A micromort is a 1 in 1million chance of death. As a new way of looking at the world, I reckon this is genius.
Consider. A car gives a reassuring 250 miles per micromort, a bike 20, walking 17 and a motorbike just 6 miles.
Alternatively consider the risk to troops in Afghanistan (33 micromorts per day) versus a spell in hospital (75), although the comparison of a fit young soldier to the average NHS patient is perhaps not a very valid one.
Risk of general anaesthetic: 10 micromorts. Not negligible. Giving birth: 80 micromorts in UK. 50 in Sweden. 170 in US.
Plus has a great piece on micromorts with some rather nice animations.