Risk factors of new-onset asthma in adults: a population-based international cohort study.

BACKGROUND: The occurrence of new-onset asthma during adulthood is common, but there is insufficient understanding of its determinants including the role of atopy. OBJECTIVE: To assess the risk factors for the development of new-onset asthma in middle-aged adults and to compare them according to atopy. METHODS: A longitudinal analysis of 9175 young adults who participated in two surveys of the European Community Respiratory Health Survey (ECRHS) conducted 9 years apart. FINDINGS: We observed 179 cases of new-onset asthma among 4588 participants who were free of asthma and reported at the beginning of the follow-up that they had never had asthma (4.5 per 1000 person-years). In a logistic regression, the following risk factors were found to increase the risk of new-onset asthma: female gender (OR: 1.97; 95% confidence interval (CI): 1.38, 2.81), bronchial hyperresponsiveness (3.25; 2.19, 4.83), atopy (1.55; 1.08, 2.21), FEV(1) < 100 % predicted (1.87; 1.34, 2.62), nasal allergy (1.98;1.39,2.84) and maternal asthma (1.91; 1.13; 3.21). Obesity, respiratory infections in early life and high-risk occupations increased the risk of new-onset asthma although we had limited power to confirm their role. Among the atopics, total IgE and sensitization to cat were independently related to the risk of new-onset asthma. The proportion of new-onset asthma attributable to atopy varied from 12% to 21%. CONCLUSION: Adults reporting that they had never had asthma were at a substantial risk of new-onset asthma as a result of multiple independent risk factors including lung function. Atopy explains a small proportion of new-onset adult asthma.

Intake fraction distributions for indoor VOC sources in five European cities.

UNLABELLED: Distributions of intake fractions for indoor air emissions were estimated for five cities in the EXPOLIS study (Athens, Basel, Helsinki, Oxford, and Prague). Intake fractions are an expression of the mass of a pollutant that reaches a target compared with the mass emitted by a source. They facilitate direct comparisons of the relative impact of different sources on individual or population exposure and dose. The computation of the distributions was obtained through Monte Carlo simulations, based on distributions of residence volume, air exchange rates and time-activity data, calculated from the EXPOLIS database, as well as on distributions from the literature. Some approximations were made that are valid for persistent pollutants and continuous sources, such as emissions from building materials, pesticides, molds, as well as for certain non-continuous sources such as cooking or cleaning products. For these categories of sources, intake fractions are approximately independent of the actual indoor concentrations and irrespective of the source. Intake fractions in the five populations examined followed approximately lognormal distributions. The mean individual intake fractions exhibited some variability across cities, ranging from 1.5x10(-3) in Athens to 4.5x10(-3) in Helsinki. Intake fractions for all the people in a household followed similar distributions, with mean values ranging from 4.6x10(-3) in Athens to 11.8x10(-3) in Helsinki. This modest variability mostly reflects the differences in climates and consequent air-tightness of the buildings. The 95th percentile of the distributions were two to three times the mean values, indicating substantial homogeneity within each population as well. These results compare well with previous estimates for environmental tobacco smoke and cooking, and are two to three orders of magnitude larger than estimates for outdoor sources. PRACTICAL IMPLICATIONS: Emissions from indoor sources were estimated to be approximately 1000 times more likely to reach a human target than emissions from outdoor sources. Strategies to reduce exposure to indoor sources can only realistically focus on reducing the strength of the emissions.

A predictive model for the home outdoor exposure to nitrogen dioxide.

The aim of this study is to find and test a predictive model that could be suitable to estimate the outdoor NO(2) concentrations at individual level, by integrating ecological measurements recorded by local monitoring stations with individual information collected by a questionnaire. For this purpose, the data from the Italian centres of the European Community Respiratory Health Survey II (ECRHS II) has been used. Outdoor NO(2) concentrations were measured using NO(2) passive sampling tubes (PS-NO(2)), exposed outdoor for 14 days, between January 2001 and January 2003. Simultaneously, average NO(2) concentrations were collected from all the monitoring stations of the three centres (MS-NO(2)). Individual measurements carried out with passive samplers were compared with the corresponding NO(2) 2-week concentrations obtained as the average of all local (background and traffic) monitoring stations (MS-NO(2)). A multiple linear regression model was fitted to the data using the 2-week PS-NO(2) concentrations as the response variable and questionnaire information and MS-NO(2) concentrations as predictors. The model minimizing the root mean square error (RMSE), obtained from a ten-fold cross validation, was selected. The model with the best predictive ability included centre, season of the survey, MS-NO(2) concentrations, type and age of building, residential area and reported intensity of heavy-duty traffic and explained the 68.9% of the variance. The non-parametric correlation between PS-NO(2) and the concentrations estimated by the model is 0.81 (95% CI: 0.77-0.85). This study shows that over short periods (2 weeks) a good prediction of home outdoor exposure to NO(2) can be achieved by simply combining routinely collected ecological data with dwelling characteristics and self-reported intensity of heavy traffic. Further studies are needed to extend this prediction to long-term exposure.

The European Community Respiratory Health Survey: what are the main results so far? European Community Respiratory Health Survey II.

The European Community Respiratory Health Survey (ECRHS) was the first study to assess the geographical variation in asthma and allergy in adults using the same instruments and definitions. The database of the ECRHS includes information from approximately 140,000 individuals from 22 countries. The aim of this review is to summarize the results of the ECRHS to date. The ECRHS has shown that there are large geographical differences in the prevalence of asthma, atopy and bronchial responsiveness, with high prevalence rates in English speaking countries and low prevalence rates in the Mediterranean region and Eastern Europe. Analyses of risk factors have highlighted the importance of occupational exposure for asthma in adulthood. The association between sensitization to individual allergens and bronchial responsiveness was strongest for indoor allergens (mite and cat). Analysis of treatment practices has confirmed that the treatment of asthma varies widely between countries and that asthma is often undertreated. In conclusion, the European Community Respiratory Health Survey has shown that the prevalence of asthma varies widely. The fact that the geographical pattern is consistent with the distribution of atopy and bronchial responsiveness supports the conclusion that the geographical variations in the prevalence of asthma are true and most likely due to environmental factors.

Fine particle (PM25) measurement methodology, quality assurance procedures, and pilot results of the EXPOLIS study.

EXPOLIS is a European multicenter (Athens, Basel, Grenoble, Helsinki, Milan, and Prague) air pollution exposure study. It is the first international, population-based, large-scale study, where personal exposures to PM2.5 aerosol particles (together with volatile organic compounds and carbon monoxide) are being monitored. EXPOLIS is performed in six different centers across Europe, the sampled aerosol concentrations vary greatly, and the microenvironmental samples are not collected with the same equipment as the personal samples. Therefore careful equipment selection, methods development and testing, and thorough quality assurance and quality control (QA & QC) procedures are essential for producing reliable and comparable PM2.5 data. This paper introduces the equipment, the laboratory test results, the pilot results, the standard operating procedures, and the QA & QC procedures of EXPOLIS. Test results show good comparability and repeatability between personal and microenvironmental monitors for PM2.5 at different concentration levels measured across Europe in EXPOLIS centers.