Improved techniques for sampling airborne fungal particles in highly contaminated environments.

Nuclepore filters (polycarbonate) were compared with a slit sampler for the collection of airborne fungi particles. To enable high spore-concentration sampling, the slit sampler method was modified by the use of collection gels consisting of agar or glycerol/gelatin. The exposed gels were homogenized (agar) or melted (glycerol/gelatin), diluted, and spread on cultivation media. No significant difference was found between the Nuclepore filter method and the slit sampler method when glycerol/gelatin gels were used in the interval 10(3)-10(8) colony-forming units (cfu) per cubic meter. The lower trapping efficiency with agar gel was probably caused by water evaporating from the medium. The efficiency of a personal cascade impactor (Sierra) was compared with that of the Nuclepore filter method. The collection media used in the personal cascade impactor was modified for the determination of colony-forming units by moistening the collection filters with glycerol. The exposed filters were extracted with sterile water, and the suspension was diluted and spread on cultivation media. In trapping efficiency, the personal cascade impactor was similar to the Nuclepore filter method. The cut point of the personal cascade impactor showed high conformity with that of an Andersen sampler.