When thrown, sand of obscurement created an instantaneious mini sandstorm, effectively blinding anything within the storm. This effect lasted for 2-8 minutes and covered 50 cubic feet (15 cubic meters). Those caught within the sandstorm were not only blinded for the duration of the storm, but also for up to 10 minutes after the storm dissipated while they tried to cleanse the sand from their eyes. Blinded victims could shorten this time by flushing their eyes with water. Each additional handful of sand used did not increase the area of effect, but did extend the duration of the sandstorm by several minutes.
It should be noted that someone using sand of obscurement was not immune to the blinding sand, they were merely prepared for its release and could shut their eyes before it activated.