Air pollution and asthma severity in adults

Living in environmental justice areas worsens asthma severity and control: Differential interactions with disease duration, age at onset, and pollution

BACKGROUND

Impoverished and historically marginalized communities often reside in areas with increased air pollution.

OBJECTIVE

We evaluated the association between environmental justice (EJ) track and asthma severity and control as modified by traffic-related air pollution (TRAP).

METHODS

We performed a retrospective study of 1526 adult asthma patients in Allegheny County, Pa, enrolled in an asthma registry during 2007-20. Asthma severity and control were determined using global guidelines. EJ tract designation was based on residency in census tracts with ≥30% non-White and/or ≥20% impoverished populations. TRAP exposures (NO2 and black carbon) for each census tract were normalized into pollution quartiles. Generalized linear model analyses determined the effect of EJ tract and TRAP on asthma.

RESULTS

TRAP exposure in the highest quartile range was more frequent among patients living in an EJ tract (66.4% vs 20.8%, P < .05). Living in an EJ tract increased the odds of severe asthma in later onset asthma. The odds of uncontrolled asthma increased with disease duration in all patients living in EJ tracts (P < .05). Living in the highest quartile of NO2 also increased the odds of uncontrolled asthma in patients with severe disease (P < .05), while there was no effect of TRAP on uncontrolled asthma in patients with less severe disease (P > .05).

CONCLUSIONS

Living in an EJ tract increased the odds of severe and uncontrolled asthma and was influenced by age at onset, disease duration, and potentially by TRAP exposure. This study underscores the need to better understand the complex environmental interactions that affect lung health in groups that have been economically and/or socially marginalized.

Impacts of residential indoor air quality and environmental risk factors on adult asthma-related health outcomes in Chicago, IL

BACKGROUND

Residential environments are known to contribute to asthma.

OBJECTIVE

To examine the joint impacts of exposures to residential indoor and outdoor air pollutants and housing risk factors on adult asthma-related health outcomes.

METHODS

We analyzed >1-year of data from 53 participants from 41 homes in the pre-intervention period of the Breathe Easy Project prior to ventilation and filtration retrofits. Health outcomes included surveys of asthma control, health-related quality of life, stress, and healthcare utilizations. Environmental assessments included quarterly measurements of indoor and outdoor pollutants (e.g., HCHO, CO, CO2, NO2, O3, and PM), home walk-throughs, and surveys of environmental risk factors. Indoor pollutant concentrations were also matched with surveys of time spent at home to estimate indoor pollutant exposures.

RESULTS

Cross-sectional analyses using mixed-effects models indicated that lower annual average asthma control test (ACT) scores were associated (p < 0.05) with higher indoor NO2 (concentration/exposure: β = -2.42/-1.57), indoor temperature (β = -1.03 to -0.94), and mold/dampness (β = -3.09 to -2.41). In longitudinal analysis, lower ACT scores were also associated (p < 0.05) with higher indoor NO2 concentrations (β = -0.29), PM1 (concentration/exposure: β = -0.12/-0.24), PM2.5 (concentration/exposure: β = -0.12/-0.26), and PM10 (concentration/exposure: β = 10.14/-0.28). Emergency department visits were associated with poorer asthma control [incidence rate ratio (IRR) = 0.84; p < 0.001], physical health (IRR = 0.95; p < 0.05), mental health (IRR = 0.95; p < 0.05), higher I/O NO2 ratios (IRR = 1.30; p < 0.05), and higher indoor temperatures (IRR = 1.41; p < 0.05).

SIGNIFICANCE

Findings suggest that residential risk factors, including indoor air pollution (especially NO2 and particulate matter), higher indoor temperature, and mold/dampness, may contribute to poorer asthma control.

IMPACT

This study highlights the importance of residential indoor air quality and environmental risk factors for asthma control, health-related quality of life, and emergency department visits for asthma. Two timescales of mixed models suggest that exposure to indoor NO2 and particulate matter, higher indoor temperature, and mold/dampness was associated with poorer asthma control. Additionally, emergency department visits were associated with poorer asthma control and health-related quality of life, as well as higher I/O NO2 ratios and indoor temperatures. These findings deepen our understanding of the interrelationships between housing, air quality, and health, and have important implications for programs and policy.

Derivation of asthma severity from electronic prescription records using British thoracic society treatment steps

Background:

Asthma severity is typically assessed through a retrospective assessment of the treatment required to control symptoms and to prevent exacerbations. The joint British Thoracic Society and Scottish Intercollegiate Guidelines Network (BTS/SIGN) guidelines encourage a stepwise approach to pharmacotherapy, and as such, current treatment step can be considered as a severity categorisation proxy. Briefly, the steps for adults can be summarised as: no controller therapy (Step 0), low-strength Inhaled Corticosteroids (ICS; Step 1), ICS plus Long-Acting Beta-2 Agonist (LABA; Step 2), medium-dose ICS + LABA (Step 3), and finally either an increase in strength or additional therapies (Step 4). This study aimed to investigate how BTS/SIGN Steps can be estimated from across a large cohort using electronic prescription records, and to describe the incidence of each BTS/SIGN Step in a general population.

Methods:

There were 41,433,707 prescriptions, for 671,304 individuals, in the Asthma Learning Health System Scottish cohort, between 1/2009 and 3/2017. Days on which an individual had a prescription for at least one asthma controller (preventer) medication were labelled prescription events. A rule-based algorithm was developed for extracting the strength and volume of medication instructed to be taken daily from free-text data fields. Asthma treatment regimens were categorised by the combination of medications prescribed in the 120 days preceding any prescription event and categorised into BTS/SIGN treatment steps.

Results:

Almost 4.5 million ALHS prescriptions were for asthma controllers. 26% of prescription events had no inhaled corticosteroid prescriptions in the preceding 120 days (Step 0), 16% were assigned to BTS/SIGN Step 1, 7% to Step 2, 21% to Step 3, and 30% to Step 4. The median days spent on a treatment step before a step-down in treatment was 297 days, whereas a step-up only took a median of 134 days.

Conclusion

We developed a reproducible methodology enabling researchers to estimate BTS/SIGN asthma treatment steps in population health studies, providing valuable insights into population and patient-specific trajectories, towards improving the management of asthma.

Digital Healthcare for Airway Diseases from Personal Environmental Exposure

Digital technologies have emerged in various dimensions of human life, ranging from education to professional services to well-being. In particular, health products and services have expanded by the use and development of artificial intelligence, mobile health applications, and wearable electronic devices. Such advancements have enabled accurate and updated tracking and modeling of health conditions. For instance, digital health technologies are capable of measuring environmental pollution and predicting its adverse health effects. Several health conditions, including chronic airway diseases such as asthma and chronic obstructive pulmonary disease, can be exacerbated by pollution. These diseases impose substantial health burdens with high morbidity and mortality. Recently, efforts have been made to develop digital technologies to alleviate such conditions. Moreover, the COVID-19 pandemic has facilitated the application of telemedicine and telemonitoring for patients with chronic airway diseases. This article reviews current trends and studies in digital technology utilization for investigating and managing environmental exposure and chronic airway diseases. First, we discussed the recent progression of digital technologies in general environmental healthcare. Then, we summarized the capacity of digital technologies in predicting exacerbation and self-management of airway diseases. Concluding these reviews, we provided suggestions to improve digital health technologies' abilities to reduce the adverse effects of environmental exposure in chronic airway diseases, based on personal exposure-response modeling.

External Environmental Pollution as a Risk Factor for Asthma

Air pollution is a worrisome risk factor for global morbidity and mortality and plays a special role in many respiratory conditions. It contributes to around 8 million deaths/year, with outdoor exposure being responsible for more than 4.2 million deaths throughout the world, while more than 3.8 million die from situations related to indoor pollution. Pollutant agents induce several respiratory symptoms. In addition, there is a clear interference in numerous asthma outcomes, such as incidence, prevalence, hospital admission, visits to emergency departments, mortality, and asthma attacks, among others. The particulate matter group of pollutants includes coarse particles/PM₁₀, fine particles/PM_2.5, and ultrafine particles/PM_0.1. The gaseous components include ground-level ozone, nitrogen dioxide, sulfur dioxide, and carbon monoxide. The timing, load, and route of allergen exposure are other items affecting allergic disease phenotypes. The complex interaction between pollutant exposures and human host factors has an implication in the development and rise of asthma as a public health problem. However, there are hiatuses in the understanding of the pathways in this disease. The routes through which pollutants induce asthma are multiple, and include the epigenetic changes that occur in the respiratory tract microbiome, oxidative stress, and immune dysregulation. In addition, the expansion of the modern Westernized lifestyle, which is characterized by intense urbanization and more time spent indoors, resulted in greater exposure to polluted air. Another point to consider is the different role of the environment according to age groups. Children growing up in economically disadvantaged neighborhoods suffer more important negative health impacts. This narrative review highlights the principal polluting agents, their sources of emission, epidemiological findings, and mechanistic evidence that links environmental exposures to asthma.

Long-term air pollution exposure is associated with increased severity of rhinitis in 2 European cohorts

BACKGROUND

Very few studies have examined the association between long-term outdoor air pollution and rhinitis severity in adults.

OBJECTIVE

We sought to assess the cross-sectional association between individual long-term exposure to air pollution and severity of rhinitis.

METHODS

Participants with rhinitis from 2 multicenter European cohorts (Epidemiological Study on the Genetics and Environment on Asthma and the European Community Respiratory Health Survey) were included. Annual exposure to NO₂, PM₁₀, PM_2.5, and PM_coarse (calculated by subtracting PM_2.5 from PM₁₀) was estimated using land-use regression models derived from the European Study of Cohorts for Air Pollution Effects project, at the participants' residential address. The score of rhinitis severity (range, 0-12), based on intensity of disturbance due to symptoms reported by questionnaire, was categorized into low (reference), mild, moderate, and high severity. Polytomous logistic regression models with a random intercept for city were used.

RESULTS

A total of 1408 adults with rhinitis (mean age, 52 years; 46% men, 81% from the European Community Respiratory Health Survey) were included. The median (1st quartile-3rd quartile) score of rhinitis severity was 4 (2-6). Higher exposure to PM₁₀ was associated with higher rhinitis severity (adjusted odds ratio [95% CI] for a 10 μg/m³ increase in PM₁₀: for mild: 1.20 [0.88-1.64], moderate: 1.53 [1.07-2.19], and high severity: 1.72 [1.23-2.41]). Similar results were found for PM_2.5. Higher exposure to NO₂ was associated with an increased severity of rhinitis, with similar adjusted odds ratios whatever the level of severity. Adjusted odds ratios were higher among participants without allergic sensitization than among those with, but interaction was found only for NO_2. CONCLUSIONS: People with rhinitis who live in areas with higher levels of pollution are more likely to report more severe nasal symptoms. Further work is required to elucidate the mechanisms of this association.

Does the oxidative stress play a role in the associations between outdoor air pollution and persistent asthma in adults? Findings from the EGEA study

BACKGROUND

Evidences that oxidative stress plays a role in the associations between outdoor air pollution and asthma are growing. We aimed to study the role of plasma fluorescent oxidation products levels (FlOPs; an oxidative stress-related biomarker), as potential mediators, in the associations between outdoor air pollution and persistent asthma.

METHODS

Analyses were conducted in 204 adult asthmatics followed up in the French case-control and family study on asthma (EGEA; the Epidemiological study of the Genetic and Environmental factors of Asthma). Persistent asthma was defined as having current asthma at EGEA2 (baseline, 2003-2007) and EGEA3 (follow-up, 2011-2013). Exposures to nitrogen dioxide, nitrogen oxides, road traffic, particulate matter with a diameter ≤ 10 μm (PM₁₀) and ≤ 2.5 μm were estimated by ESCAPE models (2009-2010), and ozone (O₃) by IFEN models (2004). We used a mediation analysis to assess the mediated effect by FlOPs levels and the interaction between FlOPs levels and air pollution.

RESULTS

FlOPs levels increased with PM₁₀ and O₃ (adjusted β = 0.04 (95%CI 0.001-0.08), aβ = 0.04 (95%CI 0.009-0.07) per 10 μg/m³, respectively), and the risk of persistent asthma increased with FlOPs levels (aOR = 1.81 (95%CI 1.08-3.02)). The risk of persistent asthma decreased with exposures to NO₂, NOx and PM_2.5 (aOR ranging from 0.62 to 0.94), and increased with exposures to PM₁₀, O₃, O_3-summer and road traffic, the greater effect being observed for O₃ (aOR = 1.78, 95% CI 0.73-4.37, per 10 μg/m³). Using mediation analysis, we observed a positive total effect (aOR = 2.16, 95%CI 0.70-11.9), a positive direct effect of O₃ on persistent asthma (OR = 1.68, 95%CI 0.57-7.25), and a positive indirect effect mediated by FIOPs levels (aOR = 1.28 (95%CI 1.01-2.29)) accounting for 41% of the total effect.

CONCLUSIONS

Our results add insights on the role of oxidative stress in the association between air pollution and persistent asthma.

Distributions of Human Exposure to Ozone During Commuting Hours in Connecticut Using the Cellular Device Network

Epidemiologic studies have established associations between various air pollutants and adverse health outcomes for adults and children. Due to high costs of monitoring air pollutant concentrations for subjects enrolled in a study, statisticians predict exposure concentrations from spatial models that are developed using concentrations monitored at a few sites. In the absence of detailed information on when and where subjects move during the study window, researchers typically assume that the subjects spend their entire day at home, school, or work. This assumption can potentially lead to large exposure assignment bias. In this study, we aim to determine the distribution of the exposure assignment bias for an air pollutant (ozone) when subjects are assumed to be static as compared to accounting for individual mobility. To achieve this goal, we use cell-phone mobility data on approximately 400,000 users in the state of Connecticut, USA during a week in July 2016, in conjunction with an ozone pollution model, and compare individual ozone exposure assuming static versus mobile scenarios. Our results show that exposure models not taking mobility into account often provide poor estimates of individuals commuting into and out of urban areas: the average 8-h maximum difference between these estimates can exceed 80 parts per billion (ppb). However, for most of the population, the difference in exposure assignment between the two models is small, thereby validating many current epidemiologic studies focusing on exposure to ozone.

Supplementary materials accompanying this paper appear online.

Longitudinal Effect of Ambient Air Pollution and Pollen Exposure on Asthma Control: The Patient-Reported Outcomes Measurement Information System (PROMIS) Pediatric Asthma Study

OBJECTIVE

Although exposure to air pollution and pollen is associated with asthma exacerbation and increased health care use, longitudinal effects of fine particulate matter 2.5 (PM_2.5), ozone (O₃), and pollen exposure on asthma control status in pediatric patients are understudied. This study investigated effects of exposure to PM_2.5, O₃, and pollen on asthma control status among pediatric patients with asthma.

METHODS

A total of 229 dyads of pediatric patients with asthma and their parents were followed for 15 months. The Asthma Control and Communication Instrument was used to measure asthma control, which was reported weekly by parents during a 26-week period. PM_2.5 and O₃ data were collected from the US Environmental Protection Agency Air Quality System. Pollen data were obtained from Intercontinental Marketing Services Health. Mean air pollutant and pollen exposures within 7 days before the reporting of asthma control were used to estimate weekly exposures for each participant. Linear mixed-effects models were performed to test associations of PM_2.5, O₃, and pollen exposure with asthma control status. Sensitivity analyses were performed to evaluate the robustness of findings by different exposure monitoring days per week and distances between monitoring sites and participants' residences.

RESULTS

Elevated PM_2.5 concentration and pollen severity were associated with poorer asthma control status (P < .05), yet elevated O₃ concentration was marginally associated with better asthma control (P < .1).

CONCLUSIONS

Poorer asthma control status was associated with elevated PM_2.5 and pollen severity. Reducing harmful outdoor environmental ambient exposure may improve asthma outcomes in children and adolescents.

Association between processed meat intake and asthma symptoms in the French NutriNet-Santé cohort

PURPOSE

Processed meat intake may adversely affect lung health, but data on asthma remains sparse. The magnitude of the processed meat-asthma association may also depend on other unhealthy behaviors. We investigated the association between processed meat intake and the asthma symptom score, and the combined role of unhealthy weight, smoking, low diet quality, and high processed meat intake on the asthma score.

METHODS

In 2017, 35,380 participants to the NutriNet-Santé cohort answered a detailed respiratory web-questionnaire. Asthma was defined by the asthma symptom score (sum of 5 questions; continuous variable). Based on repeated 24-h dietary records collected on a dedicated website, processed meat consumption was classified as 0, < 2, 2-5, > 5 servings/week. We examined the combined role of body mass index (BMI) (< 25 vs. ≥ 25 kg/m²), smoking (never vs. ever), diet quality score (highest vs. lowest), and processed meat (≤ 5 vs. > 5 servings/week) on the asthma symptom score.

RESULTS

Participants were aged 54 on average (women: 75%, smokers: 49%, BMI ≥ 25: 32%, ≥ 1 asthma symptoms: 27%). After adjustment for confounders, processed meat intake was positively and significantly associated with asthma symptom score: odds ratios (ORs) (95% CI) for > 5 vs. 0 servings/week were 1.15 (1.04-1.27) in women; 1.23 (1.01-1.50) in men. Compared to participants with 0 unhealthy behaviors, ORs for the asthma symptom score among participants with the 4 combined unhealthy behaviors were 2.18 (1.91-2.48) in women; 2.70 (2.10-3.45) in men.

CONCLUSION

High processed meat consumption was associated with higher asthma symptoms, and combining overweight/obesity, smoking, low diet quality, with high processed meat intake was strongly associated with asthma symptoms.

An approach estimating the short-term effect of NO2 on daily mortality in Spanish cities

BACKGROUND

Road traffic is the most significant source of urban air pollution. PM_2.5 is the air pollutant whose health effects have been most closely studied, and is the variable most commonly used as a proxy indicator of exposure to air pollution, whereas evidence on NO₂ concentrations per se is still under study. In the case of Spain, there are no specific updated studies which calculate short-term NO₂-related mortality.

OBJECTIVE

To quantify the relative risks (RRs) and attributable risks (ARs) of daily mortality associated with NO₂ concentrations recorded in Spain across the study period, 2000-2009; and to calculate the number of NO₂-related deaths.

MATERIAL AND METHODS

We calculated daily mortality due to natural causes (ICD-10: A00 R99), circulatory causes (ICD-10: I00 I99) and respiratory causes (ICD-10: J00 J99) for each province across the period 2000-2009, using data supplied by the National Statistics Institute. Mean daily NO₂ concentrations in μg/m³ for each provincial capital were furnished by the Ministry of Agriculture & Environment, along with the equivalent figures for the control pollutants (PM₁₀). To estimate RRs and ARs, we used generalised linear models with a Poisson link, controlling for maximum and minimum daily temperature, trend of the series, seasonalities, and the autoregressive nature of the series. A meta-analysis with random effects was used to estimate RRs and ARs nationwide.

RESULTS

The overall RRs obtained for Spain, corresponding to increases of 10 μg/m³ in NO₂ concentrations were 1.012 (95% CI: 1.010 1.014) for natural-cause mortality, 1.028 (95% CI: 1.019 1.037) for respiratory-cause mortality, and 1.016 (95% CI: 1.012 1.021) for circulatory-cause mortality. This amounted to an annual overall 6085 deaths (95% CI: 3288 9427) due to natural causes, 1031 (95% CI: 466 1585) due to respiratory causes, and 1978 (95% CI: 828 3197) due to circulatory causes.

CONCLUSION

By virtue of the number of cities involved and the nature of the analysis performed, with quantification of the RRs and ARs of the short-term impact of NO₂ on daily mortality in Spain, this study provides an updated estimate of the effect had by this type of pollutant on causes of mortality, and constitutes an important basis for reinforcing public health measures at a national level.

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

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

Level of asthma control and risk factors for poor asthma control among clinic patients seen at a Referral Hospital in Addis Ababa, Ethiopia

OBJECTIVE

Uncontrolled asthma negatively impacts patients, families, and the community. The level of symptom control among asthmatics in Ethiopia has not been well studied. We investigated the level of asthma control and risk factors for poor asthma control in clinic patients seen in the largest public hospital in Ethiopia.

RESULTS

In this cross-sectional study, we studied all 182 consecutive subjects with a physician diagnosis of asthma who were seen in chest clinic at Tikur Anbessa Specialized Hospital between July and December 2015. Of the 182 subjects, 68.1% were female. The mean age was 52 ± 12 years and the median duration of asthma was 20 ± 12.7 years. One hundred and seventeen subjects (64.3%) had nighttime awakening due to asthma. Fifty-eight (31%) were not using controller medications and 62 (34.6%) had improper inhaler technique. Only 44 (24.2%) subjects had well-controlled asthma. On multivariate analysis, variables associated with uncontrolled asthma included: use of biomass fuel for cooking, longer duration of asthma (> 30 year), incorrect inhalation technique, and asthma exacerbation in the last 12 months. Most asthmatics attending in the largest public hospital in Ethiopia, had uncontrolled asthma. Several risk factors for poor asthma control were identified. Improved asthma control is possible through directed interventions.

Assessment of asthma severity in adults with ever asthma: A continuous score

BACKGROUND

In epidemiological studies, continuous measures of asthma severity should be used to catch the heterogeneity of phenotypes. This study aimed at developing and validating continuous measures of asthma severity in adult patients with ever asthma from the general population, to be used in epidemiological studies.

METHODS

Respiratory symptoms, anti-asthmatic treatment and lung function were measured on 520 patients with ever asthma aged 20-64 years from the general Italian population (GEIRD study; 2007/2010). The variables that represent the same dimension of asthma severity were identified through an exploratory factor analysis and were summarized through a multiple factor analysis.

RESULTS

Only respiratory symptoms and anti-asthmatic treatment were summarized in a continuous score (STS). STS ranges from 0 (no symptoms/treatment) to 10 (maximum symptom frequency and treatment intensity). STS was positively correlated with the Global Initiative for Asthma classification of asthma severity computed on the 137 cases with a doctor's diagnosis (Spearman's coefficient = 0.61, p-value<0.0001) (concurrent validity). Furthermore, using a cohort of 1,097 European asthmatics (ECRHS II study; 1999/2002), increasing STS levels at baseline (1991/1993) were positively associated with long-term outcomes (hospitalization and lost workdays for breathing problems, asthma attack frequency and use of asthma controllers) (predictive validity). Finally, the STS scores computed from the GEIRD and ECRHS II data were comparable (Lin's coefficient = 0.95, p-value<0.0001) (replication analysis).

CONCLUSIONS

STS is a valid and replicable measure of asthma severity in adults, which could be used in association studies.

Respiratory virus transmission dynamics determine timing of asthma exacerbation peaks: Evidence from a population-level model

Asthma exacerbations exhibit a consistent annual pattern, closely mirroring the school calendar. Although respiratory viruses--the "common cold" viruses--are implicated as a principal cause, there is little evidence to link viral prevalence to seasonal differences in risk. We jointly fit a common cold transmission model and a model of biological and environmental exacerbation triggers to estimate effects on hospitalization risk. Asthma hospitalization rate, influenza prevalence, and air quality measures are available, but common cold circulation is not; therefore, we generate estimates of viral prevalence using a transmission model. Our deterministic multivirus transmission model includes transmission rates that vary when school is closed. We jointly fit the two models to 7 y of daily asthma hospitalizations in adults and children (66,000 events) in eight metropolitan areas. For children, we find that daily viral prevalence is the strongest predictor of asthma hospitalizations, with transmission reduced by 45% (95% credible interval =41-49%) during school closures. We detect a transient period of nonspecific immunity between infections lasting 19 (17-21) d. For adults, hospitalizations are more variable, with influenza driving wintertime peaks. Neither particulate matter nor ozone was an important predictor, perhaps because of the large geographic area of the populations. The school calendar clearly and predictably drives seasonal variation in common cold prevalence, which results in the "back-to-school" asthma exacerbation pattern seen in children and indirectly contributes to exacerbation risk in adults. This study provides a framework for anticipating the seasonal dynamics of common colds and the associated risks for asthmatics.

[Genetic and environmental factors of asthma and allergy: Results of the EGEA study]

INTRODUCTION AND METHODS

The EGEA study (epidemiological study on the genetics and environment of asthma, bronchial hyperresponsiveness and atopy), which combines a case-control and a family-based study of asthma case (n=2120 subjects) with three surveys over 20 years, aims to identify environmental and genetic factors associated with asthma and asthma-related phenotypes. We summarize the results of the phenotypic characterization and the investigation of environmental and genetic factors of asthma and asthma-related phenotypes obtained since 2007 in the EGEA study (42 articles).

RESULTS

Both epidemiological and genetic results confirm the heterogeneity of asthma. These results strengthen the role of the age of disease onset, the allergic status and the level of disease activity in the identification of the different phenotypes of asthma. The deleterious role of active smoking, exposure to air pollution, occupational asthmogenic agents and cleaning products on the prevalence and/or activity of asthma has been confirmed. Accounting for gene-environment interactions allowed the identification of new genetic factors underlying asthma and asthma-related traits and better understanding of their mode of action.

CONCLUSION

The EGEA study is contributing to the advances in respiratory research at the international level. The new phenotypic, environmental and biological data available in EGEA study will help characterizing the long-term evolution of asthma and the factors associated to this evolution.

Quality of life in relation to the traffic pollution indicators NO2 and NOx: results from the Swedish GA(2)LEN survey

BACKGROUND

Asthma is a chronic disease that may affect daily activities and quality of life. Asthmatics have higher incidence of chronic rhinosinusitis (CRS) and asthma is associated with sinonasal inflammation and nasal symptoms, that all impair quality of life. Worsening of asthma has been found associated with levels of nitrogen dioxide as traffic indicator.

AIMS

The aim of the study was to evaluate the impact of traffic pollution indicated by nitrogen oxides (NO2 and NOx) on quality of life in asthmatic persons, individuals with CRS and controls.

METHODS

Within the Swedish Ga(2)len (Global Allergy and Asthma European Network), 605 asthmatics with and without CRS, 110 individuals with CRS only and 226 controls from four cities were surveyed. The mini Asthma Quality of life Questionnaire (mAQLQ) and the Euro Quality of Life (EQ-5D) health questionnaire were used. Air pollution concentrations at the home address were modelled using dispersion models.

RESULTS

Levels of NO2 (geometric mean 10.1 μg/m(3) (95% CI 9.80 to 10.5) and NOx (12.1 μg/m(3), 11.7 to 12.6) were similar among conditions (controls, asthmatics, individuals with CRS and asthmatics with CRS). The mAQLQ overall score was not found associated with levels of NO2 or NOx, with or without adjustments, and neither was scores within each of the four domains of mAQLQ: symptoms, activity limitations, emotional functions and effects of environmental stimuli. The mean EQ-5D index value, based on the five dimensions mobility, self-care, usual activities, pain/discomfort and anxiety depression, was also found unrelated to NO2 and NOx.

CONCLUSIONS

At moderate exposure levels traffic pollution appears not to affect quality of life.

Forecasting asthma-related hospital admissions in London using negative binomial models

Health forecasting can improve health service provision and individual patient outcomes. Environmental factors are known to impact chronic respiratory conditions such as asthma, but little is known about the extent to which these factors can be used for forecasting. Using weather, air quality and hospital asthma admissions, in London (2005-2006), two related negative binomial models were developed and compared with a naive seasonal model. In the first approach, predictive forecasting models were fitted with 7-day averages of each potential predictor, and then a subsequent multivariable model is constructed. In the second strategy, an exhaustive search of the best fitting models between possible combinations of lags (0-14 days) of all the environmental effects on asthma admission was conducted. Three models were considered: a base model (seasonal effects), contrasted with a 7-day average model and a selected lags model (weather and air quality effects). Season is the best predictor of asthma admissions. The 7-day average and seasonal models were trivial to implement. The selected lags model was computationally intensive, but of no real value over much more easily implemented models. Seasonal factors can predict daily hospital asthma admissions in London, and there is a little evidence that additional weather and air quality information would add to forecast accuracy.

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.

Climate change and Occupational Health and Safety in a temperate climate: potential impacts and research priorities in Quebec, Canada

The potential impacts of climate change (CC) on Occupational Health and Safety (OHS) have been studied a little in tropical countries, while they received no attention in northern industrialized countries with a temperate climate. This work aimed to establish an overview of the potential links between CC and OHS in those countries and to determine research priorities for Quebec, Canada. A narrative review of the scientific literature (2005-2010) was presented to a working group of international and national experts and stakeholders during a workshop held in 2010. The working group was invited to identify knowledge gaps, and a modified Delphi method helped prioritize research avenues. This process highlighted five categories of hazards that are likely to impact OHS in northern industrialized countries: heat waves/increased temperatures, air pollutants, UV radiation, extreme weather events, vector-borne/zoonotic diseases. These hazards will affect working activities related to natural resources (i.e. agriculture, fishing and forestry) and may influence the socioeconomic context (built environment and green industries), thus indirectly modifying OHS. From this consensus approach, three categories of research were identified: 1) Knowledge acquisition on hazards, target populations and methods of adaptation; 2) Surveillance of diseases/accidents/occupational hazards; and 3) Development of new occupational adaptation strategies.

OBSTRUCTIVE LUNG DISEASE AND EXPOSURE TO BURNING BIOMASS FUEL IN THE INDOOR ENVIRONMENT

It is estimated that up to half of the world's population burns biomass fuel (wood, crop residues, animal dung and coal) for indoor uses such as cooking, lighting and heating. As a result, a large proportion of women and children are exposed to high levels of household air pollution (HAP). The short and long term effects of these exposures on the respiratory health of this population are not clearly understood. On May 9-11, 2011 NIH held an international workshop on the "Health Burden of Indoor Air Pollution on Women and Children," in Arlington, VA. To gather information on the knowledge base on this topic and identify research gaps, ahead of the meeting we conducted a literature search using PubMed to identify publications that related to HAP, asthma, and chronic obstructive pulmonary disease (COPD). Abstracts were all analyzed and we report on those considered by the respiratory sub study group at the meeting to be most relevant to the field. Many of the studies published are symptom-based studies (as opposed to objective measures of lung function or clinical examination etc.) and measurement of HAP was not done. Many found some association between indoor exposures to biomass smoke as assessed by stove type (e.g., open fire vs. liquid propane gas) and respiratory symptoms such as wheeze and cough. Among the studies that examined objective measures (e.g. spirometry) as a health outcome, the data supporting an association between biomass smoke exposure and COPD in adult women are fairly robust, but the findings for asthma are mixed. If an association was observed between the exposures and lung function, most data seemed to demonstrate mild to moderate reductions in lung function, the pathophysiological mechanisms of which need to be investigated. In the end, the group identified a series of scientific gaps and opportunities for research that need to be addressed to better understand the respiratory effects of exposure to indoor burning of the different forms of biomass fuels.

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.

Plasma and exhaled breath condensate nitrite-nitrate level in relation to environmental exposures in adults in the EGEA study

This study evaluated the associations between biological markers in the nitrate-nitrite-NO pathway and four environmental exposures among subjects examined in the second survey (2003-2007) of the French Epidemiological study on Genetics and Environment of Asthma (EGEA). Total nitrite and nitrate (NO(2)(-) /NO(3)(-)) levels were measured both in plasma and in exhaled breath condensate (EBC) in 949 adults. Smoking, diet and exposure to chlorine products were assessed using standardized questionnaires. Exposure to air pollutants was estimated by using geostatistical models. All estimates were obtained with generalized estimating equations for linear regression models. Median levels of NO(2)(-)/NO(3)(-) were 36.3 μM (1st-3rd quartile: 25.7, 51.1) in plasma and 2.0 μmol/mg proteins (1st-3rd quartile 0.9, 3.9) in EBC. After adjustment for asthma, age, sex and menopausal status, plasma NO(2)(-)/NO(3)(-) level increased with leafy vegetable consumption (above versus below median=0.04 (95%CI: 0.001, 0.07)) and decreased in smokers (versus non/ex-smokers=-0.08 (95%CI: -0.11, -0.04). EBC NO(2)(-)/NO(3)(-) level decreased in smokers (-0.08 (95%CI: -0.16, -0.001)) and with exposure to ambient O(3) concentration (above versus below median=-0.10 (95%CI: -0.17, -0.03)). Cured meat, chlorine products, PM(10) and NO(2) concentrations were not associated with NO(2)(-)/NO(3)(-) levels. Results suggest that potential modifiable environmental and behavioral risk factors may modify NO(2)(-)/NO(3)(-) levels in plasma and EBC according to the route of exposure.

Acute effects of air pollution on peak expiratory flow rates and symptoms among asthmatic patients in Chiang Mai, Thailand

The open burnings and forest fires have been recognized as the major sources of severe air pollution in the upper north of Thailand; however, there have been no clear evidences to show the associations between the air pollution and health effects in the area. We assessed the effects of air pollutants on the peak expiratory flow rates (PEFR) and symptoms in asthmatics. A cohort of 121 asthmatics was followed daily, for 306 days, for their PEFR and asthma symptoms. The daily air pollutants, including particulate matter with aerodynamic diameter <2.5 μm, particulate matter with aerodynamic diameter <10 μm (PM(10)), carbon monoxide, ozone, nitrogen dioxide (NO(2)), and sulfur dioxide (SO(2)), and the meteorological parameters, including pressure, temperature, relative humidity, rain quantity, and sunshine duration, were monitored. The PEFRs were fitted with general linear mixed models. The asthma symptoms were analyzed with the generalized estimating equations. There were positive associations of NO(2) with morning PEFR, with a coefficient of 0.06 [95% confidence interval (CI), 0.00-0.12]; of SO(2) with evening PEFR [with a range of coefficients of 0.88-1.00 (95% CI, 0.31-1.54)] and daily average PEFR [with a coefficient of 0.47 (95% CI, 0.00-0.94)]; of PM(10) with evening PEFR, with a coefficient of 0.02 (95% CI, 0.00-0.04). There was also negative association of PM(10) with ΔPEFR, with a coefficient of -0.01 (95% CI, -0.01 to -0.00). No pollutants were related to asthma symptoms. More studies are needed, particularly at low dose in adult asthmatics, to validate our findings.

Formaldehyde interferes with airway epithelium integrity and functions in a dose- and time-dependent manner

Formaldehyde (HCHO) is a common indoor air pollutant. To assess its potential role and mechanism of action in asthma, we exposed the bronchial epithelial cell lines Calu-3 and 16HBE to HCHO (70-7000 μM) according to two exposure schedules (30 min and 24 h), before measuring cell viability, necrosis and apoptosis, reactive oxygen species production, cytokine release, as well as trans-epithelial electrical resistance (TEER) of cell monolayers. Whereas exposure to HCHO for 30 min had a limited effect on cell viability, exposure for 24h to 1400-7000 μM HCHO induced a pronounced dose-dependent cell death. The important decrease in cell viability observed after 24h exposure to the highest concentrations of HCHO (1400-7000 μM) was accompanied by important LDH release and ROS production, whereas a 4h exposure to lower HCHO concentrations (350 μM) induced cell apoptosis. Also, exposure to HCHO for 30 min dose-dependently inhibited basal and lipopolysaccharide-induced interleukin-6 (IL-6) and IL-8 production by bronchial epithelial cells. As well, HCHO triggered a dose- and time-dependent decrease in TEER of Calu-3 cell monolayers. The present work demonstrates that HCHO interferes with airway epithelium integrity and functions, and may thus modulate the onset and the severity of asthma. However, importantly, conditions of exposure to HCHO, e.g. level and duration, are determinant in the nature of the effects triggered by the pollutant.

Air quality and outpatient visits for asthma in adults during the 2008 Summer Olympic Games in Beijing

To fulfill its commitment to a successful 2008 Olympic and Paralympic Games, the Chinese government made unprecedented efforts to improve the air quality in Beijing. We report findings on air quality and outpatient visits for asthma among adults in Beijing during the 2008 Summer Olympic Games. Three study periods were defined: summer baseline (June 1-June 30: before any air pollution controls), pre-Olympics (July 1-August 7: transportation restrictions in effect), and Olympics (August 8-September 20: further restrictions on industrial emissions). Daily data on outpatient asthma visits were obtained from the asthma registry of Beijing Chaoyang Hospital. We used time-series Poisson regression models to estimate the relative risk (RR) for asthma visits associated with pollution levels. The average numbers of outpatient visit for asthma were 12.5 per day at baseline and 7.3 per day during the Olympics. Compared with baseline, the Games were associated with a significant reduction in asthma visits (RR 0.54, 95%CI: 0.39-0.75). Our analysis showed that even in a heavily-polluted city, decreased concentrations of small particles were associated with some reduction in asthma visits in adults.