Air samples from 2 commercial pig nursery buildings were taken from March to May 1999. Odour threshold was analysed with dynamic forced-choice olfactometry. Odour intensity and offensiveness were also determined by the panellists. The average odour concentration of building air ranged from 93 to 635 OU with arithmetic and geometric means of 226 and 190 OU, respectively. Outdoor odour concentration ranged from 7 to 85 OU with arithmetic and geometric means of 23 and 18 OU, respectively. The average odour emission rate of the 2 nursery rooms was 51+or-30 OU/s-AU or 2.1+or-1.5 OU/s-m2. Odour intensity was linearly proportional to log10 concentration. Odour offensiveness was inversely proportional to the log10 of odour concentration. Odour offensiveness was inversely proportional to odour intensity according to the following regression: O=-1.95 I+1.3 (R2=0.72).