The government will investigate claims that contaminated air in planes is making pilots and passengers ill. Figures suggest that one in every 2,000 flights is polluted with engine oil but unions claim that the problem occurs much more often. Last year there were 116 contaminated flights reported to the Aviation Authority. Pilots and passengers have reported symptoms including nausea, headaches, dizziness and lethargy. The investigation will use equipment to measure the cabin air on five different types of aircraft from five different airlines to try and identify any toxins that might be in the air filters.