Environmental and clinical mould spore risk thresholds

Abstract

Escalating environmental pollution and urbanization is associated with a rise in fungal contamination, which contributes to a variety of health concerns, particularly respiratory tract ailments such as allergic rhinitis, asthma, bronchitis, and sick building syndrome. Spore trap testing serves as a straightforward method for evaluating the number of spores/m³ in the air. Multiple studies indicate that 1000 spores/m³ represents the upper threshold for normal levels of mould exposure, with levels above this linked to adverse health effects, thereby establishing the environmental threshold. According to the literature, the clinical threshold is 3000 spores/m³ for Cladosporium and 100 spores/m³ for Alternaria. This mini review provides an overview of the existing environmental and clinical thresholds for fungal contamination to assess risk. We examine fungal threshold levels in both outdoor and indoor settings, encompassing residential homes, libraries, buildings, workplaces, and hospitals. In conclusion, environmental scientists, microbiologists/mycologists, occupational hygienists, insurance assessors, the real estate sector, clinical healthcare staff, and others must use and apply both environmental and clinical threshold levels to assess fungal contamination risk in indoor environments to protect public health. And finally, this mini review highlights the need for increased focus and research to ensure that appropriate guidelines and industry standards are developed, applied, and enforced that incorporate objective spore thresholds to quantify risk from fungal mediated adverse health in various indoor environments.