Acrolein (CAS No. 107-02-8) with several other chemicals was evaluated for sensory (upper airway) irritation in a modified Alarie Mouse Sensory Irritation Test. Four each male Swiss Albino CD-1 mice were administered dynamic head only exposures to vapor concentrations of 0.0 to 8.7 ppm in air over 10 minutes to characterize type response as either immediate and persisting, immediate with accommodation (ameliorated with time), or immediate and progressive during exposures. Concentrations below 2 ppm produced a linear response (breaths/minute/animal) curve, while maximal responses (decreased respiration rate) occurred after 10 minutes' exposure, thus indicating a progressive response to exposure without physiological accommodation or compensation; an RD50 (linear regression determination of that concentration causing 50% reduction of respiratory rate) was 1.27 ppm (R=0.89; 95% CL 1.07-1.52 ppm). Response data were not provided.