Exposure to airborne nano-titanium dioxide during airless spray painting and sanding

Abstract

The objectives of the study were to measure and characterize exposure to airborne nanoscale titanium dioxide during airless spraying and sanding of a nano-enabled paint, and to evaluate the effectiveness of dust capture methods in reducing airborne nanoparticle concentrations. A tradesperson performed the work activities in an environmentally controlled chamber. Samples were collected in the tradesperson's breathing zone and in surrounding areas to assess bystander exposure. Filter-based samples were analyzed using gravimetric methods, scanning electron microscopy, and energy dispersive spectroscopy. Differential particle count data were obtained by means of a scanning mobility particle sizer. Local exhaust ventilation provided statistically significant reductions of airborne nanoparticle concentrations during sanding. Sanding the paint after drying with a handheld power sander generated relatively low levels of airborne titanium dioxide. In contrast, task-based exposure measurements collected during the initial airless spray application of the nano-enabled paint suggested a potential for occupational exposures to exceed the time-weighted average exposure limit for ultrafine titanium dioxide recommended by the National Institute for Occupational Safety and Health. Painters applying nano-enabled coatings may have little recourse but to rely, in some instances, on lower tiers of the hierarchy of controls, such as personal protective equipment. In light of these findings, employers and industrial hygienists should characterize exposures and implement the hierarchy of controls to ensure painters are sufficiently protected.

Keywords:

• Construction
• engineering controls
• inhalation
• local exhaust ventilation
• nano-enabled
• nanomaterials

Acknowledgments

The authors would like to express their appreciation to Richard Cavalere of TSI Inc. for technical support and use of real-time instrumentation; to Spencer Schwegler, John Burcaw, and the International Union of Painters and Allied Trades for guidance on tool and material selection and work practices; to Jenny Roberts and Charles Geraci at NIOSH for their advice and input; and to Earl Dotter for photographing the sampling activities conducted for this study. Any mention of specific companies or products does not imply that they are endorsed or recommended by CPWR or NIOSH. Opinions expressed are those of the authors and do not necessarily represent the official views of CPWR or NIOSH.

Funding

The National Institute for Occupational Safety and Health (NIOSH) supported and funded this study through a cooperative agreement (Number U60-OH009762) with The Center for Construction Research and Training (CPWR). The authors have declared no conflicts of interest.

Figure 9. Comparison of background adjusted airborne nanoparticle concentrations while sanding painted or unpainted boards with either the dust collection bag or local exhaust ventilation (LEV): Center lines show the medians; box limits indicate the 25th and 75th percentiles; whiskers extend 1.5 times the interquartile range (IQR); n = 22, 22, 21, 22 sample points. The notches are defined as +/-1.58*IQR/sqrt(n) and represent the 95% confidence interval for each median. Non-overlapping notches give roughly 95% confidence that 2 medians differ.

Additional information

Funding

The National Institute for Occupational Safety and Health (NIOSH) supported and funded this study through a cooperative agreement (Number U60-OH009762) with The Center for Construction Research and Training (CPWR). The authors have declared no conflicts of interest