Participants
allergy
ALLERGY, UPPER RESPIRATORY INFECTION
A total of 206 healthy non-smokers (106 men, mean age = 22.15 years, s.d. = 2.43, range = 18–34; and 100 women, mean age = 20.50 years, s.d. = 1.69, range = 18–29 years) were recruited for this study. All participants reported to be Han Chinese and heterosexual (Kinsey score = 0) and have normal or corrected-to-normal vision, a normal sense of smell and no respiratory allergy or upper respiratory infection. The sample size was determined based on the effect size reported in previous studies (