Personal exposure to average weekly ultrafine particles, lung function, and respiratory symptoms in asthmatic and non-asthmatic adolescents

•Ultrafine particles (UFP) cause respiratory health effects including exacerbation of existing asthma due to their size, composition, and respiratory deposition.•During a one-week sampling campaign, adolescents with and without asthma completed personal UFP monitoring. Respiratory symptoms were reported using ecological momentary assessment and validated questionnaires. Lung function was measured at the completion of the sampling following ATS/ERS criteria.•Median weekly exposure to ultrafine particles was not associated with lung function after covariate adjustment.•Median weeklyUFP exposurewas associated with an increased risk forrespiratory symptomsamong adolescents with asthma.