Vick’s vapo-rub. A small thimbleful is enough. Good for colds and smelly situations. You never know how long the voyage of the person sitting next to you has been or if the plane ride is particularly rough, who might lose their lunch. This helps keep you from smelling the offending odour. I was given this idea from a senior flight attendant with over 30 years experience. She pulled hers out as we were getting a rather offensive smelling odour from a passenger who had been sick in the rear of the plane. It worked well. It may sound rude but if the person next to you has the most delicious smelling French fries and you are not in a position to get any for the next 4-8 hours you may be thanking me.