Assessment of Levels of Heavy Metals in Paints from Interior Walls and Indoor Dust from Residential Houses in Nairobi City County, Kenya

Aim: This study assessed the levels of Pb, Cr, Cd and Zn in settled indoor dust and paint chips.

Study Design: Samples were obtained from twelve selected residential houses within Nairobi County, Kenya.

Place and Duration of Study: GoK Laboratories, Department of Chemistry, JKUAT between February 2016 and November 2016.

Methodology: A modified version of EPA method SW846 3050B was used to digest the samples, and Flame Atomic Absorption Spectrophotometer (Shimadzu AAS-6200) used to analyze samples for the metals. Pearson correlation coefficient was determined for the various metal pairs in paint chips as well as in the dust samples. Also, it was calculated for the given metals in the dust and paint chips samples from a particular sampling point.

Results: The mean concentration of the metals in both the dust and paint chip samples were in the order Zn>Pb>Cr>Cd. The mean concentrations of Zn, Pb, Cr and Cd were 366.14 µg/g, 129.12 µg/g, 82.65 µg/g, and 27.40 µg/g for the dust samples and 321.77 µg/g, 289.59 µg/g, 77.54 µg/g, and 73.45 µg/g for the paint chip samples respectively. Pb, Cd, and Zn in the paint chips showed a negative relationship while Cr had a positive correlation.

Conclusion: The metals in the paint chips were found to be of common origin while the correlation of the various metal pairs in the dust suggested more diverse sources. Paint from interior walls is not the only contributor of heavy metals in the settled indoor dust.