Identification of Green Dust


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


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


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.