It should be open again by 2.30pm
The entire Mountain Road is currently closed, from Ramsey to the Creg-Ny-Baa.
The emergency closure is to allow for the road to be swept following a diesel spillage along its entire length.
The Department of Infrastructure says it should be open again by 2.30pm.
Emergency access will be maintained throughout the period of the closure.
Census officers to make home visits to households yet to complete the form