Prediction of Aerosolized Fungal Spores by Determining Respiratory Intensity of the Growing Colony

Xian Li,Tengfei Zhang,Shugang Wang,Jihong Wang

doi:10.4209/aaqr.2020.01.0024

Xian Li, Tengfei Zhang + Show 2 more

Open Access

https://doi.org/10.4209/aaqr.2020.01.0024

Copy DOI

Abstract

ABSTRACT Aerosolization of fungal spores from moldy surfaces can cause adverse health effects. The spores of an older colony are more easily detached than those of a younger colony. When the growth age of a colony is known, the aerosolization of spores can be more accurately predicted. This study proposed the adoption of respiratory intensity as an indicator of the growth age of Aspergillus niger colonies. Respiratory intensity is the mass of carbon dioxide produced by the respiration of a colony per unit quantity of spores within a certain time. Two types of colonies, with homogeneous and heterogeneous age distributions, were aerosolized in a wind tunnel to determine the spore release proportion and validate the method. The results revealed that the respiratory intensity of the homogeneous colony is closely correlated with the growth age when the age of the colony is less than 14 days under standard growth conditions. The spore release proportion increases with the growth age and the blowing speed. The predicted spore release proportion for a heterogeneous colony is more precise when the colony is divided into multiple sub-colonies to characterize the growth age for each individual spore release proportion. The relative errors of the predicted spore release proportions as compared with the test values were less than 10%.

Highlights

21% of indoor air quality problems originate from microbial contamination (Meharzi et al, 2017; Humbal et al, 2018; Yao, 2018)
The averaging of the growth age of the heterogeneous colony by the global method resulted in underestimation of the spore release proportions, especially under a blowing air speed higher than 3.00 m s–1
This paper proposed the use of respiratory intensity as an indicator of growth age and for prediction of the spore aerosolization of Aspergillus niger colonies

Summary

Introduction

21% of indoor air quality problems originate from microbial contamination (Meharzi et al, 2017; Humbal et al, 2018; Yao, 2018). Microorganisms include bacteria, viruses and fungi, among which fungi are a heterogeneous group that impact human health (Rim and Novoselac, 2009; Wu et al, 2016; Mu et al, 2019; Norback et al, 2019; Zhao et al, 2019). Routes of fungal exposure include respiratory inhalation and skin deposition once the fungal spores or fragments are aerosolized (Wang et al, 2018). When a fungal colony develops on a moldy surface, fungal propagules may be released from the surface into the Aerosolization of fungal spores from moldy surfaces in indoor environments is driven mainly by aerodynamic forces (Wang et al, 2018; Fang et al, 2019). The spore release rate from colonies was found to increase with the blowing air speed. Previous studies found that gusty airflow with high turbulence intensity could enhance spore aerosolization (Gopalakrishnan et al, 2016)

Objectives

Methods

Results

Conclusion