Typical Outdoor Levels of Airborne Non-Viable Fungal Spores Collected at the Ground Level During the Spring and Early Summer in Florida

Abstract

RATIONALE: Ground-level air samples (GLAS) are collected during the course of building evaluations to determine types and levels of non-viable fungal spores (NVFS) indoors versus outdoors. However, outdoor reference levels of NVFS collected in GLAS are limited. This is a study to determine these levels during the spring and early summer in Florida.METHODS: 234 outdoor GLAS were collected for NVFS analysis from April to July 2005 in Florida, utilizing a Zefon Bio-PumpTM and Air-O-Cell cassettesTM. These samples were analyzed by optical microscopy. Non-parametric statistical analysis was performed. Percentile categories were established for continuous variables, according to the criteria proposed by the American Academy of Allergy Asthma and Immunology National Allergy Bureau, as low (<50th), moderate (50th-75th), high (75th-99th), and very high (>99th).RESULTS: Total spores as well as individual Ascospores, Basidiospores, Cladosporium, and Penicillium/Aspergillus follow continuous distributions. Low, moderate, high, and very high levels (in spores/m3) of total spores are <4,813; 4,813-8,164; 8,165-108,509; and >108,509, respectively. The corresponding individual Ascospore levels are <1,117; 1,117-2,206; 2,207-12,975; and >12,975, respectively. Basidiospore levels are <1,064; 1,064-2,506; 2,507-23,861; and >23,861, respectively. Cladosporium levels are <744; 744-1,635; 1,636-19,278; and >19,278, respectively. Penicillium/Aspergillus levels are <650; 650-1,076; 1,077-14,887; and >14,887, respectively.CONCLUSIONS: The levels of the most common types of outdoor NVFS collected in GLAS during the spring and early summer in Florida have scattered distributions. Year-round studies in Florida and other locations are needed to refine these reference levels during different seasons. This information would facilitate the interpretation of laboratory reports generated during the course of building evaluations. RATIONALE: Ground-level air samples (GLAS) are collected during the course of building evaluations to determine types and levels of non-viable fungal spores (NVFS) indoors versus outdoors. However, outdoor reference levels of NVFS collected in GLAS are limited. This is a study to determine these levels during the spring and early summer in Florida. METHODS: 234 outdoor GLAS were collected for NVFS analysis from April to July 2005 in Florida, utilizing a Zefon Bio-PumpTM and Air-O-Cell cassettesTM. These samples were analyzed by optical microscopy. Non-parametric statistical analysis was performed. Percentile categories were established for continuous variables, according to the criteria proposed by the American Academy of Allergy Asthma and Immunology National Allergy Bureau, as low (<50th), moderate (50th-75th), high (75th-99th), and very high (>99th). RESULTS: Total spores as well as individual Ascospores, Basidiospores, Cladosporium, and Penicillium/Aspergillus follow continuous distributions. Low, moderate, high, and very high levels (in spores/m3) of total spores are <4,813; 4,813-8,164; 8,165-108,509; and >108,509, respectively. The corresponding individual Ascospore levels are <1,117; 1,117-2,206; 2,207-12,975; and >12,975, respectively. Basidiospore levels are <1,064; 1,064-2,506; 2,507-23,861; and >23,861, respectively. Cladosporium levels are <744; 744-1,635; 1,636-19,278; and >19,278, respectively. Penicillium/Aspergillus levels are <650; 650-1,076; 1,077-14,887; and >14,887, respectively. CONCLUSIONS: The levels of the most common types of outdoor NVFS collected in GLAS during the spring and early summer in Florida have scattered distributions. Year-round studies in Florida and other locations are needed to refine these reference levels during different seasons. This information would facilitate the interpretation of laboratory reports generated during the course of building evaluations.