Size fractionation of bioaerosol emissions from green-waste composting

Robert M.W Ferguson,Charlotte E.E Neath,Zaheer A Nasir,Sonia Garcia-Alcega,Sean Tyrrel,Frederic Coulon,Alex J Dumbrell,Ian Colbeck,Corinne Whitby

doi:10.1016/j.envint.2020.106327

Robert M.W Ferguson, Charlotte E.E Neath + Show 7 more

Open Access

https://doi.org/10.1016/j.envint.2020.106327

Copy DOI

Abstract

Particle size is a significant factor in determining the dispersal and inhalation risk from bioaerosols. Green-waste composting is a significant source of bioaerosols (including pathogens), but little is known about the distribution of specific taxa across size fractions. To characterise size fractionated bioaerosol emissions from a compost facility, we used a Spectral Intensity Bioaerosol Sensor (SIBS) to quantify total bioaerosols and qPCR and metabarcoding to quantify microbial bioaerosols. Overall, sub-micron bioaerosols predominated, but molecular analysis showed that most (>75%) of the airborne microorganisms were associated with the larger size fractions (>3.3 µm da). The microbial taxa varied significantly by size, with Bacilli dominating the larger, and Actinobacteria the smaller, size fractions. The human pathogen Aspergillus fumigatus dominated the intermediate size fractions (>50% da 1.1–4.7 µm), indicating that it has the potential to disperse widely and once inhaled may penetrate deep into the respiratory system. The abundance of Actinobacteria (>60% at da < 2.1 µm) and other sub-micron bioaerosols suggest that the main health effects from composting bioaerosols may come from allergenic respiratory sensitisation rather than directly via infection. These results emphasise the need to better understand the size distributions of bioaerosols across all taxa in order to model their dispersal and to inform risk assessments of human health related to composting facilities.

Highlights

Bioaerosols represent a significant and growing health concern (Douwes et al, 2003; Douglas et al, 2017)
This is consistent with the particulate matter (PM) emitted from the compost site, where the highest concentration was in the PM7.5 mass fraction (Figure S2)
This indicates that microorganisms emitted from the compost site were associated with the coarse fraction of PM, but that overall, microbial bioaerosols formed a component of a total bioaerosol emission comprising a large number of submicron par ticles

Summary

Introduction

Bioaerosols (i.e. biogenic aerosols sized ~0.05–100 μm) represent a significant and growing health concern (Douwes et al, 2003; Douglas et al, 2017). Recycling of organic waste by composting is one of the biggest emitters of human health relevant bioaerosols (He et al, 2019; Veillette et al, 2018; Mbareche et al, 2017; Pankhurst et al, 2009, 2012; Pearson et al, 2015; Wery, 2014; Conza et al, 2013; Robertson et al, 2019; Douglas et al, 2018). Predicting exposure to bioaerosols from composting has been performed using dispersion modelling to explore associations with health. Such approaches have been used as a key tool for regulators of the waste and recycling industry (Douglas et al, 2018a, 2017b, 2017c, 2016d; Wil liams et al, 2019). We need detailed characterisations of the emission sources of bioaerosols from compost sites in order to parameterise these models and improve exposure predictions (Douglas et al, 2016a, 2016b)

Methods

Results

Discussion

Conclusion