below epa standards. the portable air purifier costs £75 and its noise level is marketed at less than 30 decibels, also known as whisper quiet. so it could double up as white noise to help you sleep. now that this has been taken care of, it's time to look at surfaces, and for that i have the cleansebot. at first glance it's not immediately obvious how this works, but let me show you. it doesn't seem to know exactly where it's mapping, but i'm quite impressed by its ability to not fall off the bed. it has got about 18 sensors, so it makes sense. and interestingly, when it went underneath covers, the uv lights at the top turned on, so it knows exactly when it is in an open space and when it is covered, so it is quite clever.