Not to stop John's string of impressive posts, but a funny thing just happened that shows just how tough it is to collect data for measuring the value of pollution reductions. I have a student in China trying to measure urban household willingness to pay to reduce the health effects of transportation pollution. She is trying to put a survey in the field as I write this. Here's the problem:
Tim, Sorry but I have to ask you to have a look at the files I sent you as soon as possible. Our collaborator is pushing me. Because it's getting hotter now. Not every resident in China has AC at home. At summer, some people just wear shorts or even underwear at home. In this case, it'll be difficult to enter people's homes.
The bench scientists are, in a sense, lucky because they have labs where they can control outside influences on their experiments. Despite the fairly recent emergence of experimental economics as an accepted field of inquiry, economists still face the problem of trying to use messy real world data.
Drats! Foiled by underwear.