AerocatS2A
That's right MOR, the bleed air system on the 146s includes a filter downstream of the recirc fan, this collects the oil after it's been run through the air-conditioning and the cabin and then returns it to the engines via the low pressure bleed return line. The amount that is retained in the passenger's lungs is insignificant .
That's why we never used the recirc fan...
At least one Q400 has had a fumes incident, it can happen on any aircraft equipped with turbine engines.