
A team of two companies and a medical college is developing a silent alarm system to let hearing-impaired people know of a fire by an irritating odor of Japanese horseradish....When a fire breaks out, the alarm emits horseradish components outside upon accepting a signal from a commercially available fire detector put into operation. There are many smells to shake up people, including the smell of mint, but they are not immediately effective when people are asleep. The smell of horseradish is easy to notice. The companies have selected horseradish as it is used as a spice for food, familiar to people, quite antibacterial and highly volatile. Besides, its smell is harmless to human bodies and also environmentally friendly. Makoto Imai, a lecturer at the university, carried out a clinical test on 14 people in their 20s to 40s, some of them hearing-impaired, and found that except one person with a blocked nose, all 13 others awoke in 20 seconds to 2 minutes after the smell reached their bedsides...more..
Looks like this story is all over the web right now. Inventorspot has a BBC video report on the alarm here