title: Viability of fungal and actinomycetal spores after microwave radiation of building materials.
abstract: The effects of microwave radiation on viability of fungal and actinomycetal spores growing on agar (medium optimal for growth) as well as on wooden panel and drywall (common building construction/finishing materials) were studied. All materials were incubated at high (97-99%) and low (32-33%) relative humidity to mimic "wet" and "dry" environmental conditions. Two microwave power densities (10 and 60 mW/cm2) and three times of exposure (5, 30, and 60 min) were tested to find the most effective parameters of radiation which could be applied to non-invasive reduction or cleaning of building materials from microbial contaminants. Additionally, a control of the surface temperature during the experiments allowed differentiation between thermal and microwave effect of such radiation. The results showed that the viability of studied microorganisms differed depending on their strains, growth conditions, power density of microwave radiation, time of exposure, and varied according to the applied combination of the two latter elements. The effect of radiation resulting in a decrease of spore viability on "wet" wooden panel and drywall was generally observed at 60 min exposure. Shorter exposure times decreased the viability of fungal spores only, while in actinomycetes colonizing the studied building materials, such radiation caused an opposite (supporting growth) effect.
authors.affiliation: Department of Biohazards, Institute of Occupational Medicine and Environmental Health, Sosnowiec, Poland. r.gorny@imp.sosnowiec.pl
authors.forename: Rafał L
authors.initials: RL
authors.lastname: Górny
authors.forename: Gediminas
authors.initials: G
authors.lastname: Mainelis
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Wlazło
authors.forename: Anna
authors.initials: A
authors.lastname: Niesler
authors.forename: Danuta O
authors.initials: DO
authors.lastname: Lis
authors.forename: Stanisław
authors.initials: S
authors.lastname: Marzec
authors.forename: Ewa
authors.initials: E
authors.lastname: Siwińska
authors.forename: Beata
authors.initials: B
authors.lastname: Łudzeń-Izbińska
authors.forename: Aleksander
authors.initials: A
authors.lastname: Harkawy
authors.forename: Joanna
authors.initials: J
authors.lastname: Kasznia-Kocot
mesh_terms: D000192:Actinomycetales / Q000254:growth & development / Q000528:radiation effects; D000391:Air Microbiology; D000392:Air Movements; D016902:Air Pollution, Indoor / Q000032:analysis; D003252:Construction Materials / Q000382:microbiology*; D004307:Dose-Response Relationship, Radiation; D006813:Humidity; D008872:Microwaves; D003904:Mitosporic Fungi / Q000254:growth & development / Q000528:radiation effects; D013171:Spores, Bacterial / Q000254:growth & development / Q000528:radiation effects*; D013172:Spores, Fungal / Q000254:growth & development / Q000528:radiation effects*; D013997:Time Factors