Relation of indoor and outdoor airborne fungal spore levels in the Kansas City metropolitan area.

BACKGROUND: Environmental control is an important component of asthma management for persons with asthma. A damp indoor environment and elevated airborne spore levels are factors in housing environmental control.

OBJECTIVES: We investigated if indoor airborne fungal spore levels correlated with outdoor ground-level airborne fungal spores or outdoor centrally collected spore levels as to types and abundance.

METHODS: Air collections were taken from home interiors, outdoor areas adjacent to the homes, and at a central location in the metropolitan area at the approximate same time. All air collections were examined and enumerated microscopically, and airborne spore estimates per cubic meter of air were reported for total fungal spores and for 11 identifiable spore groups.

RESULTS: The 244 homes in the study were typical of the North American Midwest. The overall mean total spore counts in spores per cubic meter of air was indoors (4076 spores/m3), outdoors at ground level (8899 spores/m3), and outdoor metropolitan area (8342 spores/m3). All of the major indoor taxa were strongly correlated with the mean total spores present in the home. Total outdoor ground spore levels were highly correlated with levels of major outdoor taxa, such as ascospores and Cladosporium. Correlations of indoor spore levels with outdoor spore levels are strong for most major outdoor taxa. Indoor Aspergillus-Penicillium and Chaetomium are significantly correlated between indoor and local ground-level outdoor air.

CONCLUSION: Although conditions may exist where indoor or outdoor spore levels were not well aligned, in most circumstances, the outdoor airborne spore community was reflected in the indoor airborne spore community.