Nanosized titanium dioxide particle emission potential from a commercial indoor air purifier photocatalytic surface: A case study

Antti Joonas Koivisto; Sara Trabucco; Fabrizio Ravegnani; Francescopiero Calzolari; Alessia Nicosia; Benedetta Del Secco; Marko Altin; Elisa Morabito; Magda Blosi; Anna Costa; Franco Belosi

doi:10.12688/openreseurope.14771.1

Nanosized titanium dioxide particle emission potential from a commercial indoor air purifier photocatalytic surface: A case study

Open Res Eur. 2022 Jul 4:2:84. doi: 10.12688/openreseurope.14771.1. eCollection 2022.

Authors

Antti Joonas Koivisto^{1

2

3}, Sara Trabucco⁴, Fabrizio Ravegnani⁴, Francescopiero Calzolari⁴, Alessia Nicosia⁴, Benedetta Del Secco⁴, Marko Altin⁵, Elisa Morabito⁶, Magda Blosi⁷, Anna Costa⁷, Franco Belosi⁴

Affiliations

¹ Air Pollution Management (APM), Mattilanmäki 38, 33610 Tampere, Finland.
² Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, PL 64, FI-00014, Helsinki, Finland.
³ ARCHE Consulting, Liefkensstraat 35D, B-9032 Wondelgem, Belgium.
⁴ ISAC-CRN, Institute of Atmospheric Sciences and Climate, National Research Council of Italy, Via Gobetti, 101, 40129 Bologna, Italy.
⁵ Witek srl, Via Siena 47, 50142 Firenze, 50142, Italy.
⁶ Department of Environmental Sciences, Informatics and Statistics, Cá Foscari University, Via Torino 155, 30172 Venice, Italy.
⁷ ISTEC-CNR, Institute of Science and Technology for Ceramics, National Research Council, Via Granarolo 64, 48018 Faenza, Italy.

Abstract

Background: Photocatalytic air purifiers based on nano-titanium dioxide (TiO ₂) visible light activation provide an efficient solution for removing and degrading contaminants in air. The potential detachment of TiO ₂ particles from the air purifier to indoor air could cause a safety concern. A TiO ₂ release potential was measured for one commercially available photocatalytic air purifier "Gearbox Wivactive" to ensure a successful implementation of the photocatalytic air purifying technology. Methods: In this study, the TiO ₂ release was studied under laboratory-simulated conditions from a Gearbox Wivactive consisting of ceramic honeycombs coated with photocatalytic nitrogen doped TiO ₂ particles. The TiO ₂ particle release factor was measured in scalable units according to the photoactive surface area and volume flow (TiO ₂-ng/m ²×m ³). The impact of Gearbox Wivactive on indoor concentration level under reasonable worst-case conditions was predicted by using the release factor and a well-mixed indoor aerosol model. Results: The instrumentation and experimental setup was not sufficiently sensitive to quantify the emissions from the photoactive surfaces. The upper limit for TiO ₂ mass release was <185×10 ^-3 TiO ₂-ng/m ²×m ³. Under realistic conditions the TiO ₂ concentration level in a 20 m ³ room ventilated at rate of 0.5 1/h and containing two Gearbox Wivactive units resulted <20×10 ^-3 TiO ₂-ng/m ³. Conclusions: The release potential was quantified for a photocatalytic surface in generalized units that can be used to calculate the emission potential for different photocatalytic surfaces used in various operational conditions. This study shows that the TiO ₂ nanoparticle release potential was low in this case and the release does not cause relevant exposure as compared to proposed occupational exposure limit values for nanosized TiO ₂. The TiO ₂ release risk was adequately controlled under reasonable worst-case operational conditions.

Keywords: Nanomaterial; TiO2; emission; exposure; indoor aerosol; indoor air purifier; photocatalytic oxidation; release.

Grants and funding

This research was financially supported by the European Union’s Horizon 2020 research and innovation programme under the grant agreement No 862444 (Anticipating Safety Issues at the Design Stage of NAno Product Development, ASINA). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.