A breath of fresh air?

Mobile phones could soon be used as “bad breath barometers”. Siemens, the phone company, is working on microchip sensors, about 1mm in size, which will detect the faintest of foul odours. This has more than a social pleasantries practical application – the device will also be able to measure how much alcohol you’re had to drink, the level of oxygen in the air, and whether there is a gas leak or fire nearby. (This could have been useful to a colleague mentioned some time ago who was robbed as he slept in his hotel room after gas was pumped into the room.)