Identification of Green Dust

THE PROBLEM:

A green dust accumulating on the surface of several desks in an office had employees concerned about possible health issues.

THE ANALYSIS:

The greenish, granular, gritty dust was examined by polarized light microscopy (PLM), scanning electron microscopy (SEM) equipped with energy dispersive x-ray detector (EDS) and Fourier transform infrared spectrophotometry (Micro-FTIR).

The dust was comprised of green, blue-green, brown, tan and white aggregated materials (Figure 1). 

The brown, rust-colored material was found to be consistent with rust, while the blue-green material was copper-rich, and consistent with copper corrosion products (Figure 2).

Identification of unknown dust by light and electron microscopyCorrosion particles analyzed by light and electron microscopy

THE OUTCOME:

MVA’s analyses indicated the dust was mainly chlorine-induced copper corrosion debris. Armed with this knowledge, the building manager located and replaced the corroded copper pipes used as a supply line in the building’s HVAC system.