A lot of mummies asked me questions about the mattress cleaning so here are more details.
The cleaners use this 25kg vacuum to suck out the skin cells and use UV(C) rays (the vacuum has a separate light attachment) to kill the remaining dust mites. According to wikipedia, the Sun emits ultraviolet radiation in the UVA, UVB, and UVC bands, but because of absorption in the atmosphere's ozone layer, 98.7% of the ultraviolet radiation that reaches the Earth's surface is UVA. (Some of the UVB and UVC radiation is responsible for the generation of the ozone layer.) UVC rays are the highest energy, most dangerous type of ultraviolet light. Little attention has been given to UVC rays in the past since they are filtered out by the atmosphere.
The vacuum system can penetrate about 4 inches so they flipped the mattress over to do the other side. After each cleaning, they also spray with this orange essential oil alcohol solution to stop the dust mites from multiplying again.
For those who are interested, please visit http://www.dh-asia.com/about.html. Alamak, should charge commission/referral fees. Hee. ;P