>>> Purpose: This presentation gives an introduction to aircraft cabin air contamination with an emphasis on contamination due to jet engine oil entering the cabin from the jet engine or auxiliary power unit (APU) via the bleed air system and the air conditioning system. The possible application of sensors and filters is discussed. Filters can be retrofitted. A bleed-free air conditioning architecture, however, seems only financially viable for newly designed aircraft. >>> Design/methodology/approach: The presentation collects existing facts and combines them with own thoughts. >>> Findings: There is a real health and flight safety risk due to contaminated cabin air. For the infrequent flyer the risk is very low. Also aviation statistics are not dominated by cabin air related accidents. Nevertheless, a bleed air based air conditioning system can be regarded as applying a fundamentally wrong systems engineering approach. Measures have to be taken to solve this. >>> Research limitations/implications: This review study is based on references. Own measurements have not been made. >>> Practical implications: The topic has been presented as background information for respiratory physicians. >>> Originality/value: Engineering based information with a critical view on the topic seems to be missing in public. This presentation tries to fill this gap.