Importance of the number emission factor of combustion-generated aerosols from nano-enabled products

Michael Persson,Wendel Wohlleben,Adrian Wichser,Nathan Bossa,Sabyasachi Gaan,Milijana Jovic,Ken Lehner,Ana Sofia Fonseca,Jing Wang,Tobias Hammer,Emmanuel Ruggiero

doi:10.1016/j.impact.2021.100307

Abstract

Accidental or open waste burning and incineration of nano-enabled products (NEPs) might lead to the release of incidental aerosols in the nano size range into the environment resulting in harmful effects on humans.We have investigated combustion-generated aerosol release during accidental burning for several real-life NEPs such as paints with silica (SiO2) and spruce wood panels containing SiO2 and Fe2O3 nanomaterials (NMs), paper with SiO2 and Fe2O3 NMs and polymeric composites with CuPhthtalocyanine NMs in poly lactic acid (PLA), polyamide 6 (PA6) and thermoplastic pol-urethane (TPU) matrices.Chemical compositions, aerosols number emission factors (nefs) and concentrations of the signature elements of the NMs of the combustion-generated aerosols were investigated. In addition, the residual ash was analyzed. The outcomes of this study shed light on how NM and matrix types influenced the properties of the released aerosols. Based on our results it was established that the combustion-generated aerosols were composed of transformed NMs with modified physical–chemical characteristics compared to the pristine NMs. In addition to aerosols with transformed NMs, there were also particles due to incomplete combustion of the matrix.Types of the pristine NMs and matrices affected the characteristics of the released aerosols. Since the effect of the aerosols is related to the inhaled aerosol number concentration, the nef is an important parameter. Our results showed that the nefs in the size range of 5.6 to 560 nm depended strongly on the type of combusted NEP, which indicated that the NEPs could be categorized according to their potential to release aerosols in this size range when they were burnt. The generated release data facilitate the assessment of human and environmental exposure and the associated risk assessment of combustion-generated aerosols from NEPs.

Highlights

We have investigated combustion-generated aerosol release during accidental burning for several real-life nano-enabled products (NEPs) such as paints with silica (SiO2) and spruce wood panels containing SiO2 and Fe2O3 nanomaterials (NMs), paper with SiO2 and Fe2O3 NMs and polymeric composites with CuPhthtalocyanine NMs in poly lactic acid (PLA), polyamide 6 (PA6) and thermoplastic pol-urethane (TPU) matrices
We investigated combustion-induced NM release during accidental / outdoor burning for several real-life NEPs such as applied paints containing SiO2 or Fe2O3 NMs on spruce wood panels, paper with SiO2 and Fe2O3 NMs and polymeric composites with CuPhthtalocyanine NMs in poly lactic acid (PLA), polyamide 6 (PA6) and thermoplastic polyurethane (TPU) matrices
For some cases, NEPs with NMs showed a higher nefs compared to the reference without NMs, whereas in other cases there was no significant difference between the reference material and the NEP

Summary

Introduction

To take advantage of the extraordinary physical–chemical properties of nanomaterials (NMs), the amount of NMs used in consumer and in dustrial applications is continuously increasing (Breuer and Sundararaj, 2004, Nowack and Bucheli, 2007, Potts et al, 2011, Limited, 2011, Le et al, 2014, Singh et al, 2016, Gonçalves et al 2018). NM pigments such as CuPhthalocyanine or Fe2O3 have extremely intense color due to their excellent light-scattering properties (Kotnarowska et al, 2014) and SiO2 nanoparticles have high mechanical stability (Mahrholz et al, 2009; Sow et al, 2011) To profit from these properties, NMs are applied in socalled nano-enabled products (NEPs) such as construction materials, paints, paper, cosmetics, sports products or in airplanes or automobiles (Kittelson et al, 2004; Nowack and Bucheli, 2007; Kuhlbusch et al., 2010; Brar et al, 2010; Sow et al, 2011; Bello et al, 2013; Wang et al, 2017; Part et al, 2018; Surendhiran et al, 2020). High temperatures and fragmentation and oxidation processes during the combustion lead to thermal decomposition of the NEPs and the release of incidental, process-generated nanoparticles in the form of fly ash into the air (Chivas-Joly et al, 2014; Wang et al, 2017; Singh et al, 2017; Singh et al, 2019; Hansen et al, 2015)

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