Effects of different sizes of ambient particulate matter and household fuel use on physical function: National cohort study in China

BACKGROUND

Impact of outdoor and household air pollution on physical function remains unelucidated. This study examined the influence of various ambient particulate sizes (PM1, PM2.5, and PM10) and household fuel usage on physical function.

METHODS

Data from the China Health and Retirement Longitudinal Study (CHARLS) spanning 2011 and 2015 were utilized. The physical functional score was computed by summing scores from four tests: grip strength, gait speed, chair stand test, and balance. Multivariate linear and linear mixed-effects models were used to explore the separate and combined effects of PM1, PM2.5, PM10 and household fuel use on physical function in the cross-sectional and longitudinal analyses, respectively, and to further observe the effects of fuel cleanup on physical function in the context of air pollution exposure.

RESULTS

Both cross-sectional and longitudinal analyses revealed negative correlations between PM1 (β = -0.044; 95% CI: -0.084, -0.004), PM2.5 (β = -0.024; 95% CI: -0.046, -0.001), PM10 (β = -0.041; 95% CI: -0.054, -0.029), and physical function, with a more pronounced impact observed for fine particulate matter (PM1). Cleaner fuel use was associated with enhanced physical function compared to solid fuels (β = 0.143; 95% CI: 0.070, 0.216). The presence of air pollutants and use of solid fuels had a negative impact on physical function, while cleaner fuel usage mitigated the adverse effects of air pollutants, particularly in areas with high exposure.

CONCLUSION

This study underscores the singular and combined detrimental effects of air pollutants and solid fuel usage on physical function. Addressing fine particulate matter, specifically PM1, and prioritizing efforts to improve household fuel cleanliness in regions with elevated air pollution levels are crucial for preventing physical disability.

Ambient particulate matter and surrounding greenness in relation to sleep quality among pregnant women: A nationwide cohort study

Background

Particulate air pollution and residential greenness are associated with sleep quality in the general population; however, their influence on maternal sleep quality during pregnancy has not been assessed.

Objective

This cross-sectional study investigated the individual and interactive effects of exposure to particulate matter (PM) air pollution and residential greenness on sleep quality in pregnant women.

Methods

Pregnant women (n = 4933) enrolled in the Korean Children's Environmental Health Study with sleep quality information and residential address were included. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). The average concentrations of PM (PM2.5 and PM10) during pregnancy were estimated through land use regression, and residential greenness in a 1000 m buffer area around participants' residences was estimated using the Normalized Difference Vegetation Index (NDVI1000-m). Modified Poisson regression models were used to estimate the associations between PM and NDVI and poor sleep quality (PSQI >5) after controlling for a range of covariates. A four-way mediation analysis was conducted to examine the mediating effects of PM.

Results

After adjusting for confounders, each 10 μg/m3 increase in PM2.5 and PM10 exposure was associated with a higher risk of poor sleep quality (relative risk [RR]: 1.06; 95% confidence interval [CI]: 1.01, 1.11; and RR: 1.09; 95% CI: 1.06, 1.13, respectively), and each 0.1-unit increase in NDVI1000-m was associated with a lower risk of poor sleep quality (RR: 0.97; 95% CI: 0.95, 0.99). Mediation analysis showed that PM mediated approximately 37%-56% of the association between residential greenness and poor sleep quality.

Conclusions

This study identified a positive association between residential greenness and sleep quality. Furthermore, these associations are mediated by a reduction in exposure to particulate air pollution and highlight the link between green areas, air pollution control, and human health.

Short-term associations of particulate matter with different aerodynamic diameters with mortality due to mental disorders and dementia in Ningde, China

Limited evidence is available regarding the impact of ambient inhalable particulate matter (PM) on mental disorder (MD) or dementia-related deaths, particularly PM1, PM1-2.5, and coarse particles (PM2.5-10). Moreover, individual confounders have rarely been considered. In addition, evidence from low-pollution areas is needed but is inadequate. Using death records from the Death Registration System during 2015-2021 in Ningde, a coastal city in southeast China, we combined a conditional quasi-Poisson model with a distributed lag nonlinear model to estimate the nonlinear and lagged associations of PM exposure with MD or dementia-related deaths in Ningde, China, comprehensively controlling for individual time-invariant confounders using a time-stratified case-crossover design. The attributable fraction and number were calculated to quantify the burden of MD or dementia-related deaths that were related to PMs. We found J-shaped relationships between MD or dementia-related deaths and PMs, with different thresholds of 13, 9, 19, 33 and 12 μg/m3 for PM1, PM1-2.5, PM2.5, PM10 and PM2.5-10. An inter-quartile range increase for PM1, PM1-2.5, PM2.5, PM10 and PM2.5-10 above the thresholds led to an increase of 31.8% (95% confidence interval, 14.3-51.9%), 53.7% (22.4-93.1%), 32.6% (15.0-53.0%), 35.1% (17.7-55.0%) and 25.9% (13.0-40.3%) in MD-related deaths at lag 0-3 days, respectively. The associations were significant in the cool season rather than in the warm season and were significantly greater among people aged 75-84 years than in others. The fractions of MD-related deaths attributable to PM1, PM1-2.5, PM2.5, PM10 and PM2.5-10 were 5.55%, 6.49%, 7.68%, 10.66%, and 15.11%, respectively; however, only some of them could be protected by the concentrations recommended by the World Health Organisation or China grade I standard. Smaller associations and similar patterns were observed between PMs and dementia-related death. These findings suggest stricter standards, and provide evidence for the development of relevant policies and measures.

Associations between exposure to ambient particulate matter and advanced liver fibrosis in Chinese MAFLD patients

BACKGROUND & AIMS

Liver fibrosis is an important feature in patients with metabolic dysfunction-associated fatty liver disease (MAFLD). This study aimed to explore the association between long-term ambient particulate matter (PM) exposure and advanced liver fibrosis (ALF) in MAFLD participants.

METHODS

A cross-sectional study of 23170 adults recruited from 33 provinces of China from 2010 to 2020. ALF was detected using the nonalcoholic fatty liver disease fibrosis score (NFS). The annual average levels of particulate matter with aerodynamic diameters of ≤ 1 µm (PM1), ≤ 2.5 µm (PM2.5) and ≤ 10 µm (PM10) were calculated using validated spatiotemporal models. Generalized additive models were applied to analyze the association between PM and ALF in patients with MAFLD.

RESULTS

One-year exposure to higher levels of all PM was found to increase the risk of ALF, with odds ratios (ORs) of 1.10 (95% CI 1.06-1.14), 1.05 (1.03-1.07), and 1.03(1.02-1.04) for each 10 μg/m3 increase in PM1, PM2.5 and PM10, respectively. With the dissection of the impact of PM1 in PM2.5, PM2.5 in PM10 and PM1 in PM10, we found that PM2.5 had a stronger impact on ALF (both Pinteraction＜0.05) in comparison with PM1 and PM10.

CONCLUSIONS

Long-term exposure to PM is associated with ALF in patients with MAFLD, with PM2.5 playing a dominant role.

Association of hypothyroidism during pregnancy with preconception and early pregnancy exposure to ambient particulate matter

BACKGROUND

Limited research has been conducted on the association between preconception exposure to ambient particulate matter (PM) and hypothyroidism. This study aimed to investigate the relationship between preconception PM exposure and hypothyroidism.

METHODS

A retrospective case-control study at China-Japan Friendship Hospital was performed. Fine particulate matter (PM2.5) and inhalable particulate matter (PM10) were obtained from the China High Air Pollution Dataset. Buffer analysis methods were used to calculate the exposure of pregnant women to PM in a circular area of 250, 500, and 750 m in diameter at preconception and in early pregnancy. Logistic regression models were used to assess the relationship between PM and hypothyroidism. Odd ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate the effect of PM on the risk of hypothyroidism.

RESULTS

A total of 3,180 participants were studied, and they comprised 795 hypothyroid patients and 2,385 matched controls. The mean age was 31.01 years (standard deviation: 3.66) in the control group and 31.16 years (standard deviation: 3.71) in the case group. Logistic regression analysis showed that exposure to PM2.5 and PM10 in the 60-day period before the last menstrual period month (LMPM), 30-day period before the LMPM, and LMP, across all distance buffers, was associated with an increased risk of hypothyroidism (all P < 0.05). The most pronounced effect was observed during the LMPM, with PM2.5 (OR: 1.137, 95% CI: 1.096-1.180) and PM10 (OR: 1.098, 95% CI: 1.067-1.130) in the 250-m buffer. Subgroup analysis in the Changping District yielded consistent results with the main analysis.

CONCLUSION

Our study shows that preconception PM2.5 and PM10 exposure increases the risk of hypothyroidism during pregnancy.

Unique regulatory roles of ncRNAs changed by PM2.5 in human diseases

PM_2.5 is a type of particulate matter with an aerodynamic diameter smaller than 2.5 µm, and exposure to PM_2.5 can adversely damage human health. PM_2.5 may impair health through oxidative stress, inflammatory reactions, immune function alterations and chromosome or DNA damage. Through increasing in-depth studies, researchers have found that noncoding RNAs (ncRNAs), particularly microRNAs (miRNAs), circular RNAs (circRNAs) as well as long noncoding RNAs (lncRNAs), might play significant roles in PM_2.5-related human diseases via some of the abovementioned mechanisms. Therefore, in this review, we mainly discuss the regulatory function of ncRNAs altered by PM_2.5 in human diseases and summarize the potential molecular mechanisms. The findings reveal that these ncRNAs might induce or promote diseases via inflammation, the oxidative stress response, cell autophagy, apoptosis, cell junction damage, altered cell proliferation, malignant cell transformation, disruption of synaptic function and abnormalities in the differentiation and status of immune cells. Moreover, according to a bioinformatics analysis, the altered expression of potential genes caused by these ncRNAs might be related to the development of some human diseases. Furthermore, some ncRNAs, including lncRNAs, miRNAs and circRNAs, or processes in which they are involved may be used as biomarkers for relevant diseases and potential targets to prevent these diseases. Additionally, we performed a meta-analysis to identify more promising diagnostic ncRNAs as biomarkers for related diseases.

Associations between long-term exposure to ambient fine particulate pollution with the decline of kidney function and hyperuricemia: a longitudinal cohort study

Evidence of associations between ambient fine particulate matter (PM_2.5) and risks of decline of kidney function and hyperuricemia is limited. We aimed to investigate the associations between long-term exposure to PM_2.5 with decline of kidney function and hyperuricemia in China. We conducted a two-stage study based on China Health and Retirement Longitudinal Study (CHARLS) from 2011 to 2015. Cox proportional hazard regression models and restricted cubic splines were used to evaluate the associations of PM_2.5 with risks of decline of kidney function and hyperuricemia. Latent class trajectory models (LCTM) were used to identify trajectories of PM_2.5 from 2011 to 2015 in the sensitivity analysis. A total of 9760 participants were included in baseline analysis, and 5902 participants were in follow-up analysis. PM_2.5 was associated with the risks of decline of kidney function [hazard ratio (HR): 2.14; 95% confidence interval (CI): (1.03, 4.44)] and hyperuricemia [HR 1.40 (95% CI: 1.10, 1.79)] in the second quartile group versus the lowest quartile group of PM_2.5. We also observed nonlinear relationships between PM_2.5 and the risks of the decline of kidney function and hyperuricemia (P_non-linear < 0.001). In sensitivity analysis, four trajectory groups were identified. "Maintaining a high PM_2.5" [odds ratio (OR): 2.20; 95%CI: (1.78, 2.73)] and "moderately high starting PM_2.5 then steadily decreased" [OR (95%CI): 5.15 (1.55, 16.13)] were associated with hyperuricemia risk, using "low starting PM_2.5 then steadily decreased" trajectory as reference. In conclusion, improved air quality is essential for prevention of decline of kidney function and hyperuricemia.

Hawthorn total flavonoids ameliorate ambient fine particulate matter-induced insulin resistance and metabolic abnormalities of lipids in mice

Recent studies have shown a strong correlation between ambient fine particulate matter (PM2.5) exposure and diabetes risk, including abnormal lipid accumulation and systemic insulin resistance (IR). Hawthorn total flavonoids (HF) are the main groups of active substances in Hawthorn, which showed anti-hyperlipidemic and anti-hyperglycemic effects. Therefore, we hypothesized that HF may attenuate PM2.5-induced IR and abnormal lipid accumulation. Female C57BL/6 N mice were randomly assigned to the filtered air exposure (FA) group, concentrated PM2.5 exposure (PM) group, PM2.5 exposure maintained on a low-dose HF diet (LHF) group, and PM2.5 exposure maintained on a high-dose HF diet (HHF) group for an 8-week PM2.5 exposure using a whole-body exposure device. Body glucose homeostasis, lipid profiles in the liver and serum, and enzymes responsible for hepatic lipid metabolism were measured. We found that exposure to PM2.5 impaired glucose tolerance and insulin sensitivity. In addition, triacylglycerol (TAG) in serum elevated, whereas hepatic TAG levels were decreased after PM2.5 exposure, accompanied by inhibited fatty acid uptake, lipogenesis, and lipolysis in the liver. HF administration, on the other hand, balanced the hepatic TAG levels by increasing fatty acid uptake and decreasing lipid export, leading to alleviated systemic IR and hyperlipidemia in PM2.5-exposed mice. Therefore, HF administration may be an effective strategy to protect against PM2.5-induced IR and metabolic abnormalities of lipids.

Identification of the susceptible subpopulations for wide pulse pressure under long-term exposure to ambient particulate matters

Wide pulse pressure (WPP) is a preclinical indicator for arterial stiffness and cardiovascular diseases. Long-term exposure to ambient particulate matters (PMs) would increase the risk of WPP. Although reducing pollutants emissions and avoiding outdoor activity during a polluted period are effective ways to blunt the adverse effects. Identifying and protecting the susceptible subpopulation is another crucial way to reduce the disease burdens. Therefore, we aimed to identify the susceptible subpopulations of WPP under long-term exposure to PMs. The WPP was defined as pulse pressure over 60 mmHg. Three-year averages of PMs were estimated using random forest approaches. Associations between WPP and PMs exposure were estimated using generalized propensity score weighted logistic regressions. Demographic, socioeconomic characteristics, health-related behaviors, and hematological biomarkers were collected to detect the modification effects on the WPP-PMs associations. Susceptible subpopulations were defined as those with significantly higher risks of WPP under PMs exposures. The PMs-WPP associations were significant with ORs (95%CI) of 1.126 (1.094, 1.159) for PM₁, 1.174 (1.140, 1.210) for PM_2.5, and 1.111 (1.088, 1.135) for PM₁₀. There were 17 subpopulations more sensitive to WPP under long-term exposure to PMs. The susceptibility was higher in subpopulations with high BMI (Q3-Q4 quartiles), high-intensive physical activity (Q3 or Q4 quartile), insufficient or excessive fruit intake (Q1 or Q5 quartile), insufficient or too long sleep length (<7 or >8 h). Subpopulations with elevated inflammation markers (WBC, LYM, BAS, EOS: Q3-Q4 quartiles) and glucose metabolism indicators (HbA1c, GLU: Q3-Q4 quartiles) were more susceptible. Besides, elder, urban living, low socioeconomic level, and excessive red meat and sodium salt intake were also related to higher susceptibility. Our findings on the susceptibility characteristics would help to develop more targeted disease prevention and therapy strategies. Health resources can be allocated more effectively by putting more consideration to subpopulations with higher susceptibility.

Aryl hydrocarbon receptor activation-mediated vascular toxicity of ambient fine particulate matter: contribution of polycyclic aromatic hydrocarbons and osteopontin as a biomarker

BACKGROUND

Exposure to ambient fine particulate matter (PM_2.5) is associated with vascular diseases. Polycyclic aromatic hydrocarbons (PAHs) in PM_2.5 are highly hazardous; however, the contribution of PM_2.5-bound PAHs to PM_2.5-associated vascular diseases remains unclear. The ToxCast high-throughput in vitro screening database indicates that some PM_2.5-bound PAHs activate the aryl hydrocarbon receptor (AhR). The present study investigated whether the AhR pathway is involved in the mechanism of PM_2.5-induced vascular toxicity, identified the PAH in PM_2.5 that was the major contributor of AhR activation, and identified a biomarker for vascular toxicity of PM_2.5-bound PAHs.

RESULTS

Treatment of vascular smooth muscle cells (VMSCs) with an AhR antagonist inhibited the PM_2.5-induced increase in the cell migration ability; NF-κB activity; and expression of cytochrome P450 1A1 (CYP1A1), 1B1 (CYP1B1), interleukin-6 (IL-6), and osteopontin (OPN). Most PM_2.5-bound PAHs were extracted into the organic fraction, which drastically enhanced VSMC migration and increased mRNA levels of CYP1A1, CYP1B1, IL-6, and OPN. However, the inorganic fraction of PM_2.5 moderately enhanced VSMC migration and only increased IL-6 mRNA levels. PM_2.5 increased IL-6 secretion through NF-κB activation; however, PM_2.5 and its organic extract increased OPN secretion in a CYP1B1-dependent manner. Inhibiting CYP1B1 activity and silencing OPN expression prevented the increase in VSMC migration ability caused by PM_2.5 and its organic extract. The AhR activation potencies of seven PM_2.5-bound PAHs, reported in the ToxCast database, were strongly correlated with their capabilities of enhancing the migration ability of VSMCs. Benzo(k)fluoranthene (BkF) contributed the most to the AhR agonistic activity of ambient PM_2.5-bound PAHs. The association between PM_2.5-induced vascular toxicity, AhR activity, and OPN secretion was further verified in mice; PM_2.5-induced intimal hyperplasia in pulmonary small arteries and OPN secretion were alleviated in mice with low AhR affinity. Finally, urinary concentrations of 1-hydroxypyrene, a major PAH metabolite, were positively correlated with plasma OPN levels in healthy humans.

CONCLUSIONS

The present study offers in vitro, animal, and human evidences supporting the importance of AhR activation for PM_2.5-induced vascular toxicities and that BkF was the major contributor of AhR activation. OPN is an AhR-dependent biomarker of PM_2.5-induced vascular toxicity. The AhR activation potency may be applied in the risk assessment of vascular toxicity in PAH mixtures.

Oxidative stress generated by polycyclic aromatic hydrocarbons from ambient particulate matter enhance vascular smooth muscle cell migration through MMP upregulation and actin reorganization

Background

Epidemiological studies have suggested that elevated concentrations of particulate matter (PM) are strongly associated with the incidence of atherosclerosis, however, the underlying cellular and molecular mechanisms of atherosclerosis by PM exposure and the components that are mainly responsible for this adverse effect remain to be established. In this investigation, we evaluated the effects of ambient PM on vascular smooth muscle cell (VSMC) behavior. Furthermore, the effects of polycyclic aromatic hydrocarbons (PAHs), major components of PM, on VSMC migration and the underlying mechanisms were examined.

Results

VSMC migration was significantly increased by treatment with organic matters extracted from ambient PM. The total amount of PAHs contained in WPM was higher than that in SPM, leading to higher ROS generation and VSMC migration. The increased migration was successfully inhibited by treatment with the anti-oxidant, N-acetyl-cysteine (NAC). The levels of matrix metalloproteinase (MMP) 2 and 9 were significantly increased in ambient PM-treated VSMCs, with MMP9 levels being significantly higher in WPM-treated VSMCs than in those treated with SPM. As expected, migration was significantly increased in all tested PAHs (anthracene, ANT; benz(a)anthracene, BaA) and their oxygenated derivatives (9,10-Anthraquinone, AQ; 7,12-benz(a)anthraquinone, BAQ, respectively). The phosphorylated levels of focal adhesion kinase (FAK) and formation of the focal adhesion complex were significantly increased in ambient PM or PAH-treated VSMCs, and these effects were blocked by administration of NAC or α-NF, an inhibitor of AhR, the receptor that allows PAH uptake. Subsequently, the levels of phosphorylated Src and NRF, the downstream targets of FAK, were altered with a pattern similar to that of p-FAK.

Conclusions

PAHs, including oxy-PAHs, in ambient PM may have dual effects that lead to an increase in VSMC migration. One is the generation of oxidative stress followed by MMP upregulation, and the other is actin reorganization that results from the activation of the focal adhesion complex.

Food bioactives lowering risks of chronic diseases induced by fine particulate air pollution: a comprehensive review

Airborne particulate matter (PM) exerts huge negative impacts on human health worldwide, not only targeting the respiratory system but more importantly inducing and aggravating associated chronic diseases like asthma, lung cancer, atherosclerosis, diabetes mellitus and Alzheimer diseases. Food-derived bioactive compounds like vitamins, dietary polyphenols, omega-3 polyunsaturated fatty acids and sulforaphane are feasible alternative therapeutic approaches against PM-mediated potential health damages, drawing great attention in recent years. In this review, the association between PM exposure and risks of developing chronic diseases, and the detailed mechanisms underlying the detrimental effects of PM will be discussed. Subsequently, principal food-derived bioactive compounds, with emphasize on the preventative or protective effects against PM, along with potential mechanisms will be elucidated. This comprehensive review will discuss and present current research findings to reveal the nutritional intervention as a preventative or therapeutic strategy against ambient air pollution, thereby lowering the risk of developing chronic diseases.

Greenness alleviates the effects of ambient particulate matter on the risks of high blood pressure in children and adolescents

Both ambient particulate matter (PM) and decrease of greenness have been suggested as risk factors for high blood pressure (HBP) in children and adolescents. But most evidence were from cross-sectional studies with limited data from prospective cohorts. In this cohort study, we included 588,004 children and adolescents aged 7 to 18 years without HBP from 2005 to 2018 in Beijing (240,081) and Zhongshan (347,923) city of China. The cumulative incidence of HBP was 32.04%, and incidence rate was 14.86 per 100 person-year. After adjustment for confounders, the ten-unit increase in PM₁, PM_2.5, and PM₁₀ exposure was significantly associated with 43%, 70%, and 43%- higher risks of HBP, respectively, but the 0.1-unit increase in NDVI exposure was significantly associated with a 25% lower risk of HBP. The HRs of PM₁ on the HBP risk were 1.486 and 1.150 in the low and the high-level of greenness, and they were 2.635 and 2.507 for PM_2.5, and for PM₁₀ 1.367 and 1.702 in the two groups. The attributable fraction (AFs) of PM₁, PM_2.5, and PM₁₀ on HBP incidents were 13.74%, 40.08%, and 15.47% in the low-level of greenness, which simultaneously was higher than those in the high-level of greenness (AF = 4.62%, 17.28%, and 9.96%). The exposure to higher ambient PM air pollution and lower greenness around schools were associated with a higher risk of HBP in children and adolescents, but higher greenness alleviated the adverse effects of ambient PM₁ and PM_2.5 on the HBP risks. Our findings highlighted a synergic strategy in preventing childhood HBP by decreasing air pollution reduction and improving greenness concurrently.

The health effects of wearing facemasks on cardiopulmonary system of healthy young adults: A double-blinded, randomized crossover trial

BACKGROUND

Facemask had increasingly been utilized as a personal protective measure to reduce exposure to ambient particulate matter (PM) during heavily-polluted days and routine life. However, evidence on the potential effects on cardiovascular system by wearing particulate-filtering facemask was limited.

METHODS

We conducted a double-blinded randomized crossover trial (RCT) to evaluate the effects of wearing N95 facemasks on the molecular responses of cardiopulmonary system among 52 healthy college students in Beijing, China. We measured cardiopulmonary health indicators and collected biological samples before and after (up to 5 h at multiple time points) a 2-h walk to examine the changes in lung function, biomarkers of respiratory and systemic oxidative stress/inflammation. We applied linear mixed-effect models to evaluate the effect of the facemask-intervention on the health of cardio-pulmonary system.

RESULTS

In the trial wearing real facemasks, FEV₁ increased by 2.05% (95% CI: 0.27%-3.87%), 2.80% (95% CI: 1.00%-4.63%), and 2.87% (95% CI: 1.07%-4.70%) at V1 (30-min), V2 (3-h), and V3 (5-h) after the 2-h walk outsides, respectively. Compared with participants wearing the sham mask, the percentage change of nitrate in EBC was lower among those wearing the real mask. After the 2-h exposure, urinary MDA levels increased compared to the baseline in both trials. Real trial was lower than sham trial for 6 cytokines (i.e., IL-6, IL-10, IL-13, IL-17A, IFN-γ and TNF-α) in serum at 5-h post-exposure. Wearing facemasks on polluted days produced better improvement, however, on cleaner days, the improvement was weaker.

CONCLUSIONS

Short-term use of N95 facemasks appeared to effectively reduce the levels of lung function declines, the respiratory oxidative stress, and the systemic inflammation/oxidative stress which may be induced by short-term exposure to PM. Wearing facemasks on polluted days (PM_2.5 > 75 μg/m³) presented larger beneficial effects on the cardiopulmonary health than in clean days (PM_2.5 < 75 μg/m³).

Association between ambient particulate matter exposure and platelet counts in adults: a retrospective cohort study

Associations between ambient particulate matter exposure and platelet counts are inconsistent in previous studies, and study on the effect of long-term exposure especially in Asian populations is limited. We explored the associations between long-term PM2.5 (particulate matter < 2.5 μm) exposure and platelet counts using a prospective cohort study in Northeast China. We used a logistic regression model to analyze the effects of different PM2.5 increments and platelet count elevation. Mixed linear models were used to analyze the association between PM2.5 concentration and platelet counts. Interaction and sub-group analyses were also conducted. Results showed that every 1 μg/m3 increment of PM2.5 exposure was associated with 0.29% (95%CI: 0.25-0.32%) increase in platelet counts and 10% (95%CI: 8-12%) higher risk of platelet elevation. Effects of long-term PM2.5 exposure on platelet elevation were stronger in male participants, of Han ethnicity, and without diabetes. Long-term PM2.5 exposure would increase platelet counts in adults in Northeast area of China, which might add more evidence to the potential biological mechanisms responsible for the effect of air pollution exposure on cardiovascular disease.

The short-term harvesting effects of ambient particulate matter on mortality in Taiyuan elderly residents: A time-series analysis with a generalized additive distributed lag model

The evaluation on mortality displacement and distributed lag effects of airborne particulate matter (PM) on death risks is important to understand the positive association of short-term pollution from both ambient PM₁₀ and PM_2.5 with daily mortality. Herein, short-term influences of urban PM₁₀ and PM_2.5 exposure on the mortality of respiratory diseases (RD) and cardiovascular diseases (CVD) were studied at Taiyuan, China, a typical inland city suffering from heavy ambient PM loading and having high morbidity of RD and CVD. Using a time-series analysis with generalized additive distributed lag model (DLM), the potential mortality displacement was determined and the single-day and cumulative lag-day effects of PM on mortality were estimated after the daily mass concentrations of urban PM_2.5 and PM₁₀ from January 2013 to October 2015 and the daily number of non-accidental death (NAD) and cause-specific mortality in the residents aged more than 65 years old were obtained. Results showed there were significant associations of PM_2.5 and PM₁₀ with daily mortality on the current day and within one week. And a statistically significant increase (P < 0.05) in the cumulative effect estimates of PM_2.5 and PM₁₀ on CVD, ischemic heart disease (IHD), and myocardial infarction (MI) mortality (as well as PM_2.5 on NAD) was observed, while the associations of PM_2.5 with RD and pneumonia mortality, PM₁₀ with NAD and RD mortality were not statistically significant, when the exposure window was extended to lag 0-30 days. It was concluded that there were harvesting effects and cumulative effects of ambient PM_2.5 and PM₁₀ on the elderly residents' mortality due to RD and CVD at Taiyuan and they could be estimated quantitatively when the broader time window was used, suggesting that the underestimation on the association of ambient PM with non-accidental death can be avoided using the present method in our study.

Urban air PM modifies differently immune defense responses against bacterial and viral infections in vitro

Epidemiological evidence has shown the association between exposure to ambient fine particulate matter (PM) and increased susceptibility to bacterial and viral respiratory infections. However, to date, the underlying mechanisms of immunomodulatory effects of PM remain unclear. Our objective was to explore how exposure to relatively low doses of urban air PM alters innate responses to bacterial and viral stimuli in vitro. We used secondary alveolar epithelial cell line along with monocyte-derived macrophages to replicate innate lung barrier in vitro. Co-cultured cells were first exposed for 24 h to PM_2.5-1 (particle aerodynamic diameter between 1 and 2.5 μm) and subsequently for an additional 24 h to lipopolysaccharide (TLR4), polyinosinic-polycytidylic acid (TLR3), and synthetic single-stranded RNA oligoribonucleotides (TLR7/8) to mimic bacterial or viral stimulation. Toxicological endpoints included pro-inflammatory cytokines (IL-8, IL-6, and TNF-α), cellular metabolic activity, and cell cycle phase distribution. We show that cells exposed to PM_2.5-1 produced higher levels of pro-inflammatory cytokines following stimulation with bacterial TLR4 ligand than cells exposed to PM_2.5-1 or bacterial ligand alone. On the contrary, PM_2.5-1 exposure reduced pro-inflammatory responses to viral ligands TLR3 and TLR7/8. Cell cycle analysis indicated that viral ligands induced cell cycle arrest at the G2-M phase. In PM-primed co-cultures, however, they failed to induce the G2-M phase arrest. Contrarily, bacterial stimulation caused a slight increase in cells in the sub-G1 phase but in PM_2.5-1 primed co-cultures the effect of bacterial stimulation was masked by PM_2.5-1. These findings indicate that PM_2.5-1 may alter responses of immune defense differently against bacterial and viral infections. Further studies are required to explain the mechanism of immune modulation caused by PM in altering the susceptibility to respiratory infections.

Effect of probiotics on nasal and intestinal microbiota in people with high exposure to particulate matter ≤ 2.5 μm (PM2.5): a randomized, double-blind, placebo-controlled clinical study

Background

Extended exposure to high concentrations of PM2.5 changes the human microbiota profile, which in turn may increase morbidity and mortality due to respiratory system damage. A balanced microecosystem is crucial to human health, and certain health-related problems may be addressed by effective microecosystem regulation. Recent studies have confirmed that probiotics may reduce the incidence of respiratory diseases. However, few studies have investigated probiotic treatment outcomes in subjects exposed to high concentrations of PM2.5.

Methods

This study is designed as a prospective, randomized, participants- and assessor-blinded, placebo-controlled trial. One hundred and twenty eligible volunteers recruited from October 2019 to July 2020 in downtown Chengdu, China, will be treated with either probiotics or placebo over 4 consecutive weeks. The primary outcome will be 16SrRNA sequencing assay data from nasal and intestinal secretions. Secondary outcomes will be pulmonary function, score on a gastrointestinal symptom rating scale, COOP/WONCA charts, and the Short-Form Health Survey 36 for quality of life. Results will be analyzed to assess differences in clinical efficacy between groups. Six-month follow-up examinations will evaluate the long-term value of probiotics on cardiovascular and respiratory disease end-point events.

Discussion

We will explore the characteristics of nasal and intestinal microbiota in a population with high exposure to PM2.5. Probiotics and placebo interventions will be tested for efficacy in microbial balance regulation, effects on lung and physical functions, and quality of life improvement. This study is expected to provide reliable evidence to support the widespread promotion of probiotics in clinical practice for the protection of individuals with high exposure to PM2.5.

Trial registration

Chinese Clinical Trial Registry ChiCTR1900025469. Registered on 27 August 2019.

Association between exposure to ambient fine particulate matter and prevalence of type 2 diabetes in Iran: an ecological study

Epidemiological evidence for the link between long-term exposure to air particulate matter (PM_2.5) and occurrence of type 2 diabetes (T2D) is limited such that little is known about the effect of PM_2.5 exposure and adult T2D prevalence. Thus, the aim of this ecological study is to evaluate the contribution of ambient PM_2.5 exposure to the adult T2D prevalence in the large population of Iran. The study was conducted based on Iran's large-scale cross-sectional surveilling non-communicable diseases (NCDs) risk factors (Timpka et al. 2015b). A total of 31,050 participants were enrolled in three sequential processes of study using cluster random sampling. PM_2.5 data in the urban area of 31 provinces of Iran were acquired from Tehran Air Quality Control Company (AQCC) and the Department of Environment (DoE) of Iran during 2012-2016. Moreover, major and minor diabetes risk factors were considered; the Pearson correlation and a stepwise regression model were performed to estimate associations between risk factors and diabetes and prediabetes prevalence. The results showed T2D prevalence was more frequent among women (10.61%) than men (9.35%). A weak positive correlation was observed between PM_2.5 level and diabetes prevalence with a correlation coefficient of 0.275, although there was no significant association between PM_2.5 value and prediabetes prevalence. Moreover, none of the variables included in the regression model could predict the prevalence of diabetes and prediabetes. According to our study results, it can be suggested that investigating the association between PM_2.5 exposure and T2D prevalence at individual level may provide a better understanding of PM_2.5 exposure and the risk of T2D prevalence.

Geographic variations in the blood pressure responses to short-term fine particulate matter exposure in China

Results from recent studies on associations between blood pressure (BP) and short-term exposure to fine particulate matter (PM_2.5) have been inconsistent. Most studies have been evaluations of small geographic areas, with no national study in China. This study aimed to examine the acute BP responses to ambient PM_2.5 among the general population of Chinese adults. During 2012-2015, systolic and diastolic BP levels were obtained from a large national representative sample, the China Hypertension Survey database (n = 479,842). Daily PM_2.5 average exposures with a spatial resolution of 0.1° were estimated using a data assimilation that combines satellite measurements, air model simulations, and monitoring values. Overall, a 10-μg/m³ increase in daily PM_2.5 was associated with a 0.035 (95% confidence interval: 0.020, 0.049) mmHg change in systolic BP and 0.001 (-0.008, 0.011) mmHg in diastolic BP after adjustments. Stratified by geographic regions, the systolic and diastolic BP levels varied from -0.050 (-0.109, 0.010) to 0.242 (0.176, 0.307) mmHg, and from -0.026 (-0.053, 0.001) to 0.051 (0.020, 0.082) mmHg, respectively. Statistically significant positive BP-PM_2.5 associations were only found in South and North China for systolic levels and in Southwest China for diastolic levels. We further explored the regional study population characteristics and exposure-response curves, and found that the geographic variations in BP-PM_2.5 associations were probably due to different population compositions or different PM_2.5 exposure levels. Our study provided national-level evidence on the associations between ambient PM_2.5 exposure and elevated BP levels. The magnitude of the estimated associations varied substantially by geographic location in China. CLINICAL TRIAL REGISTRATION: The Clinical trial registration name was Survey on prevalence of hypertension in China; the registration number was ChiCTR-ECS-14004641. http://www.chictr.org.cn/showproj.aspx?proj=4932.

Oxygenated polycyclic aromatic hydrocarbons from ambient particulate matter induce electrophysiological instability in cardiomyocytes

Background

Epidemiologic studies have suggested that elevated concentrations of particulate matter (PM) are strongly associated with an increased risk of developing cardiovascular diseases, including arrhythmia. However, the cellular and molecular mechanisms by which PM exposure causes arrhythmia and the component that is mainly responsible for this adverse effect remains to be established. In this study, the arrhythmogenicity of mobilized organic matter from two different types of PM collected during summer (SPM) and winter (WPM) seasons in the Seoul metropolitan area was evaluated. In addition, differential effects between polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (oxy-PAHs) on the induction of electrophysiological instability were examined.

Results

We extracted the bioavailable organic contents of ambient PM, measuring 10 μm or less in diameter, collected from the Seoul metropolitan area using a high-volume air sampler. Significant alterations in all factors tested for association with electrophysiological instability, such as intracellular Ca²⁺ levels, reactive oxygen species (ROS) generation, and mRNA levels of the Ca²⁺-regulating proteins, sarcoplasmic reticulum Ca²⁺ATPase (SERCA2a), Ca²⁺/calmodulin-dependent protein kinase II (CaMK II), and ryanodine receptor 2 (RyR2) were observed in cardiomyocytes treated with PM. Moreover, the alterations were higher in WPM-treated cardiomyocytes than in SPM-treated cardiomyocytes. Three-fold more oxy-PAH concentrations were observed in WPM than SPM. As expected, electrophysiological instability was induced higher in oxy-PAHs (9,10-anthraquinone, AQ or 7,12-benz(a) anthraquinone, BAQ)-treated cardiomyocytes than in PAHs (anthracene, ANT or benz(a) anthracene, BaA)-treated cardiomyocytes; oxy-PAHs infusion of cells mediated by aryl hydrocarbon receptor (AhR) was faster than PAHs infusion. In addition, ROS formation and expression of calcium-related genes were markedly more altered in cells treated with oxy-PAHs compared to those treated with PAHs.

Conclusions

The concentrations of oxy-PAHs in PM were found to be higher in winter than in summer, which might lead to greater electrophysiological instability through the ROS generation and disruption of calcium regulation.

Short-term exposure to PM2.5 and risk of venous thromboembolism: A case-crossover study

BACKGROUND

Short-term exposure to air pollution increases the risk of cardiovascular mortality and morbidity but little evidence is available on pollution effects on venous thromboembolism (VTE), a common vascular disease.

METHODS

We conducted a case-crossover analysis of all urgent hospitalizations for deep vein thrombosis (DVT) or pulmonary embolism (PE) among patients >35 years during the period 2006 to 2017 in Rome (Italy). We examined whether 1) short-term exposure to particulate matter with aerodynamic diameter <2.5 μg (PM_2.5) increases the risk of hospitalization for DVT or PE, and 2) if the associations are modified by the period of the year (warm and cold seasons), sex, age and comorbidity.

RESULTS

We found that short-term exposure to PM_2.5 was associated with an increase of PE hospitalization risk of during the warm season (April to September) of 19.6% (95% confidence intervals: 8.3, 31%) per 10 μg/m³, while no statistically significant effects were displayed during the cold season or the whole year or for DVT hospitalizations. The effect of PM_2.5 remained significant (%change: 21.3; 95%CI: 5.4, 39.5) after adjustment for nitrogen dioxide (NO₂) co-exposure (a marker of traffic sources) and when limiting to primary diagnosis of PE (%change: 19.1; 95%CI: 4.2, 36.1). Age, sex and comorbid conditions did not modify the association.

CONCLUSIONS

Our results suggested a positive association between short-term exposure to PM_2.5 and pulmonary embolism during the warm period of the year while no evidence emerged for deep vein thrombosis.

Ambient particulate matter concentration levels of Ahvaz, Iran, in 2017

Dust storm in Khuzestan region is strongly influenced by transportation and influx of large amount of particulate matter from internal sources (Hawizeh Marshes and East Ahwaz) and external sources (the Arabian Desert in Saudi Arabia, Jordan, Syria and the Sahara Desert). Particulate matter is one of the main components of indoor and outdoor air quality that can be very dangerous for human. The principal objective of this study was the pinpoint of the source of airborne particulate matter by the NOAA HYSPLIT model in Ahvaz City, southwest of Iran. The investigation of dust storm and their origin was performed by the GFSG Meteorological Data (backward trajectories ending analysis of the NOAA HYSPLIT model) and collecting particulate samples with high-volume air samplers during the fall and winter seasons. The results showed the average ambient particulate matter concentration in the cold and warm seasons was 158 and 161 µg/m³, respectively. Moreover, the average particulate matter concentration in the cold season was significantly higher than the standard level as presented in the National Ambient Air Quality Standard. Consequently, it seems essential to develop green space, decrease particulate emission from source and make determined efforts to control dust at governmental and international scales.

Bio3Air, an integrative system for monitoring individual-level air pollutant exposure with high time and spatial resolution

BACKGROUND

Air pollution is a leading cause of global disease burden. Lack of suitable methods for long term measuring exposure level at individual level is crippling environmental epidemiology research of air pollution.

METHODS

We report an integrative system, Bio³Air, for long term measurement of individual level air pollution exposure, currently focusing on ambient particulate matter (PM). The novel system in real-time quantifies individual's outdoor/indoor status, geological location, lung ventilation rate and PM concentration of individual's surrounding environment, and these metrics are subsequently incorporated in calculating PM exposure.

RESULTS

The system is fully developed and tested in China, USA and Canada, and has been successfully applied in epidemiology study. Bio³Air offers high reliability, sensitivity, reproducibility (>99%) and accuracy. It has high time- and spatial- resolution (≤ 2 min and ≤ 20 m, respectively). Bio³Air achieved 91.89% consistency with "gold-standard" method (membrane collection and off-line analysis).

CONCLUSIONS

Bio³Air represents a substantial methodological advance in environmental health research of air pollution. It captures information relevant in measuring individual's PM exposure (e.g. real-time outdoor/indoor status, location and lung ventilation rate). Such information is typically missed by conventional approaches. Additional features of Bio³Air include easy-to-use, cost-effectiveness and automated data collection, making it a powerful tool facilitating studies of air pollution exposure and health consequences.

Ambient fine and coarse particles in Japan affect nasal and bronchial epithelial cells differently and elicit varying immune response

Ambient particulate matter (PM) epidemiologically exacerbates respiratory and immune health, including allergic rhinitis (AR) and bronchial asthma (BA). Although fine and coarse particles can affect respiratory tract, the differences in their effects on the upper and lower respiratory tract and immune system, their underlying mechanism, and the components responsible for the adverse health effects have not been yet completely elucidated. In this study, ambient fine and coarse particles were collected at three different locations in Japan by cyclone technique. Both particles collected at all locations decreased the viability of nasal epithelial cells and antigen presenting cells (APCs), increased the production of IL-6, IL-8, and IL-1β from bronchial epithelial cells and APCs, and induced expression of dendritic and epithelial cell (DEC) 205 on APCs. Differences in inflammatory responses, but not in cytotoxicity, were shown between both particles, and among three locations. Some components such as Ti, Co, Zn, Pb, As, OC (organic carbon) and EC (elemental carbon) showed significant correlations to inflammatory responses or cytotoxicity. These results suggest that ambient fine and coarse particles differently affect nasal and bronchial epithelial cells and immune response, which may depend on particles size diameter, chemical composition and source related particles types.

Data set on concentrations, bioavailability, dose and lung deposition of labile metals bound to inhalable and respirable fractions of ambient particulate matters in Akure suburbs

This article consists of data sets of concentrations, dose and deposition of some labile metals bound to inhale ambient particulate matter collected at human breathing height of 1.5–2 m in Akure, South Western Nigeria. Ten (10) data points, of different air quality, were selected for study using active sampling method; during the dry season months of November, 2016 to March, 2017. At each data point, the dust particles were collected four times, sorted into inhalable and respirable fractions. The metal concentrations in each fraction were determined using Perkin-Elmer 6000 Inductively Coupled Plasma - Atomic Emission Spectrometry (ICP-AES) analysis. The data set were processed and analyzed via descriptive statistics (averages and standard deviations), and numerical analyses. The data were explored further to estimate the exposure dose of metal particles and deposition in various regions of lung (alveolar, trachea-bronchial and extra thoracic) in adults (male and female) dwelling in the area. The data revealed that the highest dose and deposition of metals (Pb, Cd and Cr) occur in the alveolar region of the lung of adults.

Interactions between oxidative stress, autophagy and apoptosis in A549 cells treated with aged black carbon

After emitted from incomplete combustion of fossil fuels and biomass, ambient black carbon (BC) was then undergone photochemical oxidization processes in the air to form aged BC particles, also called oxidized BC (OBC). This study aimed to investigate the interactions between oxidative stress, autophagy and apoptosis induced by OBC in A549 cells and to explore associated molecular mechanisms. First, OBC could stimulate oxidative stress, autophagy and apoptosis dose-dependently, as evidenced by increased intercellular reactive oxygen species (ROS) levels, up-regulated autophagosome markers (light chain 3, LC3), and elevated apoptosis rate. Inhibitors of oxidative stress (N-acetylcysteine, NAC), autophagy (bafilomycin A1, Baf) and apoptosis (Z-DEVD-FMK) were used to investigate their interactions. NAC pretreatment could significantly reduce autophagy and apoptosis. Additionally, pretreatment with Baf or Z-DEVD-FMK could also significantly suppress the other two biological effects. Furthermore, OBC up regulated the expressions of DNA-dependent protein kinase catalytic subunit (DNA-PKcs), phosphorylated protein kinase B (Akt) and mammalian target of rapamycin (mTOR). The Akt inhibitor (MK-2206) significantly reduced both autophagy and apoptosis. Taken together, dual-direction regulation existed between each two of oxidative stress, autophagy, and apoptosis in A549 cells exposed to OBC. In addition, the autophagy process is modulated by the PI3K/Akt pathway regardless of mTOR activity.

Toxicoproteomic analysis of human lung epithelial cells exposed to steel industry ambient particulate matter (PM) reveals possible mechanism of PM related carcinogenesis

Toxicoproteomic analysis of steel industry ambient particulate matter (PM) that contain high concentrations of PAHs and metals was done by treating human lung cancer cell-line, A549 and the cell lysates were analysed using quantitative label-free nano LC-MS/MS. A total of 18,562 peptides representing 1576 proteins were identified and quantified, with 196 proteins had significantly altered expression in the treated cells. Enrichment analyses revealed that proteins associated to redox homeostsis, metabolism, and cellular energy generation were inhibited while, proteins related to DNA damage and repair and other stresses were over expressed. Altered activities of several tumor associated proteins were observed. Protein-protein interaction network and biological pathway analysis of these differentially expressed proteins were carried out to obtain a systems level view of proteome changes. Together it could be inferred that PM exposure induced oxidative stress which could have lead into DNA damage and tumor related changes. However, lowering of cellular metabolism, and energy production could reduce its ability to overcome these stress. This kind of disequilibrium between the DNA damage and ability of the cells to repair the DNA damage may lead into genomic instability that is capable of acting as the driving force during PM induced carcinogenesis.

The effects of facemasks on airway inflammation and endothelial dysfunction in healthy young adults: a double-blind, randomized, controlled crossover study

Background

Facemasks are increasingly worn during air pollution episodes in China, but their protective effects are poorly understood. We aimed to evaluate the filtration efficiencies of N95 facemasks and the cardiopulmonary benefits associated with wearing facemasks during episodes of pollution.

Results

We measured the filtration efficiencies of particles in ambient air of six types of N95 facemasks with a manikin headform. The most effective one was used in a double-blind, randomized, controlled crossover study, involving 15 healthy young adults, conducted during 2 days of severe pollution in Beijing, China. Subjects were asked to walk along a busy-traffic road for 2 h wearing authentic or sham N95 facemasks. Clinical tests were performed four times to determine changes in the levels of biomarkers of airway inflammation, endothelial dysfunction, and oxidative stress within 24 h after exposure.

The facemasks removed 48–75% of number concentrations of ambient air particles between 5.6 and 560 nm in diameter. After adjustments for multiple comparison, the exhaled nitric oxide level and the levels of interleukin-1α, interleukin-1β, and interleukin-6 in exhaled breath condensate increased significantly in all subjects; however, the increases in those wearing authentic facemasks were statistically significantly lower than in the sham group. No significant between-group difference was evident in the urinary creatinine-corrected malondialdehyde level. In arterial stiffness indicators, the ejection duration of subjects wearing authentic facemasks was higher after exposure compared to the sham group; no significant between-group difference was found in augmentation pressure or the augmentation index.

Conclusions

In young healthy adults, N95 facemasks partially reduced acute particle-associated airway inflammation, but neither systemic oxidative stress nor endothelial dysfunction improved significantly. The clinical significance of these findings long-term remains to be determined.

Trial registration

The trial registration number (TRN) for this study is ChiCTR1800016099, which was retrospectively registered on May 11, 2018.

Electronic supplementary material

The online version of this article (10.1186/s12989-018-0266-0) contains supplementary material, which is available to authorized users.

Effect of long-term exposure to ambient particulate matter on prevalence of type 2 diabetes and hypertension in Iranian adults: an ecologic study

Air pollution is considered as an environmental risk to health worldwide. Current evidence is mostly from Western populations exposed to lower levels of pollutants. This study was to explore the association of type 2 diabetes (T2D) and hypertension prevalence with exposure to high levels of air pollution in Iranian adults. The air pollution data were obtained from the air quality monitoring stations of five large cities in Iran from 2006 to 2011. The air quality monitoring stations could only detect ambient particulate matter_10 (PM₁₀) during the study period; therefore, the average PM₁₀ concentration was considered for comparison. We grouped the cities as group 1 (Tehran, Shiraz) with PM₁₀ concentration < 100 μg/m³, and group 2 (Kermanshah, Ahwaz, Esfahan) with PM₁₀ concentration > 100 μg/m³. Data from the Surveillance of Risk Factors of Non-Communicable Disease (SuRFNCD) study were used to calculate the prevalence of T2D and hypertension. We assessed the association between air pollution and the prevalence of T2D using logistic regression models. Odds ratios (ORs) with 95% CI for each outcome were calculated after adjusting for age, sex, BMI, physical activity, and other covariates. The 5-year average of PM₁₀ concentration was higher in group 2 (120.15 ± 6.81 μg/m³) compared to group 1 (83.95 ± 7.81 μg/m³). The prevalence of T2D in group 2 was 13.8%, while it was 10.7% in group 1 (p = 0.01), OR = 1.32 (95% CI 1.03-1.69). Similarly, hypertension was more prevalent in group 2 (15.7 vs. 11.9%, p = 0.005, OR = 1.55, 95% CI 1.20-1.99). PM₁₀ is associated with higher prevalence of T2D and hypertension in Iranian adults.

Typical airborne quinones modulate oxidative stress and cytokine expression in lung epithelial A549 cells

Quinones that exist in ambient particulate matter (PM) are hypothesized to be associated with adverse health effects through the generation of reactive oxygen species (ROS). However, the impacts of the quinones on the inflammatory processes have yet to be clearly understood. In this study, we examined the oxidative potentials and biological effects of typical airborne quinones in the human lung epithelial A549 cells. Significant change of redox status, loss of mitochondrial membrane potentials (△Ψ) and increase of superoxide dismutase (SOD) activity were induced by exposure to quinones. Some pro-inflammatory genes including interleukin-6 (IL-6), interleukin-8 (IL-8), tumor necrosis factor (TNF-α) and monocyte chemoattractant protein-1 (MCP-1); two aromatic hydrocarbon receptor-regulated genes, cytochromes P450 1A1 (Cyp1a1) and cytochromes P450 1B1 (Cyp1b1); and oxidative stress-related gene heme oxygenase-1 (HO-1) were up-regulated after quinones treatment. Among these quinones, 1,2-naphthoquinone (1,2-NQ) up-regulated expressions of IL-6, IL-8, TNF-α, Cyp1a1, and HO-1; 2-methoxy-1,4-naphthoquinone (MNQ) up-regulated MCP-1, Cyp1b1, Cyp1a1, and HO-1; 2-methylanthraquinone (MAQ) up-regulated IL-6, IL-8, TNF-α, MCP-1, Cyp1b1, and Cyp1a1; acenaphthenequinone (ACQ) up-regulated IL-8, TNF-α, MCP-1, Cyp1b1, and Cyp1a1. These results suggested that all these five quinones had a considerable pro-inflammatory potential by inducing oxidative stress and releasing different types of cytokines/chemokines.

A critical review of approaches and limitations of inhalation bioavailability and bioaccessibility of metal(loid)s from ambient particulate matter or dust

Inhalation of metal(loid)s in ambient particulate matter (APM) represents a significant exposure pathway to humans. Although exposure assessment associated with this pathway is currently based on total metal(loid) content, a bioavailability (i.e. absorption in the systemic circulation) and/or bioaccessibility (i.e. solubility in simulated lung fluid) based approach may more accurately quantify exposure. Metal(loid) bioavailability-bioaccessibility assessment from APM is inherently complex and lacks consensus. This paper reviews the discrepancies that impede the adoption of a universal protocol for the assessment of inhalation bioaccessibility. Exposure assessment approaches for in-vivo bioavailability, in-vitro cell culture and in-vitro bioaccessibility (composition of simulated lungs fluid, physico-chemical and methodological considerations) are critiqued in the context of inhalation exposure refinement. An important limitation of bioavailability and bioaccessibility studies is the use of considerably higher than environmental metal(loid) concentration, which diminishing their relevance to human exposure scenarios. Similarly, individual metal(loid) studies have been criticised due to complexities of APM metal(loid) mixtures which may impart synergistic or antagonistic effects compared to single metal(loid) exposure. Although a number of different simulated lung fluid (SLF) compositions have been used in metal(loid) bioaccessibility studies, information regarding the comparative leaching efficiency among these different SLF and comparisons to in-vivo bioavailability data is lacking. In addition, the particle size utilised is often not representative of what is deposited in the lungs while assay parameters (extraction time, solid to liquid ratio, temperature and agitation) are often not biologically relevant. Research needs are identified in order to develop robust in-vitro bioaccessibility protocols for the assessment or prediction of metal(loid) bioavailability in APM for the refinement of inhalation exposure.

Differential DNA methylation and PM2.5 species in a 450K epigenome-wide association study

Although there is growing evidence that exposure to ambient particulate matter is associated with global DNA methylation and gene-specific methylation, little is known regarding epigenome-wide changes in DNA methylation in relation to particles and, especially, particle components. Using the Illumina Infinium HumanMethylation450 BeadChip, we examined the relationship between one-year moving averages of PM_2.5 species (Al, Ca, Cu, Fe, K, Na, Ni, S, Si, V, and Zn) and DNA methylation at 484,613 CpG probes in a longitudinal cohort that included 646 subjects. Bonferroni correction was applied to adjust for multiple comparisons. Bioinformatics analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment was also performed. We observed 20 Bonferroni significant (P-value < 9.4× 10^-9) CpGs for Fe, 8 for Ni, and 1 for V. Particularly, methylation at Schlafen Family Member 11 (SLFN11) cg10911913 was positively associated with measured levels of all 3 species. The SLFN11 gene codes for an interferon-induced protein that inhibits retroviruses and sensitizes cancer cells to DNA-damaging agents. Bioinformatics analysis suggests that gene targets may be relevant to pathways including cancers, signal transduction, and cell growth and death. Ours is the first study to examine the epigenome-wide association between ambient particles species and DNA methylation. We found that long-term exposures to specific components of ambient particle pollution, especially particles emitted during oil combustion, were associated with methylation changes in genes relevant to immune responses. Our findings provide insight into potential biologic mechanisms on an epigenetic level.

Meta-Analysis Methods to Estimate the Shape and Uncertainty in the Association Between Long-Term Exposure to Ambient Fine Particulate Matter and Cause-Specific Mortality Over the Global Concentration Range

Estimates of excess mortality associated with exposure to ambient concentrations of fine particulate matter have been obtained from either a single cohort study or pooling information from a small number of studies. However, standard frequentist methods of pooling are known to underestimate statistical uncertainty in the true risk distribution when the number of studies pooled is small. Alternatively, Bayesian pooling methods using noninformative priors yield unrealistically large amounts of uncertainty in this case. We present a new hybrid frequentist-bayesian framework for meta-analysis that incorporates features of both frequentist and Bayesian approaches, yielding estimated uncertainty distributions that are more useful for burden estimation. We also present an example of mortality risk due to long-term exposure to ambient fine particulate matter obtained from a small number of cohort studies conducted in the United States and Europe. We compare our new risk uncertainty distribution to that obtained by the integrated exposure-response (IER) model used in the Global Burden of Disease 2010 project for which risk was modeled over the entire global concentration range. We suggest a method to incorporate our new risk uncertainty distribution based on the relatively low concentrations observed in the United States and western Europe into the IER model, thus extending risk estimation to the global concentration range.

Spatiotemporal analysis for the effect of ambient particulate matter on cause-specific respiratory mortality in Beijing, China

This study explored the association between particulate matter with an aerodynamic diameter of less than 10 μm (PM10) and the cause-specific respiratory mortality. We used the ordinary kriging method to estimate the spatial characteristics of ambient PM10 at 1-km × 1-km resolution across Beijing during 2008-2009 and subsequently fit the exposure-response relationship between the estimated PM10 and the mortality due to total respiratory disease, chronic lower respiratory disease, chronic obstructive pulmonary disease (COPD), and pneumonia at the street or township area levels using the generalized additive mixed model (GAMM). We also examined the effects of age, gender, and season in the stratified analysis. The effects of ambient PM10 on the cause-specific respiratory mortality were the strongest at lag0-5 except for pneumonia, and an inter-quantile range increase in PM10 was associated with an 8.04 % (95 % CI 4.00, 12.63) increase in mortality for total respiratory disease, a 6.63 % (95 % CI 1.65, 11.86) increase for chronic lower respiratory disease, and a 5.68 % (95 % CI 0.54, 11.09) increase for COPD, respectively. Higher risks due to the PM10 exposure were observed for females and elderly individuals. Seasonal stratification analysis showed that the effects of PM10 on mortality due to pneumonia were stronger during spring and autumn. While for COPD, the effect of PM10 in winter was statistically significant (15.54 %, 95 % CI 5.64, 26.35) and the greatest among the seasons. The GAMM model evaluated stronger associations between concentration of PM10. There were significant associations between PM10 and mortality due to respiratory disease at the street or township area levels. The GAMM model using high-resolution PM10 could better capture the association between PM10 and respiratory mortality. Gender, age, and season also acted as effect modifiers for the relationship between PM10 and respiratory mortality.

Short-term exposure to particulate air pollution and risk of myocardial infarction: a systematic review and meta-analysis

A growing number of studies have associated short-term exposure to ambient particulate matter air pollution (PM) and risk of specific cardiovascular events, just as myocardial infarction (MI). However, the results of the recent studies were inconsistent; therefore, a systematic review and meta-analysis was performed. To synthetically quantify the association between short-term exposure to PM and risk of MI, a meta-analysis was conducted to combine the estimates of effect for a relationship between short-term exposure to PM10, PM2.5 (particulate matter ≤ 10 μm, 2.5 μm in diameter) and risk of MI. Electronic database searches for all relevant published studies were updated in January 2015. And, a random-effects model was performed to estimate pooled relative risk (RR) and 95 % confidence intervals (95 % CI). Thirty-one published observational epidemiological studies were identified. Risk of MI was significantly associated with per 10 μg/m(3) increment in PM10 (OR = 1.005; 95 % CI 1.001-1.008) and PM2.5 (OR = 1.022; 95 % CI 1.015-1.030). The risk of PM2.5 exposure was relatively greater than PM10. In the subgroup analysis by study design, location, quality score, and lag exposure, the results were basically consistent with the former overall results in PM2.5 but slightly changed in PM10. Short-term exposure to particulate matter (PM2.5, PM10) was a risk factor for MI, and the results further confirmed the discovery in the previous meta-analysis.

Ambient PM2.5 exposure exacerbates severity of allergic asthma in previously sensitized mice

OBJECTIVE

Epidemiological studies have shown that elevated concentrations of ambient particulate matter (aerodynamic diameter ≤2.5 μm; PM2.5) correlates with increased incidence of asthma. The aim of this study was to determine whether PM2.5 participates in the exacerbation of asthma.

METHODS

Effects of 1, 10 and 100 μg PM2.5 instilled intratracheally in ovalbumin (OVA)-sensitized or asthmatic mice were compared.

RESULTS

PM2.5 exposure in the OVA-sensitized and especially asthmatic groups increased Mch responsiveness in a dose-dependent manner. In OVA-sensitized groups, exposure to 1 μg of PM2.5 caused no detectable lung inflammation, while 10 and 100 μg of PM2.5 resulted in a slightly increased trend in numbers of neutrophils and macrophages. Compared with the asthmatic control group, both 10 and 100 μg of PM2.5 provoked a significant increase in eosnophils and neutrophils whereas only 100 μg of PM2.5 noticeably enhanced lymphocytes. In asthmatic groups, administration of 100 μg of PM2.5 greatly increased levels of the pro-inflammatory cytokine TNF-α and Th2-related cytokines IL-4 and IL-10 in bronchoalveolar lavage fluid, but it decreased Th1-related INF-γ. In addition, 10 and 100 μg of PM2.5 exacerbated inflammatory infiltration, goblet cell metaplasia and lung ultrastructure lesions in asthmatic mice.

CONCLUSIONS

Our results suggested that acute exposure of PM2.5 could synergize with allergens in the subsequent challenge to aggravate the severity of asthma in sensitized mice, possibly by promoting a Th2-biased immune response.

Measurement of Soluble and Total Hexavalent Chromium in the Ambient Airborne Particles in New Jersey

Hexavalent chromium (Cr(VI)) in ambient airborne particulate matter (PM) is a known pulmonary carcinogen and may have both soluble and insoluble forms. The sum of the two forms is defined as total Cr(VI). Currently, there were no methods suitable for large-scale monitoring of total Cr(VI) in ambient PM. This study developed a method to measure total Cr(VI) in ambient PM. This method includes PM collection using a Teflon filter, microwave extraction with 3% Na₂CO₃-2% NaOH at 95°C for 60 minutes, and Cr(VI) analysis by 1,5-diphenylcarbazide colorimetry at 540 nm. The recoveries of total Cr(VI) were 119.5 ± 10.4% and 106.3 ± 16.7% for the Cr(VI)-certified reference materials, SQC 012 and SRM 2700, respectively. Total Cr(VI) in the reference urban PM (NIST 1648a) was 26.0 ± 3.1 mg/kg (%CV = 11.9%) determined by this method. The method detection limit was 0.33 ng/m³. This method and the one previously developed to measure ambient Cr(VI), which is soluble in pH ~9.0 aqueous solution, were applied to measure Cr(VI) in ambient PM₁₀ collected from three urban areas and one suburban area in New Jersey. The total Cr(VI) concentrations were 1.05-1.41 ng/m³ in the winter and 0.99-1.56 ng/m³ in the summer. The soluble Cr(VI) concentrations were 0.03-0.19 ng/m³ in the winter and 0.12-0.37 ng/m³ in the summer. The summer mean ratios of soluble to total Cr(VI) were 14.3-43.7%, significantly higher than 4.2-14.4% in the winter. The winter concentrations of soluble and total Cr(VI) in the suburban area were significantly lower than in the three urban areas. The results suggested that formation of Cr(VI) via atmospheric chemistry may contribute to the higher soluble Cr(VI) concentrations in the summer.

The combined effects of physicochemical properties of size-fractionated ambient particulate matter on in vitro toxicity in human A549 lung epithelial cells

Epidemiological and toxicological studies have suggested that the health effects associated with exposure to particulate matter (PM) are related to the different physicochemical properties of PM. These effects occur through the initiation of differential cellular responses including: the induction of antioxidant defenses, proinflammatory responses, and ultimately cell death. The main objective of this study was to investigate the effects of size-fractionated ambient PM on epithelial cells in relation to their physicochemical properties. Concentrated ambient PM was collected on filters for three size fractions: coarse (aerodynamic diameter [AD] 2.5-10 μm), fine (0.15-2.5 μm), and quasi-ultrafine (<0.2 μm), near a busy street in Toronto, Ontario, Canada. Filters were extracted and analyzed for chemical composition and redox activity. Chemical analyses showed that the coarse, fine, and quasi-ultrafine particles were comprised primarily of metals, water-soluble species, and organic compounds, respectively. The highest redox activity was observed for fine PM. After exposure of A549 cells to PM (10-100 μg/ml) for 4 h, activation of antioxidant, proinflammatory and cytotoxic responses were assessed by determining the expression of heme oxygenase (HMOX-1, mRNA), interleukin-8 (IL-8, mRNA), and metabolic activity of the cells, respectively. All three size fractions induced mass-dependent antioxidant, proinflammatory, and cytotoxic responses to different degrees. Quasi-ultrafine PM caused significant induction of HMOX-1 at the lowest exposure dose. Correlation analyses with chemical components suggested that the biological responses correlated mainly with transition metals and organic compounds for coarse and fine PM and with organic compounds for quasi-ultrafine PM. Overall, the observed biological responses appeared to be related to the combined effects of size and chemical composition and thus both of these physicochemical properties should be considered when explaining PM toxicity.

Exposure to fine airborne particulate matter induces macrophage infiltration, unfolded protein response, and lipid deposition in white adipose tissue

Recent epidemiological studies have suggested a link between exposure to ambient air-pollution and susceptibility to metabolic disorders such as Type II diabetes mellitus. Previously, we provided evidence that both short- and long-term exposure to concentrated ambient particulate matter with aerodynamic diameter <2.5 μm (PM2.5) induces multiple abnormalities associated with the pathogenesis of Type II diabetes mellitus, including insulin resistance, visceral adipose inflammation, brown adipose mitochondrial adipose changes, and hepatic endoplasmic reticulum (ER) stress. In this report, we show that chronic inhalation exposure to PM2.5 (10 months exposure) induces macrophage infiltration and Unfolded Protein Response (UPR), an intracellular stress signaling that regulates cell metabolism and survival, in mouse white adipose tissue in vivo. Gene expression studies suggested that PM2.5 exposure induces two distinct UPR signaling pathways mediated through the UPR transducer inositol-requiring 1α (IRE1α): 1) ER-associated Degradation (ERAD) of unfolded or misfolded proteins, and 2) Regulated IRE1-dependent Decay (RIDD) of mRNAs. Along with the induction of the UPR pathways and macrophage infiltration, expression of genes involved in lipogenesis, adipocyte differentiation, and lipid droplet formation was increased in the adipose tissue of the mice exposed to PM2.5. In vitro study confirmed that PM2.5 can trigger phosphorylation of the UPR transducer IRE1α and activation of macrophages. These results provide novel insights into PM2.5-triggered cell stress response in adipose tissue and increase our understanding of pathophysiological effects of particulate air pollution on the development of metabolic disorders.