Although accessed through a mine, the laboratory proper is maintained as a class-2000 cleanroom, with very low levels of dust and background radiation.
SNOLAB is the world's second-deepest underground lab facility; its 6,800 feet (2,070m)overburden of rock provides 6010 metre water equivalent (MWE) shielding from cosmic rays, providing a low-background environment for experiments requiring high sensitivities and extremely low counting rates.
History
The Sudbury Neutrino Observatory was the world's deepest underground experiment since the Kolar Gold Fields experiments ended with the closing of that mine in 1992. With the deepest underground laboratory in North America at 2100metre water equivalent depth, and the deepest in the world at 4800m.w.e., many other groups were interested in conducting experiments in the 6000m.w.e. location.