Concentrated ambient air particles induce mild pulmonary inflammation in healthy human volunteers

Obesity as a susceptibility factor to indoor particulate matter health effects in COPD

Our goal was to investigate whether obesity increases susceptibility to the adverse effects of indoor particulate matter on respiratory morbidity among individuals with chronic obstructive pulmonary disease (COPD). Participants with COPD were studied at baseline, 3 and 6 months. Obesity was defined as a body mass index ≥30 kg·m(-2). At each time point, indoor air was sampled for 5-7 days and particulate matter (PM) with an aerodynamic size ≤2.5 μm (PM2.5) and 2.5-10 μm (PM2.5-10) was measured. Respiratory symptoms, health status, rescue medication use, exacerbations, blood biomarkers and exhaled nitric oxide were assessed simultaneously. Of the 84 participants enrolled, 56% were obese and all were former smokers with moderate-to-severe COPD. Obese participants tended to have less severe disease as assessed by Global Initiative for Chronic Obstructive Pulmonary Disease stage and fewer pack-years of smoking. There was evidence that obesity modified the effects of indoor PM on COPD respiratory outcomes. Increases in PM2.5 and PM2.5-10 were associated with greater increases in nocturnal symptoms, dyspnoea and rescue medication use among obese versus non-obese participants. The impact of indoor PM on exacerbations, respiratory status and wheeze also tended to be greater among obese versus non-obese participants, as were differences in airway and systemic inflammatory responses to indoor PM. We found evidence that obesity was associated with exaggerated responses to indoor fine and coarse PM exposure among individuals with COPD.

Social disparities in heart disease risk and survivor bias among autoworkers: an examination based on survival models and g-estimation

OBJECTIVES

To examine gender and racial disparities in ischaemic heart disease (IHD) mortality related to metalworking fluid exposures and in the healthy worker survivor effect.

METHODS

A cohort of white and black men and women autoworkers in the USA was followed from 1941 to 1995 with quantitative exposure to respirable particulate matter from water-based metalworking fluids. Separate analyses used proportional hazards models and g-estimation.

RESULTS

The HR for IHD among black men was 3.29 (95% CI 1.49 to 7.31) in the highest category of cumulative synthetic fluid exposure. The HR for IHD among white women exposed to soluble fluid reached 2.44 (95% CI 0.96 to 6.22). However, no increased risk was observed among white men until we corrected for the healthy worker survivor effect. Results from g-estimation indicate that if white male cases exposed to soluble or synthetic fluid had been unexposed to that fluid type, then 1.59 and 1.20 years of life would have been saved on average, respectively.

CONCLUSIONS

We leveraged the strengths of two different analytic approaches to examine the IHD risks of metalworking fluids. All workers may have the same aetiological risk; however, black and female workers may experience more IHD from water-based metalworking fluid exposure because of a steeper exposure-response or weaker healthy worker survivor effect.

Investigating the spill-over hypothesis: analysis of the association between local inflammatory markers in sputum and systemic inflammatory mediators in plasma

Exposure to air pollutants represents a risk factor not only for respiratory diseases and lung cancer, but also for cardiometabolic diseases. It has been hypothesised that local inflammation in the lung and systemic subclinical inflammation are linked by impaired lung function and the spill-over of proinflammatory factors from the lung into the circulation which could act as intermediaries between environmental exposures and disease risk. We wanted to investigate whether local and systemic inflammatory markers are associated, which would support the spill-over hypothesis. Sputum and plasma samples were obtained from 257 women of the German SALIA cohort. We performed immunoassays to measure multiple biomarkers of airway inflammation in sputum as well as cytokines, chemokines and soluble adhesion molecules in plasma. Correlations were calculated and adjusted for potentially confounding variables. Even though several significant associations were detected between inflammatory mediators in sputum and plasma, correlation coefficients were rather low ranging from r≥-0.20 to r≤0.20. Comparatively stronger associations were observed between nitrite, eosinophil cationic protein, leukotrienes C/D/E4 and interleukin-8 in sputum. Notably, correlations were positive with all proinflammatory biomarkers and interleukin-1 receptor antagonist in plasma, whereas negative correlations were observed with the anti-inflammatory adipokine adiponectin. In conclusion, local inflammation in the lung and systemic subclinical inflammation appear mainly independently regulated in elderly women from the general population. Although we found multiple significant correlations between inflammatory biomarkers in sputum and plasma, our results do not provide clear support for the spill-over hypothesis.

Biomarkers of oxidative stress and inflammation after wood smoke exposure in a reconstructed Viking Age house

Exposure to particles from combustion of wood is associated with respiratory symptoms, whereas there is limited knowledge about systemic effects. We investigated effects on systemic inflammation, oxidative stress and DNA damage in humans who lived in a reconstructed Viking Age house, with indoor combustion of wood for heating and cooking. The subjects were exposed to high indoor concentrations of PM2.5 (700-3,600 µg/m(3)), CO (10.7-15.3 ppm) and NO2 (140-154 µg/m(3)) during a 1-week stay. Nevertheless, there were unaltered levels of genotoxicity, determined as DNA strand breaks and formamidopyrimidine DNA glycosylase and oxoguanine DNA glycosylase 1 sensitive sites in peripheral blood mononuclear cells. There were also unaltered expression levels of OGG1, HMOX1, CCL2, IL8, and TNF levels in leukocytes. In serum, there were unaltered levels of C-reactive protein, IL6, IL8, TNF, lactate dehydrogenase, cholesterol, triglycerides, and high-density lipoproteins. The wood smoke exposure was associated with decreased serum levels of sICAM-1, and a tendency to decreased sVCAM-1 levels. There was a minor increase in the levels of circulating monocytes expressing CD31, whereas there were unaltered expression levels of CD11b, CD49d, and CD62L on monocytes after the stay in the house. In conclusion, even a high inhalation exposure to wood smoke was associated with limited systemic effects on markers of oxidative stress, DNA damage, inflammation, and monocyte activation.

Air pollution exposure affects circulating white blood cell counts in healthy subjects: the role of particle composition, oxidative potential and gaseous pollutants - the RAPTES project

Studies have linked air pollution exposure to cardiovascular health effects, but it is not clear which components drive these effects. We examined the associations between air pollution exposure and circulating white blood cell (WBC) counts in humans. To investigate independent contributions of particulate matter (PM) characteristics, we exposed 31 healthy volunteers at five locations with high contrast and reduced correlations amongst pollutant components: two traffic sites, an underground train station, a farm and an urban background site. Each volunteer visited at least three sites and was exposed for 5 h with intermittent exercise. Exposure measurements on-site included PM mass and number concentration, oxidative potential (OP), elemental- and organic carbon, metals, O3 and NO2. Total and differential WBC counts were performed on blood collected before and 2 and 18 h post-exposure (PE). Changes in total WBC counts (2 and 18 h PE), number of neutrophils (2 h PE) and monocytes (18 h PE) were positively associated with PM characteristics that were high at the underground site. These time-dependent changes reflect an inflammatory response, but the characteristic driving this effect could not be isolated. Negative associations were observed for NO2 with lymphocytes and eosinophils. These associations were robust and did not change after adjustment for a large suite of PM characteristics, suggesting an independent effect of NO2. We conclude that short-term air pollution exposure at real-world locations can induce changes in WBC counts in healthy subjects. Future studies should indicate if air pollution exposure-induced changes in blood cell counts results in adverse cardiovascular effects in susceptible individuals.

Hourly differences in air pollution and risk of respiratory disease in the elderly: a time-stratified case-crossover study

BACKGROUND

Epidemiological studies have shown adverse effects of short-term exposure to air pollution on respiratory disease outcomes; however, few studies examined this association on an hourly time scale. We evaluated the associations between hourly changes in air pollution and the risk of respiratory disease in the elderly, using the time of the emergency call as the disease onset for each case.

METHODS

We used a time-stratified case-crossover design. Study participants were 6,925 residents of the city of Okayama, Japan, aged 65 or above who were taken to hospital emergency rooms between January 2006 and December 2010 for onset of respiratory disease. We calculated city-representative hourly average concentrations of air pollutants from several monitoring stations. By using conditional logistic regression models, we estimated odds ratios per interquartile-range increase in each pollutant by exposure period prior to emergency call, adjusting for hourly ambient temperature, hourly relative humidity, and weekly numbers of reported influenza cases aged ≥60.

RESULTS

Suspended particulate matter (SPM) exposure 24 to <72 hours prior to the onset and ozone exposure 48 to <96 hours prior to the onset were associated with the increased risk of respiratory disease. For example, following one interquartile-range increase, odds ratios were 1.05 (95% confidence interval: 1.01, 1.09) for SPM exposure 24 to <48 hours prior to the onset and 1.13 (95% confidence interval: 1.04, 1.23) for ozone exposure 72 to <96 hours prior to the onset. Sulfur dioxide (SO2) exposure 0 to <24 hours prior to onset was associated with the increased risk of pneumonia and influenza: odds ratio was 1.07 per one interquartile-range increase (95% confidence interval: 1.00, 1.14). Elevated risk for pneumonia and influenza of SO2 was observed at shorter lags (i.e., 8-18 hours) than the elevated risks for respiratory disease of SPM or ozone. Overall, the effect estimates for chronic obstructive pulmonary disease and allied conditions were equivocal.

CONCLUSIONS

This study provides further evidence that hourly changes in air pollution exposure increase the risks of respiratory disease, and that SO2 may be related with more immediate onset of the disease than other pollutants.

β₂-Adrenergic agonists augment air pollution-induced IL-6 release and thrombosis

Acute exposure to particulate matter (PM) air pollution causes thrombotic cardiovascular events, leading to increased mortality rates; however, the link between PM and cardiovascular dysfunction is not completely understood. We have previously shown that the release of IL-6 from alveolar macrophages is required for a prothrombotic state and acceleration of thrombosis following exposure to PM. Here, we determined that PM exposure results in the systemic release of catecholamines, which engage the β2-adrenergic receptor (β2AR) on murine alveolar macrophages and augment the release of IL-6. In mice, β2AR signaling promoted the development of a prothrombotic state that was sufficient to accelerate arterial thrombosis. In primary human alveolar macrophages, administration of a β2AR agonist augmented IL-6 release, while the addition of a beta blocker inhibited PM-induced IL-6 release. Genetic loss or pharmacologic inhibition of the β2AR on murine alveolar macrophages attenuated PM-induced IL-6 release and prothrombotic state. Furthermore, exogenous β2AR agonist therapy further augmented these responses in alveolar macrophages through generation of mitochondrial ROS and subsequent increase of adenylyl cyclase activity. Together, these results link the activation of the sympathetic nervous system by β2AR signaling with metabolism, lung inflammation, and an enhanced susceptibility to thrombotic cardiovascular events.

Short-term effects of particulate matter on stroke attack: meta-regression and meta-analyses

Background and Purpose

Currently there are more and more studies on the association between short-term effects of exposure to particulate matter (PM) and the morbidity of stroke attack, but few have focused on stroke subtypes. The objective of this study is to assess the relationship between PM and stroke subtypes attack, which is uncertain now.

Methods

Meta-analyses, meta-regression and subgroup analyses were conducted to investigate the association between short-term effects of exposure to PM and the morbidity of different stroke subtypes from a number of epidemiologic studies (from 1997 to 2012).

Results

Nineteen articles were identified. Odds ratio (OR) of stroke attack associated with particular matter (“thoracic particles” [PM₁₀]<10 µm in aerodynamic diameter, “fine particles” [PM_2.5]<2.5 µm in aerodynamic diameter) increment of 10 µg/m³ was as effect size. PM₁₀ exposure was related to an increase in risk of stroke attack (OR per 10 µg/m³ = 1.004, 95%CI: 1.001∼1.008) and PM_2.5 exposure was not significantly associated with stroke attack (OR per 10 µg/m³ = 0.999, 95%CI: 0.994∼1.003). But when focused on stroke subtypes, PM_2.5 (OR per 10 µg/m³ = 1.025; 95%CI, 1.001∼1.049) and PM₁₀ (OR per 10 µg/m³ = 1.013; 95%CI, 1.001∼1.025) exposure were statistically significantly associated with an increased risk of ischemic stroke attack, while PM_2.5 (all the studies showed no significant association) and PM₁₀ (OR per 10 µg/m³ = 1.007; 95%CI, 0.992∼1.022) exposure were not associated with an increased risk of hemorrhagic stroke attack. Meta-regression found study design and area were two effective covariates.

Conclusion

PM_2.5 and PM₁₀ had different effects on different stroke subtypes. In the future, it's worthwhile to study the effects of PM to ischemic stroke and hemorrhagic stroke, respectively.

Air quality impacts mortality in acute medical admissions

BACKGROUND

Air quality degraded by black smoke (particulate matter, PM10), sulphur dioxide (SO2) and nitrogen oxide (NO(x)) affects human health. Improvements following national legislation have lowered death rates. Whether background air pollution levels continue to affect human health remains unclear.

AIM

To determine impact of air pollutant concentrations (PM10, SO2 and NO(x)) on in-hospital mortality for acute medical admissions to St James's Hospital over a decade (2002-11).

DESIGN

All emergency admissions (55,596 episodes in n = 32,581 patients) were tracked prospectively and mortality assessed. Daily levels of PM10, SO2 and NO(x) were obtained from monitoring stations in our catchment area.

METHODS

Univariate and multivariate logistic regression was employed to examine relationships between pollutant concentration and odds ratio (OR) for death following adjustment for other mortality predictors.

RESULTS

Mortality related to each pollutant variable assessed (as quintiles of increasing atmospheric concentration) was significantly predictive. For PM10 and SO2, mortality in the highest three quintile concentrations (compared with base quintile) was significantly increased (P < 0.001) with univariate ORs of 1.24, 1.36 and 1.25 for PM10 and 1.43, 1.54 and 1.58 for SO2, respectively. Mortality in all quintile concentrations (compared with base quintile) was significantly increased (P < 0.05) for NO(x) with univariate ORs of 1.14, 1.18, 1.28 and 1.35, respectively. Following adjustment for other mortality predictors such as acute illness severity, all three air pollutants were independently predictive of mortality.

CONCLUSION

Despite improvement to air quality in Dublin, the prevailing background pollutant concentrations continue to affect human health at levels considered safe and below that previously recognized.

Brachial artery responses to ambient pollution, temperature, and humidity in people with type 2 diabetes: a repeated-measures study

BACKGROUND

Extreme weather and air pollution are associated with increased cardiovascular risk in people with diabetes.

OBJECTIVES

In a population with diabetes, we conducted a novel assessment of vascular brachial artery responses both to ambient pollution and to weather (temperature and water vapor pressure, a measure of humidity).

METHODS

Sixty-four 49- to 85-year-old Boston residents with type 2 diabetes completed up to five study visits (279 repeated measures). Brachial artery diameter (BAD) was measured by ultrasound before and after brachial artery occlusion [i.e., flow-mediated dilation (FMD)] and before and after nitroglycerin-mediated dilation (NMD). Ambient concentrations of fine particulate mass (PM2.5), black carbon (BC), organic carbon (OC), elemental carbon, particle number, and sulfate were measured at our monitoring site; ambient concentrations of carbon monoxide, nitrogen dioxide, and ozone were obtained from state monitors. Particle exposure in the home and during each trip to the clinic (home/trip exposure) was measured continuously and as a 5-day integrated sample. We used linear models with fixed effects for participants, adjusting for date, season, temperature, and water vapor pressure on the day of each visit, to estimate associations between our outcomes and interquartile range increases in exposure.

RESULTS

Baseline BAD was negatively associated with particle pollution, including home/trip-integrated BC (-0.02 mm; 95% CI: -0.04, -0.003, for a 0.28 μg/m3 increase in BC), OC (-0.08 mm; 95% CI: -0.14, -0.03, for a 1.61 μg/m3 increase) as well as PM2.5, 5-day average ambient PM2.5, and BC. BAD was positively associated with ambient temperature and water vapor pressure. However, exposures were not consistently associated with FMD or NMD.

CONCLUSION

Brachial artery diameter, a predictor of cardiovascular risk, decreased in association with particle pollution and increased in association with ambient temperature in our study population of adults with type 2 diabetes.

CITATION

Zanobetti A, Luttmann-Gibson H, Horton ES, Cohen A, Coull BA, Hoffmann B, Schwartz JD, Mittleman MA, Li Y, Stone PH, de Souza C, Lamparello B, Koutrakis P, Gold DR. 2014. Brachial artery responses to ambient pollution, temperature, and humidity in people with type 2 diabetes: a repeated-measures study. Environ Health Perspect 122:242-248; http://dx.doi.org/10.1289/ehp.1206136.

Toxicological and epidemiological studies of cardiovascular effects of ambient air fine particulate matter (PM2.5) and its chemical components: coherence and public health implications

Recent investigations on PM2.5 constituents' effects in community residents have substantially enhanced our knowledge on the impacts of specific components, especially the HEI-sponsored National Particle Toxicity Component (NPACT) studies at NYU and UW-LRRI that addressed the impact of long-term PM2.5 exposure on cardiovascular disease (CVD) effects. NYU's mouse inhalation studies at five sites showed substantial variations in aortic plaque progression by geographic region that was coherent with the regional variation in annual IHD mortality in the ACS-II cohort, with both the human and mouse responses being primarily attributable to the coal combustion source category. The UW regressions of associations of CVD events and mortality in the WHI cohort, and of CIMT and CAC progression in the MESA cohort, indicated that [Formula: see text] had stronger associations with CVD-related human responses than OC, EC, or Si. The LRRI's mice had CVD-related biomarker responses to [Formula: see text]. NYU also identified components most closely associated with daily hospital admissions (OC, EC, Cu from traffic and Ni and V from residual oil). For daily mortality, they were from coal combustion ([Formula: see text], Se, and As). While the recent NPACT research on PM2.5 components that affect CVD has clearly filled some major knowledge gaps, and helped to define remaining uncertainties, much more knowledge is needed on the effects in other organ systems if we are to identify and characterize the most effective and efficient means for reducing the still considerable adverse health impacts of ambient air PM. More comprehensive speciation data are needed for better definition of human responses.

Incident ischemic heart disease and recent occupational exposure to particulate matter in an aluminum cohort

Fine particulate matter (PM(2.5)) in air pollution, primarily from combustion sources, is recognized as an important risk factor for cardiovascular events but studies of workplace PM(2.5) exposure are rare. We conducted a prospective study of exposure to PM(2.5) and incidence of ischemic heart disease (IHD) in a cohort of 11,966 US aluminum workers. Incident IHD was identified from medical claims data from 1998 to 2008. Quantitative metrics were developed for recent exposure (within the last year) and cumulative exposure; however, we emphasize recent exposure in the absence of interpretable work histories before follow-up. IHD was modestly associated with recent PM(2.5) overall. In analysis restricted to recent exposures estimated with the highest confidence, the hazard ratio (HR) increased to 1.78 (95% CI: 1.02, 3.11) in the second quartile and remained elevated. When the analysis was stratified by work process, the HR rose monotonically to 1.5 in both smelter and fabrication facilities, though exposure was almost an order of magnitude higher in smelters. The differential exposure-response may be due to differences in exposure composition or healthy worker survivor effect. These results are consistent with the air pollution and cigarette smoke literature; recent exposure to PM(2.5) in the workplace appears to increase the risk of IHD incidence.

Experimental human exposure to air pollutants is essential to understand adverse health effects

Air pollution has been found to cause significant global mortality, with 6.8 million excess deaths attributed to air pollution each year, and similarly large numbers of exacerbations of asthma, chronic obstructive pulmonary disease, and cardiovascular diseases. Epidemiological research has identified associations, and experimental human exposure has provided critical information on dose-response relationships of adverse effects caused by controlled human exposure to individual pollutants. Human exposures further enable examination of the relationship of adverse effects such as symptoms and pulmonary function changes to presumed mechanisms of disease revealed through analysis of bronchoalveolar lavage fluid obtained from the lower respiratory tract. In this Perspective, we analyze the ethics of human exposure, the importance of the information gained, and the risks of such exposure. We find that these studies appear to have been done with proper approval of institutional review boards, were done with informed consent from the participants, and have rarely been associated with serious adverse events.

Air pollution, inflammation and preterm birth: a potential mechanistic link

Preterm birth is a public health issue of global significance, which may result in mortality during the perinatal period or may lead to major health and financial consequences due to lifelong impacts. Even though several risk factors for preterm birth have been identified, prevention efforts have failed to halt the increasing rates of preterm birth. Epidemiological studies have identified air pollution as an emerging potential risk factor for preterm birth. However, many studies were limited by study design and inadequate exposure assessment. Due to the ubiquitous nature of ambient air pollution and the potential public health significance of any role in causing preterm birth, a novel focus investigating possible causal mechanisms influenced by air pollution is therefore a global health priority. We hypothesize that air pollution may act together with other biological factors to induce systemic inflammation and influence the duration of pregnancy. Evaluation and testing of this hypothesis is currently being conducted in a prospective cohort study in Mexico City and will provide an understanding of the pathways that mediate the effects of air pollution on preterm birth. The important public health implication is that crucial steps in this mechanistic pathway can potentially be acted on early in pregnancy to reduce the risk of preterm birth.

Pulmonary responses in current smokers and ex-smokers following a two hour exposure at rest to clean air and fine ambient air particles

Background

Increased susceptibility of smokers to ambient PM may potentially promote development of COPD and accelerate already present disease.

Objectives

To characterize the acute and subacute lung function response and inflammatory effects of controlled chamber exposure to concentrated ambient fine particles (CAFP) with MMAD ≤ 2.5 microns in ex-smokers and lifetime smokers.

Methods

Eleven subjects, aged 35–74 years, came to the laboratory 5 times; a training day and two exposure days separated by at least 3 weeks, each with a post-exposure visit 22 h later. Double-blind and counterbalanced exposures to “clean air” (mean 1.5 ± 0.6 μg/m³) or CAFP (mean 108.7 ± 24.8 μg/m³ ) lasted 2 h with subjects at rest.

Results

At 3 h post-exposure subjects’ DTPA clearance half-time significantly increased by 6.3 min per 100 μg/m³ of CAFP relative to “clean air”. At 22 h post-exposure they showed significant reduction of 4.3% per 100 μg/m³ in FEV₁ and a significant D_LCO decrease by 11.1% per 100 μg/m³ of CAFP relative to “clean air”. At both 3 h and 22 h the HDL cholesterol level significantly decreased by 4.5% and 4.1%, respectively. Other blood chemistries and markers of lung injury, inflammation and procoagulant activity were within the normal range of values at any condition.

Conclusions

The results suggest that an acute 2 h resting exposure of smokers and ex-smokers to fine ambient particulate matter may transiently affect pulmonary function (spirometry and D_LCO) and increase DTPA clearance half-time. Except for a post exposure decrease in HDL no other markers of pulmonary inflammation, prothrombotic activity and lung injury were significantly affected under the conditions of exposure.

Associations between arrhythmia episodes and temporally and spatially resolved black carbon and particulate matter in elderly patients

OBJECTIVES

Ambient air pollution has been associated with sudden deaths, some of which are likely due to ventricular arrhythmias. Defibrillator discharge studies have examined the association of air pollution with arrhythmias in sensitive populations. No studies have assessed this association using residence-specific estimates of air pollution exposure.

METHODS

In the Normative Aging Study, we investigated the association between temporally resolved and spatially resolved black carbon (BC) and PM2.5 and arrhythmia episodes (bigeminy, trigeminy or couplets episodes) measured as ventricular ectopy (VE) by 4 min ECG monitoring in repeated measures of 701 subjects, during the years 2000-2010. We used a binomial distribution (having or not a VE episode) in a mixed effect model with a random intercept for subject, controlling for seasonality, temperature, day of the week, medication use, smoking, having diabetes, body mass index and age. We also examined whether these associations were modified by genotype or phenotype.

RESULTS

We found significant increases in VE with both pollutants and lags; for the estimated concentration averaged over the 3 days prior to the health assessment, we found increases in the odds of having VE with an OR of 1.52 (95% CI 1.19 to 1.94) for an IQR (0.30 μg/m(3)) increase in BC and an OR of 1.39 (95% CI 1.12 to 1.71) for an IQR (5.63 μg/m(3)) increase in PM2.5. We also found higher effects in subjects with the glutathione S-transferase theta-1 and glutathione S-transferase mu-1 variants and in obese (p<0.05).

CONCLUSIONS

Increased levels of short-term traffic-related pollutants may increase the risk of ventricular arrhythmia in elderly subjects.

Cumulative exposure to particulate matter air pollution and long-term post-myocardial infarction outcomes

INTRODUCTION

Chronic environmental exposure to particulate matter <2.5μm in diameter (PM2.5) has been associated with cardiovascular disease; however, the effect of air pollution on myocardial infarction (MI) survivors is not clear. We studied the association of chronic exposure to PM2.5 with death and recurrent cardiovascular events in MI survivors.

METHODS

Consecutive patients aged ≤65years admitted to all medical centers in central Israel after first-MI in 1992-1993 were followed through 2005 for cardiovascular events and 2011 for survival. Data on sociodemographic and prognostic factors were collected at baseline and during follow-up. Residential exposure to PM2.5 was estimated for each patient based on data recorded at air quality monitoring stations. Cox and Andersen-Gill proportional hazards models were used to study the pollution-outcome association.

RESULTS

Among the 1120 patients, 469 (41.9%) died and 541 (48.3%) experienced one or more recurrent cardiovascular event. The adjusted hazard ratios associated with a 10μg/m(3) increase in PM2.5 exposure were 1.3 (95% CI 0.8-2.1) for death and 1.5 (95% CI 1.1-1.9) for multiple recurrences of cardiovascular events (MI, heart failure and stroke).

CONCLUSION

When adjustment for socio-demographic factors is performed, cumulative chronic exposure to PM2.5 is positively associated with recurrence of cardiovascular events in patients after a first MI.

Endotoxin in concentrated coarse and fine ambient particles induces acute systemic inflammation in controlled human exposures

BACKGROUND

Knowledge of the inhalable particulate matter components responsible for health effects is important for developing targeted regulation.

OBJECTIVES

In a double-blind randomised cross-over trial of controlled human exposures to concentrated ambient particles (CAPs) and their endotoxin and (1→3)-β-D-glucan components, we evaluated acute inflammatory responses.

METHODS

35 healthy adults were exposed to five 130-min exposures at rest: (1) fine CAPs (~250 µg/m(3)); (2) coarse CAPs (200 µg/m(3)); (3) second coarse CAPs (~200 µg/m(3)); (4) filtered air; and (5) medical air. Induced sputum cell counts were measured at screening and 24 h postexposure. Venous blood total leucocytes, neutrophils, interleukin-6 and high-sensitivity C reactive protein (CRP) were measured pre-exposure, 3 and 24 h postexposure.

RESULTS

Relative to filtered air, an increase in blood leucocytes 24 h (but not 3 h) postexposure was significantly associated with coarse (estimate=0.44×10(9) cells/L (95% CI 0.01 to 0.88); n=132) and fine CAPs (0.68×10(9) cells /L (95% CI 0.19 to 1.17); n=132), but not medical air. Similar associations were found with neutrophil responses. An interquartile increase in endotoxin (5.4 ng/m(3)) was significantly associated with increased blood leucocytes 3 h postexposure (0.27×10(9) cells/L (95% CI 0.03 to 0.51); n=98) and 24 h postexposure (0.37×10(9) cells/L (95% CI 0.12 to 0.63); n=98). This endotoxin effect did not differ by particle size. There were no associations with glucan concentrations or interleukin-6, CRP or sputum responses.

CONCLUSIONS

In healthy adults, controlled coarse and fine ambient particle exposures independently induced acute systemic inflammatory responses. Endotoxin contributes to the inflammatory role of particle air pollution.

Short-term chamber exposure to low doses of two kinds of wood smoke does not induce systemic inflammation, coagulation or oxidative stress in healthy humans

Introduction:

Air pollution increases the risk of cardiovascular diseases. A proposed mechanism is that local airway inflammation leads to systemic inflammation, affecting coagulation and the long-term risk of atherosclerosis. One major source of air pollution is wood burning. Here we investigate whether exposure to two kinds of wood smoke, previously shown to cause airway effects, affects biomarkers of systemic inflammation, coagulation and lipid peroxidation.

Methods:

Thirteen healthy adults were exposed to filtered air followed by two sessions of wood smoke for three hours, one week apart. One session used smoke from the start-up phase of the wood-burning cycle, and the other smoke from the burn-out phase. Mean particle mass concentrations were 295 µg/m³ and 146 µg/m³, and number concentrations were 140 000/cm³ and 100 000/cm³, respectively. Biomarkers were analyzed in samples of blood and urine taken before and several times after exposure. Results after wood smoke exposure were adjusted for exposure to filtered air.

Results:

Markers of systemic inflammation and soluble adhesion molecules did not increase after wood smoke exposure. Effects on markers of coagulation were ambiguous, with minor decreases in fibrinogen and platelet counts and mixed results concerning the coagulation factors VII and VIII. Urinary F₂-isoprostane, a consistent marker of in vivo lipid peroxidation, unexpectedly decreased after wood smoke exposure.

Conclusions:

The effects on biomarkers of inflammation, coagulation and lipid peroxidation do not indicate an increased risk of cardiovascular diseases in healthy adults by short-term exposure to wood smoke at these moderate doses, previously shown to cause airway effects.

Environmental exposure to combustion-derived air pollution is associated with reduced functional capacity in apparently healthy individuals

Prior toxicological exposure reports demonstrated the decremental effect of several air pollutants on the metabolic equivalents achieved during exercise testing (METs). There are no prior large scale epidemiological reports about the effect of environmental air pollution exposure on those parameters. We analyzed a cohort of apparently healthy individuals attending a screening survey program held between 2003 and 2009. Participants were included if residing within an 11 km radius from the nearest air pollution monitoring station. Linear regression models were fitted for the metabolic equivalents and adjusted to short- and long-term air pollutant exposure (particulate matter under 10 micron, sulfur dioxide, nitrogen dioxide, carbon monoxide and ozone). The models were adjusted for possible confounders that affect air pollution and stress testing measurements. The study population comprised 6,612 individuals (4,201 males and 2,411 females). We found a statistically significant short- and long-term negative correlation between air pollutants, mainly CO and NO2 and between the metabolic equivalents achieved. A similar short-term effect was found for SO2. We conclude that exposure to combustion-derived air pollutants has a short- and long-term decremental effect on cardiorespiratory fitness as measured by exercise stress testing. Our epidemiological data support previous toxicological reports.

Associations of ambient air pollution with chronic obstructive pulmonary disease hospitalization and mortality

RATIONALE

Ambient air pollution has been suggested as a risk factor for chronic obstructive pulmonary disease (COPD). However, there is a lack of longitudinal studies to support this assertion.

OBJECTIVES

To investigate the associations of long-term exposure to elevated traffic-related air pollution and woodsmoke pollution with the risk of COPD hospitalization and mortality.

METHODS

This population-based cohort study included a 5-year exposure period and a 4-year follow-up period. All residents aged 45-85 years who resided in Metropolitan Vancouver, Canada, during the exposure period and did not have known COPD at baseline were included in this study (n = 467,994). Residential exposures to traffic-related air pollutants (black carbon, particulate matter <2.5 μm in aerodynamic diameter, nitrogen dioxide, and nitric oxide) and woodsmoke were estimated using land-use regression models and integrating changes in residences during the exposure period. COPD hospitalizations and deaths during the follow-up period were identified from provincial hospitalization and death registration databases.

MEASUREMENTS AND MAIN RESULTS

An interquartile range elevation in black carbon concentrations (0.97 × 10(-5)/m, equivalent to 0.78 μg/m(3) elemental carbon) was associated with a 6% (95% confidence interval, 2-10%) increase in COPD hospitalizations and a 7% (0-13%) increase in COPD mortality after adjustment for covariates. Exposure to higher levels of woodsmoke pollution (tertile 3 vs. tertile 1) was associated with a 15% (2-29%) increase in COPD hospitalizations. There were positive exposure-response trends for these observed associations.

CONCLUSIONS

Ambient air pollution, including traffic-related fine particulate pollution and woodsmoke pollution, is associated with an increased risk of COPD.

Ischemic heart disease mortality and PM(3.5) in a cohort of autoworkers

BACKGROUND

Increased risk of ischemic heart disease (IHD) has been associated with particulate matter (PM) from air pollution. Yet evidence of increased risk associated with higher workplace exposures is scant.

METHODS

We examined the exposure-response relationship between IHD mortality and PM(3.5) (<3.5 µm diameter) from current and cumulative exposure to straight metalworking fluid in a cohort of 39,412 autoworkers followed from 1941 to 1995. Age, calendar year of follow up, sex, race, and plant were included in each model.

RESULTS

To address the decrease in polycyclic-aromatic hydrocarbon (PAH) content in the straight metalworking fluid over time, analyses were stratified by calendar time. Increased risk of IHD mortality was associated with current exposure to PM(3.5) before 1971 and with cumulative exposure to PM(3.5) after 1971.

CONCLUSIONS

Results provide modest evidence that occupational exposure to fine PM from straight fluids, especially fluid with higher PAH, may increase the risk of IHD mortality.

Synergistic effects of exposure to concentrated ambient fine pollution particles and nitrogen dioxide in humans

CONTEXT

Exposure to single pollutants e.g. particulate matter (PM) is associated with adverse health effects, but it does not represent a real world scenario that usually involves multiple pollutants.

OBJECTIVES

Determine if simultaneous exposure to PM and NO₂ results in synergistic interactions.

MATERIALS AND METHODS

Healthy young volunteers were exposed to clean air, nitrogen dioxide (NO₂, 0.5 ppm), concentrated fine particles from Chapel Hill air (PM(2.5)CAPs, 89.5 ± 10.7 µg/m³), or NO₂+PM(2.5)CAPs for 2 h. Each subject performed intermittent exercise during the exposure. Parameters of heart rate variability (HRV), changes in repolarization, peripheral blood endpoints and lung function were measured before and 1 and 18 h after exposure. Bronchoalveolar lavage (BAL) was performed 18 h after exposure.

RESULTS

NO₂ exposure alone increased cholesterol and HDL 18 h after exposure, decreased high frequency component of HRV one and 18 h after exposure, decreased QT variability index 1 h after exposure, and increased LDH in BAL fluid. The only significant change with PM(2.5)CAPs was an increase in HDL 1 h after exposure, likely due to the low concentrations of PM(2.5)CAPs in the exposure chamber. Exposure to both NO₂ and PM(2.5)CAPs increased BAL α1-antitrypsin, mean t wave amplitude, the low frequency components of HRV and the LF/HF ratio. These changes were not observed following exposure to NO₂ or PM(2.5)CAPs alone, suggesting possible interactions between the two pollutants.

DISCUSSION AND CONCLUSIONS

NO₂ exposure may produce and enhance acute cardiovascular effects of PM(2.5)CAPs. Assessment of health effects by ambient PM should consider its interactions with gaseous copollutants.

The biological effects of individual-level PM(2.5) exposure on systemic immunity and inflammatory response in traffic policemen

BACKGROUND

Ambient fine-particle particulate matter (PM2.5) exposure is associated with the decline in pulmonary function, prevalence of coronary heart disease and incidence of myocardial infarction. The study is to observe the effects of ambient PM2.5 on the cardiovascular system and to explore the potential inflammatory and immune mechanisms.

METHODS

The subjects included 110 traffic policemen in Shanghai, China, who were aged 25-55 years. Two-times continuous 24 h individual-level PM2.5 measurements were performed in winter and summer, respectively. The inflammatory marker (high-sensitivity C-reactive protein, hs-CRP), immune parameters (IgA, IgG, IgM and IgE) and lymphocyte profiles (CD4 T cells, CD8 T cells, CD4/CD8 T cells) were measured in blood. The associations between individual-level PM2.5 and inflammatory marker and immune parameters were analysed by multiple linear regression.

RESULTS

The average concentration of 24 h personal PM2.5 for participants was 116.98 μg/m(3) and 86.48 μg/m(3) in winter and summer, respectively. In the main analysis, PM2.5 exposure is associated with the increases in hs-CRP of 1.1%, IgG of 6.7%, IgM of 11.2% and IgE of 3.3% in participants, and decreases in IgA of 4.7% and CD8 of 0.7%, whereas we found no statistical association in CD4 T cells and CD4/CD8 T cells. In the adjusted model, the results showed that the increase of PM2.5 was associated with the changes of inflammatory markers and immune markers both in winter and summer.

CONCLUSIONS

Traffic policeman have been a high-risk group suffering inflammatory response or immune injury because of the high exposure to PM2.5. These findings provided new insight into the mechanisms linking ambient PM2.5 and inflammatory and immune response.

Feasibility of using biomarkers in blood serum as markers of effect following exposure of the lungs to particulate matter air pollution

Particulate matter (PM) air pollution has significant cardiopulmonary health effects. Serum biomarkers may elucidate the disease mechanisms involved and provide a means for biomonitoring exposed populations, thereby enabling accurate policy decisions on air quality standards to be made. For this review, research investigating association of blood serum biomarkers and exposure to PM was identified, finding 26 different biomarkers that were significantly associated with exposure. Recent evidence links different effects to different components of PM. Future research on biomarkers of effect will need to address exposure by all PM size fractions.

Seasonal influences on CAPs exposures: differential responses in platelet activation, serum cytokines and xenobiotic gene expression

Increasing evidence suggests a role for a systemic pro-coagulant state in the pathogenesis of cardiac dysfunction subsequent to inhalation of airborne particulate matter (PM). We evaluated platelet activation, systemic cytokines and pulmonary gene expression in mice exposed to concentrated ambient particulate matter (CAPs) in the summer of 2008 (S08) and winter of 2009 (W09) from the San Joaquin Valley of California, a region with severe PM pollution episodes. Additionally, we characterized the PM from both exposures including organic compounds, metals, and polycyclic aromatic hydrocarbons. Mice were exposed to an average of 39.01 μg/m(3) of CAPs in the winter and 21.7 μg/m3 CAPs in the summer, in a size range less than 2.5 μm for 6 h/day for 5 days per week for 2 weeks. Platelets were analyzed by flow cytometry for relative size, shape, CD41, P-selectin and lysosomal associated membrane protein-1 (LAMP-1) expression. Platelets from W09 CAPs-exposed animals had a greater response to thrombin stimulation than platelets from S08 CAPs-exposed animals. Serum cytokines were analyzed by bead based immunologic assays. W09 CAPs-exposed mice had elevations in IL-2, MIP-1α, and TNFα. Laser capture microdissection (LCM) of pulmonary vasculature, parenchyma and airways all showed increases in CYP1a1 gene expression. Pulmonary vasculature showed increased expression of ICAM-1 and Nox-2. Our findings demonstrate that W09 CAPs exposure generated a greater systemic pro-inflammatory and pro-coagulant response to inhalation of environmentally derived fine and ultrafine PM. Changes in platelet responsiveness to agonists, seen in both exposures, strongly suggests a role for platelet activation in the cardiovascular and respiratory effects of particulate air pollution.

Air pollution and arrhythmic risk: the smog is yet to clear

Epidemiologic evidence has demonstrated that air pollution may impair cardiovascular health, leading to potentially life-threatening arrhythmias. Efforts have been made, with the use of epidemiologic data and controlled exposures in diverse animal and human populations, to verify the relationship between air pollution and arrhythmias. The purpose of this review is to examine and contrast the epidemiologic and toxicologic evidence to date that relates airborne pollutants with cardiac arrhythmia. We have explored the potential biological mechanisms driving this association. Using the PubMed database, we conducted a literature search that included the terms "air pollution" and "arrhythmia" and eventually divergent synonyms such as "particulate matter," "bradycardia," and "atrial fibrillation." We reviewed epidemiologic studies and controlled human and animal exposures independently to determine whether observational conclusions were corroborated by toxicologic results. Numerous pollutants have demonstrated some arrhythmic capacity among healthy and health-compromised populations. However, some exposure studies have shown no significant correlation of air pollutants with arrhythmia, which suggests some uncertainty about the arrhythmogenic potential of air pollution and the mechanisms involved in arrhythmogenesis. While data from an increasing number of controlled exposures with human volunteers suggest a potential mechanistic link between air pollution and altered cardiac electrophysiology, definite conclusions regarding air pollution and arrhythmia are elusive as the direct arrhythmic effects of air pollutants are not entirely consistent across all studies.

Chemical speciation of Fe and Ni in residual oil fly ash fine particulate matter using X-ray absorption spectroscopy

Epidemiological studies have linked residual oil fly ash fine particulate matter with aerodynamic diameter <2.5 μm (ROFA PM(2.5)) to morbidity and mortality from cardiovascular and respiratory illnesses. Bioavailable transition metals within PM have been cited as one of the components that induce such illnesses. By combining synchrotron-based X-ray absorption spectroscopy with leaching experiment, we studied the effect of residual oil compositions and combustion conditions on the speciation of Fe and Ni in ROFA PM(2.5) and the implication of these species for human health and environment. PM(2.5) samples were obtained from two types of combustors, a fire tube boiler (FTB) and a refractory line combustor (RLC). The study reveals that only Fe(2)(SO(4))(3)·nH(2)O is present in RLC PM(2.5) while Fe(2)(SO(4))(3)·nH(2)O predominates in FTB PM(2.5) with inclusion of varying amounts of nickel ferrite. The finding that RLC PM(2.5) is more bioavailable and hence more toxic than FTB PM(2.5) is significant. The reduction of toxicity of FTB PM(2.5) is due to the immobilization of a portion of Fe and Ni in the formation of an insoluble NiFe(2)O(4). This may explain the variation of toxicity from exposure to different ROFA PM(2.5). Additionally, the speciation data are sought for developing emission inventories for source apportionment study and understanding the mechanism of PM formation.

Air pollution, vascular disease and thrombosis: linking clinical data and pathogenic mechanisms

The public health burden of air pollution has been increasingly recognized over the last decades. Following the first assessed adverse effects on respiratory diseases and lung cancer, a large body of epidemiologic and clinical studies definitely documented an even stronger association of air pollution exposure with cardiovascular mortality and morbidity, particularly related to atherothrombotic (coronary and cerebrovascular) disease. Particulate matter (PM), mainly that with lower aerodynamic diameter (fine and ultrafine PM), is responsible for the most severe effects, due to its capacity to transport toxic substances deep into the lower airways. These effects have been shown to occur not only after short-term exposure to elevated concentrations of pollutants, but even after long-term relatively low levels of exposure. Vulnerable subjects (elderly persons and those with preexisting cardiopulmonary diseases) show the highest impact. Fewer and conflicting data also suggest an association with venous thromboembolism. Although not completely elucidated, a series of mechanisms have been hypothesized and tested in experimental settings. These phenomena, including vasomotor and cardiac autonomic dysfunction, hemostatic unbalance, oxidative stress and inflammatory response, have been shown to change over time and differently contribute to the short-term and long-term adverse effects of pollution exposure. Beyond environmental health policies, crucial for improving air quality and reducing the impact of such an elusive threat to public health, the recognition and assessment of the individual risk, together with specific advice, should be routinely implemented in the strategies of primary and secondary cardiovascular prevention.

Cardiovascular effects of particulate air pollution exposure: time course and underlying mechanisms

Air pollution is now recognized as an important independent risk factor for cardiovascular morbidity and mortality and may be responsible for up to 3 million premature deaths each year worldwide. The mechanisms underlying the observed effects are poorly understood but are likely to be multifactorial. Here, we review the acute and chronic effects of air pollution exposure on the cardiovascular system and discuss how these effects may explain the observed increases in cardiovascular morbidity and mortality.

Inflammatory and oxidative stress responses of healthy young adults to changes in air quality during the Beijing Olympics

RATIONALE

Unprecedented pollution control actions during the Beijing Olympics provided a quasi-experimental opportunity to examine biologic responses to drastic changes in air pollution levels.

OBJECTIVES

To determine whether changes in levels of biomarkers reflecting pulmonary inflammation and pulmonary and systemic oxidative stress were associated with changes in air pollution levels in healthy young adults.

METHODS

We measured fractional exhaled nitric oxide, a number of exhaled breath condensate markers (H(+), nitrite, nitrate, and 8-isoprostane), and urinary 8-hydroxy-2-deoxyguanosine in 125 participants twice in each of the pre- (high pollution), during- (low pollution), and post-Olympic (high pollution) periods. We measured concentrations of air pollutants near where the participants lived and worked. We used mixed-effects models to estimate changes in biomarker levels across the three periods and to examine whether changes in biomarker levels were associated with changes in pollutant concentrations, adjusting for meteorologic parameters.

MEASUREMENTS AND MAIN RESULTS

From the pre- to the during-Olympic period, we observed significant and often large decreases (ranging from -4.5% to -72.5%) in levels of all the biomarkers. From the during-Olympic to the post-Olympic period, we observed significant and larger increases (48-360%) in levels of these same biomarkers. Moreover, increased pollutant concentrations were consistently associated with statistically significant increases in biomarker levels.

CONCLUSIONS

These findings support the important role of oxidative stress and that of pulmonary inflammation in mediating air pollution health effects. The findings demonstrate the utility of novel and noninvasive biomarkers in the general population consisting largely of healthy individuals.

Comparison of WTC dust size on macrophage inflammatory cytokine release in vivo and in vitro

Background

The WTC collapse exposed over 300,000 people to high concentrations of WTC-PM; particulates up to ∼50 mm were recovered from rescue workers’ lungs. Elevated MDC and GM-CSF independently predicted subsequent lung injury in WTC-PM-exposed workers. Our hypotheses are that components of WTC dust strongly induce GM-CSF and MDC in AM; and that these two risk factors are in separate inflammatory pathways.

Methodology/Principal Findings

Normal adherent AM from 15 subjects without WTC-exposure were incubated in media alone, LPS 40 ng/mL, or suspensions of WTC-PM_10–53 or WTC-PM_2.5 at concentrations of 10, 50 or 100 µg/mL for 24 hours; supernatants assayed for 39 chemokines/cytokines. In addition, sera from WTC-exposed subjects who developed lung injury were assayed for the same cytokines. In the in vitro studies, cytokines formed two clusters with GM-CSF and MDC as a result of PM_10–53 and PM_2.5. GM-CSF clustered with IL-6 and IL-12(p70) at baseline, after exposure to WTC-PM_10–53 and in sera of WTC dust-exposed subjects (n = 70) with WTC lung injury. Similarly, MDC clustered with GRO and MCP-1. WTC-PM_10–53 consistently induced more cytokine release than WTC-PM_2.5 at 100 µg/mL. Individual baseline expression correlated with WTC-PM-induced GM-CSF and MDC.

Conclusions

WTC-PM_10–53 induced a stronger inflammatory response by human AM than WTC-PM_2.5. This large particle exposure may have contributed to the high incidence of lung injury in those exposed to particles at the WTC site. GM-CSF and MDC consistently cluster separately, suggesting a role for differential cytokine release in WTC-PM injury. Subject-specific response to WTC-PM may underlie individual susceptibility to lung injury after irritant dust exposure.

Short-term effects of ambient air pollution on stroke: who is most vulnerable?

Several studies have demonstrated positive associations between day-to-day increases in air pollution and stroke. These findings have been inconsistent, and the influence of patient characteristics has been largely ignored. In this study, we investigated the short-term effects of air pollution on stroke using a time-stratified case-crossover design. Data for hospital visits for stroke were extracted from 5927 medical charts of patients who presented to emergency departments between 2003 and 2009 in Edmonton, Canada. Daily concentrations of five air pollutants (NO(2), PM (2.5), CO, O(3), and SO(2)) were obtained from fixed-site monitors. Relative humidity and temperature were obtained from a metrological station operating at the city's airport. Chart data included: disease history, medication use, and smoking status. Conditional logistic regression was used to estimate the odds ratio (OR) of stroke in relation to an increase in the interquartile range for each pollutant. Positive associations were observed between ischemic stroke and air pollution during the 'warm' season (April through September). Specifically, the OR for an increase in 9.4 ppb in the 3-day average of NO(2) was 1.50 (95% CI: 1.12, 2.01). There were no statistically significant associations with any of the other pollutants after adjusting for NO(2) concentrations. Associations with ischemic stroke were stronger for those with a history of stroke (OR=2.31; 95% CI: 1.39, 3.83), heart disease (OR=1.99; 95% CI: 1.20, 3.28), and taking medication for diabetes (OR=2.03; 95% CI: 1.14, 3.59). Temperature was inversely associated with ischemic stroke during the 'warm' season, but no associations were evident with the other stroke subtypes. Air pollution was not associated with hemorrhagic stroke or transient ischemic attacks. The findings suggest that specific patient characteristics modify associations between air pollution and ischemic stroke.

Controlled exposure of healthy young volunteers to ozone causes cardiovascular effects

BACKGROUND

Recent epidemiology studies have reported associations between short-term ozone exposure and mortality. Such studies have previously reported associations between airborne particulate matter pollution and mortality, and support for a causal relationship has come from controlled-exposure studies that describe pathophysiological mechanisms by which particulate matter could induce acute mortality. In contrast, for ozone, almost no controlled-human-exposure studies have tested whether ozone exposure can modulate the cardiovascular system.

METHODS AND RESULTS

Twenty-three young healthy individuals were exposed in a randomized crossover fashion to clean air and to 0.3-ppm ozone for 2 hours while intermittently exercising. Blood was obtained immediately before exposure, immediately afterward, and the next morning. Continuous Holter monitoring began immediately before exposure and continued for 24 hours. Lung function was performed immediately before and immediately after exposure, and bronchoalveolar lavage was performed 24 hours after exposure. Immediately after ozone exposure, we observed a 98.9% increase in interleukin-8, a 21.4% decrease in plasminogen activator inhibitor-1, a 51.3% decrease in the high-frequency component of heart rate variability, and a 1.2% increase in QT duration. Changes in interleukin-1B and plasminogen activator inhibitor-1 were apparent 24 hours after exposure. In agreement with previous studies, we also observed ozone-induced drops in lung function and an increase in pulmonary inflammation.

CONCLUSIONS

This controlled-human-exposure study shows that ozone can cause an increase in vascular markers of inflammation and changes in markers of fibrinolysis and markers that affect autonomic control of heart rate and repolarization. We believe that these findings provide biological plausibility for the epidemiology studies that associate ozone exposure with mortality.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01492517.

Effect of nanoparticle-rich diesel exhaust on testicular and hippocampus steroidogenesis in male rats

BACKGROUND

Nanoparticle-rich diesel exhaust (NR-DE) has potentially adverse effects on testicular steroidogenesis. However, it is unclear whether NR-DE influences steroidogenic systems in the brain.

OBJECTIVE

To investigate the effect of NR-DE on hippocampal steroidogenesis of adult male rats in comparison with its effect on the testis.

METHODS

F344 male rats (8-week-old) were randomly divided into four groups (n = 8 or 9 per group) and exposed to clean air with 4.6 ± 3.2 μg/m(3) in mass concentration, NR-DE with 38 ± 3 μg/m(3) (a level nearly equivalent to the environmental standard in Japan (low NR-DE)), NR-DE with 149 ± 8 μg/m(3) (high NR-DE), or filtered diesel exhaust with 3.1 ± 1.9 μg/m(3) (F-DE), for 5 hours/day, 5 days/week, for 1, 2 or 3 months. F-DE was prepared by removing only particulate matters from high NR-DE with an HEPA filter.

RESULTS

Exposures to the high NR-DE for 1 month, and low NR-DE for 2 months, significantly increased or tended to increase plasma and testicular testosterone levels compared to clean air exposure, which might have resulted from the increased expression of mRNA of steroidogenic acute regulatory protein and its protein in the testes of rats. In the hippocampus, high NR-DE exposure for 1 month significantly increased the androstendione level compared to the clean air exposure, while no significant difference was observed in the steroidogenesis between fresh air exposure and any exposure to NR-DE or F-DE.

CONCLUSION

NR-DE may influence steroidogenic enzymes in the testis, but not those in the hippocampus.

Association between changes in air pollution levels during the Beijing Olympics and biomarkers of inflammation and thrombosis in healthy young adults

CONTEXT

Air pollution is a risk factor for cardiovascular diseases (CVD), but the underlying biological mechanisms are not well understood.

OBJECTIVE

To determine whether markers related to CVD pathophysiological pathways (biomarkers for systemic inflammation and thrombosis, heart rate, and blood pressure) are sensitive to changes in air pollution.

DESIGN, SETTING, AND PARTICIPANTS

Using a quasi-experimental opportunity offered by greatly restricted air pollution emissions during the Beijing Olympics, we measured pollutants daily and the outcomes listed below in 125 healthy young adults before, during, and after the 2008 Olympics (June 2-October 30). We used linear mixed-effects models to estimate the improvement in outcome levels during the Olympics and the anticipated reversal of outcome levels after pollution controls ended to determine whether changes in outcome levels were associated with changes in pollutant concentrations.

MAIN OUTCOME MEASURES

C-reactive protein (CRP), fibrinogen, von Willebrand factor, soluble CD40 ligand (sCD40L), soluble P-selectin (sCD62P) concentrations; white blood cell count (WBC); heart rate; and blood pressure.

RESULTS

Concentrations of particulate and gaseous pollutants decreased substantially (-13% to -60%) from the pre-Olympic period to the during-Olympic period. Using 2-sided tests conducted at the .003 level, we observed statistically significant improvements in sCD62P levels by -34.0% (95% CI, -38.4% to -29.2%; P < .001) from a pre-Olympic mean of 6.29 ng/mL to a during-Olympic mean of 4.16 ng/mL and von Willebrand factor by -13.1% (95% CI, -18.6% to -7.5%; P < .001) from 106.4% to 92.6%. After adjustments for multiple comparisons, changes in the other outcomes were not statistically significant. In the post-Olympic period when pollutant concentrations increased, most outcomes approximated pre-Olympic levels, but only sCD62P and systolic blood pressure were significantly worsened from the during-Olympic period. The fraction of above-detection-limit values for CRP (percentage ≥ 0.3 mg/L) was reduced from 55% in the pre-Olympic period to 46% in the during-Olympic period and reduced further to 36% in the post-Olympic period. Interquartile range increases in pollutant concentrations were consistently associated with statistically significant increases in fibrinogen, von Willebrand factor, heart rate, sCD62P, and sCD40L concentrations.

CONCLUSIONS

Changes in air pollution levels during the Beijing Olympics were associated with acute changes in biomarkers of inflammation and thrombosis and measures of cardiovascular physiology in healthy young persons. These findings are of uncertain clinical significance.

Access rate to the emergency department for venous thromboembolism in relationship with coarse and fine particulate matter air pollution

Particulate matter (PM) air pollution has been associated with cardiovascular and respiratory disease. Recent studies have proposed also a link with venous thromboembolism (VTE) risk. This study was aimed to evaluate the possible influence of air pollution-related changes on the daily flux of patients referring to the Emergency Department (ED) for VTE, dissecting the different effects of coarse and fine PM. From July 1(st), 2007, to June 30(th), 2009, data about ED accesses for VTE and about daily concentrations of PM air pollution in Verona district (Italy) were collected. Coarse PM (PM(10-2.5)) was calculated by subtracting the finest PM(2.5) from the whole PM(10). During the index period a total of 302 accesses for VTE were observed (135 males and 167 females; mean age 68.3 ± 16.7 years). In multiple regression models adjusted for other atmospheric parameters PM(10-2.5), but not PM(2.5), concentrations were positively correlated with VTE (beta-coefficient = 0.237; P = 0.020). During the days with high levels of PM(10-2.5) (≥ 75(th) percentile) there was an increased risk of ED accesses for VTE (OR 1.69 with 95%CI 1.13-2.53). By analysing days of exposure using distributed lag non-linear models, the increase of VTE risk was limited to PM(10-2.5) peaks in the short-term period. Consistently with these results, in another cohort of subjects without active thrombosis (n = 102) an inverse correlation between PM(10-2.5) and prothrombin time was found (R = -0.247; P = 0.012). Our results suggest that short-time exposure to high concentrations of PM(10-2.5) may favour an increased rate of ED accesses for VTE through the induction of a prothrombotic state.

Diesel exhaust particles and airway inflammation

PURPOSE OF REVIEW

Epidemiologic investigation has associated traffic-related air pollution with adverse human health outcomes. The capacity of diesel exhaust particles (DEPs), a major emission source air pollution particle, to initiate an airway inflammation has subsequently been investigated. We review the recent controlled human exposures to diesel exhaust and DEPs, and summarize the investigations into the associations between this emission source air pollution particle and airway inflammation.

RECENT FINDINGS

Using bronchoalveolar lavage, bronchial biopsies, and sputum collection, studies have demonstrated inflammation in the airways of healthy individuals after exposure to diesel exhaust and DEPs. This inflammation has included neutrophils, eosinophils, mast cells, and lymphocytes. Elevated expression and concentrations of inflammatory mediators have similarly been observed in the respiratory tract after diesel exhaust and DEP exposure. An increased sensitivity of asthmatic individuals to the proinflammatory effects of DEPs has not been confirmed.

SUMMARY

Inflammation after diesel exhaust and DEP exposure is evident at higher concentrations only; there appears to be a threshold dose for DEPs approximating 300 μg/m. The lack of a biological response to DEPs at lower concentrations may reflect a contribution of gaseous constituents or interactions between DEPs and gaseous air pollutants to the human inflammatory response and function loss.

Short-term exposure to air pollution and incidence of stroke and acute myocardial infarction in a Japanese population

BACKGROUND

Exposure to high levels of air pollution can increase the risk of cardiovascular events. However, there is no clear information in Japan on the effect of pollution on the incidence of stroke and acute myocardial infarction (AMI). Therefore, we investigated the effects of air pollution on the incidence of stroke and AMI in a setting where pollutant levels are rather low.

METHODS

Data were obtained from the Takashima Stroke and AMI Registry, which covers a population of approximately 55,000 in Takashima County in central Japan. We applied a time-stratified, bidirectional, case-crossover design to estimate the effects of air pollutants, which included suspended particulate matter (SPM), sulfur dioxide (SO(2)), nitrogen dioxide (NO(2)) and photochemical oxidants (Ox). We used the distributed lag model to estimate the effect of pollutant exposure 0-3 days before the day of event onset and controlled for meteorological covariates in all of the models.

RESULTS

There were 2,038 first-ever strokes (1,083 men, 955 women) and 429 first-ever AMI cases (281 men, 148 women) during 1988-2004. The mean pollutant levels were as follows: SPM 26.9 μg/m(3); SO(2) 3.9 ppb; NO(2) 16.0 ppb, and Ox 28.4 ppb. In single-pollutant and two-pollutant models, SO(2) was associated with the risk of cerebral hemorrhage. Other stroke subtypes and AMI were not associated with air pollutant levels.

CONCLUSIONS

We observed an association between SO(2) and hemorrhagic stroke; however, we found inconclusive evidence for a short-term effect of air pollution on the incidence of other stroke types and AMI.

Lack of association between air pollutant exposure and short-term risk of ischaemic stroke in Lyon, France

BACKGROUND

Some observational and experimental studies have suggested a short-term relationship between air pollutants and ischaemic stroke; however, the results conflict.

AIMS

The objective of this study was to investigate the association between particulate matter less than 2·5 and 10 microns in aerodynamic diameter, nitrogen dioxide, sulphur dioxide and ozone, and short-term risk of ischaemic stroke in Lyon, France.

METHODS

The AVC69 study was a multicenter cohort study in which all consecutive adult patients admitted to one of the emergency or neurological departments of the Rhône area for suspicion of stroke were included during a seven-month period. Only patients with ischaemic stroke living within the study area, composed of Lyon and 18 neighbouring communities with homogenous air pollutants exposure, formed the basis of our study. We adopted a time-stratified case-crossover design to analyse the short-term effect (up to two-days) of air pollutants on ischaemic stroke incidence. Models were adjusted for temperature, variation of atmospheric pressure, minimal relative humidity, influenza epidemics, pollen count, and holidays. Stratified analyses by gender and class age were performed. Different lag times were analysed.

RESULTS

376 patients were included. Mean age was 76·6 years (± 13·7). 53·7% were women. No association was observed between air pollutants and short-term risk of ischaemic stroke after adjustment for main confounding factors. Results remained unchanged whatever the gender or age.

CONCLUSIONS

These results suggest a lack of association between air pollutant exposure and short-term risk of ischaemic stroke in a French urban area.

Pollutant particles induce arginase II in human bronchial epithelial cells

Exposure to particulate matter (PM) is associated with adverse pulmonary effects, including induction and exacerbation of asthma. Recently arginase was shown to play an important role in the pathogenesis of asthma. In this study, it was postulated that PM exposure might induce arginase. Human bronchial epithelial cells (HBEC) obtained from normal individuals by endobronchial brushings cultured on an air-liquid interface were incubated with fine Chapel Hill particles (PM₂.₅, 100 μg/ml) for up to 72 h. Arginase activity, protein expression, and mRNA of arginase I and arginase II were measured. PM₂.₅ increased arginase activity in a time-dependent manner. The rise was primarily due to upregulation of arginase II. PD153035 (10 μM), an epidermal growth factor (EGF) receptor antagonist, attenuated the PM₂.₅-induced elevation in arginase activity and arginase II expression. Treatment of HBEC with human EGF increased arginase activity and arginase II expression. Pretreatment with catalase (200 U/ml), superoxide dismutase (100 U/ml), or apocynin (5 μg/ml), an NAD(P)H oxidase inhibitor, did not markedly affect arginase II expression. Treatment of HBEC with arginase II siRNA inhibited the expression of arginase II by 60% and increased IL-8 release induced by PM₂.₅. These results indicate that PM exposure upregulates arginase II activity and expression in human bronchial epithelial cells, in part via EGF-dependent mechanisms independent of oxidative stress. The elevated arginase II activity and expression may be a mechanism underlying adverse effects induced by PM exposure in asthma patients.

Influence of season and location on pulmonary response to California's San Joaquin Valley airborne particulate matter

Season and location have documented impacts on particulate matter (PM)-induced morbidity and mortality. Seasonal and regional influences on the physical and chemical properties of PM₂.₅ (also known as fine/ultrafine PM) contribute to differences in exposure burden and adverse respiratory health outcomes experienced in California's San Joaquin Valley (SJV), which ranks among the worst in the nation for PM pollution. Current regulations are driven by the association between mass concentrations and adverse health outcomes. However, this association is difficult to reproduce in toxicological studies and suggests a role for other parameters, such as chemical composition, involved in PM-induced adverse pulmonary health effects. Pulmonary toxicity of summer/winter and rural/urban SJV PM was evaluated given the unique geography, metereology and sources of the region. Healthy juvenile male mice inhaled summer/winter and urban/rural concentrated ambient PM (CAP) or ambient PM for 6 h/d for 10 d, and pulmonary inflammatory responses were measured 48 h postexposure. Exposure concentrations ranged from 10 to 20 μg/m³ for ambient air control mice and from 86 to 284 μg/m³. Mice exposed to rural but not urban CAP, displayed significant neutrophil influx that was more than 50-fold greater than control levels, which ranged from 21 to 60 neutrophils/ml for all experiments. Pulmonary neutrophilic inflammation was measured despite lower CAP concentrations in the rural compared to the urban location and in the absence of cytotoxicity, oxidative stress, or elevations in cytokine and chemokines expression. Further, the inflammatory responses induced by rural winter CAP were associated with the highest levels of organic carbon (OC) and nitrates (NO₃⁻). Evidence indicates that regional/seasonal influences on PM chemical composition rather than PM mass may be associated with increased PM-induced adverse health effects.

Air pollution-associated procoagulant changes: the role of circulating microvesicles

BACKGROUND

Epidemiological studies suggest an association between exposure to particulate matter (PM) in air pollution and the risk of venous thromboembolism (VTE).

OBJECTIVES

To investigate the underlying pathophysiological pathways linking PM exposure and VTE.

PATIENTS AND METHODS

We assessed potential associations between PM exposure and coagulation and inflammation parameters, including circulating microvesicles, in a group of 233 patients with diabetes.

RESULTS

The numbers of circulating blood platelet-derived and annexin V-binding microvesicles were inversely associated with the current levels of PM(2.5) or PM(10), measured on the day of sampling. Recent past exposure to PM(10), up to 1 week prior to blood sampling, estimated at the patients' residential addresses, was associated with elevated high-sensitivity C-reactive protein (CRP), leukocytes and fibrinogen, as well as with tissue factor (TF)-dependent procoagulant changes in thrombin generation assays. When longer windows of past exposure were considered, up to 1 year preceding blood sampling, procoagulant changes were evident from the strongly increased numbers of red blood cell-derived circulating microvesicles and annexin V-binding microvesicles, but they no longer associated with TF. Past PM exposure was never associated with activated partial thromboplastin time (aPTT), prothrombin time (PT), or factor (F) VII, FVIII, FXII or D-dimers. Residential distance to a major road was only marginally correlated with procoagulant changes in FVIII and thrombin generation.

CONCLUSIONS

Increases in the number of microvesicles and in their procoagulant properties, rather than increases in coagulation factors per se, seem to contribute to the risk of VTE, developing during prolonged exposure to air pollutants.

Composition of air pollution particles and oxidative stress in cells, tissues, and living systems

Epidemiological studies demonstrated an association between increased levels of ambient air pollution particles and human morbidity and mortality. Production of oxidants, either directly by the air pollution particles or by the host response to the particles, appears to be fundamental in the biological effects seen after exposure to particulate matter (PM). However, the precise components and mechanisms responsible for oxidative stress following PM exposure are yet to be defined. Direct oxidant generation by air pollution particles is attributed to organic and metal components. Organic compounds generate an oxidative stress through redox cycling of quinone-based radicals, by complexing of metal resulting in electron transport, and by depletion of antioxidants by reactions between quinones and thiol-containing compounds. Metals directly support electron transport to generate oxidants and also diminish levels of antioxidants. In addition to direct generation of oxidants by organic and metal components, cellular responses contribute to oxidative stress after PM exposure. Reactive oxygen species (ROS) production occurs in the mitochondria, cell membranes, phagosomes, and the endoplasmic reticulum. Oxidative stress following PM exposure initiates a series of cellular reactions that includes activation of kinase cascades and transcription factors and release of inflammatory mediators, which ultimately lead to cell injury or apoptosis. Consequently, oxidative stress in cells and tissues is a central mechanism by which PM exposure leads to injury, disease, and mortality.

Direct and indirect effects of particulate matter on the cardiovascular system

Human exposure to particulate matter (PM) elicits a variety of responses on the cardiovascular system through both direct and indirect pathways. Indirect effects of PM on the cardiovascular system are mediated through the autonomic nervous system, which controls heart rate variability, and inflammatory responses, which augment acute cardiovascular events and atherosclerosis. Recent research demonstrates that PM also affects the cardiovascular system directly by entry into the systemic circulation. This process causes myocardial dysfunction through mechanisms of reactive oxygen species production, calcium ion interference, and vascular dysfunction. In this review, we will present key evidence in both the direct and indirect pathways, suggest clinical applications of the current literature, and recommend directions for future research.

The effect of air pollution on haemostasis

Ambient environmental air pollutants include gaseous and particulate components. In polluted air, especially particulate matter seems responsible for cardiovascular complications: It consists of a heterogeneous mixture of solid and liquid particles with different diameters ranging from large thoracic to ultrafine particles, with a diameter <100 nm. Ultrafines can penetrate deeply into the lung to deposit in the alveoli. Cardiovascular manifestations result both from short-term and long-term exposure and have been linked to interference with the autonomic nervous system, direct translocation into the systemic circulation, pulmonary inflammation and oxidative stress. Thrombotic complications associated with air pollution comprise arterial and probably venous thrombogenicity. This review describes the existing epidemiological and experimental evidence to explain the rapid induction of myocardial infarction within 1-2 hours after exposure to polluted air and advances several explanations as to why more chronic exposure will lead to enhanced venous thrombogenicity. Mechanisms such as platelet activation, endothelial dysfunction, coagulation factor changes and microvesicle production are discussed.

In-traffic air pollution exposure and CC16, blood coagulation, and inflammation markers in healthy adults

BACKGROUND

Exposure to traffic-related air pollution is a risk factor for cardiovascular events, probably involving mechanisms of inflammation and coagulation. Little is known about effects of the short exposures encountered while participating in traffic.

OBJECTIVES

The objective of the study was to examine effects of exposure of commuters to air pollution on cardiovascular biomarkers.

METHODS

Thirty-four healthy adult volunteers commuted for 2 hr by bus, car, or bicycle during the morning rush hour. During the commute, exposure to particle number, particulate matter (PM) ≤ 2.5 µm in aerodynamic diameter (PM2.5), PM ≤ 10 µm in diameter (PM10), and soot was measured. We estimated inhaled doses based on heart rate monitoring. Shortly before exposure and 6 hr after exposure, blood samples were taken and analyzed for CC16 (Clara cell protein 16), blood cell count, coagulation markers, and inflammation markers. Between June 2007 and June 2008, 352 pre- and postexposure blood samples were collected on 47 test days. We used mixed models to analyze the associations between exposure and changes in health parameters.

RESULTS

We observed no consistent associations between the air pollution exposures and doses and the various biomarkers that we investigated.

CONCLUSIONS

Air pollution exposure during commuting was not consistently associated with acute changes in inflammation markers, blood cell counts, or blood coagulation markers.