Dust particles, which by definition, are particles of solid matter, ranging in size from 1-420 um, are found everywhere free in nature. They, in addition to being annoying for housekeeping chores and causing air pollution, are also notorious for causing untoward effects on human health, especially affecting the Respiratory, Circulatory and other Endocrinal functions. Commercially available cleaning and disinfecting products, i.e., bleach, is exposed to indoor dust, there is a risk of some unwanted chemical reactions taking place between the two, and, when such particles are respired or inhaled, they have a potential of causing harm not only to our airways but overall systematic functions of the body by entering the blood stream.

This study aims to investigate the chemical reacti...[ Read more ]

Dust particles, which by definition, are particles of solid matter, ranging in size from 1-420 um, are found everywhere free in nature. They, in addition to being annoying for housekeeping chores and causing air pollution, are also notorious for causing untoward effects on human health, especially affecting the Respiratory, Circulatory and other Endocrinal functions. Commercially available cleaning and disinfecting products, i.e., bleach, is exposed to indoor dust, there is a risk of some unwanted chemical reactions taking place between the two, and, when such particles are respired or inhaled, they have a potential of causing harm not only to our airways but overall systematic functions of the body by entering the blood stream.

This study aims to investigate the chemical reactions between dust particles and cleaning products, altering the bio-chemical activity of indoor dust, to see the adverse effects of dust particles on human health, to look into the physical, chemical and biological characterization of dust particles from different indoor environments i.e., office and healthcare settings. The objectives of study were fulfilled by dividing it in two major parts, one being the assessment of bio-chemical activity of dust particles with the help of different bioassays i.e., Acute toxicity, Yeast Estrogenic Screen on micro-organisms, MTT Assay and DCFH-DA Assay using the Human Lung Alveolar Epithelial Cells A-549. The physical, chemical and biological characteristics of dust particles were assessed with different analytic techniques i.e., Optical Microscopy, Scanning electron Microscopy and EDX analysis, Gas Chromatography-Mass Spectrometry and Thermogravimetric analysis. The dust samples were inoculated onto the bacterial and fungal agar media to enumerate microorganisms associated with them.

The results of this study have shown an alteration in the bio-chemical activity of the dust particles from indoor environment of office and healthcare settings. For the bioassays, acute toxicity, MTT assay for cell viability and DCFH-DA assay for oxidative stress to the cells, showed an increase in toxicity level after dust was treated with bleach. However, there was a decrease in the estrogenic effect of dust particles after bleach treatment. The optical and SEM results depicted the dust from healthcare settings to be more complex in physical characteristics, but no significant difference in organic and inorganic compositions was found for two different samples. Additionally, the office dust was found to be more biologically hazardous as compared to the dust from healthcare setting, both in terms of viable microbial load and types of MDROs.

Consequently, the findings direct to either abandon the use of commercially available bleach for cleaning purposes and find better, safe alternatives, or optimize its concentration to such levels at which it does not have the potential to harm human health. The investigation can be extended at a large scale with an increased sample size, and measures can be taken to minimize the health risks for individuals living in such indoor settings, especially in the healthcare systems where most of the individuals are already immunocompromised and more prone to be affected.