| dc.description.abstract | Abstract Background: Asthma prevalence has increased over the last decades due to the complex interaction of genes and environmental factors. Exposure to environmental factors like low levels of air pollution greatly impacts the development of asthma throughout the lifespan and across generations. Exposure to high levels of air pollution for short periods is associated with aggravation of respiratory symptoms and increased respiratory mortality. As asthma has become a global health problem, we should have more knowledge of associations between long-term pollution exposure and asthma to enhance disease control and prevention and ensure efficient disease management. Objective of study: To investigate if air pollution exposure 20 years ago is associated with increased risk for asthma among adults. Method: The study design is a population-based prospective cohort study. For the study purpose, we used data from Respiratory Health in Northern Europe (RHINE) study collected from 1990 to 2010. The RHINE study was a questionnaire follow-up in 2000 and 2010 of all subjects from seven Northern European centres that participated in the ECRHS I stage 1. The participants were from seven different centres: Aarhus (DK); Gothenburg, Umea, and Uppsala (S); Reykjavik (IS); Tartu (EST); and Bergen (N). But in this study, only the participants from Gothenburg, Umea, Uppsala, and Bergen were included as the data for air pollution for the three-time points were only available for these four centres. The study population of 6,193 who have information on both asthma symptoms and exposure to air pollution and registered on sex were included in this study. The association between air pollutant with asthma severity and asthma symptoms were analysed by using logistic regression and negative binomial regression. The analyses were stratified based on sex and parental asthma. Result: Males who were exposed to NO2 20 years ago were associated with a small but significant increased risk of asthma severity defined as 3 or more current asthma symptoms (OR :1.03; 95% CI: 1.00, 1.07). However, in females, no significant association was observed between exposure to any air pollutants (NO2, PM10, and PM2.5) in any of the three-time points with regard to asthma severity. The stratified analyses based on parental asthma history showed no significant association between exposure to air pollutants (NO2, PM10, and PM2.5) at any of the three-time points and asthma severity. The negative binomial regression analyses stratified by sex showed that males exposed to NO2 20 years ago were associated with a small but significantly increased asthma symptoms risk (OR:1.01; 95% CI:1.00, 1.03). However, a borderline significant association was observed in females between current exposure to PM10 and asthma symptoms (OR:1.06; 95% CI:0.99, 1.13). In the negative binominal regression stratified by parental asthma, no significant association was observed between exposure to air pollutants (NO2, PM10, and PM2.5) at any time point and asthma symptoms. Conclusion: The study found that exposure to NO2 20 years ago was associated with both asthma severity and asthma symptoms only among males. But, for females, a borderline significant association was observed between asthma symptoms with current exposure to PM10. No association was found between asthma severity and asthma symptoms with any air pollutants for three-time points in the analysis stratified by parent asthma. | |
