Acute effects of ambient inhalable particles in asthmatic and nonasthmatic children

Application of geostatistical approaches to predict the spatio-temporal distribution of summer ozone in Houston, Texas

Mitigation of adverse effects of air pollution requires understanding underlying exposures, such as ambient ozone concentrations. Geostatistical approaches were employed to analyze temporal trends and estimate spatial patterns of summertime ozone concentrations for Houston, Texas, based on hourly ozone observations obtained from the Texas Commission on Environmental Quality. We systematically assess the accuracy of several spatial interpolation methods, comparing inverse distance weighting, simple kriging, ordinary kriging, and universal kriging methods utilizing the hourly ozone observations and meteorological measurements from monitoring sites. Model uncertainty was assessed by leave-one-out cross-validation. Kriging methods performed better, showing greater consistency in the generated surfaces, fewer interpolation errors, and lower biases. Universal kriging did not significantly improve the interpolation results compared to ordinary kriging, and thus ordinary kriging was determined to be the optimal method, striking a balance between accuracy and simplicity. The resulting spatial patterns indicate that the more industrialized areas east and northeast of Houston exhibit the highest summertime ozone concentrations. Estimated daily maximum 8 h ozone concentration fields generated will be used to inform research on population health risks from exposure to surface ozone in Houston.

Health effects of environmental pollution in population living near industrial complex areas in Korea

Several epidemiological studies have reported an association between environmental pollution and various health conditions in individuals residing in industrial complexes. To evaluate the effects of pollution from industrial complex on human health, we performed a pooled analysis of environmental epidemiologic monitoring data for residents living near national industrial complexes in Korea. The respiratory and allergic symptoms and the prevalence of acute and chronic diseases, including cancer, were used as the outcome variables for health effects. Multiple logistic regression analysis was used to analyze the relationship between exposure to pollution from industrial complexes and health conditions. After adjusting for age, sex, smoking status, occupational exposure, level of education, and body mass index, the residents near the industrial complexes were found to have more respiratory symptoms, such as cough (odds ratio [OR], 1.18; 95% confidence interval [CI], 1.06 to 1.31) and sputum production (OR, 1.13; 95% CI, 1.03 to 1.24), and symptoms of atopic dermatitis (OR, 1.10; 95% CI, 1.01 to 1.20). Among residents of the industrial complexes, the prevalence of acute eye disorders was approximately 40% higher (OR, 1.39; 95% CI, 1.04 to 1.84) and the prevalence of lung and uterine cancer was 3.45 times and 1.88 times higher, respectively, than those among residents of the control area. This study showed that residents living in the vicinity of industrial complexes have a high risk of acute and chronic diseases including respiratory and allergic conditions. These results can be used as basic objective data for developing health management measures for individuals residing near industrial complexes.

Air pollution as a risk factor in health impact assessments of a travel mode shift towards cycling

BACKGROUND

Promotion of active commuting provides substantial health and environmental benefits by influencing air pollution, physical activity, accidents, and noise. However, studies evaluating intervention and policies on a mode shift from motorized transport to cycling have estimated health impacts with varying validity and precision.

OBJECTIVE

To review and discuss the estimation of air pollution exposure and its impacts in health impact assessment studies of a shift in transport from cars to bicycles in order to guide future assessments.

METHODS

A systematic database search of PubMed was done primarily for articles published from January 2000 to May 2016 according to PRISMA guidelines.

RESULTS

We identified 18 studies of health impact assessment of change in transport mode. Most studies investigated future hypothetical scenarios of increased cycling. The impact on the general population was estimated using a comparative risk assessment approach in the majority of these studies, whereas some used previously published cost estimates. Air pollution exposure during cycling was estimated based on the ventilation rate, the pollutant concentration, and the trip duration. Most studies employed exposure-response functions from studies comparing background levels of fine particles between cities to estimate the health impacts of local traffic emissions. The effect of air pollution associated with increased cycling contributed small health benefits for the general population, and also only slightly increased risks associated with fine particle exposure among those who shifted to cycling. However, studies calculating health impacts based on exposure-response functions for ozone, black carbon or nitrogen oxides found larger effects attributed to changes in air pollution exposure.

CONCLUSION

A large discrepancy between studies was observed due to different health impact assessment approaches, different assumptions for calculation of inhaled dose and different selection of dose-response functions. This kind of assessments would improve from more holistic approaches using more specific exposure-response functions.

Respiratory hospital admissions in young children living near metal smelters, pulp mills and oil refineries in two Canadian provinces

BACKGROUND

Industrial plants emit air pollutants like fine particles (PM2.5), sulfur dioxide (SO2) and nitrogen dioxide (NO2) that may affect the health of individuals living nearby.

OBJECTIVE

To assess the effects of community exposure to air emissions of PM2.5, SO2, and NO2 from pulp mills, oil refineries, metal smelters, on respiratory hospital admissions in young children in Quebec (QC) and British Columbia (BC), Canada.

METHODS

We assessed QC, BC and pooled associations between the following estimates of exposure and hospital admissions for asthma and bronchiolitis in children aged 2-4years for the years 2002-2010: i) Crude emission exposures at the residential postal codes of children, calculated by multiplying estimated daily emissions of PM2.5, SO2, or NO2 from all nearby (<7.5km) pulp mills, oil refineries, metal smelters emitting yearly ≥50t and their total emissions, by the percent of the day each postal code was downwind; ii) Daily levels of these pollutants at central ambient monitoring stations nearby the industries and the children's residences.

RESULTS

Seventy-one major industries were selected between QC and BC, with a total of 2868 cases included in our analyses. More cases were exposed to emissions from major industries in QC than in BC (e.g. 2505 admissions near SO2 industrial emitters in QC vs 334 in BC), although air pollutant levels were similar. Odds ratios (ORs) for crude refinery and smelter emissions were positive in QC but more variable in BC. For example with PM2.5 in QC, ORs were 1.13 per 0.15t/day (95% CI: 1.00-1.27) and 1.03 (95% CI: 0.99-1.07) for refinery and smelter emissions, respectively. Pooled results of QC and BC for crude total SO2 emissions from all sources indicated a 1% increase (0-3%) in odds of hospital admissions per 1.50t/day increase in exposure. Associations with measured pollutant levels were only seen in BC, with SO2 and NO2.

CONCLUSION

Hospital admissions for wheezing diseases in young children were associated with community exposure to industrial air pollutant emissions. Future work is needed to better assess the risk of exposure to complex mixture of air pollutants from multiple industrial sources.

Regression calibration with instrumental variables for longitudinal models with interaction terms, and application to air pollution studies

In this paper, we derive forms of estimators and associated variances for regression calibration with instrumental variables in longitudinal models that include interaction terms between two unobservable predictors and interactions between these predictors and covariates not measured with error; the inclusion of the latter interactions generalize results we previously reported. The methods are applied to air pollution and health data collected on children with asthma. The new methods allow for the examination of how the relationship between health outcome leukotriene E4 (LTE₄, a biomarker of inflammation) and two unobservable pollutant exposures and their interaction are modified by the presence or absence of upper respiratory infections. The pollutant variables include secondhand smoke and ambient (outdoor) fine particulate matter. Simulations verify the accuracy of the proposed methods under various conditions.

Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE)

An increasing recognition has emerged of the complexities of the global health agenda—specifically, the collision of infections and noncommunicable diseases and the dual burden of over- and undernutrition. Of particular practical concern are both 1) the need for a better understanding of the bidirectional relations between nutritional status and the development and function of the immune and inflammatory response and 2) the specific impact of the inflammatory response on the selection, use, and interpretation of nutrient biomarkers. The goal of the Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE) is to provide guidance for those users represented by the global food and nutrition enterprise. These include researchers (bench and clinical), clinicians providing care/treatment, those developing and evaluating programs/interventions at scale, and those responsible for generating evidence-based policy. The INSPIRE process included convening 5 thematic working groups (WGs) charged with developing summary reports around the following issues: 1) basic overview of the interactions between nutrition, immune function, and the inflammatory response; 2) examination of the evidence regarding the impact of nutrition on immune function and inflammation; 3) evaluation of the impact of inflammation and clinical conditions (acute and chronic) on nutrition; 4) examination of existing and potential new approaches to account for the impact of inflammation on biomarker interpretation and use; and 5) the presentation of new approaches to the study of these relations. Each WG was tasked with synthesizing a summary of the evidence for each of these topics and delineating the remaining gaps in our knowledge. This review consists of a summary of the INSPIRE workshop and the WG deliberations.

Respiratory effects of fine and ultrafine particles from indoor sources--a randomized sham-controlled exposure study of healthy volunteers

Particulate air pollution is linked to impaired respiratory health. We analyzed particle emissions from common indoor sources (candles burning (CB), toasting bread (TB), frying sausages (FS)) and lung function in 55 healthy volunteers (mean age 33.0 years) in a randomized cross-over controlled exposure study. Lung-deposited particle surface area concentration (PSC), size-specific particle number concentration (PNC) up to 10 µm, and particle mass concentration (PMC) of PM₁, PM_2.5 and PM₁₀ were determined during exposure (2 h). FEV₁, FVC and MEF_25%–75% was measured before, 4 h and 24 h after exposure. Wilcoxon-rank sum tests (comparing exposure scenarios) and mixed linear regression using particle concentrations and adjusting for personal characteristics, travel time and transportation means before exposure sessions were performed. While no effect was seen comparing the exposure scenarios and in the unadjusted model, inverse associations were found for PMC from CB and FS in relation to FEV₁ and MEF_25%–75%. with a change in 10 µg/m³ in PM_2.5 from CB being associated with a change in FEV₁ of −19 mL (95%-confidence interval:−43; 5) after 4 h. PMC from TB and PNC of UFP were not associated with lung function changes, but PSC from CB was. Elevated indoor fine particles from certain sources may be associated with small decreases in lung function in healthy adults.

Urban particulate matter induces pro-remodeling factors by airway epithelial cells from healthy and asthmatic children

CONTEXT

Chronic exposure to ambient particulate matter pollution during childhood is associated with decreased lung function growth and increased prevalence of reported respiratory symptoms. The role of airway epithelium-derived factors has not been well determined.

OBJECTIVE

To determine if urban particulate matter (UPM) stimulates production of vascular endothelial growth factor (VEGF) and transforming growth factor-β2 (TGF-β2), and gene expression of mucin 5AC (MUC5AC) and interleukin-(IL)-8 by primary airway epithelial cells (AECs) obtained from carefully phenotyped healthy and atopic asthmatic school-aged children.

METHODS

Primary AECs from 9 healthy and 14 asthmatic children were differentiated in air--liquid interface (ALI) culture. The apical surface was exposed to UPM suspension or phosphate buffered saline (PBS) vehicle control for 96 h. VEGF and TGF-β2 concentrations in cell media at baseline, 48 and 96 h were measured via ELISA. MUC5AC and IL-8 expression by AECs at 96 h was measured via quantitative polymerase chain reaction.

RESULTS

Baseline concentrations of VEGF, but not TGF-β2, were significantly higher in asthmatic versus healthy cultures. UPM stimulated production of VEGF, but not TGF-β2, at 48 and 96 h; the magnitude of change was comparable across groups. At 96 h there was greater MUC5AC and IL-8 expression by UPM exposed compared to PBS exposed AECs.

CONCLUSIONS

Induction of the pro-remodeling cytokine VEGF may be a potential mechanism by which UPM influences lung function growth in children irrespective of asthma status. Respiratory morbidity associated with UPM exposure in children may be related to increased expression of MUC5AC and IL-8.

Short-term effects of the particulate pollutants contained in Saharan dust on the visits of children to the emergency department due to asthmatic conditions in Guadeloupe (French Archipelago of the Caribbean)

Background

The prevalence of asthma in children is a significant phenomenon in the Caribbean. Among the etiologic factors aggravating asthma in children, environmental pollution is one of the main causes. In Guadeloupe, pollution is primarily transported by Saharan dust including inhalable particles.

Methods

This study assesses, over one year (2011), the short-term effects of pollutants referred to as PM₁₀ (PM₁₀: particulate matter <10 µm) and PM_2.5–10 (PM_2.5–10: particulate matter >2.5 µm and <10 µm) contained in Saharan dust, on the visits of children aged between 5 and 15 years for asthma in the health emergency department of the main medical facility of the archipelago of Guadeloupe. A time-stratified case-crossover model was applied and the data were analysed by a conditional logistic regression for all of the children but also for sub-groups corresponding to different age classes and genders.

Results

The visits for asthma concerned 836 children including 514 boys and 322 girls. The Saharan dust has affected 15% of the days of the study (337 days) and involved an increase in the average daily concentrations of PM₁₀ (49.7 µg/m³ vs. 19.2 µg/m³) and PM _2.5–10 (36.2 µg/m³ vs. 10.3 µg/m³) compared to days without dust. The excess risk percentages (IR%) for visits related to asthma in children aged between 5 and 15 years on days with dust compared to days without dust were, for PM_{10, (}(IR %: 9.1% (CI95%, 7.1%–11.1%) versus 1.1%(CI95%, −5.9%–4.6%)) and for PM_2.5–10 (IR%: 4.5%(CI95%, 2.5%–6.5%) versus 1.6% (CI95%, −1.1%–3.4%). There was no statistical difference in the IR% for periods with Saharan dust among different age group of children and between boys and girls for PM₁₀ and PM_2.5–10.

Conclusion

The PM₁₀ and PM_2.5–10 pollutants contained in the Saharan dust increased the risk of visiting the health emergency department for children with asthma in Guadeloupe during the study period.

Personal exposure measurement of students to various microenvironments inside and outside the college campus

This study characterizes the exposure of a typical Indian Institute of Technology Kanpur student to particulate matter and gaseous co-pollutants like carbon monoxide, volatile organic compounds, and nitrogen dioxide in various microenvironments, within and outside the college campus. Chemical analysis of filter, used for the particulate matter measurement, was also carried out to determine the concentration of various elements such as Ca, Cd, Cr, Cu, Fe, Mg, Pb, Zn, and anions like F(-), Cl(-), NO3 (-), and SO4 (2-). Furthermore, time activity diary along with temperature data was maintained for the precise evaluation and analysis of results for various microenvironments. The results showed PM10 and PM2.5 concentrations to be higher at some outdoor microenvironments, particularly near the Ganga riverbank. From the chemical analysis, concentrations of chloride and fluoride were found higher in indoor microenvironments as compared to outdoors. Also, nitrate concentrations were quite higher within the laboratory premises. Concentrations of Ca, Fe, and Mg were significant outdoors, whereas Na, Ca, Fe, and K were prominent indoors. The study highlights the real-time personal exposure of a student cohort to various toxic pollutants typically found within their breathing levels and their potential sources both indoors and outdoors.

Epidemiology of cough in relation to China

Cough is one of the most common complaints for which patients seek medical attention. Misdiagnosis and mistreatment of cough exist commonly in China. The prevalence of acute cough caused by upper airway infection fluctuates between 9% and 64% in the community, for chronic cough, the prevalence >10% in most surveys, ranging from 7.2%-33%. The common causes of chronic cough are upper airway cough syndrome (previously called as post nasal drip syndrome [PNDS]), cough variant asthma (CVA), gastroesophageal reflux related cough (GERD) and eosinophilic bronchitis (EB). There is a regional discrepancy regarding the prevalence of common causes of cough and distribution of gender among China, UK, USA, the most common cause of chronic cough in China are CVA, followed by UACS, EB and atopic cough (AC), the male is almost equal to female in numbers in China. The risk factors for cough includes cold air, smoking, environmental pollutants, noxious substances and allergens, and unreasonable diet habits.

Environmental Toxicology: Children at Risk

Children today live in a world that is vastly different from a few generations ago. While industrialization has maximized (for many) children’s opportunities to survive, develop and enjoy high levels of health, education, recreation, and fulfillment, it has also added significant challenges to their development.

Theoretical models of carcinogenic particle deposition and clearance in children's lungs

INTRODUCTION

Deposition and clearance of carcinogenic particles in the lungs of subjects belonging to four different age groups (infants, children, adolescents, and adults) were theoretically investigated. The study is thought to contribute to the improvement of our knowledge concerning the behaviour of inhaled particles in lungs that may be attributed to different stages of development.

METHODS

Particle deposition and clearance were simulated by using a well established stochastic lung model, allowing the generation of nearly realistic scenarios. For the computation of particle deposition all main deposition forces were considered. Additionally, any influences on particle behaviour due to particle geometry were covered by using the aerodynamic diameter concept. Particle clearance was simulated by defining both a fast mucociliary clearance phase and a slow bronchial/alveolar clearance phase, the latter of which is based on previously published models and suggestions.

RESULTS

As clearly provided by the modelling computations, lung deposition of particles with aerodynamic diameters ranging from 1 nm to 10 µm may significantly differ between the studied age groups. Whilst in infants and children most particles are accumulated in the extrathoracic region and in the upper bronchi, in adolescents and adults high percentages of inhaled particular substances may also reach the lower bronchi and alveoli. Although mucus velocities are significantly lower in young subjects compared to the older ones, fast clearance is more efficient in small lungs due to the shorter clearance paths that have to be passed. Slow clearance is commonly characterized by insignificant discrepancies between the age groups.

CONCLUSIONS

From the study presented here it may be concluded that particle behaviour in infants' and children's lungs has to be regarded in a different light with respect to that in adolescents and adults. Although young subjects possess natural mechanisms of protecting their lungs from hazardous aerosols (e.g., expressed by breathing behaviour and lung size), they are much more sensitive to any particle exposure, since particle concentrations per lung tissue area may reach alarming values within a short period of inhalation.

Environmental and non-infectious factors in the aetiology of pharyngitis (sore throat)

Objectives

The aim of this review is to examine the causes, pathophysiology and experimental models of non-infectious pharyngitis (sore throat).

Introduction

The causes of sore throat can be infectious (viruses, bacteria, and fungi) or non-infectious, although the relative proportion of each is not well documented.

Methods

A PubMed database search was performed for studies of non-infectious sore throat.

Results and conclusions

Non-infectious causes of sore throat include: physico-chemical factors, such as smoking, snoring, shouting, tracheal intubation, medications, or concomitant illness; and environmental factors including indoor and outdoor air pollutants, temperature and humidity, and hazardous or occupational irritants. The pathophysiology underlying non-infectious sore throat is largely uncharacterised, although neurogenic inflammation looks to be a promising candidate. It is likely that there will be individual disposition factors or the coincidence of more than one irritant with possible—up to now unknown—interactions between them. Therefore, experimental models with defined conditions and objective endpoints are needed. A new model using cold dry air to directly induce pharyngeal irritation in humans, with pharyngeal lavage to measure biomarkers, may provide a useful tool for the study of mechanisms and treatment of non-infectious sore throat.

Effects of exposure to rice-crop residue burning smoke on pulmonary functions and oxygen saturation level of human beings in Patiala (India)

Pulmonary Function Tests (PFTs) like Force Vital Capacity (FVC), Force Expiratory Volume in one second (FEV₁), Peak Expiratory Flow (PEF) and Force Expiratory Flow between 25 and 75% of FVC (FEF(25-75%)) and Oxygen Saturation (SpO₂) level of 50 healthy inhabitants with respect to rice crop residue burning were investigated for three rice cultivation periods from 2007 to 2009. The subjects were residents of five sampling sites selected in Patiala city. Concentration of Suspended Particulate Matter (SPM), Sulfur dioxide (SO₂), Nitrogen dioxide (NO₂) and Particulate Matter (PM) of size less than 10 and 2.5 μm (PM₁₀ and PM₂.₅) were measured by using High Volume Sampler (HVS) and Cascade Anderson Impactor. Results show that rice crop residue burning increases the pollution level in the ambient air, and PFTs undergo a significant decrease in their respective values. No significant change was seen in SpO₂ level during rice crop residue burning. In 2008, an increase of 10 μg m⁻³ in PM₂.₅, PM₁₀, SPM and NO₂ was associated significantly with decrease in FVC in percentages predicted -1.541, -1.002, -1.178, -0.232%, respectively. The decrease in air quality due to open rice crop residue burning has sub acute effect on pulmonary functions of healthy subjects and that SO₂ and NO₂ have less adverse effects on pulmonary functions than with different size Particulate Matter.

Air quality and exercise-related health benefits from reduced car travel in the midwestern United States

BACKGROUND

Automobile exhaust contains precursors to ozone and fine particulate matter (PM ≤ 2.5 µm in aerodynamic diameter; PM2.5), posing health risks. Dependency on car commuting also reduces physical fitness opportunities.

OBJECTIVE

In this study we sought to quantify benefits from reducing automobile usage for short urban and suburban trips.

METHODS

We simulated census-tract level changes in hourly pollutant concentrations from the elimination of automobile round trips ≤ 8 km in 11 metropolitan areas in the upper midwestern United States using the Community Multiscale Air Quality (CMAQ) model. Next, we estimated annual changes in health outcomes and monetary costs expected from pollution changes using the U.S. Environmental Protection Agency Benefits Mapping Analysis Program (BenMAP). In addition, we used the World Health Organization Health Economic Assessment Tool (HEAT) to calculate benefits of increased physical activity if 50% of short trips were made by bicycle.

RESULTS

We estimate that, by eliminating these short automobile trips, annual average urban PM2.5 would decline by 0.1 µg/m3 and that summer ozone (O3) would increase slightly in cities but decline regionally, resulting in net health benefits of $4.94 billion/year [95% confidence interval (CI): $0.2 billion, $13.5 billion), with 25% of PM2.5 and most O3 benefits to populations outside metropolitan areas. Across the study region of approximately 31.3 million people and 37,000 total square miles, mortality would decline by approximately 1,295 deaths/year (95% CI: 912, 1,636) because of improved air quality and increased exercise. Making 50% of short trips by bicycle would yield savings of approximately $3.8 billion/year from avoided mortality and reduced health care costs (95% CI: $2.7 billion, $5.0 billion]. We estimate that the combined benefits of improved air quality and physical fitness would exceed $8 billion/year.

CONCLUSION

Our findings suggest that significant health and economic benefits are possible if bicycling replaces short car trips. Less dependence on automobiles in urban areas would also improve health in downwind rural settings.

The effects of outdoor air pollutants on the costs of pediatric asthma hospitalizations in the United States, 1999 to 2007

BACKGROUND

Acute exposure to outdoor air pollutants has been associated with increased pediatric asthma morbidity. However, the impact of subchronic exposures is largely unknown.

OBJECTIVE

To examine the association between subchronic exposure to 6 outdoor air pollutants (PM2.5, PM10, ozone, nitrogen oxides, sulfur oxides, carbon monoxide) and pediatric asthma hospitalization length of stay, charges, and costs.

METHODS

We linked pediatric asthma hospitalization discharge data from a nationally representative dataset, the 1999-2007 Nationwide Inpatient Sample, with outdoor air pollution data from the Environmental Protection Agency. Hospitals with no air quality data within 10 miles were excluded. Our predictor was the average concentration of 6 pollutants near the hospital during the month of admission. We conducted bivariate analyses using Spearman correlations and multivariable analyses using Poisson regression for length of stay and linear regression for log-transformed charges and costs, controlling for patient demographics, hospital characteristics, and month of admission.

RESULTS

In unadjusted analyses, all 6 pollutants had minimal correlation with the 3 outcomes (ρ<0.1, P<0.001). In multivariable analyses, a 1-unit (μg/m) increase in monthly PM2.5 led to a $123 increase in charges (95% confidence interval $40-249) and a $47 increase in costs (95% confidence interval $15-93). No other pollutants were significant predictors of charges or costs or length of stay.

CONCLUSION

Subchronic PM2.5 exposure is associated with increased costs for pediatric asthma hospitalizations. Policy changes to reduce outdoor subchronic pollutant exposure may lead to improved asthma outcomes and substantial savings in healthcare spending.

The response of children with asthma to ambient particulate is modified by tobacco smoke exposure

RATIONALE

Ambient particulate matter concentrations have been positively associated with urinary leukotriene E(4) (LTE(4)) levels and albuterol usage in children with asthma but interactions with environmental tobacco smoke (ETS) exposure have not been demonstrated despite obvious exposure to both pollutants in an urban setting.

OBJECTIVES

To assess the health effects of concurrent ETS and ambient particulate matter exposure in children with asthma.

METHODS

Albuterol usage and LTE(4) levels were monitored in 82 urban schoolchildren with asthma over three consecutive fall to spring school periods. Concentrations of morning maximum ambient particulate matter <2.5 μm in aerodynamic diameter (mmPM(2.5)) and urine cotinine levels were also measured daily.

MEASUREMENTS AND MAIN RESULTS

Albuterol usage and LTE(4) were related to mmPM(2.5) concentrations on days when urine cotinine levels were low (<10 ng/ml/mg creatinine); on these days, mean albuterol usage and LTE(4) increased up to 5 or 6% per 10 μg/m(3) increase in mmPM(2.5). In contrast, no significant relationship was observed when cotinine was high, although mean albuterol usage and LTE(4) levels were greater in this case. Model fits for LTE(4) levels as a function of mmPM(2.5) concentrations were improved when mmPM(2.5) concentrations were logged, suggesting a nonlinear dose-response relationship between particulate matter exposure concentrations and airway mediators of asthma, for which the relationship tends to flatten at higher concentrations.

CONCLUSIONS

This study suggests that ETS modifies the acute effects of low-level ambient PM(2.5) exposure on childhood asthma. This negative interaction, the smaller effect of particulate matter exposure in children exposed to higher ETS, may be related to a nonlinear dose-response relationship between asthma mediators and particulate exposures.

Environmentally persistent free radicals induce airway hyperresponsiveness in neonatal rat lungs

Background

Increased asthma risk/exacerbation in children and infants is associated with exposure to elevated levels of ultrafine particulate matter (PM). The presence of a newly realized class of pollutants, environmentally persistent free radicals (EPFRs), in PM from combustion sources suggests a potentially unrecognized risk factor for the development and/or exacerbation of asthma.

Methods

Neonatal rats (7-days of age) were exposed to EPFR-containing combustion generated ultrafine particles (CGUFP), non-EPFR containing CGUFP, or air for 20 minutes per day for one week. Pulmonary function was assessed in exposed rats and age matched controls. Lavage fluid was isolated and assayed for cellularity and cytokines and in vivo indicators of oxidative stress. Pulmonary histopathology and characterization of differential protein expression in lung homogenates was also performed.

Results

Neonates exposed to EPFR-containing CGUFP developed significant pulmonary inflammation, and airway hyperreactivity. This correlated with increased levels of oxidative stress in the lungs. Using differential two-dimensional electrophoresis, we identified 16 differentially expressed proteins between control and CGUFP exposed groups. In the rats exposed to EPFR-containing CGUFP; peroxiredoxin-6, cofilin1, and annexin A8 were upregulated.

Conclusions

Exposure of neonates to EPFR-containing CGUFP induced pulmonary oxidative stress and lung dysfunction. This correlated with alterations in the expression of various proteins associated with the response to oxidative stress and the regulation of glucocorticoid receptor translocation in T lymphocytes.

Prevalence of asthma in schoolchildren in Alta Floresta- a municipality in the southeast of the Brazilian Amazon

OBJECTIVE

To analyze the prevalence and symptoms of asthma in students of the Brazilian Amazon municipality of Alta Floresta-MT.

METHODS

Cross-sectional study on the prevalence of asthma in 6 and 7 year-old children and 13 to 14 year-old adolescents, using the Study of Asthma and Allergies in Childhood - ISAAC method, phase I in 2007. Students who answered affirmatively question 2 - "presence of wheezing in the past 12 months" were considered asthmatic.

RESULTS

Of the total 2,071 students, 1,072 (51.7%) were children and 999 (48.3%) were teenagers. The prevalence of asthma was 21.4% among schoolchildren, and 12.4% among adolescents (chi2 = 29.29; rho = 0.00). Children presented a higher prevalence than adolescents of the following asthma symptoms: wheezing sometime in life (49.9%), wheezing in the past 12 months (21.4%), 1 to 3 wheezing attacks in the past 12 months (16.4%), and dry cough at night (38.2%). Regarding physician-diagnosed asthma, no difference was observed between the two age groups, with a prevalence of around 6.0%. Male schoolchildren presented a higher prevalence of asthma, physician-diagnosed asthma and four or more wheezing episodes in the past 12 months (rho < 0.05). Male adolescents presented the highest prevalence of strong wheezing affecting speech (rho < 0.05).

CONCLUSION

Alta Floresta presents one of the highest prevalences of asthma in Latin America among schoolchildren in the 6 and 7 year-old age group.

Residential Proximity to Freeways is Associated with Uncontrolled Asthma in Inner-City Hispanic Children and Adolescents

Background. Proximity to heavy traffic has been linked to increased asthma severity. However, it is unknown whether exposure to heavy traffic is associated with the ability to maintain asthma control. Objectives. This study examines whether exposure to heavy traffic is associated with the ability to maintain asthma control in inner-city children. Methods. 756 inner-city asthmatic Hispanic children were followed for one year in a pediatric asthma management program (Breathmobile). At each scheduled visit, asthma specialist tracked patients' asthma severity and managed their asthma based on the NAEPP guidelines. The patients' residential distance from the nearest freeway was calculated based on residential address at study entry. Distance to nearest freeway was used as a surrogate marker for high exposure from traffic-related air pollutants. Results. Patients who lived near a freeway were significantly more likely to have asthma that was not well controlled (P = .03). Patients with intermittent and mild baseline severity have a two-fold increased risk of having asthma that is uncontrolled if they lived <2 miles from a freeway (OR = 2.2, P = .04). Conclusion. In children with asthma, residential proximity to freeways is associated with uncontrolled asthma.

Air pollution-related peak expiratory flow rates among asthmatic children in Chiang Mai, Thailand

The severity of air pollution in northern Thailand has long been recognized; in spite of that there have been no epidemiological studies regarding the associations between the air pollution and health effects in the area. The authors followed a cohort of 31 asthmatic children (4-11 years of age) residing in Muang district, Chiang Mai, Thailand, from 29 August 2005 to 30 June 2006, for 306 days. The daily air pollutants, including particulate matter with aerodynamic diameter < 2.5 microm, particulate matter with aerodynamic diameter < 10 microm, carbon monoxide, ozone (O(3)), nitrogen dioxide, and sulfur dioxide (SO(2)), and the meteorological parameters, including pressure, temperature, relative humidity, rain quantity, and sunshine duration, were recorded. The peak expiratory flow rates (PEFRs) were fitted with pollutants and meteorological covariates using general linear mixed models to account for random effects and autocorrelation. The authors found that there were inverse associations of SO(2) and evening PEFR, with a coefficient of -2.12 (95% confidence interval (CI) = -3.22 to -0.28); of SO(2) and daily percent deviation of PEFR, with a coefficient of -0.73 (95% CI = -1.33 to -0.12); and of O(3) combining with SO(2) and daily average PEFR, with a coefficient of -0.16 (95% CI = -0.31 to -0.00) and -1.60 (95% CI = -3.10 to -0.11), respectively. The associations of O(3) and SO(2) with PEFR were found even when SO(2) concentrations never exceeded the standard level.

Short-term effects of PM10 and NO2 on respiratory health among children with asthma or asthma-like symptoms: a systematic review and meta-analysis

OBJECTIVE

Our goal was to quantify the short-term effects of particulate matter with aerodynamic diameter < or = 10 microm (PM10) and nitrogen dioxide (NO2) on respiratory health of asthmatic children from published panel studies, and to investigate the influence of study and population characteristics as effect modifiers.

DATA EXTRACTION

After a systematic literature review, we extracted quantitative estimates of the association of PM10 and/or NO2 with respiratory symptoms and peak expiratory flow (PEF). Combined effect estimates for an increase of 10 microg/m3 were calculated by random effects meta-analysis for all studies and for different strata defined by study characteristics. The effect of publication bias was investigated with Egger's and Begg's tests and "trim-and-fill" analyses.

DATA SYNTHESIS

We identified 36 studies; 14 were part of the European Pollution Effects on Asthmatic Children in Europe (PEACE) study. Adverse associations of PM10 with asthma symptoms were statistically significant [odds ratio (OR) = 1.028; 95% confidence interval (CI), 1.006-1.051]. There were also associations, although not statistically significant, of PM10 with cough (OR = 1.012; 95% CI, 0.997-1.026) and on PEF (decrease of -0.082 L/min; 95% CI, -0.214 to 0.050). NO2 had statistically significant associations with asthma symptoms in the overall analysis considering all possible lags (OR = 1.031; 95% CI, 1.001-1.062), but not when we evaluated only the 0-1 lag. We found no publication bias, although it appeared when excluding the PEACE studies. When we applied the trim-and-fill method to the data set without the PEACE studies, the results were similar to the overall estimates from all studies. There was an indication for stronger PM10 associations for studies conducted in summer, outside of Europe, with longer lags, and in locations with higher NO2 concentrations.

CONCLUSIONS

We found clear evidence of effects of PM10 on the occurrence of asthma symptom episodes, and to a lesser extent on cough and PEF. The results for NO2 are more difficult to interpret because they depend on the lag times examined. There was an indication of effect modification by several study conditions.

Bronchial wall thickness in toll collectors

There is an increasing concern about the possible adverse effects of diesel exhaust particulates on human health. In a diesel exposed occupational group composed of 120 toll collectors, a cross-sectional study was performed to evaluate the chest radiographs and 40 toll collectors were selected for computed tomography examination according to hyperinflation and linear markings. The wall thicknesses and luminal diameters of trachea, main bronchi, and segmental bronchi of right apical and posterior basal segments were measured with manual tracing method. The walls of right upper bronchus in exsmoker toll collectors were significantly thicker than those of nonsmokers (p=0.011). A positive correlation was observed between age and the right upper bronchus wall thickness (r=0.577, p=0.000). An inverse correlation was found between the working duration and the diameter of right main bronchus (r=-0.366, p=0.020). A positive correlation was seen between smoking and the right upper bronchus wall thickness (r=0.457, p=0.005). Diesel exposure might have a role in increase of thickness of large airways wall and a decrease in the diameters of large airways. Studies in this area are needed to protect the population under the diesel exposure risk.

Prevalence of asthma in children and adolescents in a city in the Brazilian Amazon region

OBJECTIVE

To analyze the prevalence of asthma and asthma symptoms in students of two distinct age brackets residing in the city of Tangará da Serra, Brazil.

METHODS

Cross-sectional, population-based study of the prevalence of asthma in children from 6 to 7 years of age and adolescents from 13 to 14, using the standardized International Study of Asthma and Allergies in Childhood, phase 1 questionnaire, validated for use in Brazil. Students who responded affirmatively to question 2 (presence of wheezing in the preceding 12 months) were classified as suffering from asthma.

RESULTS

The study comprised 3,362 students, of whom 1,634 (48.6%) were children and 1,728 (51.4%) were adolescents. Of the 1,634 children, 816 (49.9%) were male, and 818 (50.1%) were female. Of the 1,728 adolescents, 773 (45.0%) were male, and 955 (55.0%) were female. The prevalence of asthma among the children was 25.2%, whereas that among the adolescents was 15.9% (chi2 = 8.34; p = 0.00). The children presented higher prevalences of the following symptoms of asthma than did the adolescents: wheezing ever (54.3%), nocturnal dry cough (43.9%), wheezing in the preceding 12 months (25.2%), and from 1 to 3 attacks of wheezing in the preceding 12 months (19.1%). There were no differences between the two groups regarding physician-diagnosed asthma (approximately 4.5%). There were no statistical differences regarding the prevalence of asthma by gender in the two groups.

CONCLUSIONS

Tangará da Serra has a high prevalence of asthma in children and adolescents, and this result is compatible with other studies carried out in Brazil and Latin America using the same methodology.

Potential impact of climate change on air pollution-related human health effects

The potential health impact of ambient ozone and PM2.5 concentrations modulated by climate change over the United States is investigated using combined atmospheric and health modeling. Regional air quality modeling for 2001 and 2050 was conducted using CMAQ Modeling System with meteorology from the GISS Global Climate Model, downscaled regionally using MM5,keeping boundary conditions of air pollutants, emission sources, population, activity levels, and pollution controls constant. BenMap was employed to estimate the air pollution health outcomes at the county, state, and national level for 2050 caused by the effect of meteorology on future ozone and PM2.5 concentrations. The changes in calculated annual mean PM2.5 concentrations show a relatively modest change with positive and negative responses (increasing PM2.5 levels across the northeastern U.S.) although average ozone levels slightly decrease across the northern sections of the U.S., and increase across the southern tier. Results suggest that climate change driven air quality-related health effects will be adversely affected in more then 2/3 of the continental U.S. Changes in health effects induced by PM2.5 dominate compared to those caused by ozone. PM2.5-induced premature mortality is about 15 times higher then that due to ozone. Nationally the analysis suggests approximately 4000 additional annual premature deaths due to climate change impacts on PM2.5 vs 300 due to climate change-induced ozone changes. However, the impacts vary spatially. Increased premature mortality due to elevated ozone concentrations will be offset by lower mortality from reductions in PM2.5 in 11 states. Uncertainties related to different emissions projections used to simulate future climate, and the uncertainties forecasting the meteorology, are large although there are potentially important unaddressed uncertainties (e.g., downscaling, speciation, interaction, exposure, and concentration-response function of the human health studies).

Clinical cough VI: the need for new therapies for cough: disease-specific and symptom-related antitussives

Cough is a common symptom that can be self-limiting or persistent. Ideally, treatment of the underlying cause(s) of cough with specific treatments should eliminate cough. This approach may not be successful if no cause can be established or if the treatment of the cause fails. Suppression of cough may be disease-specific or symptom-related. There has been a long tradition in acute cough usually due to upper respiratory tract infections to use symptom-related antitussives. In chronic cough, suppression of cough may be achieved by disease-specific therapies, but in many patients it may be necessary to use symptomatic antitussives. The efficacy of some over-the-counter symptomatic antitussives is often no better than that of a placebo. Currently available cough suppressants include the centrally acting opioids such as morphine, codeine, pholcodeine, and dextromethorphan. Early studies reported success in reducing cough in patients with chronic bronchitis or chronic obstructive pulmonary disease (COPD); however, a carefully conducted blinded controlled study showed no effect of codeine on cough of COPD. Success with these cough suppressants may be achieved at high doses that are associated with side effects. A slow-release preparation of morphine has been shown to have some degree of efficacy, but this should be reserved for the most severe chronic cough patient, and for patients with terminal cancer who may also benefit from its analgesic effects. There are case reports of the success of centrally acting drugs such as amitriptyline, paroxetine, gabapentin, and carbamezepine in chronic cough. New agents derived from basic research such as new opioids such as nociceptin or antagonists of transient receptor potential vanniloid-1 may turn out to have antitussive effects. Efficacy of symptomatic cough suppressants must be tested in double-blind randomized trials using validated measures of cough in patients with chronic cough not responding to specific treatments. Patients with chronic cough need effective antitussives that could be used either on demand or on a long-term basis.

Involvement of alveolar macrophages in the formation of 8-oxodeoxyguanosine associated with exogenous particles in human lungs

Lung specimens were collected from 161 non-smoking male patients with carcinoma to determine the deposition of carbon particles and oxidative damage in lung tissues. Morphologically, carbon particles deposited in human lungs with carcinoma were similar to those of diesel exhaust like particles, and mass of particles showed a significant increase with the increasing age of the patients. An increasing age of patient with carcinomas was also associated with 8-oxodeoxy-guanosine (8-oxo-dG) formation, which was analyzed using the HPLC-electrochemical detector method. In addition, it was found that 8-oxo-dG increased in cancerous tissues rather than in non-cancerous ones. To determine whether particles in lung tissues were associated with 8-oxo-dG formation, carbon particles deposited in lung tissues were partially purified by cycling of alkali fusion with 1 M KOH; mutagenic chemicals in particles were extracted and excluded by removal with an equal volume of benzene/methanol and dichloromethane. It was also found that 8-oxo-dG was formed by non-mutagenic particles, and enhanced in the in vivo test using mouse rather than in the in vitro using RAW 254.7 tissue cultured cells. The 8-oxo-dG formation in vivo was due to the fact that hydroxyl radicals might be involved with phagocytosis of non-mutagenic particles in inflammatory cells, and the mutation was induced by hydroxylation of guanine residue on DNA. These results were also demonstrated by the occurrence of alveolar macrophages and neutrophils after intratracheal instillation of particles. These observations suggest that small particles from lung cancer patients further promote oxidative damage when used to treat the mouse lung. Especially, particles from which organic chemicals were removed were highly reactive to oxidative damage and formed 8-oxo-dG.

Effects of fine carbonaceous particles containing high and low unpaired electron spin densities on lungs of female mice

The negative impacts on human health that accompany inhalation of atmospheric particles are documented in numerous epidemiologic studies, but the effect of specific chemical properties of the particles is generally unknown. We developed and employed technology for generating inhalable aerosols of carbonaceous air pollution particles that have specific physical and chemical properties. We find that inhaling particles with greater unpaired electron spin (free radical) densities stimulates greater lung inflammatory and oxidative stress responses. Cultured alveolar macrophages take up more particles of greater free radical content, develop mitochondrial abnormalities, and release more leukotriene B(4) (LTB(4)) than alveolar macrophages exposed to lesser free-radical-containing particles in vitro. Mice exposed to high free radical particles in vivo also develop mitochondrial abnormalities in alveolar macrophages and increased oxidative stress, which is reflected by increases in lung nitrotyrosine staining and lung lavage nitrogen oxide levels compared with those of lesser free radical density. These results provide insight for the unexplained geographic differences and have implications for fossil fuel combustion conditions and the impact of fine particles on health and disease.

Spatio-temporal modeling of chronic PM10 exposure for the Nurses' Health Study

Chronic epidemiological studies of airborne particulate matter (PM) have typically characterized the chronic PM exposures of their study populations using city- or countywide ambient concentrations, which limit the studies to areas where nearby monitoring data are available and which ignore within-city spatial gradients in ambient PM concentrations. To provide more spatially refined and precise chronic exposure measures, we used a Geographic Information System (GIS)-based spatial smoothing model to predict monthly outdoor PM(10) concentrations in the northeastern and midwestern United States. This model included monthly smooth spatial terms and smooth regression terms of GIS-derived and meteorological predictors. Using cross-validation and other pre-specified selection criteria, terms for distance to road by road class, urban land use, block group and county population density, point- and area-source PM(10) emissions, elevation, wind speed, and precipitation were found to be important determinants of PM(10) concentrations and were included in the final model. Final model performance was strong (cross-validation R(2)=0.62), with little bias (-0.4 mug m(-3)) and high precision (6.4 mug m(-3)). The final model (with monthly spatial terms) performed better than a model with seasonal spatial terms (cross-validation R(2)=0.54). The addition of GIS-derived and meteorological predictors improved predictive performance over spatial smoothing (cross-validation R(2)=0.51) or inverse distance weighted interpolation (cross-validation R(2)=0.29) methods alone and increased the spatial resolution of predictions. The model performed well in both rural and urban areas, across seasons, and across the entire time period. The strong model performance demonstrates its suitability as a means to estimate individual-specific chronic PM(10) exposures for large populations.

Effects of airborne particulate matter on respiratory morbidity in asthmatic children

Background

The effects of airborne particulate matter (PM) are a major human health concern. In this panel study, we evaluated the acute effects of exposure to PM on peak expiratory flow (PEF) and wheezing in children.

Methods

Daily PEF and wheezing were examined in 19 asthmatic children who were hospitalized in a suburban city in Japan for approximately 5 months. The concentrations of PM less than 2.5 µm in diameter (PM_2.5) were monitored at a monitoring station proximal to the hospital. Moreover, PM_2.5 concentrations inside and outside the hospital were measured using the dust monitor with a laser diode (PM_2.5(LD)). The changes in PEF and wheezing associated with PM concentration were analyzed.

Results

The changes in PEF in the morning and evening were significantly associated with increases in the average concentration of indoor PM_2.5(LD) 24 h prior to measurement (-2.86 L/min [95%CI: -4.12, -1.61] and -3.59 L/min [95%CI: -4.99, -2.20] respectively, for 10-µg/m³ increases). The change in PEF was also significantly associated with outdoor PM_2.5(LD) concentrations, but the changes were smaller than those observed for indoor PM_2.5(LD). Changes in PEF and concentration of stationary-site PM_2.5 were not associated. The prevalence of wheezing in the morning and evening were also significantly associated with indoor PM_2.5(LD) concentrations (odds ratios = 1.014 [95%CI: 1.006, 1.023] and 1.025 [95%CI: 1.013, 1.038] respectively, for 10-µg/m³ increases). Wheezing in the evening was significantly associated with outdoor PM_2.5(LD) concentration. The effects of indoor and outdoor PM_2.5(LD) remained significant even after adjusting for ambient nitrogen dioxide concentrations.

Conclusion

Indoor and outdoor PM_2.5(LD) concentrations were associated with PEF and wheezing among asthmatic children. Indoor PM_2.5(LD) had a more marked effect than outdoor PM_2.5(LD) or stationary-site PM_2.5.

Prevalence, pathogenesis, and causes of chronic cough

Cough is a reflex action of the respiratory tract that is used to clear the upper airways. Chronic cough lasting for more than 8 weeks is common in the community. The causes include cigarette smoking, exposure to cigarette smoke, and exposure to environmental pollution, especially particulates. Diseases causing chronic cough include asthma, eosinophilic bronchitis, gastro-oesophageal reflux disease, postnasal drip syndrome or rhinosinusitis, chronic obstructive pulmonary disease, pulmonary fibrosis, and bronchiectasis. Doctors should always work towards a clear diagnosis, considering common and rare illnesses. In some patients, no cause is identified, leading to the diagnosis of idiopathic cough. Chronic cough is often associated with an increased response to tussive agents such as capsaicin. Plastic changes in intrinsic and synaptic excitability in the brainstem, spine, or airway nerves can enhance the cough reflex, and can persist in the absence of the initiating cough event. Structural and inflammatory airway mucosal changes in non-asthmatic chronic cough could represent the cause or the traumatic response to repetitive coughing. Effective control of cough requires not only controlling the disease causing the cough but also desensitisation of cough pathways.

Acute effects of Asian dust events on respiratory symptoms and peak expiratory flow in children with mild asthma

The aim of this study was to investigate the possible adverse effects of Asian dust events on respiratory health in asthmatic children. Fifty-two children with mild asthma were studied for eight consecutive weeks in the spring of 2004 (March 8 to May 2). During the study period, five Asian dust days were identified; we included a lag period of two days following each of the events. Subjects recorded their respiratory symptom diaries and peak expiratory flow (PEF) twice daily during the study period; and they underwent methacholine bronchial challenge tests. The subjects reported a significantly higher frequency of respiratory symptoms during the Asian dust days than during the control days. They showed significantly more reduced morning and evening PEF values, and more increased PEF variability (10.1%+/-3.5% vs. 5.5%+/-2.2%) during the Asian dust days than during the control days. Methacholine PC(20) was not significantly different between before and after the study period (geometric mean: 2.82 mg/mL vs. 3.16 mg/mL). These results suggest that the short-term Asian dust events might be associated with increased acute respiratory symptoms and changes in PEF outcomes. However, there might be little long-term influence on airway hyperresponsiveness in children with mild asthma.

Currently Available Cough Suppressants for Chronic Cough

Chronic cough is a common symptom but only a fraction of patients seek medical attention. Addressing the causes of chronic cough may lead to control of cough; however, this approach is not always successful since there is a certain degree of failure even when the cause(s) of cough are adequately treated; in idiopathic cough, there is no cause to treat. Persistent cough may be associated with deterioration of quality of life, and treatment with cough suppressants is indicated. Currently available cough suppressants include the centrally acting opioids such as morphine, codeine, and dextromethorphan. Peripherally acting antitussives include moguisteine and levodropropizine. Early studies report success in reducing cough in patients with chronic bronchitis or COPD; however, a carefully conducted study showed no effect of codeine on cough of COPD. Success with these cough suppressants can be achieved at high doses that are associated with side effects. Slow-release morphine has been reported to be useful in controlling intractable cough with good tolerance to constipation and drowsiness. There have been case reports of the success of centrally acting drugs such as amitryptiline, paroxetine, gabapentin, and carbamezepine in chronic cough. New opioids such as nociceptin or antagonists of TRPV1 may turn out to be more effective. Efficacy of cough suppressants must be tested in double-blind randomised trials using validated measures of cough in patients with chronic cough not responding to specific treatments. Patients with chronic cough are in desperate need of effective antitussives that can be used either on demand or on a long-term basis.

A study of health effect estimates using competing methods to model personal exposures to ambient PM2.5

Various methods have been developed recently to estimate personal exposures to ambient particulate matter less than 2.5 microm in diameter (PM2.5) using fixed outdoor monitors as well as personal exposure monitors. One class of estimators involves extrapolating values using ambient-source components of PM2.5, such as sulfate and iron. A key step in extrapolating these values is to correct for differences in infiltration characteristics of the component used in extrapolation (such as sulfate within PM2.5) and PM2.5. When this is not done, resulting health effect estimates will be biased. Another class of approaches involves factor analysis methods such as positive matrix factorization (PMF). Using either an extrapolation or a factor analysis method in conjunction with regression calibration allows one to estimate the direct effects of ambient PM2.5 on health, eliminating bias caused by using fixed outdoor monitors and estimated personal ambient PM2.5 concentrations. Several forms of the extrapolation method are defined, including some new ones. Health effect estimates that result from the use of these methods are compared with those from an expanded PMF analysis using data collected from a health study of asthmatic children conducted in Denver, Colorado. Examining differences in health effect estimates among the various methods using a measure of lung function (forced expiratory volume in 1 s) as the health indicator demonstrated the importance of the correction factor(s) in the extrapolation methods and that PMF yielded results comparable with the extrapolation methods that incorporated correction factors.

Effective antitussives for the cough patient: an unmet need

Chronic cough is a prevalent symptom in the community but it is likely that only a small fraction of chronic coughers seek medical attention. Chronic cough can be controlled by addressing the 'cause' of the cough, but not all cough is controlled using this approach; an 'idiopathic' cough or cough of unknown aetiology is becoming more well-recognized. In these patients and in those whose cough has not responded to treatment of the cause(s), there is a lack of efficacious antitussive therapies ('non-specific' antitussives). Even in those whose cough is controlled by treatment of the cause, an efficacious antitussive for symptomatic relief would be useful for breakthrough symptoms. It is necessary to address the mechanisms underlying chronic cough, particularly the process of sensitization, both peripherally and centrally, that is the basis of chronic cough; such a process may persist even in the absence of the initiating event that first induced the cough. Currently-available antitussives in both acute and chronic cough are not very effective. Novel targets that may result in effective antitussives have been identified and with the development of clinical tools to measure cough accurately and reliably (e.g. cough counts and cough-specific quality-of-life questionnaires) and the evoked cough response (e.g. citric acid or capsaicin challenges), clinical trials should be performed. The chronic cough population is clinically heterogeneous but is characterized by an enhanced cough reflex; this should be the target population for study. Patients with chronic cough are in desperate need of effective antitussives that can be used either on demand or on a long-term basis.

Air pollution: a threat to the health of our children

BACKGROUND/METHODS

Current air pollution levels pose a threat to the health of children starting from conception. The scientific evidence is presented for mortality, morbidity, and sub-clinical effects. The first section deals with exposure data, the following sections with the evidence of health effects from epidemiology and toxicology leading to recommendations.

RESULTS

Improved air quality reduces the number of infants' deaths as well as disease and pain.

CONCLUSIONS

Medical doctors have a responsibility to know the facts and to advise their patients. Doctors when visiting their patients' homes should be aware of the possibly grave impact of the indoor environment for the respiratory health of their patients. They should recognize and advise the parents on problems associated with environmental tobacco smoke, poor ventilation, mould growth, and maintenance of heating installations. With regard to outdoor air pollution, doctors could serve as role models and also advise their patients and parents on environmentally friendly behaviour. Such behaviour not only calls for personal commitment but also for the right infrastructure to be provided (e.g. public transport, district heating). Doctors should be proactive in the community and in their country as advocates for a healthier environment for our children.

Ambient air pollution and asthma exacerbations in children: an eight-city analysis

The authors investigated the relation between ambient concentrations of five of the Environmental Protection Agency's criteria pollutants and asthma exacerbations (daily symptoms and use of rescue inhalers) among 990 children in eight North American cities during the 22-month prerandomization phase (November 1993-September 1995) of the Childhood Asthma Management Program. Short-term effects of carbon monoxide, nitrogen dioxide, particulate matter less than 10 mum in aerodynamic diameter (PM10), sulfur dioxide, and warm-season ozone were examined in both one-pollutant and two-pollutant models, using lags of up to 2 days. Lags in carbon monoxide and nitrogen dioxide were positively associated with both measures of asthma exacerbation, and the 3-day moving sum of sulfur dioxide levels was marginally related to asthma symptoms. PM10 and ozone were unrelated to exacerbations. The strongest effects tended to be seen with 2-day lags, where a 1-parts-per-million change in carbon monoxide and a 20-parts-per-billion change in nitrogen dioxide were associated with symptom odds ratios of 1.08 (95% confidence interval (CI): 1.02, 1.15) and 1.09 (95% CI: 1.03, 1.15), respectively, and with rate ratios for rescue inhaler use of 1.06 (95% CI: 1.01, 1.10) and 1.05 (95% CI: 1.01, 1.09), respectively. The authors believe that the observed carbon monoxide and nitrogen dioxide associations can probably be attributed to mobile-source emissions, though more research is required.

Ozone and PM2.5 exposure and acute pulmonary health effects: a study of hikers in the Great Smoky Mountains National Park

To address the lack of research on the pulmonary health effects of ozone and fine particulate matter (</= 2.5 microm in aerodynamic diameter; PM2.5) on individuals who recreate in the Great Smoky Mountains National Park (USA) and to replicate a study performed at Mt. Washington, New Hampshire (USA) , we conducted an observational study of adult (18-82 years of age) day hikers of the Charlies Bunion trail during 71 days of fall 2002 and summer 2003. Volunteer hikers performed pre- and posthike pulmonary function tests (spirometry), and we continuously monitored ambient O3, PM2.5, temperature, and relative humidity at the trailhead. Of the 817 hikers who participated, 354 (43%) met inclusion criteria (nonsmokers and no use of bronchodilators within 48 hr) and gave acceptable and reproducible spirometry. For these 354 hikers, we calculated the posthike percentage change in forced vital capacity (FVC) , forced expiratory volume in 1 sec (FEV1) , FVC/FEV1, peak expiratory flow, and mean flow rate between 25 and 75% of the FVC and regressed each separately against pollutant (O3 or PM2.5) concentration, adjusting for age, sex, hours hiked, smoking status (former vs. never) , history of asthma or wheeze symptoms, hike load, reaching the summit, and mean daily temperature. O3 and PM2.5 concentrations measured during the study were below the current federal standards, and we found no significant associations of acute changes in pulmonary function with either pollutant. These findings are contrasted with those in the Mt. Washington study to examine the hypothesis that pulmonary health effects are associated with exposure to O3 and PM2.5 in healthy adults engaged in moderate exercise. .

Origin and health impacts of emissions of toxic by-products and fine particles from combustion and thermal treatment of hazardous wastes and materials

High-temperature, controlled incineration and thermal treatment of contaminated soils, sediments, and wastes at Superfund sites are often preferred methods of remediation of contaminated sites under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 and related legislation. Although these methods may be executed safely, formation of toxic combustion or reaction by-products is still a cause of concern. Emissions of polycyclic aromatic hydrocarbons (PAHs) ; chlorinated hydrocarbons (CHCs) , including polychlorinated dibenzo-p-dioxins and dibenzofurans ; and toxic metals (e.g., chromium VI) have historically been the focus of combustion and health effects research. However, fine particulate matter (PM) and ultrafine PM, which have been documented to be related to cardiovascular disease, pulmonary disease, and cancer, have more recently become the focus of research. Fine PM and ultrafine PM are effective delivery agents for PAHs, CHCs, and toxic metals. In addition, it has recently been realized that brominated hydrocarbons (including brominated/chlorinated dioxins) , redox-active metals, and redox-active persistent free radicals are also associated with PM emissions from combustion and thermal processes. In this article, we discuss the origin of each of these classes of pollutants, the nature of their association with combustion-generated PM, and the mechanisms of their known and potential health impacts.

Particulate levels are associated with early asthma worsening in children with persistent disease

RATIONALE

Ambient particulate concentrations have been associated with variable physiologic effects in children with persistent asthma taking controller medications.

OBJECTIVE

To determine whether exposure to particulate matter has immediate effects on asthma control in children with persistent disease.

METHODS AND MEASUREMENTS

In a school-based cohort, 73 children, primarily with moderate and severe asthma, were followed daily over one or two winters (2001-2002, 2002-2003) in Denver, Colorado. The association among ambient fine particulate, bronchodilator use, and urinary leukotriene E4 levels was assessed.

RESULTS

Daily concentrations of fine particulate peaked in the morning hours when children were commuting to school. In a multivariable analysis that controlled for meteorology, time trends, and upper respiratory infections, an increase of one interquartile range in morning maximum fine particulate levels was related to an average increase of 3.8% in bronchodilator usage at school (95% confidence interval [CI], 0.2-7.4; p = 0.04). Children with severe asthma demonstrated significantly stronger associations (8.1% increase; 95% CI, 2.9-13.4; p = 0.003) than those with mild/moderate disease (1.6% increase; 95% CI, -2.2-5.4; p = 0.41; p = 0.03 for difference between groups). Morning maximum fine particulate levels were also associated with urinary leukotriene E4 measured during school hours (average increase of 6.2% per interquartile range increase; 95% CI, 1.9-10.5; p = 0.006). These associations were not discernable when 24-h averaged concentrations were used.

CONCLUSIONS

Peak concentrations of ambient fine particulate are associated with early increases in bronchodilator use and urinary leukotriene E4 levels among children with persistent asthma, despite the use of controller medications.

Guidelines for evaluating chronic cough in pediatrics: ACCP evidence-based clinical practice guidelines

OBJECTIVES

To review relevant literature and present evidence-based guidelines to assist general and specialist medical practitioners in the evaluation and management of children who present with chronic cough.

METHODOLOGY

The Cochrane, MEDLINE, and EMBASE databases, review articles, and reference lists of relevant articles were searched and reviewed by a single author. The date of the last comprehensive search was December 5, 2003, and that of the Cochrane database was November 7, 2004. The authors' own databases and expertise identified additional articles.

RESULTS/CONCLUSIONS

Pediatric chronic cough (ie, cough in children aged <15 years) is defined as a daily cough lasting for >4 weeks. This time frame was chosen based on the natural history of URTIs in children and differs from the definition of chronic cough in adults. In this guideline, only chronic cough will be discussed. Chronic cough is subdivided into specific cough (ie, cough associated with other symptoms and signs suggestive of an associated or underlying problem) and nonspecific cough (ie, dry cough in the absence of an identifiable respiratory disease of known etiology). The majority of this section focuses on nonspecific cough, as specific cough encompasses the entire spectrum of pediatric pulmonology. A review of the literature revealed few randomized controlled trials for treatment of nonspecific cough. Management guidelines are summarized in two pathways. Recommendations are derived from a systematic review of the literature and were integrated with expert opinion. They are a general guideline only, do not substitute for sound clinical judgment, and are not intended to be used as a protocol for the management of all children with a coughing illness. Children (aged <15 years) with cough should be managed according to child-specific guidelines, which differ from those for adults as the etiologic factors and treatments for children are sometimes different from those for adults. Cough in children should be treated based on etiology, and there is no evidence for using medications for the symptomatic relief of cough. If medications are used, it is imperative that the children are followed up and therapy with the medications stopped if there is no effect on the cough within an expected time frame. An evaluation of the time to response is important. Irrespective of diagnosis, environmental influences and parental expectations should be discussed and managed accordingly. Cough often impacts the quality of life of both children and parents, and the exploration of parental expectations and fears is often valuable in the management of cough in children.

Cough: are children really different to adults?

Worldwide paediatricians advocate that children should be managed differently from adults. In this article, similarities and differences between children and adults related to cough are presented. Physiologically, the cough pathway is closely linked to the control of breathing (the central respiratory pattern generator). As respiratory control and associated reflexes undergo a maturation process, it is expected that the cough would likewise undergo developmental stages as well. Clinically, the 'big three' causes of chronic cough in adults (asthma, post-nasal drip and gastroesophageal reflux) are far less common causes of chronic cough in children. This has been repeatedly shown by different groups in both clinical and epidemiological studies. Therapeutically, some medications used empirically for cough in adults have little role in paediatrics. For example, anti-histamines (in particular H1 antagonists) recommended as a front-line empirical treatment of chronic cough in adults have no effect in paediatric cough. Instead it is associated with adverse reactions and toxicity. Similarly, codeine and its derivatives used widely for cough in adults are not efficacious in children and are contraindicated in young children. Corticosteroids, the other front-line empirical therapy recommended for adults, are also minimally (if at all) efficacious for treating non-specific cough in children. In summary, current data support that management guidelines for paediatric cough should be different to those in adults as the aetiological factors and treatment in children significantly differ to those in adults.