Respiratory effects of exposure to diesel traffic in persons with asthma

Environmental pollution: a tangible risk for NAFLD pathogenesis

The liver is crucial for human life, and the health of this organ often mirrors the health of the individual. The liver can be the target of several diseases, the most prevalent of which, as a consequence of development and changes in human lifestyles, is the nonalcoholic fatty liver disease (NAFLD). NAFLD is a multifactorial disease that embraces many histo-pathologic conditions and is highly linked to metabolic derangements. Technological progress and industrialization have also had the consequence of releasing pollutants in the environment, for instance pesticides or solvents, as well as by-products of discharge, such as the particulate matter. In the last decade, a growing body of evidence has emerged, shedding light on the potential impact of environmental pollutants on liver health and, in particular, on NAFLD occurrence. These contaminants have a great steatogenic potential and need to be considered as tangible NAFLD risk factors. There is an urgent need for a deeper comprehension of their molecular mechanisms of action, as well as for new lines of intervention to reduce their worldwide diffusion. This review wishes to sensitize the community to the effects of several environmental pollutants on liver health.

The impact of an anti-idling campaign on outdoor air quality at four urban schools

Idling school buses may increase concentrations of air pollutants including fine particulate matter (PM2.5) and elemental carbon (EC) near schools. Efforts to reduce vehicle idling near schools have rarely included air sampling to objectively assess changes in concentrations of air pollutants. The objective was to determine the impact of an anti-idling campaign on outdoor air quality at four schools with varying exposure to bus and automobile traffic. Outdoor air sampling for PM2.5, EC and particle number concentration (PNC) was conducted at four schools for five days before and after an anti-idling campaign. Sampling began before the morning arrival of buses and concluded after their afternoon departure. Sampling was simultaneously conducted at four corresponding community sites. Differences in PM2.5, EC, and PNC measured at school and community sites for each sampling day were calculated before and after the campaign. Before the campaign, the average outdoor concentration of PM2.5 during the school day at three of the four schools exceeded community background levels and the difference was greatest (4.11 μg m(-3), p < 0.01) at the school with the most buses (n = 39). The largest difference in EC between school and community sites was also observed at the school with the greatest number of buses (0.40 μg m(-3), p < 0.01). Following the anti-idling campaign, the average difference in PM2.5 at the school with the most buses decreased from 4.11 μg m(-3) to 0.99 μg m(-3) (p < 0.05). Similarly, at this school, the difference in the EC level decreased from 0.40 μg m(-3) to 0.15 μg m(-3) and PNC decreased from 11,560 to 1690 particles per cm(3) (p < 0.05). The outdoor concentrations of pollutants at schools with fewer buses (n = 5-11) were not significantly reduced. The concentration of air pollutants near schools may significantly exceed community background levels, particularly in the presence of idling school buses. Anti-idling campaigns are effective in reducing PM2.5, EC and PNC at schools with significant amounts of buses and passenger cars.

Chronic traffic pollution exposure is associated with eosinophilic, but not neutrophilic inflammation in older adult asthmatics

OBJECTIVE

Airway inflammatory patterns in older asthmatics are poorly understood despite high asthma-related morbidity and mortality. In this study, we sought to define the relationship between exposure to traffic pollutants, biomarkers in induced sputum, and asthma control in older adults.

METHODS

Induced sputum was collected from 35 non-smoking adults ≥65 years with a physician's diagnosis of asthma and reversibility with a bronchodilator or a positive methacholine challenge. Patients completed the Asthma Control Questionnaire (ACQ), and Elemental Carbon Attributable to Traffic (ECAT), a surrogate for chronic diesel particulate exposure, was determined. Equal numbers of subjects with high (≥0.39 µg/m(3)) versus low (<0.39 µg/m(3)) ECAT were included. Differential cell counts were performed on induced sputum, and myeloperoxidase (MPO) and eosinophil peroxidase (EPO) were measured in supernatants. Regression analyses were used to evaluate the relationship between sputum findings, ACQ scores, and ECAT.

RESULTS

After adjustment for potential confounders, subjects with poorly controlled asthma based on ACQ ≥ 1.5 (n = 7) had significantly higher sputum eosinophils (median = 4.4%) than those with ACQ < 1.5 (n = 28; eosinophils = 2.6%; β = 10.1 [95% CI = 0.1-21.0]; p = 0.05). Subjects with ACQ ≥ 1.5 also had significantly higher sputum neutrophils (84.2% versus 65.2%; β = 7.1 [0.2-14.6]; p = 0.05). Poorly controlled asthma was associated with higher sputum EPO (β = 2.4 [0.2-4.5], p = 0.04), but not MPO (p = 0.9). High ECAT was associated with higher eosinophils (β = 10.1 [1.8-18.4], p = 0.02) but not higher neutrophils (p = 0.6).

CONCLUSIONS

Poorly controlled asthma in older adults is associated with eosinophilic and neutrophilic inflammation. Chronic residential traffic pollution exposure may be associated with eosinophilic, but not neutrophilic inflammation in older asthmatics.

Diesel exhaust particle induction of IL-17A contributes to severe asthma

BACKGROUND

IL-17A has been implicated in severe forms of asthma. However, the factors that promote IL-17A production during the pathogenesis of severe asthma remain undefined. Diesel exhaust particles (DEPs) are a major component of traffic-related air pollution and are implicated in asthma pathogenesis and exacerbation.

OBJECTIVE

We sought to determine the mechanism by which DEP exposure affects asthma severity using human and mouse studies.

METHODS

BALB/c mice were challenged with DEPs with or without house dust mite (HDM) extract. Airway inflammation and function, bronchoalveolar lavage fluid cytokine levels, and flow cytometry of lung T cells were assessed. The effect of DEP exposure on the frequency of asthma symptoms and serum cytokine levels was determined in children with allergic asthma.

RESULTS

In mice exposure to DEPs alone did not induce asthma. DEP and HDM coexposure markedly enhanced airway hyperresponsiveness compared with HDM exposure alone and generated a mixed T(H)2 and T(H)17 response, including IL-13(+)IL-17A(+) double-producing T cells. IL-17A neutralization prevented DEP-induced exacerbation of airway hyperresponsiveness. Among 235 high DEP-exposed children with allergic asthma, 32.2% had more frequent asthma symptoms over a 12-month period compared with only 14.2% in the low DEP-exposed group (P = .002). Additionally, high DEP-exposed children with allergic asthma had nearly 6 times higher serum IL-17A levels compared with low DEP-exposed children.

CONCLUSIONS

Expansion of T(H)17 cells contributes to DEP-mediated exacerbation of allergic asthma. Neutralization of IL-17A might be a useful potential therapeutic strategy to counteract the asthma-promoting effects of traffic-related air pollution, especially in highly exposed patients with severe allergic asthma.

Chemical constituents of fine particulate air pollution and pulmonary function in healthy adults: the Healthy Volunteer Natural Relocation study

The study examined the associations of 32 chemical constituents of particulate matter with an aerodynamic diameter ≤2.5 μm (PM₂.₅) with pulmonary function in a panel of 21 college students. Study subjects relocated from a suburban area to an urban area with changing ambient air pollution levels and contents in Beijing, China, and provided daily morning/evening peak expiratory flow (PEF) and forced expiratory volume in 1s (FEV₂₁) measurements over 6 months in three study periods. There were significant reductions in evening PEF and morning/evening FEV₂₁ associated with various air pollutants and PM₂.₅ constituents. Four PM₂.₅ constituents (copper, cadmium, arsenic and stannum) were found to be most consistently associated with the reductions in these pulmonary function measures. These findings provide clues for the respiratory effects of specific particulate chemical constituents in the context of urban air pollution.

Environment and asthma in adults

The present review addresses recent advances and especially challenging aspects regarding the role of environmental risk factors in adult-onset asthma, for which the causes are poorly established. In the first part of the review, we discuss aspects regarding some environmental risk factors for adult-onset asthma: air pollution, occupational exposures with a focus on an emerging risk represented by exposure to cleaning agents (both at home and in the workplace), and lifestyle and nutrition. The second part is focused on perspectives and challenges, regarding relevant topics on which research is needed to improve the understanding of the role of environmental factors in asthma. Aspects of exposure assessment, the complexity of multiple exposures, the interrelationships of the environment with behavioral characteristics and the importance of studying biological markers and gene-environment interactions to identify the role of the environment in asthma are discussed. We conclude that environmental and lifestyle exposures play an important role in asthma or related phenotypes. The changes in lifestyle and the environment in recent decades have modified the specific risk factors in asthma even for well-recognized risks such as occupational exposures. To better understand the role of the environment in asthma, the use of objective (quantitative measurement of exposures) or modern tools (bar code, GPS) and the development of multidisciplinary collaboration would be very promising. A better understanding of the complex interrelationships between socio-economic, nutritional, lifestyle and environmental conditions might help to study their joint and independent roles in asthma.

Airway inflammation and oxidative potential of air pollutant particles in a pediatric asthma panel

Airborne particulate matter (PM) components from fossil fuel combustion can induce oxidative stress initiated by reactive oxygen species (ROS). Reported associations between worsening asthma and PM2.5 mass could be related to PM oxidative potential to induce airway oxidative stress and inflammation (hallmarks of asthma pathology). We followed 45 schoolchildren with persistent asthma in their southern California homes daily over 10 days with offline fractional exhaled nitric oxide (FENO), a biomarker of airway inflammation. Ambient exposures included daily average PM2.5, PM2.5 elemental and organic carbon (EC, OC), NO2, O3, and endotoxin. We assessed PM2.5 oxidative potential using both an abiotic and an in vitro bioassay on aqueous extracts of daily particle filters: (1) dithiothreitol (DTT) assay (abiotic), representing chemically produced ROS; and (2) ROS generated intracellularly in a rat alveolar macrophage model using the fluorescent probe 2'7'-dicholorohidroflourescin diacetate. We analyzed relations of FENO to air pollutants in mixed linear regression models. FENO was significantly positively associated with lag 1-day and 2-day averages of traffic-related markers (EC, OC, and NO2), DTT and macrophage ROS, but not PM2.5 mass. DTT associations were nearly twice as strong as other exposures per interquartile range: median FENO increased 8.7-9.9% per 0.43 nmole/min/m(3) DTT. Findings suggest that future research in oxidative stress-related illnesses such as asthma and PM exposure would benefit from assessments of PM oxidative potential and composition.

Impact of geocoding methods on associations between long-term exposure to urban air pollution and lung function

BACKGROUND

Errors in address geocodes may affect estimates of the effects of air pollution on health.

OBJECTIVE

We investigated the impact of four geocoding techniques on the association between urban air pollution estimated with a fine-scale (10 m × 10 m) dispersion model and lung function in adults.

METHODS

We measured forced expiratory volume in 1 sec (FEV1) and forced vital capacity (FVC) in 354 adult residents of Grenoble, France, who were participants in two well-characterized studies, the Epidemiological Study on the Genetics and Environment on Asthma (EGEA) and the European Community Respiratory Health Survey (ECRHS). Home addresses were geocoded using individual building matching as the reference approach and three spatial interpolation approaches. We used a dispersion model to estimate mean PM10 and nitrogen dioxide concentrations at each participant's address during the 12 months preceding their lung function measurements. Associations between exposures and lung function parameters were adjusted for individual confounders and same-day exposure to air pollutants. The geocoding techniques were compared with regard to geographical distances between coordinates, exposure estimates, and associations between the estimated exposures and health effects.

RESULTS

Median distances between coordinates estimated using the building matching and the three interpolation techniques were 26.4, 27.9, and 35.6 m. Compared with exposure estimates based on building matching, PM10 concentrations based on the three interpolation techniques tended to be overestimated. When building matching was used to estimate exposures, a one-interquartile range increase in PM10 (3.0 μg/m3) was associated with a 3.72-point decrease in FVC% predicted (95% CI: -0.56, -6.88) and a 3.86-point decrease in FEV1% predicted (95% CI: -0.14, -3.24). The magnitude of associations decreased when other geocoding approaches were used [e.g., for FVC% predicted -2.81 (95% CI: -0.26, -5.35) using NavTEQ, or 2.08 (95% CI -4.63, 0.47, p = 0.11) using Google Maps].

CONCLUSIONS

Our findings suggest that the choice of geocoding technique may influence estimated health effects when air pollution exposures are estimated using a fine-scale exposure model.

Airway inflammatory responses to diesel exhaust in allergic rhinitics

CONTEXT

Proximity to traffic, particularly to diesel-powered vehicles, has been associated with inducing and enhancing allergies. To investigate the basis for this association, we performed controlled exposures of allergic rhinitics to diesel exhaust (DE) at a dose known to be pro-inflammatory in healthy individuals.

OBJECTIVE

We hypothesized that diesel-exhaust exposure would augment lower airway inflammation in allergic rhinitics.

MATERIALS AND METHODS

Fourteen allergic rhinitics were exposed in a double-blinded, randomized trial to DE (100 μg/m³ PM₁₀) and filtered air for 2 h on separate occasions. Bronchoscopy with endobronchial mucosal biopsies and airway lavage was performed 18 h post-exposure, and inflammatory markers were assessed.

RESULTS

No evidence of neutrophilic airway inflammation was observed post-diesel, however, a small increase in myeloperoxidase was found in bronchoalveolar lavage (p = 0.032). We found no increases in allergic inflammatory cells. Reduced mast cell immunoreactivity for tryptase was observed in the epithelium (p = 0.013) parallel to a small decrease in bronchial wash stem cell factor (p = 0.033).

DISCUSSION AND CONCLUSION

DE, at a dose previously shown to cause neutrophilic inflammation in healthy individuals, induced no neutrophilic inflammation in the lower airways of allergic rhinitics, consistent with previous reports in asthmatics. Although there was no increase in allergic inflammatory cell numbers, the reduction in tryptase in the epithelium may indicate mast cell degranulation. However, this occurred in the absence of allergic symptoms. These data do not provide a simplistic explanation of the sensitivity in rhinitics to traffic-related air pollution. The role of mast cells requires further investigation.

Advancing the application of omics-based biomarkers in environmental epidemiology

The use of omics represents a shift in approach for environmental epidemiology and exposure science. In this article, the aspects of the use of omics that will require further development in the near future are discussed, including (a) the underlying causal interpretation and models; (b) the "meet-in-the-middle" concept, with examples; (c) the role of "calibration" of measurements; and (d) the role of life-course epidemiology and the related development of adequate biostatistical models.

Allergic diseases and air pollution

The prevalence of allergic diseases has been increasing rapidly, especially in developing countries. Various adverse health outcomes such as allergic disease can be attributed to rapidly increasing air pollution levels. Rapid urbanization and increased energy consumption worldwide have exposed the human body to not only increased quantities of ambient air pollution, but also a greater variety of pollutants. Many studies clearly demonstrate that air pollutants potently trigger asthma exacerbation. Evidence that transportation-related pollutants contribute to the development of allergies is also emerging. Moreover, exposure to particulate matter, ozone, and nitrogen dioxide contributes to the increased susceptibility to respiratory infections. This article focuses on the current understanding of the detrimental effects of air pollutants on allergic disease including exacerbation to the development of asthma, allergic rhinitis, and eczema as well as epigenetic regulation.

Impact of air pollution on cystic fibrosis pulmonary exacerbations: a case-crossover analysis

BACKGROUND

Pulmonary exacerbations in cystic fibrosis (CF) contribute to the burden of disease, with a negative impact on quality of life, costs, and lung function. Our aim was to evaluate whether exacerbations, defi ned by antibiotic use, were triggered by daily fl uctuations in air pollution.

METHODS

In a case-crossover analysis, we evaluated 215 patients with CF and pollution data from January 1, 1998, to December 31, 2010. Exacerbation was defi ned as the start of IV or oral antibiotic use in a home or hospital setting. We calculated regional background levels of particulate matter with a diameter , 10 m m (PM 10 ), ozone, and nitrogen dioxide (NO 2 ) on the day of the event and on the 2 days prior to the event at each patient’s home address. We matched for day of the week and controlled for temperature on the day of the event and the 2 preceding days. In the month where antibiotic treatment was started, all days with the same temperature ( 2°C) as the event day served as control days, excluding 3 days before and after the start of treatment.

RESULTS

A total of 215 patients (male sex, 49%, mean age, 21 13 years) had 2,204 antibiotic treatments (1,107 IV and 1,097 oral). Over a period of 12 years, an increase in risk of antibiotic use was associated with increasing concentrations of PM 10 , NO 2 , and ozone on the event day and for NO 2 on the day before. A tendency toward signifi cance was seen the day before antibiotic use for PM 10 and ozone. Overall, a rise in OR was seen from 2 days before until the day of the start of antibiotics.

CONCLUSIONS

In patients with CF and exacerbations, ambient concentrations of ozone, PM 10 , and NO 2 play a role in triggering an exacerbation.

Regulation of particulate matter-induced mucin secretion by transient receptor potential vanilloid 1 receptors

Exposure to airborne particulate matter (PM) is a worldwide health problem. Previous studies have reported that PMs induced depolarizing currents and increased intracellular Ca(2+) in human bronchial epithelial cells. Ca(2+) plays important role in the regulation of mucus exocytosis, and mucin hypersecretion is a key pathological feature of inflammatory respiratory diseases. To explore more mechanisms underlying PM toxicity, we measured PM-induced mucin secretion in human bronchial epithelial (16HBE) cells. MUC5AC secretion and cyclic adenosine monophosphate (cAMP) level were detected by ELISA. Transient receptor potential vanilloid (TRPV)1 inward currents were examined by electrophysiology. Ca(2+) concentration was assessed by laser scanning confocal microscope. Exposure of PMs to 16HBE cells was found to induce mucin secretion, as a consequence of sustained Ca(2+) influx and cAMP increase through TRPV1 receptors. Mucin secretion was completely inhibited by TRPV1 receptor antagonist capsazepine. Removal of Ca(2+) by Ca(2+) chelator BAPTA or inhibition of protein kinase A (PKA) by the PKA inhibitors H-89 each partially reduced PC(2)s-induced mucin secretion. The combination of BAPTA and H-89 completely prevented mucin secretion mediated by PMs. These results suggest that PM induces mucin secretion through Ca(2+) influx and cAMP/PKA pathway by TRPV1 receptors in human bronchial epithelial cells, thereby providing a potential mechanism to reduce PM toxicity.

Ambient air quality and asthma cases in Niğde, Turkey

Urban air quality is one of the key factors affecting human health. Turkey has transformed itself into an urban society over the last 30 years. At the same time, air pollution has become a serious impairment to health in many urban areas in the country. This is due to many reasons. In this study, a nonparametric evaluation was conducted of health effects that are triggered by urban air pollution. Niğde, the city which is the administrative centre of Nigde province was chosen of the effects of air pollution since, like many central Turkish cities, it is situated on a valley where atmospheric inversion occurs. In this paper, the relationship between ambient urban air quality, namely PM10 and sulphur dioxide (SO2), and human health, specifically asthma, during the winter season is examined. Air pollution data and asthma cases from 2006 to 2010 are covered in this study. The results of our study indicate that total asthma cases reported in Nigde between 2008 and 2010 were highly dependent on ambient SO2 concentration. More asthma cases were recorded when 30 μg m(-3) or higher SO2 was present in the ambient air than those recorded under cleaner ambient air conditions. Moreover, it was determined that in Nigde in 2010, asthma cases reported in males aged between 45 and 64 were closely correlated with ambient SO2 (α=0.05).

MicroRNA expression in response to controlled exposure to diesel exhaust: attenuation by the antioxidant N-acetylcysteine in a randomized crossover study

BACKGROUND

Adverse health effects associated with diesel exhaust (DE) are thought to be mediated in part by oxidative stress, but the detailed mechanisms are largely unknown. MicroRNAs (miRNAs) regulate gene expression post-transcriptionally and may respond to exposures such as DE.

OBJECTIVES

We profiled peripheral blood cellular miRNAs in participants with mild asthma who were exposed to controlled DE with and without antioxidant supplementation.

METHODS

Thirteen participants with asthma underwent controlled inhalation of filtered air and DE in a double-blinded, randomized crossover study of three conditions: a) DE plus placebo (DEP), b) filtered air plus placebo (FAP), or c) DE with N-acetylcysteine supplementation (DEN). Total cellular RNA was extracted from blood drawn before exposure and 6 hr after exposure for miRNA profiling by the NanoString nCounter assay. MiRNAs significantly associated with DEP exposure and a predicted target [nuclear factor (erythroid-derived 2)-like 2 (NRF2)] as well as antioxidant enzyme genes were assessed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) for validation, and we also assessed the ability of N-acetylcysteine supplementation to block the effect of DE on these specific miRNAs. 8-hydroxy-2'-deoxyguanosine (8-OHdG) was measured in plasma as a systemic oxidative stress marker.

RESULTS

Expression of miR-21, miR-30e, miR-215, and miR-144 was significantly associated with DEP. The change in miR-144 was validated by RT-qPCR. NRF2 and its downstream antioxidant genes [glutamate cysteine ligase catalytic subunit (GCLC) and NAD(P)H:quinone oxidoreductase 1 (NQO1)] were negatively associated with miR-144 levels. Increases in miR-144 and miR-21 were associated with plasma 8-hydroxydeoxyguanosine 8-OHdG level and were blunted by antioxidant (i.e, DEN).

CONCLUSIONS

Systemic miRNAs with plausible biological function are altered by acute moderate-dose DE exposure. Oxidative stress appears to mediate DE-associated changes in miR-144.

Monitoring intraurban spatial patterns of multiple combustion air pollutants in New York City: design and implementation

Routine air monitoring provides data to assess urban scale temporal variation in pollution concentrations in relation to regulatory standards, but is not well suited to characterizing intraurban spatial variation in pollutant concentrations from local sources. To address these limitations and inform local control strategies, New York City developed a program to track spatial patterns of multiple air pollutants in each season of the year. Monitor locations include 150 distributed street-level sites chosen to represent a range of traffic, land-use and other characteristics. Integrated samples are collected at each distributed site for one 2-week session each season and in every 2-week period at five reference locations to track city-wide temporal variation. Pollutants sampled include PM(2.5) and constituents, nitrogen oxides, black carbon, ozone (summer only) and sulfur dioxide (winter only). During the first full year of monitoring more than 95% of designed samples were completed. Agreement between colocated samples was good (absolute mean % difference 3.2-8.9%). Street-level pollutant concentrations spanned a much greater range than did concentrations at regulatory monitors, especially for oxides of nitrogen and sulfur dioxide. Monitoring to characterize intraurban spatial gradients in ambient pollution usefully complements regulatory monitoring data to inform local air quality management.

Controlled exposure to diesel exhaust causes increased nitrite in exhaled breath condensate among subjects with asthma

OBJECTIVE

To determine whether oxidative/nitrosative stress plays a role in the acute effects of diesel exhaust (DE) on subjects with asthma.

METHODS

In this crossover study, 16 subjects with mild to moderate asthma were exposed to clean filtered air or diluted DE (300 μg/m as PM2.5) for 1 hour with intermittent exercise.

RESULTS

Airway hyperreactivity increased 24 hours after exposure to DE compared with clean filtered air (PC20, 14.9 mg/mL vs 19.7 mg/mL; P = 0.012). Nitrite in exhaled breath condensate was elevated immediately after diesel exposure (P = 0.052) and remained elevated 4 and 24 hours after exposure.

CONCLUSIONS

After exposure to DE, subjects with asthma demonstrated increased airway hyperreactivity and obstruction. Increased nitrite in exhaled breath condensate, in the absence of increased exhaled nitric oxide, suggests a noninflammatory oxidative stress mechanism by which DE affects the lung.

Small things make a big difference: particulate matter and exercise

The increased risk of morbidity and mortality among adults and children with pre-existing cardiovascular or respiratory illness from emission-derived particulate matter (PM) is well documented. However, the detrimental effects of PM inhalation on the exercising, healthy population is still in question. This review will focus on the acute and chronic responses to PM inhalation during exercise and how PM exposure influences exercise performance. The smaller ultrafine PM (<0.01 μm aerodynamic diameter) appears to have the most severe health consequences compared with the larger coarse PM (2.5 < PM <10 μm aerodynamic diameter). While the response to PM inhalation may affect those with a pre-existing condition, the healthy population is not immune to the effects of PM inhalation, especially during exercise. This population, including the competitive athlete, is susceptible to pulmonary inflammation, decreased lung function (both acute and chronic in nature), the increased risk of asthma, vascular endothelial dysfunction, mild elevations in pulmonary artery pressure and diminished exercise performance. PM exposure is usually associated with vehicular traffic, but other sources of PM, including small engines from lawn and garden equipment, cigarette smoke, wood smoke and cooking, may also impair health and performance. The physiological effects of PM are dependent on the source of PM, various environmental factors, physical attributes and nature of exercise. There are a number of measures an athlete can take to reduce exposure to PM, as well as the deleterious effects that result from the inevitable exposure to PM. Considering the acute and chronic physiological responses to PM inhalation, individuals living and exercising in urban areas in close proximity to major roadways should consider ambient air pollution levels (in particular, PM and ozone) prior to engaging in vigorous exercise, and those exposed to PM through other sources may need to make lifestyle alterations to avoid the deleterious effects of PM inhalation. Although it is clear that PM exposure is detrimental to healthy individuals engaging in exercise, further research is necessary to better understand the role of PM on athlete health and performance, as well as measures that can attenuate the harmful effects of PM.

Air quality and exercise-induced bronchoconstriction in elite athletes

A higher prevalence of airway hyperresponsiveness, airway remodeling, and asthma has been identified among athletes who compete and train in environmental conditions of cold dry air and/or high air pollution. Repeated long-duration exposure to cold/dry air at high minute ventilation rates can cause airway damage. Competition or training at venues close to busy roadways, or in indoor ice arenas or chlorinated swimming pools, harbors a risk for acute and chronic airway disorders from high pollutant exposure. This article discusses the effects of these harsh environments on the airways, and summarizes potential mechanisms and prevalence of airway disorders in elite athletes.

Respiratory health effects of ambient air pollution: an update

There is new evidence for ambient air pollution (AAP) leading to an increased incidence of respiratory diseases in adults. Research has demonstrated that co-exposures have the potential to dramatically augment the effects of AAP and lower the threshold of effect of a given pollutant. Interactions between genes related to oxidative stress and AAP seem to significantly alter the effect of AAP on an individual and population basis. A better definition of vulnerable populations may bolster local or regional efforts to remediate AAP. Advances in genetic research tools have the potential to identify candidate genes that can guide further research.

Effect of serum on diesel exhaust particles (DEP)-induced apoptosis of airway epithelial cells in vitro

Patients with chronic airway diseases may be more susceptible to adverse effects of air pollutants including diesel exhaust particles (DEP). We investigated effects of foetal calf serum (FCS) on DEP-induced changes in airway epithelial cell apoptosis and inflammation. DEP (50-200 μg/ml) increased A549 cell viability in the absence of FCS. In the presence of 3.3%FCS, DEP (50-400 μg/ml) decreased A549 cell viability. N-acetylcysteine (NAC, 33 mM) and the c-jun N-terminal kinase (JNK) inhibitor (SP600125, 33 μM) further decreased the viability in the presence of DEP (200 μg/ml) and 3.3% FCS. Under serum-free (SF) condition, DEP (50 μg/ml) reduced apoptotic cells; however, when 3.3% FCS added to the culture medium, this effect was abolished. DEP (200 μg/ml) induced mRNA expression of p21(CIP1/WAF1) both in absence or presence of 3.3% FCS and enhanced JNK2 mRNA expression only in the presence of 3.3% FCS. Under SF condition, DEP (50 μg/ml) induced mRNA expression for p27 and p53, whereas cyclin E mRNA expression was inhibited by DEP (50 and 200 μg/ml). Furthermore, DEP (200 μg/ml) decreased the release of interleukin (IL)-8 in the absence of FCS. In conclusion, FCS modulates effects of DEP on cell death, cell cycle and apoptosis regulating proteins, and IL-8 release by activating oxidant stress pathways, JNK and NF-κB. Extravasation of serum, as occurs in the inflamed airways of patients with chronic airway diseases such as asthma and COPD, may render airway epithelial cells more susceptible to the deleterious effects of DEP.

Truck traffic related air pollution associated with asthma symptoms in young boys: a cross-sectional study

OBJECTIVES

The aim of this study was to evaluate the influence of intensity of truck traffic on asthma symptomatology, and its relationship with age and gender.

STUDY DESIGN

A cross-sectional study was conducted on children and adolescents from Galicia (North-West Spain).

METHODS

Following the methodology of the International Study of Asthma and Allergies in Childhood (ISAAC): children from schools randomly selected, answered a self-administered questionnaire included questions on asthma symptoms and some risk factors. The association between self-reported truck traffic on the street of residence and symptoms of asthma were investigated by logistic regression adjusted for body mass index, maternal education and parental smoking.

RESULTS

Almost 40% of children in Galicia are exposed to the frequent and constant passing of heavy goods vehicles. The odds of 6-7 year-old boys having severe or exercise induced asthma is tripled when they live in streets with the constant passing of heavy goods vehicles, compared with those living in streets where these vehicles never pass. In adolescents and 6-7 year-old girls, no relationship was observed between truck traffic and asthma symptoms.

CONCLUSIONS

The results of this study appear to support a distinct effect of truck traffic on asthma symptoms depending on the age and sex of the exposed population, being more harmful for young males.

Cyclist route choice, traffic-related air pollution, and lung function: a scripted exposure study

BACKGROUND

A travel mode shift to active transportation such as bicycling would help reduce traffic volume and related air pollution emissions as well as promote increased physical activity level. Cyclists, however, are at risk for exposure to vehicle-related air pollutants due to their proximity to vehicle traffic and elevated respiratory rates. To promote safe bicycle commuting, the City of Berkeley, California, has designated a network of residential streets as "Bicycle Boulevards." We hypothesized that cyclist exposure to air pollution would be lower on these Bicycle Boulevards when compared to busier roads and this elevated exposure may result in reduced lung function.

METHODS

We recruited 15 healthy adults to cycle on two routes - a low-traffic Bicycle Boulevard route and a high-traffic route. Each participant cycled on the low-traffic route once and the high-traffic route once. We mounted pollutant monitors and a global positioning system (GPS) on the bicycles. The monitors were all synced to GPS time so pollutant measurements could be spatially plotted. We measured lung function using spirometry before and after each bike ride.

RESULTS

We found that fine and ultrafine particulate matter, carbon monoxide, and black carbon were all elevated on the high-traffic route compared to the low-traffic route. There were no corresponding changes in the lung function of healthy non-asthmatic study subjects. We also found that wind-speed affected pollution concentrations.

CONCLUSIONS

These results suggest that by selecting low-traffic Bicycle Boulevards instead of heavily trafficked roads, cyclists can reduce their exposure to vehicle-related air pollution. The lung function results indicate that elevated pollutant exposure may not have acute negative effects on healthy cyclists, but further research is necessary to determine long-term effects on a more diverse population. This study and broader field of research have the potential to encourage policy-makers and city planners to expand infrastructure to promote safe and healthy bicycle commuting.

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

Exposures to ambient diesel exhaust particles have been associated with respiratory symptoms and asthma exacerbations in children; however, epidemiologic evidence linking short-term exposure to ambient diesel exhaust particles with airway inflammation is limited. We conducted a panel study with asthmatic and nonasthmatic adolescents to characterize associations between ambient diesel exhaust particle exposures and exhaled biological markers of airway inflammation and oxidative stress. Over four weeks, exhaled breath condensate was collected twice a week from 18 asthmatics and 18 nonasthmatics (ages 14-19 years) attending two New York City schools and analyzed for pH and 8-isoprostane as indicators of airway inflammation and oxidative stress, respectively. Air concentrations of black carbon, a diesel exhaust particle indicator, were measured outside schools. Air measurements of nitrogen dioxide, ozone, and fine particulate matter were obtained for the closest central monitoring sites. Relationships between ambient pollutants and exhaled biomarkers were characterized using mixed effects models. Among all subjects, increases in 1- to 5-day averages of black carbon were associated with decreases in exhaled breath condensate pH, indicating increased airway inflammation, and increases in 8-isoprostane, indicating increased oxidative stress. Increases in 1- to 5-day averages of nitrogen dioxide were associated with increases in 8-isoprostane. Ozone and fine particulate matter were inconsistently associated with exhaled biomarkers. Associations did not differ between asthmatics and nonasthmatics. The findings indicate that short-term exposure to traffic-related air pollutants may increase airway inflammation and/or oxidative stress in urban youth and provide mechanistic support for associations documented between traffic-related pollutant exposures and respiratory morbidity.

Temporal variation of size-fractionated particulate matter and carbon monoxide in selected microenvironments of the Milan urban area

This article focuses on air pollution in specific urban microenvironments and conditions characterized by high relative concentration levels and by possible risk to human health. For this reason, monitoring of particle number concentration (PNC) with a wide, size-resolved particle-size range, and CO (an indicator of combustion sources, e.g., traffic), was performed in a variety of microenvironments. Concentrations of ultrafine particles (UFPs), size-fractionated particulate matter (PM), and carbon monoxide (CO) were measured in the central area of Milan over three-week-long periods, one each during summer, autumn, and winter, with three monitoring sessions per day. Experimental data were collected continuously during each monitoring period along an established urban pathway. To assess the relevance of time and spatial factors affecting atmospheric concentrations of UFPs, PM, and CO data were collected while walking or moving by different private and public means of transport. Measurements were divided on the basis of different microenvironments (MEs), seasons, days of the week, and periods of the day. Data analysis shows statistically significant differences across MEs and monitoring periods. The highest measured median concentrations and data variability were observed for busy streets, walking or moving by motorized vehicle (CO, UFP) and in metro trains (PM); the lowest concentrations were observed in park areas and in indoor environments. The highest concentrations were measured during working day morning monitoring sessions. Regarding seasonal variation, UFP, PM, and CO showed different patterns: the highest median concentrations were observed in summer for CO, and in autumn and winter for the UFP and PM. Appreciable differences among all MEs and monitoring periods were observed: concentration patterns and variations appear related to typical sources of urban pollutants (traffic), proximity to sources, and time of day. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a file containing Table VI: Tau b (Kendall) index for non-parametric correlation tau test.].

Effects of ambient fine particles on pulmonary function in children with mild atopic dermatitis

The effects of particulate pollutants on lung function in children with atopic dermatitis (AD) remain to be determined. The authors investigated the short-term effects of ambient particles on peak expiratory flow rate (PEFR) in 84 children with and without AD. Daily particulates less than 10, 2.5, and 1 μm (PM(10), PM(2.5), and PM(1)) and number concentrations of submicron particles were measured. The authors observed elevated levels of PM(10), PM(2.5), and PM(1), and accumulation-mode particles were associated with decreased PEFR in children with AD. The PEFR decrements were -2.89 L/min (95% confidence interval [CI], -4.93 to -0.89) for an interquartile-range increase of previous-day PM(10), -2.79 L/min (95% CI, -4.89 to -0.69) for PM(2.5), and -2.71 L/min (95% CI, -4.81 to -0.61) for PM(1). These results suggest that ambient fine particles may affect the pulmonary function in children with AD. The respiratory health of children with atopic skin disorders renders them more vulnerable to ambient particles than healthy subjects.

Diesel exhaust particle exposure in vitro alters monocyte differentiation and function

Air pollution by diesel exhaust particles is associated with elevated mortality and increased hospital admissions in individuals with respiratory diseases such as asthma and chronic obstructive pulmonary disease. During active inflammation monocytes are recruited to the airways and can replace resident alveolar macrophages. We therefore investigated whether chronic fourteen day exposure to low concentrations of diesel exhaust particles can alter the phenotype and function of monocytes from healthy individuals and those with chronic obstructive pulmonary disease. Monocytes were purified from the blood of healthy individuals and people with a diagnosis of chronic obstructive pulmonary disease. Monocyte-derived macrophages were generated in the presence or absence of diesel exhaust particles and their phenotypes studied through investigation of their lifespan, cytokine generation in response to Toll like receptor agonists and heat killed bacteria, and expression of surface markers. Chronic fourteen day exposure of monocyte-derived macrophages to concentrations of diesel exhaust particles >10 µg/ml caused mitochondrial and lysosomal dysfunction, and a gradual loss of cells over time both in healthy and chronic obstructive pulmonary disease individuals. Chronic exposure to lower concentrations of diesel exhaust particles impaired CXCL8 cytokine responses to lipopolysaccharide and heat killed E. coli, and this phenotype was associated with a reduction in CD14 and CD11b expression. Chronic diesel exhaust particle exposure may therefore alter both numbers and function of lung macrophages differentiating from locally recruited monocytes in the lungs of healthy people and patients with chronic obstructive pulmonary disease.

Effects of diesel exhaust particles on primary cultured healthy human conjunctival epithelium

BACKGROUND

Air pollution from road traffic is a serious public health problem. Epidemiologic studies have demonstrated adverse health effects associated with environmental pollution. Diesel exhaust is a major contributor to ambient particulate matter air pollution. We studied the effects of exposure to diesel exhaust particles on allergic conjunctivitis using cultured conjunctival epithelial cells obtained from healthy people.

OBJECTIVE

To identify the factors involved in the human conjunctival epithelial response to diesel exhaust in vitro.

METHODS

Healthy individuals underwent conjunctival biopsy, and the samples were incubated on conjunctival epithelial sheets. We investigated the effects of exposure to diesel exhaust using GeneChip arrays. The adhesion molecules and cytokines showing increased expression on GeneChip arrays were verified by real-time reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay.

RESULTS

The GeneChip array showed increased expression of adhesion molecules, cytokines, chemokines, and growth factors after exposure to diesel exhaust. Real-time reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay confirmed that the expression of intercellular adhesion molecule 1 and interleukin 6, in particular, were significantly upregulated.

CONCLUSION

Our experimental data confirm that exposure to diesel exhaust particles increases inflammatory factor expression in human conjunctiva and thereby contributes to allergic conjunctival responses.

Traffic-related fine and ultrafine particle exposures of professional drivers and illness: an opportunity to better link exposure science and epidemiology to address an occupational hazard?

Exposures to traffic-related air pollution (TRAP) can be particularly high in transport microenvironments (i.e. in and around vehicles) despite the short durations typically spent there. There is a mounting body of evidence that suggests that this is especially true for fine (<2.5 µm) and ultrafine (<100 nm, UF) particles. Professional drivers, who spend extended periods of time in transport microenvironments due to their job, may incur exposures markedly higher than already elevated non-occupational exposures. Numerous epidemiological studies have shown a raised incidence of adverse health outcomes among professional drivers, and exposure to TRAP has been suggested as one of the possible causal factors. Despite this, data describing the range and determinants of occupational exposures to fine and UF particles are largely conspicuous in their absence. Such information could strengthen attempts to define the aetiology of professional drivers' illnesses as it relates to traffic combustion-derived particles. In this article, we suggest that the drivers' occupational fine and UF particle exposures are an exemplar case where opportunities exist to better link exposure science and epidemiology in addressing questions of causality. The nature of the hazard is first introduced, followed by an overview of the health effects attributable to exposures typical of transport microenvironments. Basic determinants of exposure and reduction strategies are also described, and finally the state of knowledge is briefly summarised along with an outline of the main unanswered questions in the topic area.

Clearing the air: a review of the effects of particulate matter air pollution on human health

The World Health Organization estimates that particulate matter (PM) air pollution contributes to approximately 800,000 premature deaths each year, ranking it the 13th leading cause of mortality worldwide. However, many studies show that the relationship is deeper and far more complicated than originally thought. PM is a portion of air pollution that is made up of extremely small particles and liquid droplets containing acids, organic chemicals, metals, and soil or dust particles. PM is categorized by size and continues to be the fraction of air pollution that is most reliably associated with human disease. PM is thought to contribute to cardiovascular and cerebrovascular disease by the mechanisms of systemic inflammation, direct and indirect coagulation activation, and direct translocation into systemic circulation. The data demonstrating PM's effect on the cardiovascular system are strong. Populations subjected to long-term exposure to PM have a significantly higher cardiovascular incident and mortality rate. Short-term acute exposures subtly increase the rate of cardiovascular events within days of a pollution spike. The data are not as strong for PM's effects on cerebrovascular disease, though some data and similar mechanisms suggest a lesser result with smaller amplitude. Respiratory diseases are also exacerbated by exposure to PM. PM causes respiratory morbidity and mortality by creating oxidative stress and inflammation that leads to pulmonary anatomic and physiologic remodeling. The literature shows PM causes worsening respiratory symptoms, more frequent medication use, decreased lung function, recurrent health care utilization, and increased mortality. PM exposure has been shown to have a small but significant adverse effect on cardiovascular, respiratory, and to a lesser extent, cerebrovascular disease. These consistent results are shown by multiple studies with varying populations, protocols, and regions. The data demonstrate a dose-dependent relationship between PM and human disease, and that removal from a PM-rich environment decreases the prevalence of these diseases. While further study is needed to elucidate the effects of composition, chemistry, and the PM effect on susceptible populations, the preponderance of data shows that PM exposure causes a small but significant increase in human morbidity and mortality. Most sources agree on certain "common sense" recommendations, although there are lonely limited data to support them. Indoor PM exposure can be reduced by the usage of air conditioning and particulate filters, decreasing indoor combustion for heating and cooking, and smoking cessation. Susceptible populations, such as the elderly or asthmatics, may benefit from limiting their outdoor activity during peak traffic periods or poor air quality days. These simple changes may benefit individual patients in both short-term symptomatic control and long-term cardiovascular and respiratory complications.

Pharmacotherapy for exercise-induced asthma: allowing normal levels of activity and sport

Exercise-induced bronchoconstriction (EIB) is experienced by the majority of an estimated 300 million individuals who have asthma, a condition that affects all ages and is increasing globally. Respiratory water loss with dehydration of the airways causing mediator release and airway narrowing is considered the cause of EIB, the severity of which will be increased if the inhaled air is cold or polluted. Adequate control of asthma is essential to minimize or prevent EIB and permit normal levels of physical activity and sport. This is important because exercise is a necessary component of daily living, assists in obtaining and maintaining a healthy body and has been demonstrated to benefit asthmatics. Inhaled glucocorticosteroids and inhaled β(2)-adrenoceptor agonists (IβA) are the pharmacological agents of choice to manage asthma and minimize EIB, assisted when necessary, by other drugs including leukotriene receptor antagonists and chromones. Tolerance from daily use of IβA is of concern and more flexible drug therapy needs to be considered. Optimal use of inhalers to deliver drugs effectively requires closer attention. Pharmacogenetics may hold the key to future drug therapy.

Air pollution: impact and prevention

Air pollution is becoming a major health problem that affects millions of people worldwide. In support of this observation, the World Health Organization estimates that every year, 2.4 million people die because of the effects of air pollution on health. Mitigation strategies such as changes in diesel engine technology could result in fewer premature mortalities, as suggested by the US Environmental Protection Agency. This review: (i) discusses the impact of air pollution on respiratory disease; (ii) provides evidence that reducing air pollution may have a positive impact on the prevention of disease; and (iii) demonstrates the impact concerted polices may have on population health when governments take actions to reduce air pollution.

Environmental risk factors for persistent asthma in Lucknow

OBJECTIVE

To identify the risk factors for persistent asthma among common environmental exposures, like ambient air pollutants and second hand smoke, animals, place of residence, decreased ventilation, dust, as well as history of allergic conditions like rhinitis, dermatitis and family history of asthma in children.

METHODS

This hospital-based, cross-sectional study was conducted after institutional ethical clearance. Children aged 1-12 y with asthma were recruited after parental consent. Children were classified into asthma severity categories according to GINA 2002 and level of control categories according to GINA 2009 guidelines. Adjusted logistic regression analysis was used to identify factors associated with persistent asthma.

RESULTS

From August 2008 through October 2010, 205 asthmatic children were recruited of which 73 (35.60 %) had intermittent and 132 (64.40 %) had persistent asthma. Asthma was controlled in 19 (9.26 %), partly controlled in 90 (43.90 %) and uncontrolled in 96 (46.82 %). Patients with persistent asthma were more likely to have uncontrolled asthma (OR = 8.28; 95 % CI: 2.43-31.01; p < 0.001). Adjusting for age, sex, socioeconomic status and place of residence, persistent asthma was associated with residence within 1.5 km from heavy traffic (OR = 4.58; 95%CI: 2.18-9.59; p < 0.001) and father smoking indoors >5 cigarettes or "bidi"/day (OR = 17.76; 95 % CI: 1.85-170.76; p = 0.01).

CONCLUSIONS

Since patients with persistent asthma are more likely to have uncontrolled asthma and since persistent asthma is associated with residence closer to heavy traffic and exposure to second hand smoke, minimizing exposures to these may help in better asthma control.

Acute diesel exhaust particle exposure increases viral titre and inflammation associated with existing influenza infection, but does not exacerbate deficits in lung function

Please cite this paper as: Larcombe et al. (2012) Acute diesel exhaust particle exposure increases viral titre and inflammation associated with existing influenza infection, but does not exacerbate deficits in lung function. Influenza and Other Respiratory Viruses DOI:10.1111/irv.12012.

Background  Exposure to diesel exhaust particles (DEP) is thought to exacerbate many pre‐existing respiratory diseases, including asthma, bronchitis and chronic obstructive pulmonary disease, however, there is a paucity of data on whether DEP exacerbates illness due to respiratory viral infection.

Objectives  To assess the physiological consequences of an acute DEP exposure during the peak of influenza‐induced illness.

Methods  We exposed adult female BALB/c mice to 100 μg DEP (or control) 3·75 days after infection with 10^4·5 plaque forming units of influenza A/Mem71 (or control). Six hours, 24 hours and 7 days after DEP exposure we measured thoracic gas volume and lung function at functional residual capacity. Bronchoalveolar lavage fluid was taken for analyses of cellular inflammation and cytokines, and whole lungs were taken for measurement of viral titre.

Results  Influenza infection resulted in significantly increased inflammation, cytokine influx and impairment to lung function. DEP exposure alone resulted in less inflammation and cytokine influx, and no impairment to lung function. Mice infected with influenza and exposed to DEP had higher viral titres and neutrophilia compared with infected mice, yet they did not have more impaired lung mechanics than mice infected with influenza alone.

Conclusions  A single dose of DEP is not sufficient to physiologically exacerbate pre‐existing respiratory disease caused by influenza infection in mice.

Proximity to major roadways is a risk factor for airway hyper-responsiveness in adults

BACKGROUND

Proximity to major roads is reported to be associated with asthma and airway hyper-responsiveness in children. Similar studies using objective measurements in adults are not available in Canada.

OBJECTIVE

To test the hypothesis that adult asthmatic patients who live close to major roads and highways in an urban environment are at a risk of moderate to severe airway hyper-responsiveness.

METHODS

Airway responsiveness was determined using methacholine bronchial provocation (PC(20)) tests in a cohort of 2625 patients who attended an outpatient clinic in Hamilton, Ontario. Patient addresses were geocoded in a geographic information system to determine proximity to major roads and highways. Multivariate linear and multinomial regression analyses were used to assess whether proximity to roads was a risk factor for airway hyper-responsiveness as measured by PC(20) methacholine.

RESULTS

Patients who lived within 200 m of a major road had increased odds (OR 1.38 [95% CI 1.04 to 1.85]) of having moderate airway hyperresponsiveness (0.25 mg⁄mL <PC(20) <2.0 mg/mL) compared with having a normal response (PC(20) >16 mg/mL). Spatial analysis also revealed that the majority of patients with severe airway hyper-responsiveness lived within the urban core of the city while those with moderate to mild hyper-responsiveness were also dispersed in rural areas.

CONCLUSIONS

In an adult population of patients attending an outpatient respiratory clinic in Hamilton, living close to major roadways was associated with an increased risk of moderate airway hyper-responsiveness. This correlation suggests that exposure to traffic emissions may provoke the pathology of airway hyper-responsiveness leading to variable airflow obstruction.

Air pollution and asthma control in the Epidemiological study on the Genetics and Environment of Asthma

BACKGROUND

The associations between exposure to air pollution and asthma control are not well known. The objective of this study was to assess the association between long-term exposure to NO(2), O(3) and PM(10) and asthma control in the follow-up of the Epidemiological study on the Genetics and Environment of Asthma (EGEA2) (2003-2007).

METHODS

Modelled outdoor NO(2), O(3) and PM(10) estimates were linked to each residential address using the 4 km grid air pollutant surface developed by the French Institute of Environment in 2004. Asthma control was assessed in 481 subjects with current asthma using a multidimensional approach following the 2006-2009 Global Initiative for Asthma guidelines. Multinomial and ordinal logistic regressions were conducted adjusted for sex, age, body mass index, education, smoking and use of inhaled corticosteroids. The association between air pollution and the three domains of asthma control (symptoms, exacerbations and lung function) was assessed. ORs are reported per IQR.

RESULTS

Median concentrations (in micrograms per cubic metre) were 32 (IQR 25-38) for NO(2) (n=465), 46 (41-52) for O(3) and 21 (18-21) for PM(10) (n=481). In total, 44%, 29% and 27% had controlled, partly controlled and uncontrolled asthma, respectively. The ordinal ORs for O(3) and PM(10) with asthma control were 1.69 (95% CI 1.22 to 2.34) and 1.35 (95% CI 1.13 to 1.64), respectively. When including both pollutants in the same model, both associations persisted. Associations were not modified by sex, smoking status, use of inhaled corticosteroids, atopy, season of examination or body mass index. Both pollutants were associated with each of the three main domains of control.

CONCLUSIONS

The results suggest that long-term exposure to PM(10) and O(3) is associated with uncontrolled asthma in adults, defined by symptoms, exacerbations and lung function.

Examining the representativeness of home outdoor PM(2.5), EC, and OC estimates for daily personal exposures in Southern California

Recent studies have linked acute respiratory and cardiovascular outcomes to measurements or estimates of traffic-related air pollutants at homes or schools. However, few studies have evaluated these outdoor measurements and estimates against personal exposure measurements. We compared measured and modeled home outdoor concentrations with personal measurements of traffic-related air pollutants in the Los Angeles air basin (Whittier and Riverside). Personal exposure of 63 children with asthma and 15 homes were assessed for particulate matter with an aerodynamic diameter less than 2.5 μm (PM(2.5)), elemental carbon (EC), and organic carbon (OC) during sixteen 10-day monitoring runs. Regression models to predict daily home outdoor PM(2.5), EC, and OC were constructed using home outdoor measurements, geographical and meteorological parameters, as well as CALINE4 estimates at outdoor home sites, which represent the concentrations from local traffic sources. These home outdoor models showed the variance explained (R(2)) was 0.97 and 0.94 for PM(2.5), 0.91 and 0.83 for OC, and 0.76 and 0.87 for EC in Riverside and Whittier, respectively. The PM(2.5) outdoor estimates correlated well with the personal measurements (Riverside R(2) = 0.65 and Whittier R(2) = 0.69). However, excluding potentially inaccurate samples from Riverside, the correlation between personal exposure to carbonaceous species and home outdoor estimates in Whittier was moderate for EC (R(2) = 0.37) and poor for OC (R(2) = 0.08). The CALINE4 estimates alone were not correlated with personal measurements of EC or other pollutants. While home outdoor estimates provide good approximations for daily personal PM(2.5) exposure, they may not be adequate for estimating daily personal exposure to EC and OC. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11869-010-0099-y) contains supplementary material, which is available to authorized users.

Predicting Adult Pulmonary Ventilation Volume and Wearing Compliance by On-Board Accelerometry During Personal Level Exposure Assessments

BACKGROUND

Metabolic functions typically increase with human activity, but optimal methods to characterize activity levels for real-time predictions of ventilation volume (l/min) during exposure assessments have not been available. Could tiny, triaxial accelerometers be incorporated into personal level monitors to define periods of acceptable wearing compliance, and allow the exposures (μg/m3) to be extended to potential doses in μg/min/kg of body weight?

OBJECTIVES

In a pilot effort, we tested: 1) whether appropriately-processed accelerometer data could be utilized to predict compliance and in linear regressions to predict ventilation volumes in real time as an on-board component of personal level exposure sensor systems, and 2) whether locating the exposure monitors on the chest in the breathing zone, provided comparable accelerometric data to other locations more typically utilized (waist, thigh, wrist, etc.).

METHODS

Prototype exposure monitors from RTI International and Columbia University were worn on the chest by a pilot cohort of adults while conducting an array of scripted activities (all <10 METS), spanning common recumbent, sedentary, and ambulatory activity categories. Referee Wocket accelerometers that were placed at various body locations allowed comparison with the chest-located exposure sensor accelerometers. An Oxycon Mobile mask was used to measure oral-nasal ventilation volumes in-situ. For the subset of participants with complete data (n= 22), linear regressions were constructed (processed accelerometric variable versus ventilation rate) for each participant and exposure monitor type, and Pearson correlations computed to compare across scenarios.

RESULTS

Triaxial accelerometer data were demonstrated to be adequately sensitive indicators for predicting exposure monitor wearing compliance. Strong linear correlations (R values from 0.77 to 0.99) were observed for all participants for both exposure sensor accelerometer variables against ventilation volume for recumbent, sedentary, and ambulatory activities with MET values ~<6. The RTI monitors mean R value of 0.91 was slightly higher than the Columbia monitors mean of 0.86 due to utilizing a 20 Hz data rate instead of a slower 1 Hz rate. A nominal mean regression slope was computed for the RTI system across participants and showed a modest RSD of +/-36.6%. Comparison of the correlation values of the exposure monitors with the Wocket accelerometers at various body locations showed statistically identical regressions for all sensors at alternate hip, ankle, upper arm, thigh, and pocket locations, but not for the Wocket accelerometer located at the dominant-side wrist location (R=0.57; p=0.016).

CONCLUSIONS

Even with a modest number of adult volunteers, the consistency and linearity of regression slopes for all subjects were very good with excellent within-person Pearson correlations for the accelerometer versus ventilation volume data. Computing accelerometric standard deviations allowed good sensitivity for compliance assessments even for sedentary activities. These pilot findings supported the hypothesis that a common linear regression is likely to be usable for a wider range of adults to predict ventilation volumes from accelerometry data over a range of low to moderate energy level activities. The predicted volumes would then allow real-time estimates of potential dose, enabling more robust panel studies. The poorer correlation in predicting ventilation rate for an accelerometer located on the wrist suggested that this location should not be considered for predictions of ventilation volume.

Air pollution and the respiratory system

Over the past 250 years-since the Industrial Revolution accelerated the process of pollutant emission, which, until then, had been limited to the domestic use of fuels (mineral and vegetal) and intermittent volcanic emissions-air pollution has been present in various scenarios. Today, approximately 50% of the people in the world live in cities and urban areas and are exposed to progressively higher levels of air pollutants. This is a non-systematic review on the different types and sources of air pollutants, as well as on the respiratory effects attributed to exposure to such contaminants. Aggravation of the symptoms of disease, together with increases in the demand for emergency treatment, the number of hospitalizations, and the number of deaths, can be attributed to particulate and gaseous pollutants, emitted by various sources. Chronic exposure to air pollutants not only causes decompensation of pre-existing diseases but also increases the number of new cases of asthma, COPD, and lung cancer, even in rural areas. Air pollutants now rival tobacco smoke as the leading risk factor for these diseases. We hope that we can impress upon pulmonologists and clinicians the relevance of investigating exposure to air pollutants and of recognizing this as a risk factor that should be taken into account in the adoption of best practices for the control of the acute decompensation of respiratory diseases and for maintenance treatment between exacerbations.

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.

IL-13 in asthma and allergic disease: asthma phenotypes and targeted therapies

Decades of research in animal models have provided abundant evidence to show that IL-13 is a key T(H)2 cytokine that directs many of the important features of airway inflammation and remodeling in patients with allergic asthma. Several promising focused therapies for asthma that target the IL-13/IL-4/signal transducer and activator of transcription 6 pathway are in development, including anti-IL-13 mAbs and IL-4 receptor antagonists. The efficacy of these new potential asthma therapies depends on the responsiveness of patients. However, an understanding of how IL-13-directed therapies might benefit asthmatic patients is confounded by the complex heterogeneity of the disease. Recent efforts to classify subphenotypes of asthma have focused on sputum cellular inflammation profiles, as well as cluster analyses of clinical variables and molecular and genetic signatures. Researchers and clinicians can now evaluate biomarkers of T(H)2-driven airway inflammation in asthmatic patients, such as serum IgE levels, sputum eosinophil counts, fraction of exhaled nitric oxide levels, and serum periostin levels, to aid decision making in clinical trials and drug development and to identify subsets of patients who might benefit from therapies. Although it is unlikely that these therapies will benefit all asthmatic patients with this heterogeneous disease, advances in understanding asthma subphenotypes in relation to clinical variables and T(H)2 cytokine responses offer the opportunity to improve the efficacy and safety of proposed therapies for asthma.

Children's urinary phthalate metabolites and fractional exhaled nitric oxide in an urban cohort

RATIONALE

Phthalates are used widely in consumer products. Exposure to several phthalates has been associated with respiratory symptoms and decreased lung function. Associations between children's phthalate exposures and fractional exhaled nitric oxide (Fe(NO)), a biomarker of airway inflammation, have not been examined.

OBJECTIVES

We hypothesized that urinary concentrations of four phthalate metabolites would be positively associated with Fe(NO) and that these associations would be stronger among children with seroatopy or wheeze.

METHODS

In an urban ongoing birth cohort, 244 children had phthalate metabolites determined in urine collected on the same day as Fe(NO) measurement. Repeated sampling gathered 313 observations between ages 4.9 and 9.1 years. Seroatopy was assessed by specific IgE. Wheeze in the past year was assessed by validated questionnaire. Regression models used generalized estimating equations.

MEASUREMENTS AND MAIN RESULTS

Log-unit increases in urinary concentrations of metabolites of diethyl phthalate (DEP) and butylbenzyl phthalate (BBzP) were associated with a 6.6% (95% confidence interval [CI] 0.5-13.1%) and 8.7% (95% CI, 1.9-16.0%) increase in Fe(NO), respectively, adjusting for other phthalate metabolites and potential covariates/confounders. There was no association between concentrations of metabolites of di(2-ethylhexyl) phthalate or di-n-butyl phthalate and Fe(NO). There was no significant interaction by seroatopy. The BBzP metabolite association was significantly stronger among children who wheeze (P = 0.016).

CONCLUSIONS

Independent associations between exposures to DEP and BBzP and Fe(NO) in a cohort of inner-city children were observed. These results suggest that these two ubiquitous phthalates, previously shown to have substantial contributions from inhalation, are positively associated with airway inflammation in children.

Glutathione-S-transferase M1 regulation of diesel exhaust particle-induced pro-inflammatory mediator expression in normal human bronchial epithelial cells

Background

Diesel exhaust particles (DEP) contribute substantially to ambient particulate matter (PM) air pollution in urban areas. Inhalation of PM has been associated with increased incidence of lung disease in susceptible populations. We have demonstrated that the glutathione S-transferase M1 (GSTM1) null genotype could aggravate DEP-induced airway inflammation in human subjects. Given the critical role airway epithelial cells play in the pathogenesis of airway inflammation, we established the GSTM1 deficiency condition in primary bronchial epithelial cells from human volunteers with GSTM1 sufficient genotype (GSTM1+) using GSTM1 shRNA to determine whether GSTM1 deficiency could exaggerate DEP-induced expression of interleukin-8 (IL-8) and IL-1β proteins. Furthermore, the mechanisms underlying GSTM1 regulation of DEP-induced IL-8 and IL-1β expression were also investigated.

Methods

IL-8 and IL-1β protein levels were measured using enzyme-linked immunosorbent assay. GSTM1 deficiency in primary human bronchial epithelial cells was achieved using lentiviral GSTM1 shRNA particles and verified using real-time polymerase chain reaction and immunoblotting. Intracellular reactive oxygen species (ROS) production was evaluated using flow cytometry. Phosphorylation of protein kinases was detected using immunoblotting.

Results

Exposure of primary human bronchial epithelial cells (GSTM1+) to 25-100 μg/ml DEP for 24 h significantly increased IL-8 and IL-1β protein expression. Knockdown of GSTM1 in these cells further elevated DEP-induced IL-8 and IL-1β expression, implying that GSTM1 deficiency aggravated DEP-induced pro-inflammatory response. DEP stimulation induced the phosphorylation of extracellular signal-regulated kinase (ERK) and Akt, the downstream kinase of phosphoinositide 3-kinase (PI3K), in GSTM1+ bronchial epithelial cells. Pharmacological inhibition of ERK kinase and PI3K activity blocked DEP-induced IL-8 and IL-1β expression. DEP-induced ERK and Akt phosphorylation could be increased by GSTM1 knockdown. In addition, pretreatment of HBEC with the antioxidant N-acetyl cysteine significantly inhibited DEP-induced ERK and Akt phosphorylation, and subsequent IL-8 and IL-1β expression.

Conclusion

GSTM1 regulates DEP-induced IL-8 and IL-1β expression in primary human bronchial epithelial cells by modulation of ROS, ERK and Akt signaling.