Sun Exposure and Asthma Prevalence in Spanish Schoolchildren and Adolescents in the Global Asthma Network (GAN) Phase I Study: A Semi-Individual Study

Background/Objective: In the multifactorial genesis of asthma, environmental factors are critical, including sun exposure, either measured by sunshine hours (SH) or global solar surface irradiance (GSSI). The objective of this study is to estimate the association between sun exposure and the prevalence of asthma in Spanish schoolchildren (6-7 year-old) and adolescents (13-14 year-old) from 6 geographic centers of Spain (A Coruña, Bilbao, Canta-bria, Cartagena, Pamplona and Salamanca) included in the Global Asthma Network (GAN) study during the period 2016-2019. Methods: Measurements of SH and GSSI were obtained from the Spanish “Agencia Estatal de Meteorología”. A semi-individual design was used, and multilevel logistic regression models were employed with adjustments for age, sex, temperature, relative humidity and gross domestic product, considering center as the reference level. Results: Increments of SH and GSSI were associated with decreases of the prevalence of “asthma ever” in both the 6-7 and 13-14 year-old groups. An increase of 100 hours of an-nual sunshine was associated with a decline in “asthma ever” in schoolchildren (adjusted odds ratio [aOR] = 0.82; 95% confidence interval [CI] 0.79-0.85), and adolescents (aOR = 0.90; 95% CI 0.87-0.94). An increase of one kWh m-2 day-1 in GSSI was associated with a decrease in the prevalence of “asthma ever” in schoolchildren (aOR = 0.15; 95% CI 0.10-0.23) and adolescents (aOR = 0.37; 95% CI 0.25-0.54). Conclusions: The results suggest that sun exposure, either measured by SH or GSSI, might be a protective factor for the prevalence of asthma in schoolchildren and adolescents. This information could be useful in the prevention of this condition.