Airborne manufactured nano-objects released from commercially available spray products: temporal and spatial influences

Abstract

This paper reports a study of the dispersion of manufactured nano-objects (MNOs) through the air, both in time and space, during the use of two commercially available nano-spray products and comparable products without MNOs. The main objective was to identify whether personal exposure can occur at a greater distance than the immediate proximity of the source (>1 m from the source), that is, in the "far field" (bystanders), or at a period after the emission occurred (re-entry). The spray experiments were conducted in an experimental room with well-controlled environmental and ventilation conditions (19.5 m(3)). The concentration of MNOs was investigated by measuring real-time size distribution, number, and active surface area concentration. For off-line analysis of the particles in the air, samples for scanning/transmission electron microscopy and elemental analysis were collected. The release of MNOs was measured at ∼30 and 290 cm from the source ("near field" and "far field", respectively). For all four spray products, the maximum number and surface area concentrations in the "near field" exceeded the maximum concentrations reached in the "far field". At 2 min after the emission occurred, the concentration in both the "near field" and "far field" reached a comparable steady-state level above background level. These steady-state concentrations remained elevated above background concentration throughout the entire measurement period (12 min). The results of the real-time measurement devices mainly reflect the liquid aerosols emitted by the spray process itself rather than only the MNO, which hampers the interpretation of the results. However, the combination of the off-line analysis and the results of the real-time devices indicates that after the use of nano-spray products, personal exposure to MNOs can occur not only in the near field, but also at a greater distance than the immediate proximity of the source and at a period after emission occurred.

Physicochemical characteristics of colloidal nanomaterial suspensions and aerosolized particulates from nano‐enabled consumer spray products

“…Therefore, comparison of both suspension and aerosol analysis has been conducted in several studies 14,[16][17][18][19]32 to complement the limitations because it can suggest how the size and particle concentrations change during the spray process by the spray nozzle type. 15 There is no single analytical method or instrument able to evaluate the properties of nanoparticles in a variety of media in the F I G U R E 6 Temporal variation in count median diameter before and after spraying environment, so it could be obtained using a combination of some methods to complement the disadvantages of each method (physical properties: microscopic analysis, light scattering, field-flow fractionation, X-ray diffraction and etc; chemical composition: ICP-MS, EDX with EM, and others).…”

“…33,[38][39][40] The nano-sized fraction of the sprayed aerosols, size distribution, and particle number can be determined by online instruments such as SMPS, aerodynamic particle sampler (APS), and electrical low pressure impactor (ELPI) with the EM method that used to identify the physicochemical properties of particles. [14][15][16] In this study, ICP-MS and TEM-EDX were used to measure the physicochemical properties of ENMs both in suspensions and in aerosols and DLS was used to measure them in the product solutions. In addition, SMPS and OPS were used to measure the size distribution and particle number.…”

“…15 In previous studies on the exposure assessment for ENMs of spray products, only a few of them have differentiated the physicochemical characteristics between the suspensions and the aerosols using one or a combination of some analytical techniques. 14,[16][17][18][19] The objectives of this study were to characterize the physicochemical characteristics between ENM colloidal suspensions in consumer products and aerosolized particulates after spray application.…”

Development of CPSC nano-particle modeling tools

“…However, there is evidence that products exist that do have the potential to release ENPs into the air [8][9][10]. While specific properties of ENPs may affect their transport within the built environment, modeling ENPs in indoor air is likely to require the ability to capture transport properties similar in nature to other ultrafine particles (UFPs) [6,11,12].…”

Analysis of time series of particle size distributions in nano exposure assessment

“…Both particle number concentration and PSD have been studied using graphical methods (Brouwer et al, 2004;Demou et al, 2008;Evans et al, 2010;Bekker et al, 2014). Although the authors showed that useful information could be retrieved, graphical analysis is limited to making qualitative inferences.…”