Using near infrared spectroscopy for rapid quantification of sediment dust in the indoor environment

The aim of this study was to develop and apply a novel sensitive technique, using near infrared (NIR) reflectance spectroscopy in the 1250-2400 nm region, to account for small amounts of sediment dust that settle on indoor surfaces. In order to quantitatively characterise the dust loading process and to determine the range of applicability, two composition mixture models, representing homogeneity (talc powder) and heterogeneity [dust analogue: Environmental Protected Agency (EPA) dust] of chemical compounds, were examined. A wind tunnel was constructed in order to quantitatively characterise the dust-loading process in a simulated environment. The influence of total mass loaded and the sensitivity of spectral measurements were tested. Based on the significant results in the simulated environment, a field study was conducted in different indoor environments in the Tel-Aviv area. Multivariate data analysis based on partial least squares regression was run to predict the dust loads solely from reflectance data. Different spectral manipulations were tested. The relative standard error for validation sets accepted for indoor dust was found to be low (11.5%). We conclude that this methodology can be employed to assess dust in an indoor environment for small and relatively high dust content (ranging between 0.01 mg cm^-2 to 0.51 mg cm^-2 for artificial mixtures and between 0.02 mg cm^-2 to 0.45 mg cm^-2 for field study, respectively).