Table 1: Horse allergen levels in classrooms from Study I and II, sampled with Petri dishes.

Study IStudy II

Sampling year1997/19982003
Analysis year (enhanced ELISA assay)20052009
Median horse contact among students9%12%
No. of samples29397
Samples < dl74%29%
GM U/m2/day (Total)8.420.8
GM U/m2/day (in classes above median rate of horse contact)10.532.6
GM U/m2/day (in classes below median rate of horse contact)6.313.2