AA 1719 Boston/Charlotte - Airbus A319-100 Registration: N744P ‘American Airlines Reported a “probable” mechanical issue caused the return to the gate, it remained unclear whether that issue was the actual cause of the odour on board’. I find it incredible that an incident occurred onboard an American Airlines aircraft which caused 3 crew and 1 passenger to be taken to a hospital yet 5 hours later that same aircraft was back in service. 5 hours is nowhere near enough time to complete the ‘maintenance following a Fume event’ as recommended by the aircraft manufacturer- Airbus. There are many questions people should be asking American Airlines - * What is wrong with your aircraft N744P and what caused 3 of your crew members and 1 of your customers to be taken to a hospital? * Was the ‘odour’ a classic fume event, causing dizziness, headache, stinging/itchy eyes, breathing difficulties, tightness in the chest, coughing, nausea, tingling to fingers/arms/legs? * How much do you really care for the well-being of your customers and crew? The consequences of breathing toxic air onboard an aircraft can be devastating and life changing for those involved. Questions should also be asked of the US Regulator - the FAA. * What are they doing to protect airline crew and passengers from ‘odours’ on Aircraft and from being taken to hospital? * When are they going to make it compulsory for all aircraft using a bleed-air system to be fitted with sensors and filters?