These calculations have been done already, mostly by businesses or agencies trying to determine if some action is cost-effective. You'll get different answers depending on whose metric you're using, but for starters:

$50,000/year of quality life - insurance companies
$6,900,000 - U.S. Environmental Protection Agency
$7,900,000 - Food and Drug Administration
$6,000,000 - U.S. Department of Transportation