No abstract

The effect of long-term exposure to air pollutants was studied in a cross-sectional population-based sample of adults (aged 18 to 60 yr; n = 9,651) residing in eight different areas in Switzerland. Standardized medical examination included questionnaire data, lung function tests, skin-prick testing, and end-expiratory CO concentration. The impact of annual means of air pollutants on FVC and FEV1 was tested (controlling for age and age squared, sex, height, weight, educational level, nationality, and workplace exposure). Analyses were done separately for healthy never-smokers, ex-smokers (controlling for pack-yr), for current smokers (controlling for cigarettes per day and pack-yr smoked), and for the whole population. Significant and consistent effects on FVC and FEV1 were found for NO2, SO2, and particulate matter < 10 microm (PM10) in all subgroups and in the total population, with PM10 showing the most consistent effect of a 3.4% change in FVC per 10 microg/m3. Results for ozone were less consistent. Atopy did not influence this relationship. The limited number of study areas and high intercorrelation between the pollutants make it difficult to assess the effect of one single pollutant. Our conclusion is that air pollution from fossil fuel combustion, which is the main source of air pollution with SO2, NO2, and PM10 in Switzerland, is associated with decrements in lung function parameters in this study.

The role of N-acetylcysteine (NAC) in the treatment of chronic bronchitis is unclear. Since a number of studies have been published on this topic, a systematic review of published studies seems justified.A systematic search (Medline, Embase, Cochrane Library, bibliographies, no language restriction) for published randomized trials comparing oral NAC with placebo in patients with chronic bronchitis was performed. Dichotomous data on prevention of exacerbation, improvement of symptoms and adverse effects were extracted from original reports. The relative benefit and number-needed-to-treat were calculated for both individual trials and combined data.Thirty-nine trials were retrieved; eleven (2,011 analysed patients), published 1976± 1994, were regarded as relevant and valid according to preset criteria. In nine studies, 351 of 723 (48.5%) patients receiving NAC had no exacerbation compared with 229 of 733 (31.2%) patients receiving placebo (relative benefit 1.56 (95% confidence interval (CI) 1.37±1.77), number-needed-to-treat 5.8 (95% CI 4.5±8.1). There was no evidence of any effect of study period (12±24 weeks) or cumulative dose of NAC on efficacy. In five trials, 286 of 466 (61.4%) patients receiving NAC reported improvement of their symptoms compared with 160 of 462 (34.6%) patients receiving placebo (relative benefit 1.78 (95% CI 1.54±2.05), number-needed-to-treat 3.7 (95% CI 3.0±4.9)). With NAC, 68 of 666 (10.2%) patients reported gastrointestinal adverse effects compared with 73 of 671 (10.9%) taking placebo. With NAC, 79 of 1,207 (6.5%) patients withdrew from the study due to adverse effects, compared with 87 of 1,234 (7.1%) receiving placebo.In conclusion, with treatment periods of~12±24 weeks, oral N-acetylcysteine reduces the risk of exacerbations and improves symptoms in patients with chronic bronchitis compared with placebo, without increasing the risk of adverse effects. Whether this benefit is sufficient to justify the routine and long-term use of Nacetylcysteine in all patients with chronic bronchitis should be addressed in further studies and cost-effectiveness analyses. Eur Respir J 2000; 16: 253±262.

The association between long-term exposure to ambient air pollution and respiratory symptoms was investigated in a cross-sectional study in random population samples of adults (aged 18 to 60 yr, n = 9,651) at eight study sites in Switzerland. Information on respiratory symptoms was obtained with an extended version of the European Community Respiratory Health Survey questionnaire. The impact of annual mean concentrations of air pollutants was analyzed separately for never-, former, and current smokers. After controlling for age, body mass index, gender, parental asthma, parental atopy, low education, and foreign citizenship, we found positive associations between annual mean concentrations of NO2, total suspended particulates, and particulates of less than 10 micrometers in aerodynamic diameter (PM10) and reported prevalences of chronic phlegm production, chronic cough or phlegm production, breathlessness at rest during the day, breathlessness during the day or at night, and dyspnea on exertion. We found no associations with wheezing without cold, current asthma, chest tightness, or chronic cough. Among never-smokers, the odds ratio (95% confidence interval) for a 10 micrograms/ m3 increase in the annual mean concentration of PM10 was 1. 35 (1.11 to 1.65) for chronic phlegm production, 1.27 (1.08 to 1.50) for chronic cough or phlegm production, 1.48 (1.23 to 1.78) for breathlessness during the day, 1.33 (1.14 to 1.55) for breathlessness during the day or at night, and 1.32 (1.18 to 1.46) for dyspnea on exertion. No associations were found with annual mean concentrations of O3. Similar associations were also found for former and current smokers, except for chronic phlegm production. The observed associations remained stable when further control was applied for environmental tobacco smoke exposure, past and current occupational exposures, atopy, and early childhood respiratory infections when restricting the analysis to long-term residents and to non- alpine areas, and when excluding subjects with physician-diagnosed asthma. The high correlation between the pollutants makes it difficult to sort out the effect of one single pollutant. This study provides further evidence that long-term exposure to air pollution of rather low levels is associated with higher prevalences of respiratory symptoms in adults.

Within the framework of the SAPALDIA survey (Swiss study on Air Pollution and Lung Diseases in Adults), we studied the influence of sex, age and smoking habits on total serum IgE and allergen-specific IgE antibody concentrations (assessed by means of the Phadiatop® test) and on the prevalence of hay fever. A total of 8,344 subjects aged 18–60 years, comprising 2,776 current smokers, 1,888 former smokers and 3,680 nonsmokers, were included in the study. Smokers had both a statistically significant (p < 0.001) higher mean serum IgE concentration (geometric mean 39.7 kU/l), and a higher percentage (27.5%) of persons with elevated serum IgE ( > 100 kU/l) than nonsmokers (27.2 kU/l; respectively 20.5%). The IgE level was significantly lower in women than men (p < 0.001) in all smoking categories. The percentage of persons with positive atopic markers (positive Phadiatop test, positive skin prick tests to common inhalant allergens) and self-reported hay fever was significantly higher in nonsmokers than in smokers or former smokers. In Phadiatop positive (atopic) subjects, the IgE levels were highest, with a mean of 104.3 kU/l (99.0–109.8), and lowest in Phadiatop-negative nonsmokers at 27.2 kU/l (25.9–28.6). These findings correlate well with the current interpretation of total serum IgE values in screening for atopic diseases in adults (IgE < 20 kU/l: atopy improbable; IgE > 100 kU/l: atopy probable). In multivariate logistic regression models, the prevalence of positive Phadiatop tests, positive skin tests, and atopy decreased significantly with age. The odds of having a positive Phadiatop and skin test, or being atopic were found to decrease on average by 23.0, 21.1 and 21.0%, respectively, with every 10-year increase in age. With respect to smoking status, the odds ratios for the three atopic markers were significantly lower in current and former smokers than in non-smokers. The prevalence of (self-reported) hay fever was highest in nonsmokers, intermediate in former smokers (odds ratio = 0.81, p < 0.05) and lowest in current smokers (odds ratio = 0.76 in comparison to former smokers, p < 0.01). The odds ratio of self-reported current hay fever decreased with age at an estimated average of 23% every 10 years. The decrease in former smokers might be slightly faster than in the other two categories. In conclusion, the present results demonstrated that tobacco smoking is associated with increased IgE levels and negatively related to atopy and hay fever. In addition, it is shown that atopy prevalence decreases with age.