Tikkakoski AP, Tikkakoski A, Kivistö JE, et al. - In children after the free running exercise test, researchers sought to evaluate the association of outdoor air temperature, relative humidity (RH), and absolute humidity (AH) to airway obstruction. Between January 2012 and April 2015, all exercise challenge tests with impulse oscillometry in children in the Tampere University Hospital were analyzed. Using regression analysis, the connections of AH, RH, and temperature of outdoor air with a change in airway resistance were analyzed and compared the frequency of exercise-induced bronchoconstriction [EIB] (increase ≥ 40% in resistance at 5 Hz) at different levels of temperature and humidity. A total of 868 children (mean age: 5.4 years; range: 3.0-14.1) were included with reliable outcomes. After outdoor exercise test in children, high AH of air is linked to lower incidence of EIB. A negative test outcome at AH ≥ 10 g/m³ should be carefully interpreted.