The exposure of irritant substances, such as benzene, toluene, xylene, and ethylbenzene in the air can cause a disruption in transportation time of nasal mucociliary. The aim of this study was to find out the correlation between exposure to irritant substances and their effect on nasal mucociliary transportation time for workers at a gas station in Medan city, Indonesia. The type of research was analytical with a cross-sectional study design. There are 42 samples of subjects according to the inclusion and exclusion criteria where 31 subjects went through a deceleration of nasal mucociliary transport time. The location of exposure has a significant correlation between the nasal mucociliary transport time disorder that is as many as 31 people (100%) on direct exposure. The nasal mucociliary transport time was found to slow in the gas station workers who were exposed to a direct irritant.