Intervista della CNN a proposito di Inquinamento LuminosoNATALIE PAWELSKI: Are you talking about having people shut off all their lights at night?

DAVID CRAWFORD: Not at all. What we're saying is use the right amount of lighting for the right job.

PAWELSKI: Give me some examples of what you can do if you want to light things up at night in a way that you believe is appropriate.

CRAWFORD: Never buy a light that looks like it's going to produce glare, for your front door or for your backyard. Shine the light where you need it and when you need it and without glare. So it's got to have a shield on it. If you can see the bulb, it's not a good light. For a streetlight, you want the light on the street -- not through somebody's bedroom window, not up into the sky. Put it where you need it, use the right amount, and shut it off if you don't need it.

PAWELSKI: What's the issue with billboards?

CRAWFORD: The lighting issue is that in many locations -- maybe even most -- the billboard is lit from the bottom for more historic reasons than logic. As a result, the light coming up hits the board and tends to light it, but a lot of it is going directly up and misses the board.

PAWELSKI: So just take down the billboard?

CRAWFORD: No, we would like them to light them from the top so that the light shines down on the billboard. We think that there's no adverse impact on the board, and we're not screaming get rid of the billboards or get rid of the lit billboards. The only issue is how you're lighting it. We're saying please light it so you have minimum adverse impact on the environment.

PAWELSKI: Why does this matter if you are not an astronomer?

CRAWFORD: There's a tremendous adverse effect on sea turtles. When they land on the beaches, the mothers won't land if there's bad light. If they did and the little guys hatch, they get lost and so they get run over by cars, pile up under street lights. Birds get confused migrating by cities that are too bright, buildings which are lit all night, and get confused by towers which have bad lighting. And the birds just circle. Before long they get tired and down they go. A group based in Toronto finds that millions of birds die a year this way.