New particle formation (NPF) is a common occurrence in urban environments. Using a 500-day dataset obtained in Brisbane, Australia, we observed that NPF events occurred on 37 % of days and 10 % of nights. However, particle growth occurred on 70 % of nights. We show that when particles are measured by an instrument with a detection limit of 3 nm or above, particle growth events may be easily misidentified as NPF events. This can lead to an overestimation of the occurrence of NPF events.