When you sit in public space you share your seat with countless others who've sat there before you.
No guidelines from the FAA, FDA or even OSHA regulate how or how often airplane or other forms of public seats should be cleaned. Research suggests that thorough cleanings or seat replacements typically only occur every 18 months.
As many as 160 people use the same airplane seat per month on shorter flights - and up to 120 people per month at the movies.
Most seat covers are only replaced every 16-18 months during "C" level maintenance. On a short haul airplanes this means once every 2800+ passengers (varying by airline).
The World Health organization has found that 25% of surfaces around the headrest, tray tables and arm rests of airplane seats test positive for bacteria like E. coli and Staphylococcus.
ABC News reported when bacteria tests were performed on public seats, the worst offenders include movie theaters, airport lounges, airplanes and rental cars.