White smoke coming from the engine area may be caused by one of the following reasons.
STEP 1 Turbo Failures: Your Volvo turbocharger could be failing. If the seals in the turbocharger go bad, the turbo may cause puffs of white smoke from the exhaust when coming to an idle or begin to smoke terribly when idling for long periods of time.
STEP 2 Head Gasket Leaking: The head gasket may be leaking into the combustion chamber(s) overnight which leads to white smoke coming from the exhaust (really steam) during cold start. Once the engine is warm this smoke will disappear because it is actually burning the coolant from within the combustion chamber. Head gasket failure between two cylinders is usually the problem. You can often determine if this is the problem by removing the spark plugs to see if any of the piston tops are silver which is an indication that the coolant being burned is cleaning the carbon from the piston top.
STEP 3 Valve guide/Seal Issues: Valve guide failure can cause the engine to smoke during startup. This usually indicates a problem with either the work guides or valve stem seals which allows oil to leak past them once the engine is turned off. Rebuilding or replacing the cylinder head is the only cure.