Ah yes, one of the first things you learned in economics: opportunity costs are real and affect our decisions.
Here are links to a few articles illustrating a common (though often flawed) theme: "The economy vs. the environment":
From Freakonomics: Two economists suggest that consideration for the environment wanes during times of high unemployment.
From ABC: A March 2010 Gallup poll shows a similar trade off.
From Reuters: It's not all bad news... people create less pollution during economic downturns.
Thoughts? Can you think of micro-level examples of this (i.e household, individual, firm)?