Building upon current knowledge and techniques of indoor microbiology to construct the next era of theory into microorganisms, health, and the built environment

Abstract

In the constructed habitat in which we spend up to 90% of our time, architectural design influences occupants' behavioral patterns, interactions with objects, surfaces, rituals, the outside environment, and each other. Within this built environment, human behavior and building design contribute to the accrual and dispersal of microorganisms; it is a collection of fomites that transfer microorganisms; reservoirs that collect biomass; structures that induce human or air movement patterns; and space types that encourage proximity or isolation between humans whose personal microbial clouds disperse cells into buildings. There have been recent calls to incorporate building microbiology into occupant health and exposure research and standards, yet the built environment is largely viewed as a repository for microorganisms which are to be eliminated, instead of a habitat which is inexorably linked to the microbial influences of building inhabitants. Health sectors have re-evaluated the role of microorganisms in health, incorporating microorganisms into prevention and treatment protocols, yet no paradigm shift has occurred with respect to microbiology of the built environment, despite calls to do so. Technological and logistical constraints often preclude our ability to link health outcomes to indoor microbiology, yet sufficient study exists to inform the theory and implementation of the next era of research and intervention in the built environment. This review presents built environment characteristics in relation to human health and disease, explores some of the current experimental strategies and interventions which explore health in the built environment, and discusses an emerging model for fostering indoor microbiology rather than fearing it.

Keywords: Biomonitoring; Dermal exposure; Disease; Environmental monitoring; Epidemiology; Personal exposure.

Fig. 1

Environmental factors and subsequent effects on built environment microorganisms. a Sunlight (both UV light and visible light) have been shown to alter the survival of microorganisms living in the built environment. b Biofilms can form on common built environment surfaces, especially in moist areas such as sinks and showers in bathrooms, facilitating transfer through everyday activities and rituals. c Ambient household conditions constitute a major factor that contributes to the survival and spread of microorganisms. Moisture from daily activities, such as cooking, allows formation of biofilms while and high relative humidity increases the rate of aerosolized microbial cells and spores. Indoor air temperature alters the rate at which built environment inhabitants shed microorganisms. d Frequented household items, such as chairs, can harbor a plentiful supply of nutrients such as human skin squamous cells and other nutrients for microorganisms from built environment inhabitants such as humans, insects, pets, and many others. e Microenvironments within carpet can create pockets of high relative humidity that can aid in the growth, prolonged survival, and transfer of microorganisms from fomite to individual. f Windows provide an access point for microorganisms from the outdoors to access the built environment, contributing to each building’s unique microbial makeup. Ventilation through windows provides air exchange that aids in the reduction of potentially contaminated air. g Humans, insects, pets, and other occupants exchange microorganisms from their own personal microbiome with their built environments contributing to the two-way exchange between hosts and built environment