Abstract
Casella Simquad air samplers, with 0·5 mu;M cut-off filters, were employed to sample the air in a laboratory animal house environment. The extracts obtained were assayed for laboratory animal urinary protein allergens using the inhibition radioallergosorbent test (RAST inhibition). The results showed that the collection and assay methods were of value and studies were extended to the influence of air change rates and humidity on airborne allergen levels. Reducing the air changes increased allergen levels, whilst increasing the humidity from 54% to 77% caused a significant reduction in allergen levels.