  Infrared emission from intergalactic dust might compromise the ability of
future experiments to detect subtle spectral distortions in the Cosmic
Microwave Background (CMB) from the early Universe. We provide the first
estimate of foreground contamination of the CMB signal due to diffuse dust
emission in the intergalactic medium. We use models of the extragalactic
background light to calculate the intensity of intergalactic dust emission and
find that emission by intergalactic dust at redshifts z<0.5 exceeds the
sensitivity of the planned Primordial Inflation Explorer (PIXIE) to CMB
spectral distortions by 1-3 orders of magnitude. We place an upper limit of
0.23% on the contribution to the far-infrared background from intergalactic
dust emission.
