Traffic-related air pollutants and exhaled markers of airway inflammation and oxidative stress in New York City adolescents

Evaluation of a new method for the collection and measurement of 8-isoprostane in exhaled breath for future application in nanoparticle exposure biomonitoring

BACKGROUND

In the field of nanoparticle exposure biomonitoring, oxidative stress biomarkers measured in exhaled breath condensate appear promising to detect early respiratory effects in workers handling nanomaterials. However, condensation is known for its poor efficiency in collecting non-volatiles in exhaled breath, leading to the low sensitivity of such measurements. Moreover, to be easily used in field studies on large groups of workers, the collection device must be disposable and convenient.

OBJECTIVES

In this study, we have tested a totally disposable commercial device that allows for the easy dry collection of exhaled air after filtration on a patented filter. The suitability and efficiency of the SensAbues (SB) device for collecting 8-isoprostane were evaluated and compared to the RTube (RT).

METHODS

Seven healthy volunteers performed two 15 min collections of exhaled breath, one with the SB and one with the RT. Blank devices were used to determine the background levels induced by each device. 8-isoprostane was measured in all samples using an EIA technique.

RESULTS

The levels of 8-isoprostane in the exhaled breath of volunteers after collection with the SB were significantly higher than those after collection with the RT. Moreover, the levels obtained in volunteers with the SB were significantly higher than background levels obtained in blank devices, which was not the case for the RT.

CONCLUSIONS

This is the first study to report the ability of the SB device to collect and measure 8-isoprostane in exhaled breath. The proposed method offers better sensitivity than a classical collection with the RT device and should be further explored before future application in biomonitoring studies.

Outdoor air pollution, exhaled 8-isoprostane and current asthma in adults: the EGEA study

Associations between outdoor air pollution and asthma in adults are still scarce, and the underlying biological mechanisms are poorly understood. Our aim was to study the associations between 1) long-term exposure to outdoor air pollution and current asthma, 2) exhaled 8-isoprostane (8-iso; a biomarker related to oxidative stress) and current asthma, and 3) outdoor air pollution and exhaled 8-iso.Cross-sectional analyses were conducted in 608 adults (39% with current asthma) from the first follow-up of the French case-control and family study on asthma (EGEA; the Epidemiological study of the Genetic and Environmental factors of Asthma). Data on nitrogen dioxide, nitrogen oxides, particulate matter with a diameter ≤10 and ≤2.5 µm (PM₁₀ and PM_2.5), road traffic, and ozone (O₃) were from ESCAPE (European Study of Cohorts for Air Pollution Effects) and IFEN (French Institute for the Environment) assessments. Models took account of city and familial dependence.The risk of current asthma increased with traffic intensity (adjusted (a)OR 1.09 (95% CI 1.00-1.18) per 5000 vehicles per day), with O₃ exposure (aOR 2.04 (95% CI 1.27-3.29) per 10 µg·m^-3) and with exhaled 8-iso concentration (aOR 1.50 (95% CI 1.06-2.12) per 1 pg·mL^-1). Among participants without asthma, exhaled 8-iso concentration increased with PM_2.5 exposure (adjusted (a)β 0.23 (95% CI 0.005-0.46) per 5 µg·m^-3), and decreased with O₃ and O_3-summer exposures (aβ -0.20 (95% CI -0.39- -0.01) and aβ -0.52 (95% CI -0.77- -0.26) per 10 µg·m^-3, respectively).Our results add new insights into a potential role of oxidative stress in the associations between outdoor air pollution and asthma in adults.

Ambient air pollution and the risk of pregnancy loss: a prospective cohort study

OBJECTIVE

To estimate the association of pregnancy loss with common air pollutant exposure. Ambient air pollution exposure has been linked to adverse pregnancy outcomes, but few studies have investigated its relationship with pregnancy loss.

DESIGN

Prospective cohort study.

SETTING

Not applicable.

PATIENT(S)

A total of 343 singleton pregnancies in a multisite prospective cohort study with detailed protocols for ovulation and pregnancy testing.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Timing of incident pregnancy loss (from ovulation).

RESULT(S)

The incidence of pregnancy loss was 28% (n = 98). Pollutant levels at women's residences were estimated using modified Community Multiscale Air Quality models and averaged during the past 2 weeks (acute) and the whole pregnancy (chronic). Adjusted Cox proportional hazards models showed that an interquartile range increase in average whole pregnancy ozone (hazard ratio [HR] 1.12, 95% confidence interval [CI] 1.07-1.17) and particulate matter <2.5 μm (HR 1.13, 95% CI 1.03-1.24) concentrations were associated with faster time to pregnancy loss. Sulfate compounds also appeared to increase risk (HR 1.58, 95% CI 1.07-2.34). Last 2 weeks of exposures were not associated with loss.

CONCLUSION(S)

In a prospective cohort of couples trying to conceive, we found evidence that exposure to air pollution throughout pregnancy was associated with loss, but delineating specific periods of heightened vulnerability await larger preconception cohort studies with daily measured air quality.

DNA methylation and exposure to ambient air pollution in two prospective cohorts

Long-term exposure to air pollution has been associated with several adverse health effects including cardiovascular, respiratory diseases and cancers. However, underlying molecular alterations remain to be further investigated. The aim of this study is to investigate the effects of long-term exposure to air pollutants on (a) average DNA methylation at functional regions and, (b) individual differentially methylated CpG sites. An assumption is that omic measurements, including the methylome, are more sensitive to low doses than hard health outcomes. This study included blood-derived DNA methylation (Illumina-HM450 methylation) for 454 Italian and 159 Dutch participants from the European Prospective Investigation into Cancer and Nutrition (EPIC). Long-term air pollution exposure levels, including NO2, NOx, PM2.5, PMcoarse, PM10, PM2.5 absorbance (soot) were estimated using models developed within the ESCAPE project, and back-extrapolated to the time of sampling when possible. We meta-analysed the associations between the air pollutants and global DNA methylation, methylation in functional regions and epigenome-wide methylation. CpG sites found differentially methylated with air pollution were further investigated for functional interpretation in an independent population (EnviroGenoMarkers project), where (N=613) participants had both methylation and gene expression data available. Exposure to NO2 was associated with a significant global somatic hypomethylation (p-value=0.014). Hypomethylation of CpG island's shores and shelves and gene bodies was significantly associated with higher exposures to NO2 and NOx. Meta-analysing the epigenome-wide findings of the 2 cohorts did not show genome-wide significant associations at single CpG site level. However, several significant CpG were found if the analyses were separated by countries. By regressing gene expression levels against methylation levels of the exposure-related CpG sites, we identified several significant CpG-transcript pairs and highlighted 5 enriched pathways for NO2 and 9 for NOx mainly related to the immune system and its regulation. Our findings support results on global hypomethylation associated with air pollution, and suggest that the shores and shelves of CpG islands and gene bodies are mostly affected by higher exposure to NO2 and NOx. Functional differences in the immune system were suggested by transcriptome analyses.

Nanomaterials Versus Ambient Ultrafine Particles: An Opportunity to Exchange Toxicology Knowledge

BACKGROUND

A rich body of literature exists that has demonstrated adverse human health effects following exposure to ambient air particulate matter (PM), and there is strong support for an important role of ultrafine (nanosized) particles. At present, relatively few human health or epidemiology data exist for engineered nanomaterials (NMs) despite clear parallels in their physicochemical properties and biological actions in in vitro models.

OBJECTIVES

NMs are available with a range of physicochemical characteristics, which allows a more systematic toxicological analysis. Therefore, the study of ultrafine particles (UFP, <100 nm in diameter) provides an opportunity to identify plausible health effects for NMs, and the study of NMs provides an opportunity to facilitate the understanding of the mechanism of toxicity of UFP.

METHODS

A workshop of experts systematically analyzed the available information and identified 19 key lessons that can facilitate knowledge exchange between these discipline areas.

DISCUSSION

Key lessons range from the availability of specific techniques and standard protocols for physicochemical characterization and toxicology assessment to understanding and defining dose and the molecular mechanisms of toxicity. This review identifies a number of key areas in which additional research prioritization would facilitate both research fields simultaneously.

CONCLUSION

There is now an opportunity to apply knowledge from NM toxicology and use it to better inform PM health risk research and vice versa. https://doi.org/10.1289/EHP424.

Pulmonary challenge with carbon nanoparticles induces a dose-dependent increase in circulating leukocytes in healthy males

Background

Inhalation of particulate matter, as part of air pollution, is associated with increased morbidity and mortality. Nanoparticles (< 100 nm) are likely candidates for triggering inflammatory responses and activation of coagulation pathways because of their ability to enter lung cells and pass bronchial mucosa. We tested the hypothesis that bronchial segmental instillation of carbon nanoparticles causes inflammation and activation of coagulation pathways in healthy humans in vivo.

Methods

This was an investigator-initiated, randomized controlled, dose-escalation study in 26 healthy males. Participants received saline (control) in one lung segment and saline (placebo) or carbon nanoparticles 10 μg, 50 μg, or 100 μg in the contra-lateral lung. Six hours later, blood and bronchoalveolar lavage fluid (BALF) was collected for inflammation and coagulation parameters.

Results

There was a significant dose-dependent increase in blood neutrophils (p = 0.046) after challenge with carbon nanoparticles. The individual top-dose of 100 μg showed a significant (p = 0.05) increase in terms of percentage neutrophils in blood as compared to placebo.

Conclusions

This study shows a dose-dependent effect of bronchial segmental challenge with carbon nanoparticles on circulating neutrophils of healthy volunteers. This suggests that nanoparticles in the respiratory tract induce systemic inflammation.

Trial registration

Dutch Trial Register no. 2976. 11 July 2011. http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=2976

Electronic supplementary material

The online version of this article (10.1186/s12890-017-0463-x) contains supplementary material, which is available to authorized users.

The Toxicological Mechanisms of Environmental Soot (Black Carbon) and Carbon Black: Focus on Oxidative Stress and Inflammatory Pathways

The environmental soot and carbon blacks (CBs) cause many diseases in humans, but their underlying mechanisms of toxicity are still poorly understood. Both are formed after the incomplete combustion of hydrocarbons but differ in their constituents and percent carbon contents. For the first time, “Sir Percival Pott” described soot as a carcinogen, which was subsequently confirmed by many others. The existing data suggest three main types of diseases due to soot and CB exposures: cancer, respiratory diseases, and cardiovascular dysfunctions. Experimental models revealed the involvement of oxidative stress, DNA methylation, formation of DNA adducts, and Aryl hydrocarbon receptor activation as the key mechanisms of soot- and CB-induced cancers. Metals including Si, Fe, Mn, Ti, and Co in soot also contribute in the reactive oxygen species (ROS)-mediated DNA damage. Mechanistically, ROS-induced DNA damage is further enhanced by eosinophils and neutrophils via halide (Cl⁻ and Br⁻) dependent DNA adducts formation. The activation of pulmonary dendritic cells, T helper type 2 cells, and mast cells is crucial mediators in the pathology of soot- or CB-induced respiratory disease. Polyunsaturated fatty acids (PUFAs) were also found to modulate T cells functions in respiratory diseases. Particularly, telomerase reverse transcriptase was found to play the critical role in soot- and CB-induced cardiovascular dysfunctions. In this review, we propose integrated mechanisms of soot- and CB-induced toxicity emphasizing the role of inflammatory mediators and oxidative stress. We also suggest use of antioxidants and PUFAs as protective strategies against soot- and CB-induced disorders.

Effect of personal exposure to black carbon on changes in allergic asthma gene methylation measured 5 days later in urban children: importance of allergic sensitization

Background

Asthma gene DNA methylation may underlie the effects of air pollution on airway inflammation. However, the temporality and individual susceptibility to environmental epigenetic regulation of asthma has not been fully elucidated. Our objective was to determine the timeline of black carbon (BC) exposure, measured by personal sampling, on DNA methylation of allergic asthma genes 5 days later to capture usual weather variations and differences related to changes in behavior and activities. We also sought to determine how methylation may vary by seroatopy and cockroach sensitization and by elevated fractional exhaled nitric oxide (FeNO).

Methods

Personal BC levels were measured during two 24-h periods over a 6-day sampling period in 163 New York City children (age 9–14 years), repeated 6 months later. During home visits, buccal cells were collected as noninvasive surrogates for lower airway epithelial cells and FeNO measured as an indicator of airway inflammation. CpG promoter loci of allergic asthma genes (e.g., interleukin 4 (IL4), interferon gamma (IFNγ), inducible nitric oxide synthase (NOS2A)), arginase 2 (ARG2)) were pyrosequenced at the start and end of each sampling period.

Results

Higher levels of BC were associated with lower methylation of IL4 promoter CpG⁻⁴⁸ 5 days later. The magnitude of association between BC exposure and demethylation of IL4 CpG⁻⁴⁸ and NOS2A CpG⁺⁵⁰⁹⁹ measured 5 days later appeared to be greater among seroatopic children, especially those sensitized to cockroach allergens (RR [95% CI] 0.55 [0.37–0.82] and 0.67 [0.45–0.98] for IL4 CpG⁻⁴⁸ and NOS2A CpG⁺⁵⁰⁹⁹, respectively), compared to non-sensitized children (RR [95% CI] 0.87 [0.65–1.17] and 0.95 [0.69–1.33] for IL4 CpG⁻⁴⁸ and NOS2A CpG⁺⁵⁰⁹⁹, respectively); however, the difference was not statistically different. In multivariable linear regression models, lower DNA methylation of IL4 CpG⁻⁴⁸ and NOS2A CpG⁺⁵⁰⁹⁹ were associated with increased FeNO.

Conclusions

Our results suggest that exposure to BC may exert asthma proinflammatory gene demethylation 5 days later that in turn may link to airway inflammation. Our results further suggest that seroatopic children, especially those sensitized to cockroach allergens, may be more susceptible to the effect of acute BC exposure on epigenetic changes.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-017-0361-3) contains supplementary material, which is available to authorized users.

Acute effects of air pollutants on pulmonary function among students: a panel study in an isolated island

Background

Many epidemiological studies on the health effects of air pollutants have been carried out in regions with major sources such as factories and automobiles. However, the health effects of air pollutants in regions without major sources remain unclear. This study investigated the acute effects of ambient air pollution on pulmonary function among healthy students in an isolated island without major artificial sources of air pollutants.

Methods

A panel study was conducted of 43 healthy subjects who attended a school in an isolated island in the Seto Inland Sea, Japan. We measured the forced expiratory volume in 1 s (FEV₁) and peak expiratory flow (PEF) every morning for about 1 month in May 2014. Ambient concentrations of particulate matter ≤ 2.5 μm in diameter (PM_2.5), particulate matter between 2.5 and 10 μm in diameter (PM_10-2.5), black carbon (BC), ozone (O₃), and nitrogen dioxide (NO₂) were measured. The associations between the concentrations of air pollutants and pulmonary function were analyzed using mixed-effects models.

Results

A decrease in FEV₁ was significantly associated with BC concentrations (−27.28 mL [95%confidence interval (CI):−54.10,−0.46] for an interquartile range (IQR) increase of 0.23 μg/m³). The decrease in PEF was significantly associated with indoor O₃ concentrations (−8.03 L/min [95% CI:−13.02,−3.03] for an IQR increase of 11 ppb). Among subjects with a history of allergy, an increase in PM_2.5 concentrations was significantly associated with low FEV₁. In subjects with a history of asthma, an inverse association between the indoor O₃ concentration and pulmonary function was observed.

Conclusions

Our results demonstrate that increases in BC and O₃ concentrations have acute effects on the pulmonary function among students in an isolated island without major artificial sources of air pollutants.

Electronic supplementary material

The online version of this article (doi:10.1186/s12199-017-0646-3) contains supplementary material, which is available to authorized users.

Relación de los mecanismos inmunológicos del asma y la contaminación ambiental

Introducción. Se calcula que más de 300 millones de personas alrededor del mundo padecen asma y se estima que para el año 2025 esta cifra se incremente a 400 millones debido a los contaminantes criterio. Sin embargo, dadas sus limitaciones, los estudios epidemiológicos son controversiales sobre la contaminación y el desarrollo de asma.Objetivos. Describir las diferencias y similitudes de la respuesta inmunológica de pacientes asmáticos y los modelos animales de asma alérgica después de la exposición a contaminantes criterio y elementos biológicos, para así identificar los factores inmunológicos relacionados con el desarrollo de asma.Materiales y método. Se realizó una búsqueda sistemática en las bases de datos sobre asma y los diferentes contaminantes criterio.Resultados. La respuesta Th2 es activada por la inhalación de ozono, dióxido de nitrógeno, azufre y la exposición aguda a material particulado, mientras que el contacto con ciertos tipos de pólenes y glucanos y la exposición crónica de partículas incrementa la respuesta Th1, la cual inhibe a la respuesta Th2 produciendo un “efecto protector”.Conclusiones. La respuesta Th1 podría causar baja o nula asociación entre la exposición a contaminación y el desarrollo de asma en las diferentes ciudades, adicionando de esta manera otra limitación a los estudios epidemiológicos.

Early Exposure to Traffic-Related Air Pollution, Respiratory Symptoms at 4 Years of Age, and Potential Effect Modification by Parental Allergy, Stressful Family Events, and Sex: A Prospective Follow-up Study of the PARIS Birth Cohort

BACKGROUND

The relation between traffic-related air pollution (TRAP) exposure and the incidence of asthma/allergy in preschool children has been widely studied, but results remain heterogeneous, possibly due to differences in methodology and susceptibility to TRAP.

OBJECTIVES

We aimed to study the relation of early TRAP exposure with the development of respiratory/allergic symptoms and asthma during preschool years, and to investigate parental allergy, "stressful" family events, and sex as possible effect modifiers.

METHODS

We examined data of 2,015 children from the PARIS birth cohort followed up with repeated questionnaires completed by parents until age 4 years. TRAP exposure in each child's first year of life was estimated by nitrogen oxides (NO_x) air dispersion modeling, taking into account both home and day care locations. Association between TRAP exposure and patterns of wheezing, dry night cough, and rhinitis symptoms was studied using multinomial logistic regression models adjusted for potential confounders. Effect modification by parental history of allergy, stressful family events, and sex was investigated.

RESULTS

An interquartile range (26 μg/m³) increase in NO_x levels was associated with an increased odds ratio (OR) of persistent wheezing at 4 years (adjusted OR = 1.27; 95% confidence interval: 1.09, 1.47). TRAP exposure was positively associated with persistent wheeze, dry cough, and rhinitis symptoms among children with a parental allergy, those experiencing stressful family events, and boys, but not in children whose parents did not have allergies or experience stressful events, or in girls (all interaction p-values < 0.2).

CONCLUSIONS

This study supports the hypothesis that not all preschool children are equal regarding TRAP health effects. Parental history of allergy, stressful family events, and male sex may increase their susceptibility to adverse respiratory effects of early TRAP exposure.

Air pollution, PM2.5 composition, source factors, and respiratory symptoms in asthmatic and nonasthmatic children in Santiago, Chile

The objective of this study was to determine the association of respiratory symptoms and medication use and exposure to various air pollutants, PM_2.5 components, and source factors in a panel of asthmatic and nonasthmatic children in Santiago, Chile. To this end, 174 children (90 asthmatics and 84 nonasthmatics) were followed throughout the winter months of 2010 and 2011. During the study period, children filled out daily diaries to record respiratory symptoms and medication use. Air pollution data were obtained from government central site measurements and a PM_2.5 characterization campaign. PM_2.5 source factors were obtained using positive matrix factorization (PMF). Associations of symptoms and exposure to pollutants and source-factor daily scores were modeled separately for asthmatic and nonasthmatic children using mixed logistic regression models with random intercepts, controlling for weather, day of the week, year, and viral outbreaks. Overall, high concentrations of air pollutants and PM_2.5 components were observed. Six source factors were identified by PMF (motor vehicles, marine aerosol, copper smelter, secondary sulfates, wood burning, and soil dust). Overall, single pollutant models showed significant and strong associations between 7-day exposures for several criteria pollutants (PM_2.5, NO₂, O₃), PM_2.5 components (OC, K, S, Se, V), and source factors (secondary sulfate) and coughing, wheezing and three other respiratory symptoms in both in asthmatic and nonasthmatic children. No associations were found for use of rescue inhalers in asthmatics. Two-pollutant models showed that several associations remained significant after including PM_2.5, and other criteria pollutants, in the models, particularly components and source factors associated with industrial sources. In conclusion, exposure to air pollutants, especially PM_2.5, NO₂, and O₃, were found to exacerbate respiratory symptoms in both asthmatic and nonasthmatic children. Some of the results suggest that PM_2.5 components associated with a secondary sulfate source may have a greater impact on some symptoms than PM_2.5. In general, the results of this study show important associations at concentrations close or below current air quality standards.

Advance of antioxidants in asthma treatment

Asthma is an allergic disease, characterized as a recurrent airflow limitation, airway hyperreactivity, and chronic inflammation, involving a variety of cells and cytokines. Reactive oxygen species have been proven to play an important role in asthma. The pathogenesis of oxidative stress in asthma involves an imbalance between oxidant and antioxidant systems that is caused by environment pollutants or endogenous reactive oxygen species from inflammation cells. There is growing evidence that antioxidant treatments that include vitamins and food supplements have been shown to ameliorate this oxidative stress while improving the symptoms and decreasing the severity of asthma. In this review, we summarize recent studies that are related to the mechanisms and biomarkers of oxidative stress, antioxidant treatments in asthma.

Maternal exposure to ambient PM2.5 exaggerates fetal cardiovascular maldevelopment induced by homocysteine in rats

Maternal exposure to airborne particulate matter with aerodynamic diameter <2.5 µm (PM_2.5 ) during pregnancy and lactation periods is associated with filial congenital cardiovascular diseases. This study aimed to investigate the toxic effects of maternal exposure to ambient levels of PM_2.5 on filial cardiovascular maldevelopment induced by homocysteine. Using a 2 × 2 factorial design, rats were randomized into four groups and were exposed to ambient PM_2.5 or filtered air (FA) throughout the pregnancy and lactation periods coupled with the administration of either homocysteine (HCY) or normal saline (NS) daily from gestation days 8-10. Morphological changes in the heart, myocardial apoptosis, expressions of cardiac progenitor transcriptional factors, and levels of cytokines were investigated in the offspring. The apoptosis-like changes in the myocardium were seen in the FA plus HCY-treated group and more obviously in the PM_2.5 plus HCY-treated group, which was in accordance with an increased myocardial apoptosis rate in the two groups. PM_2.5 exposure resulted in significantly decreased Nkx2-5 protein level and GATA4 and Nkx2-5 mRNA expressions, and significantly increased TNF-α and IL-1β levels. There were significant interactions between PM_2.5 exposure and HCY-treatment that PM_2.5 exposure reduced Nkx2-5 protein levels and GATA4 and Nkx2-5 mRNA expressions in the HCY-treated groups. These results suggest that maternal exposure to PM_2.5 , even at the ambient levels in urban regions in China, exaggerates filial cardiovascular maldevelopment induced by HCY in a murine model, exacerbating structural abnormalities in the filial cardiac tissue, which is possibly associated with oxidative stress and reduced GATA4 and Nkx2-5 transcription factor expressions. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 877-889, 2017.

Outdoor Environment and Pediatric Asthma: An Update on the Evidence from North America

Introduction. The evidence about the association between asthma and outdoor environmental factors has been inadequate for certain allergens. Even less is known about how these associations vary across seasons and climate regions. We reviewed recent literature from North America for research related to outdoor environmental factors and pediatric asthma, with attention to spatial-temporal variations of these associations. Method. We included indexed literature between years 2010 and 2015 on outdoor environmental factors and pediatric asthma, by searching PubMed. Results. Our search resulted in 33 manuscripts. Studies about the link between pediatric asthma and traffic-related air pollutants (TRAP) consistently confirmed the correlation between TRAP and asthma. For general air pollution, the roles of PM_2.5 and CO were consistent across studies. The link between asthma and O₃ varied across seasons. Regional variation exists in the role of SO₂. The impact of pollen was consistent across seasons, whereas the role of polycyclic aromatic hydrocarbon was less consistent. Discussion. Recent studies strengthened the evidence about the roles of PM_2.5, TRAP, CO, and pollen in asthma, while the evidence for roles of PM_10-2.5, PM₁₀, O₃, NO₂, SO₂, and polycyclic aromatic hydrocarbon in asthma was less consistent. Spatial-temporal details of the environment are needed in future studies of asthma and environment.

Effects of PM2.5 and NO2 on the 8-isoprostane and lung function indices of FVC and FEV1 in students of Ahvaz city, Iran

The aim of this study was to determine the correlation between PM_2.5 and NO₂ pollutants and oxidative stress marker (8-isoprostane) and lung function tests (FVC and FEV₁) in healthy children who were living and studying in three different areas of Ahvaz city including A₁: Naderi site with high traffic, A₂: Alavi Alley site with average traffic, and A₃: Ein 2 site with low traffic (a rural area on the suburb of Ahvaz). 30 students in the 12-13 year-old range were selected from each studied zone (1, 2 and 3 sites) during three months of year. Of each student, one sample was taken every two weeks to measure 8-isoprostane of exhaled breath condensate (EBC). Air pollution data were collected from three air quality monitoring stations. Also, the relationship between air pollution and 8-isoprostane as well as lung function tests were determined using generalized estimating equations (GEE). The mean concentration of PM_2.5 and NO₂ in A₁, A₂ and A₃ areas were 116, 92 and 45 (μg/m³) also 77, 53 and 14 (ppb) respectively. Among all studied students, there was a significant correlation between the increase of mean concentration of PM_2.5 and NO₂ in 1-4 before sampling day, increased 8-isoprostane concentration and decreased FEV₁, while there was no significant correlation between them and decreased FVC. In A₁ site, an increase in IQR (13 μg/m³) PM_2.5 and IQR (6.5 ppb) NO₂ on 1-4 days before sampling was associated with 0.38 unit (95% CI: 0.11, 0.65) and 1.1 unit (95% CI: 0.85, 1.35) increase in 8-isoprostane concentration, also decreased 121 ml and 190 ml FEV₁, respectively. Results showed that the short-term exposure to traffic-related air pollution can decrease the values of lung function indices and increase the oxidative stress. It may adversely affect children's lungs.

Scripted drives: A robust protocol for generating exposures to traffic-related air pollution

Commuting in automobiles can contribute substantially to total traffic-related air pollution (TRAP) exposure, yet measuring commuting exposures for studies of health outcomes remains challenging. To estimate real-world TRAP exposures, we developed and evaluated the robustness of a scripted drive protocol on the NJ Turnpike and local roads between April 2007 and October 2014. Study participants were driven in a car with closed windows and open vents during morning rush hours on 190 days. Real-time measurements of PM2.5, PNC, CO, and BC, and integrated samples of NO2, were made in the car cabin. Exposure measures included in-vehicle concentrations on the NJ Turnpike and local roads and the differences and ratios of these concentrations. Median in-cabin concentrations were 11 μg/m3 PM2.5, 40 000 particles/cm3, 0.3 ppm CO, 4 μg/m3 BC, and 20.6 ppb NO2. In-cabin concentrations on the NJ Turnpike were higher than in-cabin concentrations on local roads by a factor of 1.4 for PM2.5, 3.5 for PNC, 1.0 for CO, and 4 for BC. Median concentrations of NO2 for full rides were 2.4 times higher than ambient concentrations. Results were generally robust relative to season, traffic congestion, ventilation setting, and study year, except for PNC and PM2.5, which had secular and seasonal trends. Ratios of concentrations were more stable than differences or absolute concentrations. Scripted drives can be used for generating reasonably consistent in-cabin increments of exposure to traffic-related air pollution.

Short-Term Exposure to Air Pollution and Biomarkers of Oxidative Stress: The Framingham Heart Study

BACKGROUND

Short-term exposure to elevated air pollution has been associated with higher risk of acute cardiovascular diseases, with systemic oxidative stress induced by air pollution hypothesized as an important underlying mechanism. However, few community-based studies have assessed this association.

METHODS AND RESULTS

Two thousand thirty-five Framingham Offspring Cohort participants living within 50 km of the Harvard Boston Supersite who were not current smokers were included. We assessed circulating biomarkers of oxidative stress including blood myeloperoxidase at the seventh examination (1998-2001) and urinary creatinine-indexed 8-epi-prostaglandin F2α (8-epi-PGF2α) at the seventh and eighth (2005-2008) examinations. We measured fine particulate matter (PM2.5), black carbon, sulfate, nitrogen oxides, and ozone at the Supersite and calculated 1-, 2-, 3-, 5-, and 7-day moving averages of each pollutant. Measured myeloperoxidase and 8-epi-PGF2α were loge transformed. We used linear regression models and linear mixed-effects models with random intercepts for myeloperoxidase and indexed 8-epi-PGF2α, respectively. Models were adjusted for demographic variables, individual- and area-level measures of socioeconomic position, clinical and lifestyle factors, weather, and temporal trend. We found positive associations of PM2.5 and black carbon with myeloperoxidase across multiple moving averages. Additionally, 2- to 7-day moving averages of PM2.5 and sulfate were consistently positively associated with 8-epi-PGF2α. Stronger positive associations of black carbon and sulfate with myeloperoxidase were observed among participants with diabetes than in those without.

CONCLUSIONS

Our community-based investigation supports an association of select markers of ambient air pollution with circulating biomarkers of oxidative stress.

Ambient air pollution, lung function, and airway responsiveness in asthmatic children

BACKGROUND

Although ambient air pollution has been linked to reduced lung function in healthy children, longitudinal analyses of pollution effects in asthmatic patients are lacking.

OBJECTIVE

We sought to investigate pollution effects in a longitudinal asthma study and effect modification by controller medications.

METHODS

We examined associations of lung function and methacholine responsiveness (PC20) with ozone, carbon monoxide (CO), nitrogen dioxide, and sulfur dioxide concentrations in 1003 asthmatic children participating in a 4-year clinical trial. We further investigated whether budesonide and nedocromil modified pollution effects. Daily pollutant concentrations were linked to ZIP/postal code of residence. Linear mixed models tested associations of within-subject pollutant concentrations with FEV1 and forced vital capacity (FVC) percent predicted, FEV1/FVC ratio, and PC20, adjusting for seasonality and confounders.

RESULTS

Same-day and 1-week average CO concentrations were negatively associated with postbronchodilator percent predicted FEV1 (change per interquartile range, -0.33 [95% CI, -0.49 to -0.16] and -0.41 [95% CI, -0.62 to -0.21], respectively) and FVC (-0.19 [95% CI, -0.25 to -0.07] and -0.25 [95% CI, -0.43 to -0.07], respectively). Longer-term 4-month CO averages were negatively associated with prebronchodilator percent predicted FEV1 and FVC (-0.36 [95% CI, -0.62 to -0.10] and -0.21 [95% CI, -0.42 to -0.01], respectively). Four-month averaged CO and ozone concentrations were negatively associated with FEV1/FVC ratio (P < .05). Increased 4-month average nitrogen dioxide concentrations were associated with reduced postbronchodilator FEV1 and FVC percent predicted. Long-term exposures to sulfur dioxide were associated with reduced PC20 (percent change per interquartile range, -6% [95% CI, -11% to -1.5%]). Treatment augmented the negative short-term CO effect on PC20.

CONCLUSIONS

Air pollution adversely influences lung function and PC20 in asthmatic children. Treatment with controller medications might not protect but rather worsens the effects of CO on PC20. This clinical trial design evaluates modification of pollution effects by treatment without confounding by indication.

Aeroparticles, Composition, and Lung Diseases

Urban air pollution is a serious worldwide problem due to its impact on human health. In the past 60 years, growing evidence established a correlation between exposure to air pollutants and the developing of severe respiratory diseases. Recently particulate matter (PM) is drawing more public attention to various aspects including historical backgrounds, physicochemical characteristics, and its pathological role. Therefore, this review is focused on these aspects. The most famous air pollution disaster happened in London on December 1952; it has been calculated that more than 4,000 deaths occurred during this event. Air pollution is a complex mix of gases and particles. Gaseous pollutants disseminate deeply into the alveoli, allowing its diffusion through the blood–air barrier to several organs. Meanwhile, PM is a mix of solid or liquid particles suspended in the air. PM is deposited at different levels of the respiratory tract, depending on its size: coarse particles (PM₁₀) in upper airways and fine particles (PM_2.5) can be accumulated in the lung parenchyma, inducing several respiratory diseases. Additionally to size, the composition of PM has been associated with different toxicological outcomes on clinical and epidemiological, as well as in vivo and in vitro animal and human studies. PM can be constituted by organic, inorganic, and biological compounds. All these compounds are capable of modifying several biological activities, including alterations in cytokine production, coagulation factors balance, pulmonary function, respiratory symptoms, and cardiac function. It can also generate different modifications during its passage through the airways, like inflammatory cells recruitment, with the release of cytokines and reactive oxygen species (ROS). These inflammatory mediators can activate different pathways, such as MAP kinases, NF-κB, and Stat-1, or induce DNA adducts. All these alterations can mediate obstructive or restrictive respiratory diseases like asthma, COPD, pulmonary fibrosis, and even cancer. In 2013, outdoor air pollution was classified as Group 1 by IARC based on all research studies data about air pollution effects. Therefore, it is important to understand how PM composition can generate several pulmonary pathologies.

Evaluation of Chronic Obstructive Pulmonary Disease (COPD) attributed to atmospheric O3, NO2, and SO2 using Air Q Model (2011-2012 year)

Chronic obstructive pulmonary disease (COPD) is an important disease worldwide characterized by chronically poor airflow. The economic burden of COPD on any society can be enormous if not managed. We applied the approach proposed by the World Health Organization (WHO) using the AirQ2.2.3 software developed by the WHO European Center for Environment and Health on air pollutants in Tabriz (Iran) (2011-2012 year). A 1h average of concentrations of ozone (O3), daily average concentrations of nitrogen dioxide (NO2) and sulfur dioxide (SO2) were used to assess human exposure and health effect in terms of attributable proportion of the health outcome and annual number of excess cases of Hospital Admissions for COPD (HA COPD). The results of this study showed that 2% (95% CI: 0.8-3.1%) of HA COPD were attributed to O3 concentrations over 10 μg/m(3). In addition, 0.7 % (95% CI: 0.1-1.8%) and 0.5% (95% CI: 0-1%) of HA COPD were attributed to NO2 and SO2 concentrations over 10 μg/m(3) respectively. In this study, we have shown that O3, NO2 and SO2 have a significant impact on COPD hospitalization. Given these results the policy decisions are needed in order to reduce the chronic pulmonary diseases caused by air pollution and furthermore better quantification studies are recommended.

The statistical evaluation and comparison of ADMS-Urban model for the prediction of nitrogen dioxide with air quality monitoring network

In many countries, road traffic is one of the main sources of air pollution associated with adverse effects on human health and environment. Nitrogen dioxide (NO2) is considered to be a measure of traffic-related air pollution, with concentrations tending to be higher near highways, along busy roads, and in the city centers, and the exceedances are mainly observed at measurement stations located close to traffic. In order to assess the air quality in the city and the air pollution impact on public health, air quality models are used. However, firstly, before the model can be used for these purposes, it is important to evaluate the accuracy of the dispersion modelling as one of the most widely used method. The monitoring and dispersion modelling are two components of air quality monitoring system (AQMS), in which statistical comparison was made in this research. The evaluation of the Atmospheric Dispersion Modelling System (ADMS-Urban) was made by comparing monthly modelled NO2 concentrations with the data of continuous air quality monitoring stations in Kaunas city. The statistical measures of model performance were calculated for annual and monthly concentrations of NO2 for each monitoring station site. The spatial analysis was made using geographic information systems (GIS). The calculation of statistical parameters indicated a good ADMS-Urban model performance for the prediction of NO2. The results of this study showed that the agreement of modelled values and observations was better for traffic monitoring stations compared to the background and residential stations.

Cardiopulmonary benefits of reducing indoor particles of outdoor origin: a randomized, double-blind crossover trial of air purifiers

BACKGROUND

Indoor exposure to fine particulate matter (PM2.5) from outdoor sources is a major health concern, especially in highly polluted developing countries such as China. Few studies have evaluated the effectiveness of indoor air purification on the improvement of cardiopulmonary health in these areas.

OBJECTIVES

This study sought to evaluate whether a short-term indoor air purifier intervention improves cardiopulmonary health.

METHODS

We conducted a randomized, double-blind crossover trial among 35 healthy college students in Shanghai, China, in 2014. These students lived in dormitories that were randomized into 2 groups and alternated the use of true or sham air purifiers for 48 h with a 2-week washout interval. We measured 14 circulating biomarkers of inflammation, coagulation, and vasoconstriction; lung function; blood pressure (BP); and fractional exhaled nitric. We applied linear mixed-effect models to evaluate the effect of the intervention on health outcome variables.

RESULTS

On average, air purification resulted in a 57% reduction in PM2.5 concentration, from 96.2 to 41.3 μg/m3, within hours of operation. Air purification was significantly associated with decreases in geometric means of several circulating inflammatory and thrombogenic biomarkers, including 17.5% in monocyte chemoattractant protein-1, 68.1% in interleukin-1β, 32.8% in myeloperoxidase, and 64.9% in soluble CD40 ligand. Furthermore, systolic BP, diastolic BP, and fractional exhaled nitrous oxide were significantly decreased by 2.7%, 4.8%, and 17.0% in geometric mean, respectively. The impacts on lung function and vasoconstriction biomarkers were beneficial but not statistically significant.

CONCLUSIONS

This intervention study demonstrated clear cardiopulmonary benefits of indoor air purification among young, healthy adults in a Chinese city with severe ambient particulate air pollution. (Intervention Study on the Health Impact of Air Filters in Chinese Adults; NCT02239744).

Noninvasive effects measurements for air pollution human studies: methods, analysis, and implications

Human exposure studies, compared with cell and animal models, are heavily relied upon to study the associations between health effects in humans and air pollutant inhalation. Human studies vary in exposure methodology, with some work conducted in controlled settings, whereas other studies are conducted in ambient environments. Human studies can also vary in the health metrics explored, as there exists a myriad of health effect end points commonly measured. In this review, we compiled mini reviews of the most commonly used noninvasive health effect end points that are suitable for panel studies of air pollution, broken into cardiovascular end points, respiratory end points, and biomarkers of effect from biological specimens. Pertinent information regarding each health end point and the suggested methods for mobile collection in the field are assessed. In addition, the clinical implications for each health end point are summarized, along with the factors identified that can modify each measurement. Finally, the important research findings regarding each health end point and air pollutant exposures were reviewed. It appeared that most of the adverse health effects end points explored were found to positively correlate with pollutant levels, although differences in study design, pollutants measured, and study population were found to influence the magnitude of these effects. Thus, this review is intended to act as a guide for researchers interested in conducting human exposure studies of air pollutants while in the field, although there can be a wider application for using these end points in many epidemiological study designs.

Particulate matter from both heavy fuel oil and diesel fuel shipping emissions show strong biological effects on human lung cells at realistic and comparable in vitro exposure conditions

BACKGROUND

Ship engine emissions are important with regard to lung and cardiovascular diseases especially in coastal regions worldwide. Known cellular responses to combustion particles include oxidative stress and inflammatory signalling.

OBJECTIVES

To provide a molecular link between the chemical and physical characteristics of ship emission particles and the cellular responses they elicit and to identify potentially harmful fractions in shipping emission aerosols.

METHODS

Through an air-liquid interface exposure system, we exposed human lung cells under realistic in vitro conditions to exhaust fumes from a ship engine running on either common heavy fuel oil (HFO) or cleaner-burning diesel fuel (DF). Advanced chemical analyses of the exhaust aerosols were combined with transcriptional, proteomic and metabolomic profiling including isotope labelling methods to characterise the lung cell responses.

RESULTS

The HFO emissions contained high concentrations of toxic compounds such as metals and polycyclic aromatic hydrocarbon, and were higher in particle mass. These compounds were lower in DF emissions, which in turn had higher concentrations of elemental carbon ("soot"). Common cellular reactions included cellular stress responses and endocytosis. Reactions to HFO emissions were dominated by oxidative stress and inflammatory responses, whereas DF emissions induced generally a broader biological response than HFO emissions and affected essential cellular pathways such as energy metabolism, protein synthesis, and chromatin modification.

CONCLUSIONS

Despite a lower content of known toxic compounds, combustion particles from the clean shipping fuel DF influenced several essential pathways of lung cell metabolism more strongly than particles from the unrefined fuel HFO. This might be attributable to a higher soot content in DF. Thus the role of diesel soot, which is a known carcinogen in acute air pollution-induced health effects should be further investigated. For the use of HFO and DF we recommend a reduction of carbonaceous soot in the ship emissions by implementation of filtration devices.

Gene-environment interaction from international cohorts: impact on development and evolution of occupational and environmental lung and airway disease

Environmental and occupational pulmonary diseases impose a substantial burden of morbidity and mortality on the global population. However, it has been long observed that only some of those who are exposed to pulmonary toxicants go on to develop disease; increasingly, it is being recognized that genetic differences may underlie some of this person-to-person variability. Studies performed throughout the globe are demonstrating important gene-environment interactions for diseases as diverse as chronic beryllium disease, coal workers' pneumoconiosis, silicosis, asbestosis, byssinosis, occupational asthma, and pollution-associated asthma. These findings have, in many instances, elucidated the pathogenesis of these highly complex diseases. At the same time, however, translation of this research into clinical practice has, for good reasons, proceeded slowly. No genetic test has yet emerged with sufficiently robust operating characteristics to be clearly useful or practicable in an occupational or environmental setting. In addition, occupational genetic testing raises serious ethical and policy concerns. Therefore, the primary objective must remain ensuring that the workplace and the environment are safe for all.

Ensemble-based source apportionment of fine particulate matter and emergency department visits for pediatric asthma

Epidemiologic studies utilizing source apportionment (SA) of fine particulate matter have shown that particles from certain sources might be more detrimental to health than others; however, it is difficult to quantify the uncertainty associated with a given SA approach. In the present study, we examined associations between source contributions of fine particulate matter and emergency department visits for pediatric asthma in Atlanta, Georgia (2002-2010) using a novel ensemble-based SA technique. Six daily source contributions from 4 SA approaches were combined into an ensemble source contribution. To better account for exposure uncertainty, 10 source profiles were sampled from their posterior distributions, resulting in 10 time series with daily SA concentrations. For each of these time series, Poisson generalized linear models with varying lag structures were used to estimate the health associations for the 6 sources. The rate ratios for the source-specific health associations from the 10 imputed source contribution time series were combined, resulting in health associations with inflated confidence intervals to better account for exposure uncertainty. Adverse associations with pediatric asthma were observed for 8-day exposure to particles generated from diesel-fueled vehicles (rate ratio = 1.06, 95% confidence interval: 1.01, 1.10) and gasoline-fueled vehicles (rate ratio = 1.10, 95% confidence interval: 1.04, 1.17).

Air pollution exposure: a novel environmental risk factor for interstitial lung disease?

Air pollution exposure is a well-established risk factor for several adverse respiratory outcomes, including airways diseases and lung cancer. Few studies have investigated the relationship between air pollution and interstitial lung disease (ILD) despite many forms of ILD arising from environmental exposures. There are potential mechanisms by which air pollution could cause, exacerbate, or accelerate the progression of certain forms of ILD via pulmonary and systemic inflammation as well as oxidative stress. This article will review the current epidemiologic and translational data supporting the plausibility of this relationship and propose a new conceptual framework for characterizing novel environmental risk factors for these forms of lung disease.

Online determination of polycyclic aromatic hydrocarbon formation from a flame soot generator

In this study, we produced a class of diffusion flame soot particles with varying chemical and physical properties by using the mini-Combustion Aerosol STandard (CAST) and applying varying oxidant gas flow rates under constant propane, quenching, and dilution gas supply. We varied the soot properties by using the following fuel-to-air equivalence ratios (Φ): 1.13, 1.09, 1.04, 1.00, 0.96, and 0.89. Within this Φ range, we observed drastic changes in the physical and chemical properties of the soot. Oxidant-rich flames (Φ < 1) were characterized by larger particle size, lower particle number concentration, higher black carbon (BC) concentration, lower brown carbon BrC.[BC](-1) than fuel-rich flames (Φ > 1). To investigate the polycyclic aromatic hydrocarbons (PAH) formation online, we developed a new method for quantification by using the one (13)C-containing doubly charged PAH ion in a high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS). The time-resolved concentration showed that the larger PAHs prevailed in the fuel-rich flames and diminished in the oxidant-rich flames. By comparison with the offline in situ derivatization-thermal-desorption gas-chromatography time-of-flight mass spectrometry (IDTD-GC-ToF-MS), we found that the concentration by using the HR-ToF-AMS was underestimated, especially for lower mass PAHs (C14-C18) in the fuel-rich flames possibly due to size limitation and degradation of semi-volatile species under high vacuum and desorption temperature in the latter. For oxidant-rich flames, the large PAHs (C20 and C22) were detected in the HR-ToF-AMS while it was not possible in IDTD-GC-ToF-MS due to matrix effect. The PAH formation was discussed based on the combination of our results and with respect to Φ settings.

Carcinogenicity of ambient air pollution: use of biomarkers, lessons learnt and future directions

The association between ambient air pollution (AAP) exposure and lung cancer risk has been investigated in prospective studies and the results are generally consistent, indicating that long-term exposure to air pollution can cause lung cancer. Biomarkers can enhance research on the health effects of air pollution by improving exposure assessment, increasing the understanding of mechanisms, and enabling the investigation of individual susceptibility. In this review, we assess DNA adducts as biomarkers of exposure to AAP and early biological effect, and DNA methylation as biomarker of early biological change and discuss critical issues arising from their incorporation in AAP health impact evaluations, such as confounding, individual susceptibilities, timing, intensity and duration of exposure, and investigated tissue. DNA adducts and DNA methylation are treated as paradigms. However, the lessons, learned from their use in the examination of AAP carcinogenicity, can be applied to investigations of other biomarkers involved in AAP carcinogenicity.

Urban air and tobacco smoke as conditions that increase the risk of oxidative stress and respiratory response in youth

BACKGROUND

Air pollution and tobacco smoke can induce negative effects on the human health and often leads to the formation of oxidative stress.

OBJECTIVE

The purpose of this study was to clarify the role of the urbanization degree and of passive exposure to tobacco smoke in the formation of oxidative stress. Thus, a group of non-smoking adolescents was recruited among those who live and attend school in areas with three different population densities. To each subject a spot of urine was collected to quantify 15-F2t isoprostane as a marker of oxidative stress and cotinine as a marker of passive exposure to tobacco smoke. Furthermore, respiratory functionality was also measured.

RESULTS

Multiple linear regression analysis results showed a direct correlation (p<0.0001) of 15-F2t isoprostane with both the urbanization and passive smoke. Lung function parameters proved significantly lower for the subjects living in the most populous city of Torino.

CONCLUSION

This remarks the negative effect that urbanization has on the respiratory conditions. Lastly, lung functionality presented a low inverse correlation with 15-F2t isoprostane, suggesting an independent mechanism than that of the urban factor.

Increased Levels of 8-Isoprostane in EBC of NO2-Exposed Rats

Several epidemiological studies have shown the impact on respiratory health of pollution of nitrogen dioxide (NO2), particulate matter (PM10), and ozone (O3) as an environmental mixture. However, the influence of individual components of airborne pollutants is less well known. Our study examined the cumulative effects of a single pollutant, NO2, on sensitized rats by measurement of isoprostane release in exhaled breath condensate (EBC). Three groups of six rats were used: (1) controls (only exposed to air), (2) sensitized and challenged by ovalbumin and exposed to air, and (3) sensitized, challenged by ovalbumin, and exposed to NO(2). There was no marked change in 8-isoprostane levels in EBC of sensitized rats, whereas a significant increase of 8-isoprostane was found in rats sensitized and exposed to NO2. Data indicate effect of exposure to NO2 is evident as increased 8-isoprostane levels in EBC, a relevant marker for assessment of pulmonary inflammation or oxidant stress and conventionally found in EBC of asthmatic subjects.

Pediatric asthma and ambient pollutant levels in industrializing nations

Asthma is one of the most common chronic diseases in childhood and its prevalence has been increasing within industrializing nations. The contribution of ambient pollutants to asthma symptomatology has been explored in some countries through epidemiological investigations, molecular analysis and monitoring functional outcomes. The health effects of rising environmental pollution have been of increasing concern in industrializing nations with rising urbanization patterns. This review article provides an overview of the link between pediatric asthma and exposure to rising sources of urban air pollution. It primarily focuses on the asthma-specific effects of sulfur dioxide, nitrogen dioxide, ozone and particulate matter. Worldwide trends of asthma prevalence are also provided which detail the prominent rise in asthma symptoms in many urban areas of Africa, Latin America and Asia. The molecular and functional correlation of ambient pollutants with asthma-specific airway inflammation in the pediatric population are also highlighted. The final aspect of the review considers the correlation of motor vehicle, industrial and cooking energy sources, ascribed as the major emitters among the pollutants in urban settings, with asthma epidemiology in children.

Airway oxidative stress and inflammation markers in exhaled breath from children are linked with exposure to black carbon

BACKGROUND

The current study aimed at assessing the associations between black carbon (BC) exposure and markers for airway inflammation and oxidative stress in primary school children in a Western European urban area.

METHODS

In 130 children aged 6-12 years old, the fraction of exhaled nitric oxide (FeNO), exhaled breath condensate (EBC) pH, 8-isoprostane and interleukin (IL)-1β were measured in two seasons. BC concentrations on the sampling day (2-h average, 8:00-10:00 AM) and on the day before (24-h average) were assessed using measurements at a central monitoring site. Land use regression (LUR) models were applied to estimate weekly average BC exposure integrated for the time spent at home and at school, and seasonal average BC exposure at the home address. Associations between exposure and biomarkers were tested using linear mixed effect regression models. Next to single exposure models, models combining different BC exposure metrics were used.

RESULTS

In single exposure models, an interquartile range (IQR) increase in 2-h BC (3.10 μg/m(3)) was linked with a 5.9% (95% CI: 0.1 to 12.0%) increase in 8-isoprostane. FeNO increased by 16.7% (95% CI: 2.2 to 33.2%) per IQR increase in 24-h average BC (4.50 μg/m(3)) and by 12.1% (95% CI: 2.5 to 22.8%) per IQR increase in weekly BC (1.73 μg/m(3)). IL-1β was associated with weekly and seasonal (IQR=1.70 μg/m(3)) BC with respective changes of 38.4% (95% CI: 9.0 to 75.4%) and 61.8% (95% CI: 3.5 to 153.9%) per IQR increase in BC. An IQR increase in weekly BC was linked with a lowering in EBC pH of 0.05 (95% CI: -0.10 to -0.01). All associations were observed independent of sex, age, allergy status, parental education level and meteorological conditions on the sampling day. Most of the associations remained when different BC exposure metrics were combined in multiple exposure models, after additional correction for sampling period or after exclusion of children with airway allergies. In additional analyses, FeNO was linked with 24-h PM10 levels, but the effect size was smaller than for BC. 8-Isoprostane was not linked with either 2-h or 24-h concentrations of PM2.5 or PM10.

CONCLUSION

BC exposure on the morning of sampling was associated with airway oxidative stress while 24-h and weekly exposures were linked with airway inflammation.

Domestic airborne black carbon levels and 8-isoprostane in exhaled breath condensate among children in New York City

BACKGROUND

Exposure to airborne black carbon (BC) has been associated with asthma development, respiratory symptoms and decrements in lung function. However, the mechanism through which BC may lead to respiratory symptoms has not been completely elucidated. Oxidative stress has been suggested as a potential mechanism through which BC might lead to adverse health outcomes. Exhaled breath condensate (EBC) allows for the non-invasive collection of airway lining fluid containing biomarkers of oxidative stress like 8-isoprostane, a stable by-product of lipid peroxidation. Therefore, we sought to characterize the association between domestic airborne BC concentrations and 8-isoprostane in EBC.

MATERIALS AND METHODS

Seven- and eight-year-old children participated in an asthma case-control study in New York City. During home visits, air samples and EBC were collected. Seven day averages of domestic levels of particulate matter <2.5μm (PM2.5), BC and environmental tobacco smoke (ETS) were measured. Urea and 8-isoprostane were measured by liquid chromatography tandem mass spectrometry (LC/MS/MS) in EBC.

RESULTS

In univariate models, PM2.5 and BC, but not ETS, were significantly associated with increases in 8-isoprostane in the EBC (β=0.006 and β=0.106 respectively, p<0.05 for both). These associations remained statistically significant for both PM2.5 and BC after adjustment for covariates. In a co-pollutant model including PM2.5, BC and ETS, only BC remained a statistically significant predictor of 8-isoprostane (p<0.05).

CONCLUSIONS

Our findings suggest the BC fraction of PM might contain exposure relevant to increased oxidative stress in the airways.

Obstructive airway disease in urban populations

PURPOSE OF REVIEW

Obstructive lung disease (OLD), including asthma and chronic obstructive pulmonary disease, has a more substantial prevalence and morbidity in urban populations. This review highlights recent publications examining the epidemiology, risk factors and interventions concerning OLD in urban populations.

RECENT FINDINGS

Using a variety of approaches, estimates of asthma prevalence in urban populations range from 5 to 25%. Early life exposures including in-utero cigarette smoke, postnatal bisphenol A, home and school particulates, and environmental air pollution contribute to increased OLD prevalence and symptom manifestations. Individuals with increased exposure to traffic-related pollution demonstrate abnormal inflammatory and lung function profiles. Obesity, more common in urban populations, is likely both a risk factor for asthma as well as contributor to poor control. Interventions targeted at home-based education and assessments are efficacious and cost-effective in improving outcomes of OLD in urban settings.

SUMMARY

The burden of OLD in urban populations is driven by maternal, environmental and acquired factors. There are few recent data regarding risk factors and interventions for urban cohorts with chronic obstructive pulmonary disease. The complex interplay of race, socioeconomic status, environmental exposures and healthcare access in the urban population requires continued research efforts.

Acute effects of summer air pollution on pulmonary function and airway inflammation in healthy young women

Background

Exposure to air pollution has been reported to be associated with asthma exacerbation. However, little is known about the effects of air pollutant exposure in healthy people. A panel study was conducted to evaluate the acute effects of air pollutants on pulmonary function and airway inflammation in healthy subjects.

Methods

Exhaled breath condensate (EBC) pH, fractional concentration of exhaled nitric oxide (FeNO), and pulmonary function were measured in 21 healthy young women repeatedly for two weeks in the summer in Tokyo, Japan. The concentrations of air pollutants were obtained from the monitoring stations in the neighborhoods where the subjects lived. Statistical analyses were performed using generalized estimating equations.

Results

EBC pH decreased significantly with a 10-ppb increase in the 4-day average ozone (O₃) concentration and a 10-µg/m³ increase in the 4-day average suspended particulate matter (SPM) concentration (−0.07 [95% confidence interval {CI} −0.11 to −0.03] and −0.08 [95% CI −0.12 to −0.03], respectively). Subjects with a history of rhinitis showed marked decreases in EBC pH associated with increases in O₃ and SPM. The changes in forced expiratory volume in 1 second (FEV₁) were also significantly associated with a 10-µg/m³ increase in the 3-day average concentration of SPM (−0.09 L [95% CI −0.17 to −0.01]). FeNO increased significantly in relation to the increase in O₃ and SPM among only subjects with a history of asthma.

Conclusions

Over the course of the study, EBC became significantly acidic with increases in O₃ and SPM concentrations. Furthermore, higher SPM concentrations were associated with decreased FEV₁. Subjects with a history of rhinitis or asthma are considered to be more susceptible to air pollutants.

Towards the determination of isoprene in human breath using substrate-integrated hollow waveguide mid-infrared sensors

Selected volatile organic compounds (VOCs) in breath may be considered biomarkers if they are indicative of distinct diseases or disease states. Given the inherent molecular selectivity of vibrational spectroscopy, infrared sensing technologies appear ideally suitable for the determination of endogenous VOCs in breath. The aim of this study was to determine that mid-infrared (MIR; 3-20 µm) gas phase sensing is capable of determining isoprene in exhaled breath as an exemplary medically relevant VOC by hyphenating novel substrate-integrated hollow waveguides (iHWG) with a likewise miniaturized preconcentration system. A compact preconcentrator column for sampling isoprene from exhaled breath was coupled to an iHWG serving simultaneously as highly miniaturized gas cell and light conduit in combination with a compact Fourier transform infrared spectrometer. A gas mixing system enabled extensive system calibration using isoprene standards. After system optimization, a calibration function obtaining a limit of quantification of 106 ppb was achieved. According to the literature, the obtained sensitivity is sufficient for quantifying middle to high isoprene concentrations occurring in exhaled breath. Finally, a volunteer breath sample was analysed proving comparable values of isoprene in a real-world scenario. Despite its fundamental utility, the proposed methodology contains some limitations in terms of sensitivity and temporal resolution in comparison with the readily available measurement techniques that should be addressed during future optimization of the system. Nonetheless, this study presents the first determination of endogenous VOCs in breath via advanced hollow waveguide MIR sensor technology, clearly demonstrating its potential for the analysis of volatile biomarkers in exhaled breath.

Outdoor air pollution and asthma

Traffic and power generation are the main sources of urban air pollution. The idea that outdoor air pollution can cause exacerbations of pre-existing asthma is supported by an evidence base that has been accumulating for several decades, with several studies suggesting a contribution to new-onset asthma as well. In this Series paper, we discuss the effects of particulate matter (PM), gaseous pollutants (ozone, nitrogen dioxide, and sulphur dioxide), and mixed traffic-related air pollution. We focus on clinical studies, both epidemiological and experimental, published in the previous 5 years. From a mechanistic perspective, air pollutants probably cause oxidative injury to the airways, leading to inflammation, remodelling, and increased risk of sensitisation. Although several pollutants have been linked to new-onset asthma, the strength of the evidence is variable. We also discuss clinical implications, policy issues, and research gaps relevant to air pollution and asthma.

Lung function, airway inflammation, and polycyclic aromatic hydrocarbons exposure in mexican schoolchildren: a pilot study

OBJECTIVE

To determine the association of exposure to polycyclic aromatic hydrocarbons (PAHs) with lung function and pH of exhaled breath condensate (EBC) in Mexican schoolchildren.

METHODS

A pilot study was performed in a subsample of 64 schoolchildren from Mexico City. Lung function and pH of EBC were measured and metabolites of PAHs in urine samples were determined. The association was analyzed using robust regression models.

RESULTS

A 10% increase in the concentrations of 2-hydroxyfluorene was significantly negatively associated with forced expiratory volume in 1 second (-11.2 mL, 95% CI: -22.2 to -0.02), forced vital capacity (-11.6 mL, 95% CI: -22.9 to -0.2), and pH of EBC (-0.035, 95% CI: -0.066 to -0.005).

CONCLUSION

Biomarkers of PAHs exposure were inversely associated with lung function and decrease of ph of EBC as a marker of airway inflammation in Mexican schoolchildren.

Possible molecular mechanisms linking air pollution and asthma in children

BACKGROUND

Air pollution has many effects on the health of both adults and children, but children's vulnerability is unique. The aim of this review is to discuss the possible molecular mechanisms linking air pollution and asthma in children, also taking into account their genetic and epigenetic characteristics.

RESULTS

Air pollutants appear able to induce airway inflammation and increase asthma morbidity in children. A better definition of mechanisms related to pollution-induced airway inflammation in asthmatic children is needed in order to find new clinical and therapeutic strategies for preventing the exacerbation of asthma. Moreover, reducing pollution-induced oxidative stress and consequent lung injury could decrease children's susceptibility to air pollution. This would be extremely useful not only for the asthmatic children who seem to have a genetic susceptibility to oxidative stress, but also for the healthy population. In addition, epigenetics seems to have a role in the lung damage induced by air pollution. Finally, a number of epidemiological studies have demonstrated that exposure to common air pollutants plays a role in the susceptibility to, and severity of respiratory infections.

CONCLUSIONS

Air pollution has many negative effects on pediatric health and it is recognised as a serious health hazard. There seems to be an association of air pollution with an increased risk of asthma exacerbations and acute respiratory infections. However, further studies are needed in order to clarify the specific mechanism of action of different air pollutants, identify genetic polymorphisms that modify airway responses to pollution, and investigate the effectiveness of new preventive and/or therapeutic approaches for subjects with low antioxidant enzyme levels. Moreover, as that epigenetic changes are inheritable during cell division and may be transmitted to subsequent generations, it is very important to clarify the role of epigenetics in the relationship between air pollution and lung disease in asthmatic and healthy children.

A curated review of recent literature of biomarkers used for assessing air pollution exposures and effects in humans

This is a cross-sectional review of biomarkers used in air pollution research from January 2009 through December 2012. After an initial keyword search in PubMed retrieving 426 articles, a comprehensive abstract review identified 54 articles of experimental design that used biomarkers of exposure or effect in human studies in the area of air pollution research during this specified time period. A thorough bibliographic search of the included articles retrieved an additional 65 articles meeting the inclusion criteria. This review presents these 119 studies and the 234 biomarkers employed in these air pollution research investigations. Data presented are 70 biomarkers of exposure with 54% relating to polycyclic aromatic hydrocarbons, 36% volatile organic carbons, and 10% classified as other. Of the 164 biomarkers of effect, 91 and 130 were used in investigating effects of short-term and chronic exposure, respectively. Results of biomarkers used in short-term exposure describe different lag times and pollutant components such as primary and secondary pollutants, and particle number associated with corresponding physiological mechanisms including airway inflammation, neuroinflammation, ocular, metabolic, early endothelial dysfunction, coagulation, atherosclerosis, autonomic nervous system, oxidative stress, and DNA damage. The review presents three different exposure scenarios of chronic, occupational, and extreme exposure scenarios (indoor cooking) with associated biomarker findings presented in three broad categories of (1) immune profile, (2) oxidative stress, and (3) DNA damage. This review offers a representation of the scope of data being explored by air pollution researchers through the use of biomarkers and has deliberately been restricted to this particular subject rather than an extensive or in-depth review. This article provides a contextualization of air pollution studies conducted with biomarkers in human subjects in given areas while also integrating this complex body of information to offer a useful review for investigators in this field of study.

Commentary from the Editorial Board to Vitiligo: interplay between oxidative stress and immune system (Laddha et al.)

Vitiligo pathogenesis is very puzzling, and novel mechanisms possibly involved in the development of this disorder are frequently explored. Recently, some authors proposed an interplay between oxidative stress and immune system at the basis of melanocyte loss. According to the experimental evidence, they suggest that exposition to environmental agents might lead to an association between vitiligo and other autoimmune diseases. Accordingly, it is proposed that increased reactive oxygen species due to environmental agents could induce a modification of both melanocytic structures and other tissue proteins, or might disregulate the immune system, influencing the appearance of vitiligo and autoimmune comorbidities.