Measurement of airborne fungal spore dispersal from three types of flooring materials

Research was conducted in an experimental roomto measure the effect of human activity onairborne dispersal of settled fungal sporesfrom carpet and vinyl tile flooring. A seriesof experiments were conducted in whichcommercial loop pile carpet, residential cutpile carpet, or vinyl tile installed in theexperimental room were contaminated with Penicillium chrysogenum spores. The flooringmaterials were contaminated to two differentlevels (106 and 107 colony formingunits per square meter [c.f.u./m2] offlooring surface). Airborne culturable andtotal P. chrysogenum concentrations weremeasured using Andersen single-stage impactorsamplers and Burkard personal slide impactorsamplers, respectively. Bioaerosolconcentrations were measured at floor level, 1meter, and the adult breathing zone (1.5 meter)heights before and after human activityconsisting of walking in a prescribed patternfor 1 minute in the room. Airborne P.chrysogenum concentrations were greater withthe higher surface loading for all threeflooring materials. For all flooring materialsthere was no significant difference betweensampler locations, although the data from the1-meter location were the highest, followed bythe floor level and the breathing zonelocations, respectively. The data from theseexperiments indicate that while a very smallfraction of culturable P. chrysogenumspores present on flooring materials wereaerosolized by walking, relatively highairborne concentrations of spores maybere-entrained from contaminated materials. Theairborne P. chrysogenum concentrationswere significantly higher after walking on cutpile carpet than with the other two flooringmaterials at both contamination levels, withthe differences in concentration often ≥ 2orders of magnitude. No differences weremeasured in airborne culturable P.chrysogenum between vinyl flooring and looppile carpet at both contamination levels. Total spore data from the experiments with the107 c.f.u./m2 contamination levelindicated that walking on loop pile carpetproduced higher airborne spore concentrationsthan similarly contaminated vinyl tile althoughno significant difference was observed at the106 c.f.u./m2 level.