Why can't my MacBook Air (Late 2010) stay cool?
Obviously the cooling system on any computer needs to be free of dust and fluff for it to work effectively but you've checked that.

The next stage is to remove the radiator and heat-pipe assembly to check on the state of the thermal coupling between the CPU and heat-pipe. Clean off the old thermal paste and replace using a thin, even layer applied to the CPU. Apple have had a few issues over the years with hot-running CPUs caused by excessive thermal paste, so don't put too much on. The idea is simply to fill in imperfections between the CPU die and the heat-pipe that would otherwise be filled by air (air makes a better insulator than a conductor).

A cleaned and re-pasted cooler assembly should bring your temps back down again.