Shape of the association between endotoxin in school dust and children's lung function.

Introduction: Within the framework of the SINPHONIE study, this study aimed to examine the dose-response relationship between increasing endotoxin concentrations and reduced lung function parameters, seeking potential threshold effects and accounting for regional differences. Methods: Spirometry data from 3870 schoolchildren across 21 European countries were analysed to assess the impact of endotoxin exposure on lung function parameters. A general additive model was applied, adjusting for country, age, height, weight and sex. Additionally, a linear regression model with random effects was employed, treating country as a panel variable. In that latter model, "asthma ever" was also included as a possible moderator of endotoxin effects. Results: For most parameters, a linear decline in lung function was observed with increasing endotoxin levels, with no clear threshold effect. For example, forced expiratory volume in 1 s decreased by 4.8 mL per an increase in endotoxin concentration of 1000 EU·m Conclusion: The school environment in general and endotoxin levels in particular, have an impact on children's respiratory health, calling for additional efforts for improvements, including improved cleaning measures and ventilation.