Stagn - it may remind you nostalgically of the issue of how many air con packs you selected on during the night, or what proportion of bleed/recirculated air you used, but cabin air contamination is not about that. It's about the air being poisoned with neurotoxins composed of complex organophosphates from heated oil additives when the oil seals leak. It may only have happened on a small proportion of flights, but many people's lives have been changed forever by such incidents, and they don't even know why.