta-analyses on lung function and biomarkers. RoB 2 assessments suggested that most intervention studies were with a moderate to high overall risk of bias. The certainty of evidence for intervention outcome pairs was graded very low for either portable air cleaner or respirator intervention. The common reasons to downgrade study evidence included loss to follow-up, lack of blinding, lack of washout period, small sample size, and high heterogeneity across studies.

CONCLUSIONS

The uses of indoor portable air cleaner and respirator could contribute to some beneficial changes on cardiovascular health, but with much limited evidence on respiratory health. Low certainty of the overall study evidence shed light on future research for larger sample size trials with more rigorous study design.

Ambient air pollution and inflammatory effects in a Canadian pregnancy cohort

Supplemental Digital Content is available in the text.

Background:

Epidemiologic studies have consistently reported associations between air pollution and pregnancy outcomes including preeclampsia and gestational diabetes. However, the biologic mechanisms underlying these relationships remain unclear as few studies have collected relevant biomarker data. We examined relationships between ambient PM_2.5 and NO₂ with markers of inflammation during pregnancy in a prospective cohort of Canadian women.

Methods:

We analyzed data from 1170 women enrolled in the Maternal-Infant Research on Environmental Chemicals study. Daily residential PM_2.5 and NO₂ exposures during pregnancy were estimated using satellite-based and land-use regression models and used to create 14-day and 30-day exposure windows before blood-draw. Inflammatory markers C-reactive protein, interleukin-6, interleukin-8, and tumor necrosis factor-α were measured in third trimester plasma samples. Multivariable linear regression was used to estimate associations for an interquartile range (IQR) increase in PM_2.5 and NO₂ and markers of inflammation, while adjusting for individual-level confounders.

Results:

Fourteen-day (IQR: 6.85 µg/m³) and 30-day (IQR: 6.15 µg/m³) average PM_2.5 exposures before blood-draw were positively associated with C-reactive protein after adjustment for covariates (24.6% [95% CI = 9.4, 41.9] and 17.4% [95% CI = 1.0, 35.0] increases, respectively). This association was found to be robust in several sensitivity analyses. Neither PM_2.5 nor NO₂ exposures were associated with interleukin-6, interleukin-8, or tumor necrosis factor-α.

Conclusion:

Exposure to ambient PM_2.5 is positively associated with maternal inflammatory pathways in late pregnancy. This may contribute to positive associations between ambient PM_2.5 and risk of adverse pregnancy outcomes.

Particulate respirator use and blood pressure: A systematic review and meta-analysis

People use a particulate respirator in order to reduce exposure to ambient fine particulate matter (PM_2.5). Acute exposure to PM_2.5 is known to increase blood pressure. However, systematic reviews or meta-analyses on blood pressure-related benefits of using a particulate respirator is lacking. Therefore, we reviewed randomized crossover intervention studies on blood pressure-related effects of particulate matter respirator use. We conducted a literature review of articles found on Embase, Medline, and Cochrane library on August 31, 2020. The study outcomes were systolic and diastolic blood pressure and mean arterial pressure. A random-effect model was used in the meta-analysis. Subgroup analyses, based on age (adult < 60 years, elderly ≥ 60 years), personal PM_2.5 exposure levels (High: ≥ 25 μg/m³, Low: < 25 μg/m³), and types of monitoring methods (ambulatory and resting blood pressure) were conducted. We identified 297 references, and seven studies were included in our systematic review. None of the studies used a sham respirator as control and complete allocation concealment and blinding were impossible. The use of a particulate respirator was associated with a -1.23 mmHg (95% confidence interval (CI): -2.53, 0.07) change in systolic blood pressure and a -1.57 mmHg (95% CI: -3.85, 0.71) change in mean arterial pressure. There were significant heterogeneities and possibilities for publication bias. The subgroup analyses revealed that studies involving elderly individuals, those conducted in high PM_2.5 personal exposure, and those in which resting blood pressure was monitored demonstrated a larger decrease in blood pressure resulting from respirator use. Further intervention studies with a large sample size and subjects with diverse characteristics and different personal PM_2.5 levels may add the evidence to current literature.

Association of COVID-19 transmission with high levels of ambient pollutants: Initiation and impact of the inflammatory response on cardiopulmonary disease

Ambient air pollution contributes to 7 million premature deaths annually. Concurrently, the ongoing coronavirus disease 2019 (COVID-19) pandemic, complicated with S-protein mutations and other variants, caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in over 2.5 million deaths globally. Chronic air pollution-mediated cardiopulmonary diseases have been associated with an increased incidence of hospitalization and mechanical ventilation following COVID-19 transmission. While the underlying mechanisms responsible for this association remain elusive, air pollutant-induced vascular oxidative stress and inflammatory responses have been implicated in amplifying COVID-19-mediated cytokine release and vascular thrombosis. In addition, prolonged exposure to certain types of particulate matter (PM2.5, d < 2.5 μm) has also been correlated with increased lung epithelial and vascular endothelial expression of the angiotensin-converting enzyme-2 (ACE2) receptors to which the SARS-CoV-2 spike glycoproteins (S) bind for fusion and internalization into host cells. Emerging literature has linked high rates of SARS-CoV-2 infection to regions with elevated levels of PM2.5, suggesting that COVID-19 lockdowns have been implicated in regional reductions in air pollutant-mediated cardiopulmonary effects. Taken together, an increased incidence of SARS-CoV-2-mediated cardiopulmonary diseases seems to overlap with highly polluted regions. To this end, we will review the redox-active components of air pollutants, the pathophysiology of SARS-CoV-2 transmission, and the key oxidative mechanisms and ACE2 overexpression underlying air pollution-exacerbated SARS-CoV-2 transmission.

Long-Term Ambient Air Pollution Exposures and Circulating and Stimulated Inflammatory Mediators in a Cohort of Midlife Adults

BACKGROUND

Chronic exposure to air pollution may prime the immune system to be reactive, increasing inflammatory responses to immune stimulation and providing a pathway to increased risk for inflammatory diseases, including asthma and cardiovascular disease. Although long-term exposure to ambient air pollution has been associated with increased circulating markers of inflammation, it is unknown whether it also relates to the magnitude of inflammatory response.

OBJECTIVES

The aim of this study was to examine associations between chronic ambient pollution exposures and circulating and stimulated levels of inflammatory mediators in a cohort of healthy adults.

METHODS

Circulating interleukin (IL)-6, C-reactive protein (CRP) (n=392), and lipopolysaccharide stimulated production of IL-1β, IL-6, and tumor necrosis factor (TNF)-α (n=379) were measured in the Adult Health and Behavior II cohort. Fine particulate matter [particulate matter with aerodynamic diameter less than or equal to 2.5 μm (PM2.5)] and constituents [black carbon (BC), and lead (Pb), manganese (Mn), zinc (Zn), and iron (Fe)] were estimated for each residential address using hybrid dispersion land use regression models. Associations between pollutant exposures and inflammatory measures were examined using linear regression; models were adjusted for age, sex, race, education, smoking, body mass index, and month of blood draw.

RESULTS

There were no significant correlations between circulating and stimulated measures of inflammation. Significant positive associations were found between exposure to PM2.5 and BC with stimulated production of IL-6, IL-1β, and TNF-α. Pb, Mn, Fe, and Zn exposures were positively associated with stimulated production of IL-1β and TNF-α. No pollutants were associated with circulating IL-6 or CRP levels.

DISCUSSION

Exposure to PM2.5, BC, Pb, Mn, Fe, and Zn was associated with increased production of inflammatory mediators by stimulated immune cells. In contrast, pollutant exposure was not related to circulating markers of inflammation. These results suggest that chronic exposure to some pollutants may prime immune cells to mount larger inflammatory responses, possibly contributing to increased risk for inflammatory disease. https://doi.org/10.1289/EHP7089.

The short- and long-term associations of particulate matter with inflammation and blood coagulation markers: A meta-analysis

Inflammation and the coagulation cascade are considered to be the potential mechanisms of ambient particulate matter (PM) exposure-induced adverse cardiovascular events. Tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-8 (IL-8), and fibrinogen are arguably the four most commonly assayed markers to reflect the relationships of PM with inflammation and blood coagulation. This review summarized and quantitatively analyzed the existing studies reporting short- and long-term associations of PM2.5(PM with an aerodynamic diameter ≤2.5 μm)/PM10 (PM with an aerodynamic diameter≤10 μm) with important inflammation and blood coagulation markers (TNF-α, IL-6, IL-8, fibrinogen). We reviewed relevant studies published up to July 2020, using three English databases (PubMed, Web of Science, Embase) and two Chinese databases (Wang-Fang, China National Knowledge Infrastructure). The OHAT tool, with some modification, was applied to evaluate risk of bias. Meta-analyses were conducted with random-effects models for calculating the pooled estimate of markers. To assess the potential effect modifiers and the source of heterogeneity, we conducted subgroup analyses and meta-regression analyses where appropriate. The assessment and correction of publication bias were based on Begg's and Egger's test and "trim-and-fill" analysis. We identified 44 eligible studies. For short-term PM exposure, the percent change of a 10 μg/m3 PM2.5 increase on TNF-α and fibrinogen was 3.51% (95% confidence interval (CI): 1.21%, 5.81%) and 0.54% (95% confidence interval (CI): 0.21%, 0.86%) respectively. We also found a significant short-term association between PM10 and fibrinogen (percent change = 0.17%, 95% CI: 0.04%, 0.29%). Overall analysis showed that long-term associations of fibrinogen with PM2.5 and PM10 were not significant. Subgroup analysis showed that long-term associations of fibrinogen with PM2.5 and PM10 were significant only found in studies conducted in Asia. Our findings support significant short-term associations of PM with TNF-α and fibrinogen. Future epidemiological studies should address the role long-term PM exposure plays in inflammation and blood coagulation markers level change.

Inflammatory cytokines and DNA methylation in healthy young adults exposure to fine particulate matter: A randomized, double-blind crossover trial of air filtration

Benefits of indoor air filtration in heavily polluted areas are not fully understood. This study aims to examine whether short-term air filtration intervention could attenuate the hazards from acute exposure to fine particulate matter (PM_2.5), and investigate the potential impact on inflammatory cytokines and DNA methylation. A randomized, double-blind crossover trial of true or sham indoor air filtration was conducted among 29 healthy young adults in Beijing, China. Each episode covered a typical air pollution wave, and 38 cytokines and DNAm of 20 genes were measured at 3 time points: pre-smog, during smog, and post-smog. Linear mixed-effect models were used to evaluate the associations. The indoor PM_2.5 concentration with true filtration was 67.8 % lower than sham filtration (13.8 μg/m³vs. 42.8 μg/m³). Air filtration was significantly associated with the decreases in 9 cytokines, from 6.61 % to 21.24 %. PM_2.5 exposure was significantly associated with elevated levels of 9 cytokines and changed methylation at 7 CpG sites. Notably, PM_2.5 was significantly associated with GM-CSF, sCD40L, MCP-1, and FGF-2, as well as methylation in corresponding genes, but no mediation effect was observed. This trial suggested that indoor air filtration might attenuate the adverse effects of PM_2.5 exposure through changing cytokines and DNAm.

Air Pollution-Induced Autonomic Modulation

Air pollutants pose a serious worldwide health hazard, causing respiratory and cardiovascular morbidity and mortality. Pollutants perturb the autonomic nervous system, whose function is critical to cardiopulmonary homeostasis. Recent studies suggest that pollutants can stimulate defensive sensory nerves within the cardiopulmonary system, thus providing a possible mechanism for pollutant-induced autonomic dysfunction. A better understanding of the mechanisms involved would likely improve the management and treatment of pollution-related disease.

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.

Impact of air pollution on intestinal redox lipidome and microbiome

Air pollution is a rising public health issue worldwide. Cumulative epidemiological and experimental studies have shown that exposure to air pollution such as particulate matter (PM) is linked with increased hospital admissions and all-cause mortality. While previous studies on air pollution mostly focused on the respiratory and cardiovascular effects, emerging evidence supports a significant impact of air pollution on the gastrointestinal (GI) system. The gut is exposed to PM as most of the inhaled particles are removed from the lungs to the GI tract via mucociliary clearance. Ingestion of contaminated food and water is another common source of GI tract exposure to pollutants. Recent studies have associated air pollution with intestinal diseases, including appendicitis, colorectal cancer, and inflammatory bowel disease. In addition to the liver and adipose tissue, intestine is an important organ system for lipid metabolism, and the intestinal redox lipids might be tightly associated with the intestinal and systematic inflammation. The gut microbiota modulates lipid metabolism and contributes to the initiation and development of intestinal disease including inflammatory bowel disease. Recent data support microbiome implication in air pollution-mediated intestinal and systematic effects. In this review, the associations between air pollution and intestinal diseases, and the alterations of intestinal lipidome and gut microbiome by air pollution are highlighted. The potential mechanistic aspects underlying air pollution-mediated intestinal pathology will also be discussed.

Short time exposure to ambient ozone and associated cardiovascular effects: A panel study of healthy young adults

The evidence that exposure to ambient ozone (O₃) causes acute cardiovascular effects appears inconsistent. A repeated-measure study with 61 healthy young volunteers was conducted in Xinxiang, Central China. Real-time concentrations of O₃ were monitored. Cardiovascular outcomes including blood pressure (BP), heart rate (HR), serum levels of high sensitivity C-reactive protein (hs-CRP), 8-hydroxy-2'-deoxyguanosine (8-OHdG), tissue-type plasminogen activator (t-PA), and platelet-monocyte aggregation (PMA) were repeated measured. Linear mixed-effect models were used to analyze the association of ambient O₃ with these cardiovascular outcomes. Additionally, the modifying effects of glutathione S-transferase mu 1 (GSTM1) and glutathione S-transferase theta 1 (GSTT1) polymorphisms were estimated to explore the potential mechanisms and role of the association between O₃ exposure and the above cardiovascular outcomes. A 10 μg/m³ increase in O₃ was associated with increases of 9.2 mmHg (95% confidence interval [CI]: 2.5, 15.9), 7.2 mmHg (95% CI: 0.8, 13.6), and 21.2 bpm (95% CI: 5.8, 36.6) in diastolic BP (DBP, lag1), mean arterial BP (MABP, lag1), and HR (lag01), respectively. Meanwhile, the serum concentrations of hs-CRP, 8-OHdG, and t-PA were all increased by O₃ exposure, but the PMA level was decreased. Stratification analyses showed that the estimated effects of O₃ on DBP, MABP, and HR in GSTM1-sufficient subjects were significantly higher than in GSTM1-null subjects. Moreover, GSTM1-null genotype enhanced O₃-induced increases, albeit insignificant, in levels of serum hs-CRP, 8-OHdG, and t-PA compared with GSTM1-sufficient genotype. Insignificant increases in hs-CRP and t-PA were also detected in GSTT1-null subjects. Taken together, our findings indicate that acute exposure to ambient O₃ induces autonomic alterations, systemic inflammation, oxidative stress, and fibrinolysis in healthy young subjects. GSTM1 genotype presents the trend of modifying O₃-induced cardiovascular effects.

Effect of industrial point-source air pollutants on fractional exhaled nitric oxide in healthy volunteers

BACKGROUND

Few studies have examined the effects of industrial, fixed-site sources of air pollution on lung inflammation in nearby residents. We investigated the effects of short-term exposure to ambient air near a steel plant on the fractional exhaled concentration of nitric oxide (FeNO), a measure of airway inflammation, in healthy volunteers.

METHODS

A cross-over study design was used. Fifty-nine non-smoking participants (mean age 24 years) were randomly assigned to each of two 5-day exposure scenarios: breathing ambient air adjacent to a steel plant or 5 km away at a college campus site. FeNO and on-site air pollutants were measured daily. Mixed effects linear regression models were used for data analysis, adjusting for sex, temperature, humidity and day of week.

RESULTS

Compared with the college site, PM _2.5, ultrafine PM, SO₂, NO₂ and CO levels were significantly greater near the steel plant. FeNO was 15.3% (95% CI, 6.6%, 24.8%) higher near the plant compared to the college site.

CONCLUSIONS

Exposure to ambient air near a steel plant was associated with increased airway inflammation as measured by exhaled nitric oxide.

Omics for Nurse Scientists Conducting Environmental Health Research

Nurse scientists are ideally positioned to perform environmental health research and it is critical that the role of omics in the complex relationships between environmental exposures and an individual's unique physiology in human health outcomes be appreciated. Importantly, omics can offer nurse scientists a tool to measure exposure, demonstrate molecular phenotypic changes associated with exposure, and potentially uncover mechanisms of exposure-related disease or negative health outcomes. The purpose of this summary is to serve as an overview of omics methodologies for nurse scientists conducting environmental health research and provides future directions of this work as well as exemplar funding opportunities that demonstrate the growing need and interest in this area. The intersection of nursing and exposure science will accelerate the work in environmental health and bring forth translation of research findings into clinical and community practice. Importantly, this information can better help us understand the variation in response to the environment and support environmental health policy change at the local, state, and federal level to improve community health and well-being.