Aerodynamic Diameters and Respiratory Deposition Estimates of Viable Fungal Particles in Mold Problem Dwellings

The aerodynamic size distributions of particles of major fungal genera or groups, i.e., Penicillium, Cladosporium, Aspergillus, and yeasts, were studied in real exposure situations in mold problem and reference dwellings. A new calculation method was used to estimate respiratory deposition of fungal particles on the basis of the measured data. The major fungal genera had their maximum concentrations in the size range 2.1-3.3 J.lm, where alveolar deposition for particles > 0.5 J.lm also has a maximum. According to respiratory deposition calculations for the most obvious breathing patterns in the home environment, 30%-50% of fungal particles would be deposited in the nose and 300/0-40% in the alveoli during nasal breathing, whereas 700/0 would be deposited in the alveoli during oral breathing. More Aspergillus species spores were estimated to deposit in the alveoli for occupants of mold problem versus reference dwellings whereas for yeasts the situation was reversed. Comparison of airborne fungal particle concentrations and numbers of deposited particles between mold problem and reference dwellings indicated that more accurate estimation of exposure to fungal particles is possible if one considers both particle concentration and size.